Early maturation of corpus luteum in rabbits - effect of sildenafil citrate on luteolytic capacity in the early luteal period

Background: Prostaglandin F2 alpha (PGF2 α) binds to the specific receptor (PTGFR) on the corpus luteum (CL) in mammals, inducing regression of the CL structure (luteolysis) and initiating a new cycle. While PGF2 α is effective only on mature CL, the immature CL structure (early luteal phase) resists PGF2 α. In this study, sildenafil citrate, which is used to increase blood flow in the genital organs for treating specific pregnancy issues in women, was administered during the early luteal phase in a rabbit model to test the hypothesis of enhancing blood flow to the CL, thereby promoting earlier maturation and enabling a response to PGF2 α. Materials, Methods & Results: The study was conducted in 2 sub-studies: clinical and molecular. A large number of rabbits were initially included in the sub-studies to ensure a sufficient number of pseudo-pregnant rabbits. Ovulation in rabbits was induced with buserelin acetate and was considered as day 0 of the study. The sub-studies were continued with rabbits whose pseudo-pregnancies were confirmed according to progesterone (P4 ) results. As a result, the studies were continued with a total of 41 pseudo-pregnant New Zealand female rabbits, 21 of which were included in the clinical sub-study and 20 in the molecular sub-study. In both sub-studies, on day 3 of the luteal period, rabbits in the treatment group received 5 mg/kg sildenafil citrate and all rabbits received a single dose of exogenous PGF2 α on day 4 to induce luteolysis. In the clinical sub-study, echotexture and intraovarian blood flow changes in the ovaries were determined by ultrasonography (USG) examination. In the molecular sub-study, the expression changes of Hypoxia Inducible Factor 1 Alpha (HIF1A) and Vascular Endothelial Growth Factor (VEGF) related to angiogenesis, Steroidogenic Acute Regulatory Protein (StAR) related to P4 metabolism, Prostaglandin-Endoperoxide Synthase 2 (PTGS2) related to prostaglandin (PG) mechanism and 15-Hydroxyprostaglandin Dehydrogenase (HPGD) genes at mRNA level were determined using Real Time Polymerase Chain Reaction (RT-PCR) in CL tissues obtained with ovariohysterectomy (OVH) at 1 and 12 h after PGF2 α injection. In addition, blood samples were collected for determine P4 levels from all rabbits. In the clinical sub-study; there was no difference between the groups in mean gray values (MGV), whereas there was a significant decrease in both pulsatile index (PI) and resistance index (RI) values at 40 min after PGF2 α injection (P < 0.05). In the molecular sub-study, it was determined that sildenafil citrate had no significant effect (P > 0.05) on the expression levels 1 and 12 h after PGF2 α injection. According to the results of the molecular sub-study, no significant effect of sildenafil citrate on the mRNA expression levels in the investigated genes was detected (P > 0.05). However, within each group, differences were found according to OVH time after PGF2 α injection. It was observed that PTGS2 and HPGD mRNA expressions decreased at the 12th h compared to the 1st h, while HIF1A expression increased (P < 0.05). Discussion: According to the results obtained from clinical and molecular sub-studies, it was determined that a single dose of sildenafil citrate (5 mg/kg) applied on the 3rd day of the luteal period did not contribute to the maturation process of the CL, did not increase blood flow, and was insufficient to break the resistance of the CL against PGF2 α applied on the 4th day of the luteal period. However, a significant decrease in the PI value at the 40th min after PGF2 α injection suggests that sildenafil citrate has a supportive effect, and that this decrease is also seen in the RI value, suggesting that its effect is insufficient against the vasoconstrictive effect of PGF2 α.

Application of PGF2α at the moment of fixed-time artificial insemination in crossbred beef cows

Although studies have shown positive effects of gonadotropin releasing hormone (GnRH) or prostaglandin F2α (PGF2α) at the moment of fixed-time artificial insemination (FTAI) in the conception rate (CR) of cattle, its effects on treatments based on progesterone (P4) and estradiol benzoate (EB) is still not conclusive. The objective of this study was (1) to evaluate the effect of a PGF2α analogue at FTAI in the CR of crossbred beef cows submitted to a 11d FTAI protocol based on P4 and EB; and (2) to describe the CR between PGF2α-treated and control cows in different body condition scores (BCS) and parity categories. Crossbred (½ Nellore and ½ Angus) beef cows were submitted to a synchronization protocol and randomly assigned into 2 groups: Control (n = 163), at FTAI cows received 2 mL of saline solution as a placebo, and PGF2α (n = 163), at FTAI cows were treated with PGF2α analogue (10 mg of dinoprost tromethamine). Pregnancy diagnosis was performed 33d post-FTAI. Binary logistic regression model was used to analyze the effect of PGF2α treatment on CR. There was no difference in CR between PGF2α and control groups (P > 0.05; odds ratio (OR) = 0.92; confidence interval (CI) = 0.59-1.4). A greater CR was found in heifers (P = 0.0006, OR = 2.65, CI = 1.61 - 4.38) and multiparous (P = 0.0006, OR = 2.12, CI = 1.04 - 4.3) when compared to primiparous cows. Cows with low BCS (4; 9-point scale) showed lower CR when compared with moderate BCS (5-6; 9-point scale) (P < 0.05; OR = 0.10; CI = 0.06 - 0.18). There was no numerical difference on CR between PGF2α-treated and control cows in different BCS and parity categories. The results suggested that the CR in this study was not influenced by 10 mg PGF2α analogue at FTAI.(AU)

Use of protein kinase C and phospholipase A2 inhibitors in bovine endometrial cells treated with estradiol and calcium ionophore / Uso de inibidores de proteína quinase C e fosfolipase A2 em células endometriais bovinas tratadas com estradiol e ionóforo de cálcio

The release of endometrial prostaglandin-F2α (PGF2α) in bovine females can be induced in vivo by estradiol (E2). However, its role in this mechanism has not been clarified. We hypothesized that E2 stimulates the activity and abundance of protein kinase C (PKC) and phospholipase A2 (PLA2). Our objective in this study was to analyze the effects of PKC and PLA2 inhibitors on PGF2α synthesis induced by E2 and calcium ionophore (CI) in bovine endometrial cells (BEND cells; Experiment 1). Additionally, we evaluated the abundance of PKC and PLA2 in endometrial explants of cows treated or not with E2 17 days after estrus (D17, D0 = estrus; Experiment 2). In Experiment 1, BEND cells were submitted to a PKC inhibitor (10 µM of C25H24N4O2; bisindolylmaleimide I, or BIS I), a PLA2 inhibitor (20 µM of arachydoniltrifluoromethane or AACOCF3), or none. The BEND cells were subsequently treated with E2 and CI, and PGF2α concentrations were measured in the culture medium through radioimmunoassay. For DIF-12 (PGF2α concentration 12 h after treatment subtracted from PGF2α concentration at hour 0), no PKC inhibitor effect was observed (P= 0.2709). However, DIF-12 was lower (P < 0.05) for groups treated with the PLA2 inhibitor and PLA2 inhibitor + CI + E2 groups than the control and CI + E2 groups. Thus, AACOCF3 was an efficient PLA2 inhibitor in the BEND cells culture system, and E2 did not stimulate the synthesis of PKC and PLA2. In Experiment 2, cyclic Nellore heifers received none (n = 5) or 3 mg (n = 6) of 17ß-E2 on D17 and were slaughtered 2 h after administration. The abundance of PKC and PLA2 in the endometrial tissue was evaluated using Western blotting analysis. No E2 effect was observed on PKC (P = 0.08) and PLA2 (P = 0.56). We concluded that E2 did not stimulate the activity and abundance of PKC and PLA2.(AU)

A liberação endometrial de prostaglandina-F2α (PGF2α) em fêmeas bovinas pode ser induzida in vivo pelo estradiol (E2). Entretanto o seu mecanismo de ação ainda não foi bem esclarecido. Nossa hipótese é que o E2 estimula a atividade e a abundância da proteína quinase C (PKC) e da fosfolipase A2 (PLA2). Nosso objetivo com este estudo foi analizar os efeitos de inibidores de PKC e PLA2 na síntese de PGF2α induzida por E2 e ionóforo de cálcio (CI) em células endometriais bovinas (células BEND; Experimento 1). Adicionalmente, nós avaliamos a abundância de PKC e PLA2 em explantes endometriais de vacas tratadas com ou sem E2 17 dias após o estro (D17, D0 = estro; Experimento 2). No Experimento 1, células BEND foram submetidas ao inibidor de PKC (10 µM de C25H24N4O2; bisindolylmaleimide I, ou BIS I), e ao inibidor de PLA2 (20 µM de arachydoniltrifluoromethane ou AACOCF3) ou a nenhum inibidor. As células BEND foram subsequentemente tratadas com E2 e CI e concentrações de PGF2α foram mensuradas no meio de cultura por radioimunoenssaio. Para DIF-12 (concentração de PGF2α 12 horas depois do tratamento, subtraída da concentração de PGF2α na hora 0), não foi observado efeito do inibidor de PKC (P = 0.2709). Entretanto DIF-12 foi menor (P < 0.05) nos grupos tratados com inibidor de PLA2 e inibidor de PLA2 + CI + E2 quando comparados com o grupo controle e o grupo CI + E2. O AACOCF3 foi um eficiente inibidor de PLA2 em sistema de cultura de células BEND e o E2 não estimulou a síntese de PKC e PLA2. No Experimento 2, novilhas Nelore cíclicas receberam 3 mg de 17ß-E2 (n = 6) ou nenhum tratamento (n = 5) no D17 e foram abatidas duas horas depois da administração dos tratamentos. A quantidade de PKC and PLA2 no tecido endometrial foi avaliada pela técnica de Western Blotting. Não foi observado efeito do E2 sobre a PKC (P= 0.08) e nem sobre a PLA2 (P= 0.56). Conclui-se que o E2 não estimulou a atividade e abundância de PKC e PLA2.(AU)

Use of protein kinase C and phospholipase A2 inhibitors in bovine endometrial cells treated with estradiol and calcium ionophore / Uso de inibidores de proteína quinase C e fosfolipase A2 em células endometriais bovinas tratadas com estradiol e ionóforo de cálcio

The release of endometrial prostaglandin-F2α (PGF2α) in bovine females can be induced in vivo by estradiol (E2). However, its role in this mechanism has not been clarified. We hypothesized that E2 stimulates the activity and abundance of protein kinase C (PKC) and phospholipase A2 (PLA2). Our objective in this study was to analyze the effects of PKC and PLA2 inhibitors on PGF2α synthesis induced by E2 and calcium ionophore (CI) in bovine endometrial cells (BEND cells; Experiment 1). Additionally, we evaluated the abundance of PKC and PLA2 in endometrial explants of cows treated or not with E2 17 days after estrus (D17, D0 = estrus; Experiment 2). In Experiment 1, BEND cells were submitted to a PKC inhibitor (10 µM of C25H24N4O2; bisindolylmaleimide I, or BIS I), a PLA2 inhibitor (20 µM of arachydoniltrifluoromethane or AACOCF3), or none. The BEND cells were subsequently treated with E2 and CI, and PGF2α concentrations were measured in the culture medium through radioimmunoassay. For DIF-12 (PGF2α concentration 12 h after treatment subtracted from PGF2α concentration at hour 0), no PKC inhibitor effect was observed (P= 0.2709). However, DIF-12 was lower (P < 0.05) for groups treated with the PLA2 inhibitor and PLA2 inhibitor + CI + E2 groups than the control and CI + E2 groups. Thus, AACOCF3 was an efficient PLA2 inhibitor in the BEND cells culture system, and E2 did not stimulate the synthesis of PKC and PLA2. In Experiment 2, cyclic Nellore heifers received none (n = 5) or 3 mg (n = 6) of 17ß-E2 on D17 and were slaughtered 2 h after administration. The abundance of PKC and PLA2 in the endometrial tissue was evaluated using Western blotting analysis. No E2 effect was observed on PKC (P = 0.08) and PLA2 (P = 0.56). We concluded that E2 did not stimulate the activity and abundance of PKC and PLA2.(AU)

A liberação endometrial de prostaglandina-F2α (PGF2α) em fêmeas bovinas pode ser induzida in vivo pelo estradiol (E2). Entretanto o seu mecanismo de ação ainda não foi bem esclarecido. Nossa hipótese é que o E2 estimula a atividade e a abundância da proteína quinase C (PKC) e da fosfolipase A2 (PLA2). Nosso objetivo com este estudo foi analizar os efeitos de inibidores de PKC e PLA2 na síntese de PGF2α induzida por E2 e ionóforo de cálcio (CI) em células endometriais bovinas (células BEND; Experimento 1). Adicionalmente, nós avaliamos a abundância de PKC e PLA2 em explantes endometriais de vacas tratadas com ou sem E2 17 dias após o estro (D17, D0 = estro; Experimento 2). No Experimento 1, células BEND foram submetidas ao inibidor de PKC (10 µM de C25H24N4O2; bisindolylmaleimide I, ou BIS I), e ao inibidor de PLA2 (20 µM de arachydoniltrifluoromethane ou AACOCF3) ou a nenhum inibidor. As células BEND foram subsequentemente tratadas com E2 e CI e concentrações de PGF2α foram mensuradas no meio de cultura por radioimunoenssaio. Para DIF-12 (concentração de PGF2α 12 horas depois do tratamento, subtraída da concentração de PGF2α na hora 0), não foi observado efeito do inibidor de PKC (P = 0.2709). Entretanto DIF-12 foi menor (P < 0.05) nos grupos tratados com inibidor de PLA2 e inibidor de PLA2 + CI + E2 quando comparados com o grupo controle e o grupo CI + E2. O AACOCF3 foi um eficiente inibidor de PLA2 em sistema de cultura de células BEND e o E2 não estimulou a síntese de PKC e PLA2. No Experimento 2, novilhas Nelore cíclicas receberam 3 mg de 17ß-E2 (n = 6) ou nenhum tratamento (n = 5) no D17 e foram abatidas duas horas depois da administração dos tratamentos. A quantidade de PKC and PLA2 no tecido endometrial foi avaliada pela técnica de Western Blotting. Não foi observado efeito do E2 sobre a PKC (P= 0.08) e nem sobre a PLA2 (P= 0.56). Conclui-se que o E2 não estimulou a atividade e abundância de PKC e PLA2.(AU)

Effect of additional PGF2α dose on pregnancy rate in Nellore females subjected to FTAI / Efeito de dose adicional de PGF2α sobre a taxa de gestação de fêmeas bovinas Nelore submetidas a IATF

This study examined the effect of administering an additional dose of prostaglandin F2 alpha (PGF2α), in a fixed-time artificial insemination protocol (FTAI), on the fertility of female Nellore cattle. Two experiments were carried out: the first (Experiment I) took place in the state of Tocantins and the second (Experiment II) in the state of Pará, Brazil. In Experiment I (E1), 80 cows were used in three treatments (T1, T2 and T3) in which all received the same FTAI protocol. In T1 (n = 29), the cows received 12.5 mg of Dinoprost on day 9; in T2 (n = 28), they received the additional dose on day 10; and in T3 (n = 23; control group), the animals did not receive the additional PGF2α dose. Experiment II consisted of 147 bovine females distributed into two treatment groups, namely, T1 - 72 animals receiving the same protocol as T1 of E1; and T2 - 75 animals receiving the same protocol as T3 of E1. Statistical analysis was performed using SAS software, applying the PROC NPARWAY procedure for E1, and means were compared by the Wilcoxon test at the 5% significance level. In Experiment II, the data were subjected to analysis of variance by PROC GLIMMIX and means were compared by the T test at the 5% significance level. The following pregnancy rates were obtained in Experiment I: T1 - 62.06% (18/29); T2 - 57.14% (16/28); and T3 - 52.17% (12/23), with no significant difference observed between treatments. In Experiment II, pregnancy rate in T1 was 66.67% (48/72), whereas in T2 it was 41.33% (31/75), with a significant difference detected (P < 0.05). An additional dose of PGF2α provides an increase in pregnancy rate in Nellore females.

Objetivou-se avaliar o efeito da administração de uma dose adicional de prostaglandina F2 alfa (PGF2α) em protocolo de inseminação artificial em tempo fixo (IATF) sobre a fertilidade de fêmeas bovinas da raça Nelore. Foram realizados dois experimentos, sendo um (E1) no estado do Tocantins e o segundo (E2) no estado do Pará. No experimento 1 (E1) foram utilizadas 80 fêmeas bovinas distribuídas em três tratamentos (T1, T2 e T3), todos animais receberam o mesmo protocolo de IATF, diferindo no T1 (n=29), que recebeu 12,5 mg de Dinoprost no dia 9, T2 (n=28) recebeu a dose adicional no dia 10 e o T3 (n=23) - Grupo controle, que não recebeu a dose adicional de PGF2α. O experimento 2 (E2) constituído por 147 fêmeas bovinas distribuídas em dois tratamentos. T1: com 72 animais, recebendo mesmo protocolo do T1 do E1. T2: constituído por 75 animais, com protocolo idêntico ao T3 do E1. A análise estatistica foi realizada no programa SAS, sendo no E1 utilizando-se o PROC NPARWAY e as médias comparadas pelo teste de Wilcoxon com nível de significância de 5%. No E2 os dados foram submetidos à análise de variância pelo PROC GLIMMIX e as médias comparadas pelo teste T com nível de significância de 5%. No experimento 1 a taxa de prenhez no T1 foi de 62,06% (18/29), T2 de 57,14% (16/28) e T3 de 52,17% (12/23), não sendo observada diferença significativa entre os tratamentos. No experimento 2 a taxa de prenhez do T1 foi de 66,67% (48/72), enquanto T2 foi de 41,33% (31/75), verificando-se diferença significativa (P < 0,05). A dose adicional de PGF2α promoveu incremento na taxa de prenhez de fêmeas Nelore.

Effect of additional PGF2α dose on pregnancy rate in Nellore females subjected to FTAI / Efeito de dose adicional de PGF2α sobre a taxa de gestação de fêmeas bovinas Nelore submetidas a IATF

This study examined the effect of administering an additional dose of prostaglandin F2 alpha (PGF2α), in a fixed-time artificial insemination protocol (FTAI), on the fertility of female Nellore cattle. Two experiments were carried out: the first (Experiment I) took place in the state of Tocantins and the second (Experiment II) in the state of Pará, Brazil. In Experiment I (E1), 80 cows were used in three treatments (T1, T2 and T3) in which all received the same FTAI protocol. In T1 (n = 29), the cows received 12.5 mg of Dinoprost on day 9; in T2 (n = 28), they received the additional dose on day 10; and in T3 (n = 23; control group), the animals did not receive the additional PGF2α dose. Experiment II consisted of 147 bovine females distributed into two treatment groups, namely, T1 - 72 animals receiving the same protocol as T1 of E1; and T2 - 75 animals receiving the same protocol as T3 of E1. Statistical analysis was performed using SAS software, applying the PROC NPARWAY procedure for E1, and means were compared by the Wilcoxon test at the 5% significance level. In Experiment II, the data were subjected to analysis of variance by PROC GLIMMIX and means were compared by the T test at the 5% significance level. The following pregnancy rates were obtained in Experiment I: T1 - 62.06% (18/29); T2 - 57.14% (16/28); and T3 - 52.17% (12/23), with no significant difference observed between treatments. In Experiment II, pregnancy rate in T1 was 66.67% (48/72), whereas in T2 it was 41.33% (31/75), with a significant difference detected (P < 0.05). An additional dose of PGF2α provides an increase in pregnancy rate in Nellore females.(AU)

Objetivou-se avaliar o efeito da administração de uma dose adicional de prostaglandina F2 alfa (PGF2α) em protocolo de inseminação artificial em tempo fixo (IATF) sobre a fertilidade de fêmeas bovinas da raça Nelore. Foram realizados dois experimentos, sendo um (E1) no estado do Tocantins e o segundo (E2) no estado do Pará. No experimento 1 (E1) foram utilizadas 80 fêmeas bovinas distribuídas em três tratamentos (T1, T2 e T3), todos animais receberam o mesmo protocolo de IATF, diferindo no T1 (n=29), que recebeu 12,5 mg de Dinoprost no dia 9, T2 (n=28) recebeu a dose adicional no dia 10 e o T3 (n=23) - Grupo controle, que não recebeu a dose adicional de PGF2α. O experimento 2 (E2) constituído por 147 fêmeas bovinas distribuídas em dois tratamentos. T1: com 72 animais, recebendo mesmo protocolo do T1 do E1. T2: constituído por 75 animais, com protocolo idêntico ao T3 do E1. A análise estatistica foi realizada no programa SAS, sendo no E1 utilizando-se o PROC NPARWAY e as médias comparadas pelo teste de Wilcoxon com nível de significância de 5%. No E2 os dados foram submetidos à análise de variância pelo PROC GLIMMIX e as médias comparadas pelo teste T com nível de significância de 5%. No experimento 1 a taxa de prenhez no T1 foi de 62,06% (18/29), T2 de 57,14% (16/28) e T3 de 52,17% (12/23), não sendo observada diferença significativa entre os tratamentos. No experimento 2 a taxa de prenhez do T1 foi de 66,67% (48/72), enquanto T2 foi de 41,33% (31/75), verificando-se diferença significativa (P < 0,05). A dose adicional de PGF2α promoveu incremento na taxa de prenhez de fêmeas Nelore.(AU)

The effects of separate and combined use of PGF2α and GnRH hormones and the addition of beta-carotene on fertility parameters in dairy cows with ovarian cysts

Background: Ovarian cysts are commonly observed pathologies, which interfere with normal cyclic activity and adversely affect fertility in cows. Beta-carotene is effective in the reduction of reproductive problems by inducing the natural defence mechanisms of the body. There are several methods that can be used for the treatment of ovarian cysts. The separate and combined use of GnRH and PGF2α commonly uses in the treatment of ovarian cysts. Therefore, in the presented study the effects of Beta-carotene (βC) addition for the treatment of ovarian cysts either with GnRH solely or GnRH and PGF2α in combination on the fertility parameters of dairy cows were investigated.Materials, Methods & Results: Seventy-six Holstein Friesian cows having ovarian cysts diagnosed by ultrasonography (USG) were divided into three groups. Cows in Group I (GI, n = 27), were injected with GnRH (Buserelin acetate, 5 mL, im), PGF2α (Tiaprost-trometamol, 5 mL, im) and βC (20 mL/cow, into 4 regions by im route). In Group II (GII, n = 25) GnRH (Buserelin acetate, 5 mL, im) and PGF2α (Tiaprost-trometamol, 5mL, im) were administrated while GnRH (Buserelin acetate, 5 mL, im) solely in Group III (GIII, n = 24). Cysts were monitored via USG, and blood samples were collected on the on day of treatment (day 0) and on the 7th and 14th days following the administrations. Cows shoving oestrous were inseminated and pregnancy diagnoses were performed on the 40th day following insemination. Treatment results showed that there were statistically no significant differences between GI and GII (P > 0.05). Only numerical difference obtained in time from therapy to pregnancy and overall pregnancy index (P > 0.05). Overall pregnancy rate (85 %), first service pregnancy rates (40 %) and overall pregnancy index (2.11) in GI were found significantly higher than GIII (53.3 %; 20 %; 4.12) [P 0.05).[...]

The effects of separate and combined use of PGF2α and GnRH hormones and the addition of beta-carotene on fertility parameters in dairy cows with ovarian cysts

Background: Ovarian cysts are commonly observed pathologies, which interfere with normal cyclic activity and adversely affect fertility in cows. Beta-carotene is effective in the reduction of reproductive problems by inducing the natural defence mechanisms of the body. There are several methods that can be used for the treatment of ovarian cysts. The separate and combined use of GnRH and PGF2α commonly uses in the treatment of ovarian cysts. Therefore, in the presented study the effects of Beta-carotene (βC) addition for the treatment of ovarian cysts either with GnRH solely or GnRH and PGF2α in combination on the fertility parameters of dairy cows were investigated.Materials, Methods & Results: Seventy-six Holstein Friesian cows having ovarian cysts diagnosed by ultrasonography (USG) were divided into three groups. Cows in Group I (GI, n = 27), were injected with GnRH (Buserelin acetate, 5 mL, im), PGF2α (Tiaprost-trometamol, 5 mL, im) and βC (20 mL/cow, into 4 regions by im route). In Group II (GII, n = 25) GnRH (Buserelin acetate, 5 mL, im) and PGF2α (Tiaprost-trometamol, 5mL, im) were administrated while GnRH (Buserelin acetate, 5 mL, im) solely in Group III (GIII, n = 24). Cysts were monitored via USG, and blood samples were collected on the on day of treatment (day 0) and on the 7th and 14th days following the administrations. Cows shoving oestrous were inseminated and pregnancy diagnoses were performed on the 40th day following insemination. Treatment results showed that there were statistically no significant differences between GI and GII (P > 0.05). Only numerical difference obtained in time from therapy to pregnancy and overall pregnancy index (P > 0.05). Overall pregnancy rate (85 %), first service pregnancy rates (40 %) and overall pregnancy index (2.11) in GI were found significantly higher than GIII (53.3 %; 20 %; 4.12) [P < 0.05]. No significant difference was observed in progesterone (P4) levels between the groups (P > 0.05).[...](AU)

Endometrial prostaglandin F2α in vitro production and its modulation regarding dominant follicle position in cattle / Produção in vitro de PGF F2α endometrial e sua modulação referente ao folículo dominante em bovinos

Prostaglandin F2α (PGF2α) determines luteolysis in cattle, and the ability to manipulate its endogenous synthesis is indispensible for large-scale animal breeding. Estradiol (E2) and progesterone (P4) modulate several molecular pathways in endometrial cells, including the synthesis of PGF2α; however, its specific mechanisms are still not totally known. This study investigated the production in vitro and possible modulation of endometrial PGF2α due to a local effect of endogenous E2 in the ipsilateral uterine horn (UH) containing the dominant follicle (DF) or from P4 in ipsilateral horn containing the corpus luteum (CL). The PGF2α stimulators oxytocin (OT) and phorbol 12,13-dibutyrate (PDBu) were incubated with endometrial explants, and PGF2α content was measured. For that, cycling cows were synchronized, the development of DF and CL was examined by ultrasonography and on the seventh day of the estrous cycle, endometrial explants were collected and cultured in medium supplemented with 10-6 M PDBu or 10-6 M OT or non-supplemented. Media samples were collected immediately after treatment and 60 min later. Radioimmunoassay showed that the PGF2α content of the UH ipsilateral to the DF was 49% less than that of the contralateral UH (8.22 ± 0.95 vs. 12.24 ± 0.95 pg/mL/mg tissue, respectively; P < 0.01). However, the PGF2α levels did not differ between the UHs as a function of the CL position (9.46 ± 0.95 vs. 11 ± 0.95 pg/mL/mg; P > 0.05). The cellular stimulators promoted an increase in PGF2α synthesis (P < 0.02), and the effects differed among the animals (P < 0.04). The PGF2a production was higher in the explants treated with PDBu rather than OT (13.68 ± 1.16 vs. 10.01 ± 1.16 pg/mL/mg tissue, respectively; P < 0.05). In conclusion, PGF2α synthesis is modulated by the presence of the DF (local E2) but not the CL (local P4), and both PDBu and OT stimulated PGF2a synthesis.(AU)

A prostaglandina F2α (PGF2α) determina a luteólise em bovinos. A capacidade de manipular sua síntese endógena é indispensável para a produção animal em grande escala. O estradiol (E2) e a progesterona (P4) modulam diversas vias moleculares das células endometriais, incluindo a síntese de PGF2α; no entanto, pouco se sabe sobre seus mecanismos específicos. Este trabalho investigou a produção in vitro e a possível modulação da PGF2α endometrial devido a um efeito local do E2 endógeno no corno uterino ipsilateral ao folículo dominante (FD) ou da P4 no corno ipsilateral ao corpo lúteo (CL). Os estimuladores de PGF2α oxitocina (OT) e 12,23-dibutirato de forbol (PDBu) foram incubados com explantes endometriais, e o conteúdo de PGF2α foi mensurado. Para tal, vacas cíclicas foram sincronizadas, o desenvolvimento de FD e CL foi examinado por ultrassonografia, e no 17º dia do ciclo estral os explantes endometriais foram coletados e cultivados em meio ou suplementados com PDBu 10-6M ou 10-6M OT. As amostras de meio foram coletadas imediatamente após o tratamento e sessenta minutos depois. O radioimunoensaio mostrou que o conteúdo de PGF2α do corno ipsilateral ao FD foi 49% menor que o do corno contralateral (8,22 ± 0,95 vs. 12,24 ± 0,95 pg/mL/mg de tecido, respectivamente, P < 0,01). No entanto, os níveis de PGF2α não diferiram entre os cornos em função da posição do CL (9,46 ± 0,95 versus 11 ± 0,95 pg/mL/mg; P > 0,05). Os estimuladores celulares promoveram um aumento na síntese de PGF2α (P < 0,02), e os efeitos diferiram entre os animais (P < 0,04). A produção de PGF2α foi maior nos explantes tratados com PDBu em comparação à OT (13,68 ± 1,16 versus 10,01 ± 1,16 pg/mL/mg de tecido, respectivamente, P < 0,05). A conclusão obtida foi que a síntese de PGF2α é: modulada pela presença do FD (E2 local), mas não do CL (P4 local); e estimulada por PDBu e OT.(AU)

Endometrial prostaglandin F2α in vitro production and its modulation regarding dominant follicle position in cattle / Produção in vitro de PGF F2α endometrial e sua modulação referente ao folículo dominante em bovinos

Prostaglandin F2α (PGF2α) determines luteolysis in cattle, and the ability to manipulate its endogenous synthesis is indispensible for large-scale animal breeding. Estradiol (E2) and progesterone (P4) modulate several molecular pathways in endometrial cells, including the synthesis of PGF2α; however, its specific mechanisms are still not totally known. This study investigated the production in vitro and possible modulation of endometrial PGF2α due to a local effect of endogenous E2 in the ipsilateral uterine horn (UH) containing the dominant follicle (DF) or from P4 in ipsilateral horn containing the corpus luteum (CL). The PGF2α stimulators oxytocin (OT) and phorbol 12,13-dibutyrate (PDBu) were incubated with endometrial explants, and PGF2α content was measured. For that, cycling cows were synchronized, the development of DF and CL was examined by ultrasonography and on the seventh day of the estrous cycle, endometrial explants were collected and cultured in medium supplemented with 10-6 M PDBu or 10-6 M OT or non-supplemented. Media samples were collected immediately after treatment and 60 min later. Radioimmunoassay showed that the PGF2α content of the UH ipsilateral to the DF was 49% less than that of the contralateral UH (8.22 ± 0.95 vs. 12.24 ± 0.95 pg/mL/mg tissue, respectively; P < 0.01). However, the PGF2α levels did not differ between the UHs as a function of the CL position (9.46 ± 0.95 vs. 11 ± 0.95 pg/mL/mg; P > 0.05). The cellular stimulators promoted an increase in PGF2α synthesis (P < 0.02), and the effects differed among the animals (P < 0.04). The PGF2a production was higher in the explants treated with PDBu rather than OT (13.68 ± 1.16 vs. 10.01 ± 1.16 pg/mL/mg tissue, respectively; P < 0.05). In conclusion, PGF2α synthesis is modulated by the presence of the DF (local E2) but not the CL (local P4), and both PDBu and OT stimulated PGF2a synthesis.(AU)

A prostaglandina F2α (PGF2α) determina a luteólise em bovinos. A capacidade de manipular sua síntese endógena é indispensável para a produção animal em grande escala. O estradiol (E2) e a progesterona (P4) modulam diversas vias moleculares das células endometriais, incluindo a síntese de PGF2α; no entanto, pouco se sabe sobre seus mecanismos específicos. Este trabalho investigou a produção in vitro e a possível modulação da PGF2α endometrial devido a um efeito local do E2 endógeno no corno uterino ipsilateral ao folículo dominante (FD) ou da P4 no corno ipsilateral ao corpo lúteo (CL). Os estimuladores de PGF2α oxitocina (OT) e 12,23-dibutirato de forbol (PDBu) foram incubados com explantes endometriais, e o conteúdo de PGF2α foi mensurado. Para tal, vacas cíclicas foram sincronizadas, o desenvolvimento de FD e CL foi examinado por ultrassonografia, e no 17º dia do ciclo estral os explantes endometriais foram coletados e cultivados em meio ou suplementados com PDBu 10-6M ou 10-6M OT. As amostras de meio foram coletadas imediatamente após o tratamento e sessenta minutos depois. O radioimunoensaio mostrou que o conteúdo de PGF2α do corno ipsilateral ao FD foi 49% menor que o do corno contralateral (8,22 ± 0,95 vs. 12,24 ± 0,95 pg/mL/mg de tecido, respectivamente, P < 0,01). No entanto, os níveis de PGF2α não diferiram entre os cornos em função da posição do CL (9,46 ± 0,95 versus 11 ± 0,95 pg/mL/mg; P > 0,05). Os estimuladores celulares promoveram um aumento na síntese de PGF2α (P < 0,02), e os efeitos diferiram entre os animais (P < 0,04). A produção de PGF2α foi maior nos explantes tratados com PDBu em comparação à OT (13,68 ± 1,16 versus 10,01 ± 1,16 pg/mL/mg de tecido, respectivamente, P < 0,05). A conclusão obtida foi que a síntese de PGF2α é: modulada pela presença do FD (E2 local), mas não do CL (P4 local); e estimulada por PDBu e OT.(AU)

Utilização de Cipionato de Estradiol em única aplicação associado à indução da luteólise com prostaglandina F2 para sincronização do estro de matrizes suínas nulíparas

O presente estudo objetivou avaliar a efetividade do protocolo de sincronização do estro de fêmeas suínas nulíparas por meio da indução de pseudogestação utilizando Cipionato de Estradiol em única aplicação seguido pelo uso de PF2 (Cloprostenol Sódico). Para tanto, no dia 12 do ciclo estral (D0 = primeiro dia do estro) 52 fêmeas suínas nulíparas foram distribuídas ao acaso em dois grupos experimentais: CON (n = 22) controle sem aplicação, PSG (n = 30) 10 mL Cipionato de Estradiol por via intramuscular. Foram coletadas amostras de sangue por punção jugular para determinação das concentrações hormonais de progesterona e estradiol, tendo início no dia 12 (antes da aplicação do Cipionato de Estradiol) e a cada 72 horas. A detecção de estro teve início no dia 17. As fêmeas do grupo CON foram inseminadas No dia 28 (D0 = primeiro dia em estro) as fêmeas pseudogestantes foram tratadas com duas doses (8:00 AM e 14:00 PM) de 0,263 mg de cloprostenol sódico por via intramuscular, para indução da luteólise. Para avaliação dos efeitos do protocolo sobre a fertilidade, um subgrupo de 25 fêmeas foram inseminadas e abatidas 5 dias após última inseminação. O tratamento com Cipionato de Estradiol induziu pseudogestação em 90% (27/30) das fêmeas tratadas. A duração do ciclo estral foi maior (p <0.0001) para as fêmeas do grupo PSG em comparação as fêmeas do grupo CON. As fêmeas do grupo PSG demonstraram estro sincronizado 4,04 ± 0,8 após a indução da luteólise. A duração do estro não diferiu (p = 0.16) entre as fêmeas dos grupos experimentais. A taxa de concepção foi similar (p = 0.10) para as fêmeas do grupo CON e PSG. O número de ovulações foi similar entre as fêmeas do grupo CON e PSG (p = 0.17). Nenhuma diferença foi observada na taxa de recuperação de embriões (p = 0.18) e número total de embriões por fêmea (p = 0.06). Para a análise do desenvolvimento embrionário, a percentagem de oócitos não fertilizados, de embriões fragmentados e de embriões viáveis foi similar estre as fêmeas do grupo CON e PSG (p > 0.05). O tratamento de fêmeas suínas nulíparas com uma única aplicação de10 mg de Cipionato de Estradiol no dia 12 do ciclo estral foi efetivo em induzir pseudogestação e a indução da luteólise com PGF2 resultou na sincronização do estro; além disso, o protocolo de sincronização do estro não exerceu efeito deletério sobre a fertilidade e o desenvolvimento embrionário.

The present work was designed to evaluate the effectiveness of using estrogen-induced pseudopregnancy followed by PGF2 (cloprostenol sodium) to synchronize estrus in gilts. Thus, on day 12 of the estrus cycle (D 0 = first day of standing estrous), 52 gilts were assigned at random to two experimental groups: non-treated females (CON, n = 22 ), serving as controls and (PSG, n = 30), a single treatment with 10 mg of estradiol cypionate intramuscularly. Blood samples were collected by jugular venepuncture for estradiol and progesterone determination, starting on day 12 and repeated every 72 hours. Estrus detection started on day 17 and were performed twice daily by direct contact with a mature boar. Gilts from the CON group were inseminated at onset of natural estrous. On d 28 pseudopregnant gilts were treated twice (i.e., 0800 AM and 1400 PM) with 0,263 mg of sodium cloprostenol i.m to induce luteolysis. To assess the effects of the protocol on fertility, a subgroup of 25 females were inseminated and slaughtered 5 days after the last insemination. Treatment with Estradiol Cypionate induced pseudopregnancy in 90% (27/30) of treated females. The duration of the estrous cycle was longer (p <0.0001) for females in the PSG group compared to females in the CON group. Females in the PSG group showed synchronized estrus 4.04 ± 0.8 after induction of luteolysis. The duration of estrus did not differ (p = 0.16) between females in the experimental groups. The conception rate was similar (p = 0.10) for females from CON and PSG groups. The number of ovulations was similar between females in the CON and PSG groups (p = 0.17). No difference was observed in embryo recovery rate (p = 0.18) and total number of embryos per female (p = 0.06). For the analysis of embryonic development, the percentage of unfertilized oocytes, fragmented embryos and viable embryos was similar among females from CON and PSG groups (p > 0.05). Treatment of gilts with a single application of 10 mg of Estradiol Cypionate on day 12 of the estrous cycle was effective in inducing pseudopregnancy and treatment with PGF2 resulted in synchronized estrus; in addition, the estrus synchronization protocol exerted no deleterious effect on fertility and embryonic development.

Effects of different regimens of PGF2α treatment during postpartum on reproductive performance in dairy cows / Efeito de diferentes regimes de tratamento pós-parto com PGF2α sobre o desempenho reprodutivo de vacas leiteiras

The aim of this study was to evaluate the effects of early postpartum PGF2α treatment on reproductive performance in dairy cows synchronized with targeted breeding and natural mating after voluntary waiting period. In this experiment ,120 cows were assigned to three groups irrespective of presence or absence of luteal tissue. Cows in PG- 14 group were treated with PGF2α from day 14 postpartum, cows in PG-28 group were treated with PGF2α from day 28 postpartum and cows in PG-42 group were not treated with PGF2α until the end of voluntary waiting period (d 42). After day 42 postpartum, cows in three groups were treated with PGF2α within 14-day intervals until natural mating after voluntary waiting period. Recorded reproductive parameters included days to first heat, days to first mating, days open, service per conception, conception rate, percentage of repeat breeder animals and pregnancy loss. Early PGF2α treatment from day 14 postpartum significantly decreased days to first estrus (34.9 ± 0.74, P < 0.003), days to first mating (62.35 ± 1.53, P < 0.04), days open (117.23 ± 3.1, P < 0.001) and service per conception (1.9 ± 0.09, P < 0.02); and PG-14 group presented increased conception rate (52.5%, P < 0.05). The proportion of repeat breeder syndrome tended to be affected by treatment with PGF2α from day 14 postpartum. In conclusion, treatment of cows with PGF2α from day 14 postpartum improved reproductive performance.(AU)

O objetivo do presente trabalho foi avaliar os efeitos do tratamento pós-parto precoce com PGF2α sobre o desempenho reprodutivo de vacas leiteiras sincronizadas para reprodução controlada por monta natural após o período de espera voluntário. Neste experimento, 120 vacas foram distribuídas em três grupos independentes da presença ou ausência de corpo lúteo. Vacas no grupo PG-14 foram tratadas com PGF2α a partir do 14o dia pósparto, vacas do grupo PG-28 foram tratadas com PGF2α a partir do 28o dia pós-parto e as vacas do grupo PG-42 não foram tratadas com PGF2α até o final do período de espera voluntário (d42). Após o 42o dia pós-parto as vacas dos três grupos foram tratadas com PGF2α com intervalos de 14 dias até a monta natural após o período de espera voluntário. Os registros dos parâmetros reprodutivos incluíram: dias para o primeiro estro, dias para a primeira cobertura, dias em aberto, serviços por concepção, taxa de concepção, percentagem de animais repetidores de cios e as perdas de gestações. O tratamento precoce com PGF2α, a partir do 14o dia pós-parto reduziu significativamente os dias para o primeiro estro (34,9 ± 0,74, P < 0,003), dias para a primeira cobertura (62,35 ± 1,53, P < 0,04), dias em aberto (117,23 ± 3,1, P< 0,02); e o grupo PG-14 apresentou um acréscimo na taxa de concepção (52,5%, P < 0,05). A proporção da síndrome de vacas repetidoras de cios tendeu a ser afetada pelo tratamento com PGF2α a partir do 14o dia pós-parto. A conclusão obtida foi que o tratamento das vacas com PGF2α a partir do 14o dia pós-parto melhorou o desempenho reprodutivo dos animais.(AU)

Effects of different regimens of PGF2α treatment during postpartum on reproductive performance in dairy cows / Efeito de diferentes regimes de tratamento pós-parto com PGF2α sobre o desempenho reprodutivo de vacas leiteiras

The aim of this study was to evaluate the effects of early postpartum PGF2α treatment on reproductive performance in dairy cows synchronized with targeted breeding and natural mating after voluntary waiting period. In this experiment ,120 cows were assigned to three groups irrespective of presence or absence of luteal tissue. Cows in PG- 14 group were treated with PGF2α from day 14 postpartum, cows in PG-28 group were treated with PGF2α from day 28 postpartum and cows in PG-42 group were not treated with PGF2α until the end of voluntary waiting period (d 42). After day 42 postpartum, cows in three groups were treated with PGF2α within 14-day intervals until natural mating after voluntary waiting period. Recorded reproductive parameters included days to first heat, days to first mating, days open, service per conception, conception rate, percentage of repeat breeder animals and pregnancy loss. Early PGF2α treatment from day 14 postpartum significantly decreased days to first estrus (34.9 ± 0.74, P < 0.003), days to first mating (62.35 ± 1.53, P < 0.04), days open (117.23 ± 3.1, P < 0.001) and service per conception (1.9 ± 0.09, P < 0.02); and PG-14 group presented increased conception rate (52.5%, P < 0.05). The proportion of repeat breeder syndrome tended to be affected by treatment with PGF2α from day 14 postpartum. In conclusion, treatment of cows with PGF2α from day 14 postpartum improved reproductive performance.(AU)

O objetivo do presente trabalho foi avaliar os efeitos do tratamento pós-parto precoce com PGF2α sobre o desempenho reprodutivo de vacas leiteiras sincronizadas para reprodução controlada por monta natural após o período de espera voluntário. Neste experimento, 120 vacas foram distribuídas em três grupos independentes da presença ou ausência de corpo lúteo. Vacas no grupo PG-14 foram tratadas com PGF2α a partir do 14o dia pósparto, vacas do grupo PG-28 foram tratadas com PGF2α a partir do 28o dia pós-parto e as vacas do grupo PG-42 não foram tratadas com PGF2α até o final do período de espera voluntário (d42). Após o 42o dia pós-parto as vacas dos três grupos foram tratadas com PGF2α com intervalos de 14 dias até a monta natural após o período de espera voluntário. Os registros dos parâmetros reprodutivos incluíram: dias para o primeiro estro, dias para a primeira cobertura, dias em aberto, serviços por concepção, taxa de concepção, percentagem de animais repetidores de cios e as perdas de gestações. O tratamento precoce com PGF2α, a partir do 14o dia pós-parto reduziu significativamente os dias para o primeiro estro (34,9 ± 0,74, P < 0,003), dias para a primeira cobertura (62,35 ± 1,53, P < 0,04), dias em aberto (117,23 ± 3,1, P< 0,02); e o grupo PG-14 apresentou um acréscimo na taxa de concepção (52,5%, P < 0,05). A proporção da síndrome de vacas repetidoras de cios tendeu a ser afetada pelo tratamento com PGF2α a partir do 14o dia pós-parto. A conclusão obtida foi que o tratamento das vacas com PGF2α a partir do 14o dia pós-parto melhorou o desempenho reprodutivo dos animais.(AU)

Effects of different regimens of PGF2α treatment during postpartum on reproductive performance in dairy cows / Efeito de diferentes regimes de tratamento pós-parto com PGF2α sobre o desempenho reprodutivo de vacas leiteiras

The aim of this study was to evaluate the effects of early postpartum PGF2α treatment on reproductive performance in dairy cows synchronized with targeted breeding and natural mating after voluntary waiting period. In this experiment ,120 cows were assigned to three groups irrespective of presence or absence of luteal tissue. Cows in PG- 14 group were treated with PGF2α from day 14 postpartum, cows in PG-28 group were treated with PGF2α from day 28 postpartum and cows in PG-42 group were not treated with PGF2α until the end of voluntary waiting period (d 42). After day 42 postpartum, cows in three groups were treated with PGF2α within 14-day intervals until natural mating after voluntary waiting period. Recorded reproductive parameters included days to first heat, days to first mating, days open, service per conception, conception rate, percentage of repeat breeder animals and pregnancy loss. Early PGF2α treatment from day 14 postpartum significantly decreased days to first estrus (34.9 ± 0.74, P < 0.003), days to first mating (62.35 ± 1.53, P < 0.04), days open (117.23 ± 3.1, P < 0.001) and service per conception (1.9 ± 0.09, P < 0.02); and PG-14 group presented increased conception rate (52.5%, P < 0.05). The proportion of repeat breeder syndrome tended to be affected by treatment with PGF2α from day 14 postpartum. In conclusion, treatment of cows with PGF2α from day 14 postpartum improved reproductive performance.

O objetivo do presente trabalho foi avaliar os efeitos do tratamento pós-parto precoce com PGF2α sobre o desempenho reprodutivo de vacas leiteiras sincronizadas para reprodução controlada por monta natural após o período de espera voluntário. Neste experimento, 120 vacas foram distribuídas em três grupos independentes da presença ou ausência de corpo lúteo. Vacas no grupo PG-14 foram tratadas com PGF2α a partir do 14o dia pósparto, vacas do grupo PG-28 foram tratadas com PGF2α a partir do 28o dia pós-parto e as vacas do grupo PG-42 não foram tratadas com PGF2α até o final do período de espera voluntário (d42). Após o 42o dia pós-parto as vacas dos três grupos foram tratadas com PGF2α com intervalos de 14 dias até a monta natural após o período de espera voluntário. Os registros dos parâmetros reprodutivos incluíram: dias para o primeiro estro, dias para a primeira cobertura, dias em aberto, serviços por concepção, taxa de concepção, percentagem de animais repetidores de cios e as perdas de gestações. O tratamento precoce com PGF2α, a partir do 14o dia pós-parto reduziu significativamente os dias para o primeiro estro (34,9 ± 0,74, P < 0,003), dias para a primeira cobertura (62,35 ± 1,53, P < 0,04), dias em aberto (117,23 ± 3,1, P< 0,02); e o grupo PG-14 apresentou um acréscimo na taxa de concepção (52,5%, P < 0,05). A proporção da síndrome de vacas repetidoras de cios tendeu a ser afetada pelo tratamento com PGF2α a partir do 14o dia pós-parto. A conclusão obtida foi que o tratamento das vacas com PGF2α a partir do 14o dia pós-parto melhorou o desempenho reprodutivo dos animais.

Efeito da utilização de uma dose adicional de Dinoprost Trometamina em protocolos de IATF em vacas Nelore.

O objetivo deste estudo foi avaliar se vacas Nelore, que receberam duas doses de PGF2 em protocolos de IATF a base de progesterona e estradiol, teriam melhor fertilidade em comparação a uma dose de PGF2. Foram realizados 2 experimentos em que os animais receberam o protocolo de IATF: dispositivo intravaginal de P4 (CIDR) e 2,0 mg benzoato de estradiol (i.m., 2 ml Gonadiol®, Zoetis), no d-11, dinoprost trometamina (PGF2; i.m., 2,5 ml Lutalyse®, Zoetis) no d-4, retirada do dispositivo de P4, 0,6 mg de cipionato de estradiol (i.m., 0,3 ml ECP®, Zoetis) e 300 UI de eCG (i.m., 1,5 ml Novormon®, Zoetis) no d-2, e IATF no d0. No experimento 1, as vacas (n=1.039) foram divididas aleatoriamente para receber uma ou duas doses de PGF2, sendo a primeira no d-4 e a segunda no d-2. No experimento 2, foram avaliadas 1.051 fêmeas Nelore, permanecendo para as análises deste estudo apenas fêmeas que não apresentaram um CL no d-4 (momento da primeira PGF2; n=934), os tratamentos foram os mesmos descritos no experimento 1. Foi fixado um dispositivo para avaliar a expressão do cio (Estrotect®) no d-2, avaliado o diâmetro folicular no d0, as colheitas de sangue foram realizadas no d0 e d7, para dosagem de P4. O diagnóstico de gestação (DG) foi realizado 30 dias após IA. No experimento 1, a taxa de prenhez foi maior para os animais do grupo 2PG (54,5% vs. 46,6%; P = 0,01) em relação a 1PG. No experimento 2, a taxa de sincronização e a taxa de prenhez foram maiores no grupo 2PG, (81,4% vs. 72,1%; [P= 0,01] e 55,5% vs. 45,6%; [P = 0,04], respectivamente) apenas nos animais com ECC < 5,0 (escala de 1 a 9). Já nos animais com ECC 5,0, não houve diferença entre os tratamentos. Independente de ECC, não foi observado diferença na taxa de concepção, diâmetro do maior folículo no momento da IA e expressão de cio. Houve interação entre o tratamento e o diâmetro folicular sobre a taxa de sincronização (P= 0,004). Em conclusão, a utilização de duas doses de PGF2 foi mais eficiente em sincronizar folículos menores (< 13,1 mm) e promoveu efeito positivo na taxa de sincronização e prenhez, nas vacas com ECC < 5,0.

The aim of this study was to evaluate whether Nelore cows that received two doses of PGF2 in progesterone and estradiol-based TAI protocols would have better fertility compared to one dose of PGF2. Two experiments were performed in which the animals received an TAI protocol: intravaginal P4 device (CIDR) and 2.0 mg estradiol benzoate (i.m., 2 ml Gonadiol®, Zoetis), at d-11, dinoprost tromethamine (PGF2; i.m., 2 , 5 ml Lutalyse®, Zoetis), at d-4, P4 device withdrawal, 0.6 mg estradiol cypionate (i.m., 0.3 ml ECP®, Zoetis) and 300 IU eCG (i.m., 1.5 ml Novormon®, Zoetis) at d-2, and AI at d0. In experiment 1 the animals (n = 1,039) were randomly assigned to receive one or two doses of PGF2, the first on d-4 and the second on d-2. In experiment 2, 1,051 Nelore cows were used, and remaining for the analysis of this study only females without CL on d-4 (moment of first PGF2; n=934), the treatments were the same as described in experiment 1. A device was fixed to evaluate estrus expression (Estrotect®) at d-2, measured follicular diameter at d0, blood samples were collected at d0 and d7 for P4 dosage. The pregnancy diagnosis was made 30 days after AI. In experiment 1, the pregnancy rate was higher for animals in group 2PG (54.5% vs. 46.6%; P = 0.01) compared to 1PG. In experiment 2, synchronization rate and pregnancy rate were higher in group 2PG (81.4% vs. 72.1%; [P = 0.01] and 55.5% vs. 45.6%; [P = 0.04], respectively) only in animals with BCS < 5.0 (scale from 1 to 9). In animals with BCS 5.0, there was no difference between treatments. Regardless of BCS, there was no difference in conception rate, diameter of the largest follicle at the moment of AI, and estrus expression. There was an interaction between treatment and follicular diameter on the synchronization rate (P=0.004). In conclusion, the use of two doses of PGF2 was more efficient in synchronizing small follicles (< 13.1 mm) and had a positive effect on synchronization and pregnancy rates in cows with BCS < 5.0.

Antiluteogenic effects of prostaglandin F2-alpha / Efeito antiluteogênico da prostaglandina F2-alpha

PGF2α has been studied for many years for its ability to induce luteolysis in natural cycles and after exogenous administration. In the present review, we will discuss the results of recent studies that found a novel effect of exogenous administration of PGF2α when given serially during the first days of diestrus: to prevent the formation of the corpus luteum and induce a new estrus. This phenomenom has been named “antiluteogenesis”.(AU)

A Prostaglandina F2α tem sido investigada for muitos anos como um potente agente luteolitico. Esta breve revisão se foca em um fenômeno somente descrito recentemente: a habilidade da PGF2α de prevenir a formação do corpo luteo quando administrada serialmente durante os primeiros dias do diestro. Este fenômeno é então chamado de efeito antiluteogênico.(AU)

Antiluteogenic effects of prostaglandin F2-alpha / Efeito antiluteogênico da prostaglandina F2-alpha

PGF2α has been studied for many years for its ability to induce luteolysis in natural cycles and after exogenous administration. In the present review, we will discuss the results of recent studies that found a novel effect of exogenous administration of PGF2α when given serially during the first days of diestrus: to prevent the formation of the corpus luteum and induce a new estrus. This phenomenom has been named “antiluteogenesis”.

A Prostaglandina F2α tem sido investigada for muitos anos como um potente agente luteolitico. Esta breve revisão se foca em um fenômeno somente descrito recentemente: a habilidade da PGF2α de prevenir a formação do corpo luteo quando administrada serialmente durante os primeiros dias do diestro. Este fenômeno é então chamado de efeito antiluteogênico.

AVALIAÇÃO DA EFICIÊNCIA LUTEOLÍTICA DE DIFERENTES DOSES DE CLOPROSTENOL SÓDICO E DINOPROST TROMETAMINA ADMINISTRADAS NOS DIAS 4 E 11 DO CICLO ESTRAL DE FÊMEAS BOVINAS DE CORTE

No presente estudo os objetivos foram avaliar a resposta luteolítica de meia dose (50%) ou dose inteira (100%) de cloprostenol sódico (CS) e dinoprost trometamina (DT) administrados em fêmeas bovinas de corte não lactantes cíclicas, nas fases de metaestro e diestro do ciclo estral (4 ou 11 dias após a ovulação (D0), respectivamente), quanto a: dinâmica luteínica, vascularização central e periférica, quantificação de pixels na área vascularizada do CL e dosagem de progesterona sérica (Exp.1) e morfometria das células luteínicas, imunomarcação de caspase-3 e dosagem de progesterona (P4; Exp.2). No Exp. 1, 54 fêmeas tiveram a ovulação sincronizada e receberam os seguintes tratamentos: CS 0 µg (CS0%; n=3/ grupo), CS 250 µg (CS50%; n=5/D4 e n=7/D11), CS 500 µg (CS100%; n=5/ grupo), DT 0 mg (DT0%; n=2/ grupo), DT 12,5 mg (DT50%; n=5/D4 e n=6/D11) ou DT 25 mg (DT100%; n=5/D4 e n=6/D11). No Exp. 2, 25 fêmeas foram sincronizadas, alocadas nos tratamentos no D4 e D11: CS50%; CS100%; DT50%; DT100% (n=3/ grupo, exceto DT100% no D11, n=2) e abatidas dois dias após. Os dados foram analisados por ANOVA em arranjo fatorial (2x2x3, no Exp. 1 e 2x2x2, no Exp. 2) com medidas repetidas no tempo (exceto para morfometria e imunomarcação) e teste de Tukey, com significância a 5%. No Exp. 1, animais avaliados no D4 apresentaram redução numérica da concentração de P4, das dimensões e vascularização luteais. Já animais avaliados a partir de D11 apresentaram redução para todos os parâmetros avaliados ao longo dos momentos experimentais. A utilização de 50% ou 100% da dose dos luteolíticos causaram redução semelhante nas variáveis avaliadas comparados ao controle negativo. No Exp. 2, o número de células luteais pequenas imunomarcadas para caspase-3 foi semelhante entre os tratamentos, sendo em maior número quando administradas no D11. Animais tratados com 50% da dose apresentaram maior número de células luteais grandes comparados aos tratados com 100% da dose. Para a área das células luteais grandes, os tratamentos administrados no D11 influenciaram de maneira semelhante esta variável, enquanto que no D4 a menor área foi detectada para animais tratados com CS100%. Animais tratados com CS e com 100% da dose dos ativos no D4 apresentaram maior área de células luteais pequenas. Animais tratados com DT50% apresentaram menor área de células luteais pequenas. A administração dos tratamentos em D4 e D11 causou redução na concentração de P4. A principal diferença observada após a administração de CS e DT ocorreu no efeito exercido pelos ativos sobre as células luteais grandes e pequenas. As dimensões luteais, a vascularização do CL e as concentrações séricas de P4 foram semelhantes após a administração dos ativos avaliados. A administração dos luteolíticos em D4 foi sugestiva de luteólise parcial. Já a administração no D11 foi eficiente em induzir luteólise completa. No presente trabalhou demonstrou-se também a capacidade luteolítica do uso de 50% da dose de CS e DT, quando administradas no D11.

In the present study the objectives were to evaluate the luteolytic response of half-dose (50%) or full dose (100%) of sodium cloprostenol (SC) and dinoprost tromethamine (DT) administered in beef cattle cyclic non-lactating, at the metaestrous and diestrous stages of the estrous cycle (4 or 11 days after ovulation (D0), respectively), regarding: luteal dynamics, central and peripheral vascularization, quantification of pixels in vascularized area of CL and serum progesterone levels (Exp.1) and luteal cell morphometry, caspase-3 immunolocation and progesterone levels (P4; Exp.2). In Exp. 1, 54 females were synchronized ovulation and received the following treatments: SC0µg (SC0%; n=3/group), SC250µg (SC50%; n=5/D4 and n=7/D11), SC500µg (SC100%; n=5/group), DT0mg (DT0%; n=2/group), DT12.5mg (DT50%; n=5/D4 and n=6/D11) or DT25mg (DT100%; n=5/D4 and n=6/D11). In Exp. 2, 25 females were synchronized, assigned to treatments on D4 and D11: SC50%; SC100%; DT50%; DT100% (n=3/group, except DT100% on D11, n=2) and slaughtered two days later. Data were analyzed by ANOVA in factorial arrangement (2x2x3, in Exp. 1 and 2x2x2, in Exp. 2) with repeated measures in time (except for morphometry and immunolocation) and Tukey test, at 5% level of significance. In Exp. 1, animals evaluated in D4 showed numerical reduction of P4 levels, luteal dimensions and vascularization. Animals evaluated at D11 showed reduction for all parameters evaluated over the experimental moments. The use of 50% or 100% of the luteolytic dose caused a similar reduction in the evaluated variables compared to the negative control. In Exp. 2, the number of caspase-3 immunostained small luteal cells was similar between treatments, and large when administered on D11. Animals treated with 50% of the dose presented larger number of large luteal cells compared to those treated with 100% of the dose. For the area of large luteal cells, treatments administered on D11 influenced this variable similarly, while at D4 the smallest area was detected for animals treated with SC100%. Animals treated with SC and with 100% of the dose on D4 showed larger area of small luteal cells. Animals treated with DT50% had smaller area of small luteal cells. Administration of treatments on D4 and D11 caused a reduction in P4 levels. The main difference observed after administration of SC and DT occurred in the effect exerted by the actives on the large and small luteal cells. Luteal dimensions, CL vascularization and serum P4 levels were similar after administration of the luteolytics agents. Administration of luteolytics on D4 was suggestive of partial luteolysis. The administration on D11 was efficient in inducing complete luteolysis. The study also demonstrated the luteolytic ability to use 50% of the dose of SC and DT when administered in D11.

Protocolos de indução hormonal com extrato bruto de hipófises de carpa e o perfil da prostaglandina F2 durante a maturação final e ovulação em Astyanax altiparanae

Considerando as inconsistentes informações acerca dos protocolos de indução hormonal do Astyanax altiparanae em cativeiro, o principal objetivo deste estudo foi comparar o desempenho reprodutivo utilizando ou não extrato bruto de hipófise de carpa (EBHC). Avaliamos também o efeito de diferentes doses de EBHC sobre o desempenho reprodutivo em dois distintos lotes de peixes. Em todos os experimentos, avaliamos se um eventual ganho no desempenho reprodutivo estaria associado com alterações na morfologia dos ovários e/ou com concentrações séricas de prostaglandina F2 (PGF2). Nos experimentos 1 (lote capturado na natureza) e 2 (lote nascido em cativeiro), aplicamos 3, 6 e 9 mg.kg-1 de EBHC (T1, T2 e T3 respectivamente), e um grupo controle (C). No experimento 3 (mesmo lote do experimento 2), comparamos o desempenho reprodutivo com dose única e fracionada (10% e 90% da dose total, com intervalo de 12 horas entre as doses) de EBHC, sendo 6 mg.kg-1 em dose única (H1) ou fracionada (H2) e seus respectivos controles (C1 e C2). Nos experimentos 1 e 2 o desempenho reprodutivo foi similar entre os grupos, porém os grupos T2 e T3 apresentaram elevações de PGF2 no momento da ovulação, além de variações significativas nas frequências de estruturas ovarianas, que indicam aumento da ovulação e /ou a maturação final. No experimento 3, a dose fracionada de 6 mg.kg-1 de EBHC causou um aumento na proporção de réplicas com desova e consequentemente, no volume total de desova e no número total de embriões viáveis. Esta dose também causou um aumento na frequência de complexos pós ovulatórios e no nível de PGF2 no momento da desova. Concluímos que a indução hormonal pode potencializar a desova do lambari. Os reprodutores dos diferentes lotes apresentaram um padrão similar de resposta ao tratamento com EBHC. O fracionamento da dose de EBHC propiciou melhor desempenho que a dose única, o qual, porém, só ficou evidente em análises histológicas e de concentrações de PGF2. Portanto, recomendamos o uso da dose fracionada de 6 mg.kg-1 de EBHC para indução hormonal desta espécie em cativeiro, usando as condições aqui aplicadas.

Considering the inconsistent information about the hormonal induction protocols of Astyanax altiparanae in captivity, the main objective of this study was to compare the reproductive performance with or without crude carp pituitary extract (EBHC). We also evaluated the effect of different doses of EBHC on the reproductive performance of two distinct broodstocks. In all experiments, we evaluated whether a possible gain in reproductive performance would be associated with changes in ovarian morphology and / or with serum prostaglandin F2 (PGF2) concentrations. In the experiments 1 (wild caught) and 2 (born in captivity), we applied 3, 6 and 9 mg.kg-1 EBHC (T1, T2 and T3 respectively), and one control group (C). In the experiment 3 (same broodstock as in experiment 2), we compared reproductive performance with single and fractional doses (10% e 90% of the total, with 12 hours of interval between doses) of EBHC, being: 6 mg.kg-1 in single dose (H1) or fractional (H2) and their respective controls (C1 and C2). In the experiments 1 and 2 the reproductive performance was similar between groups, but groups T2 and T3 presented elevations of PGF2 at the time of ovulation, besides significant variations in the frequencies of ovarian structures, which indicates increase in ovulation and / or final maturation. In the experiment 3, the fractional dose of 6 mg.kg-1 EBHC caused an increase in the proportion of replicates with spawn events and consequently, in the total volume of eggs and the absolute number of viable embryos. This dose also caused an increase in the frequency of post ovulatory complexes and the level of PGF2 at spawning time. We conclude that the hormonal induction can potentialize the spawning of lambari. Different broodstock presented a similar pattern of response to EBHC treatment. The fractioning of the EBHC doses gave better performance than the single dose, but, however, was only evident in histological and PGF2 concentrations analyzes. Therefore, we recommend the use of the fractional dose of 6 mg.kg-1 of EBHC for hormonal induction of this species in captivity, using the conditions applied herein.

Ações do estradiol na síntese de prostaglandina f2 em células endometriais bovinas

Em fêmeas bovinas a liberação de prostaglandina F2 (PGF2) endometrial pode ser induzida in vivo pelo estradiol (E2), entretanto, seu papel ainda não foi esclarecido. Em estudos prévios realizados pelo grupo, o tratamento com E2 in vivo duas horas antes das vacas serem abatidas no 17º dia do ciclo estral, associado à adição de cálcio ionóforo (CI) in vitro em explantes endometriais, exacerbou a síntese de PGF2 quando comparado ao grupo de vacas não tratadas com E2 e CI. O mesmo foi observado em células endometriais bovinas (BEND) expostas ao E2 e CI simultaneamente. Considerando que as concentrações plasmáticas de PGF2 aumentam a partir de 3,5 horas após da aplicação do E2 in vivo, possivelmente tais ações envolvam a síntese de proteínas. Hipotetizou-se que o E2 estimule a expressão e/ou a atividade das enzimas dependentes de cálcio, especificamente a proteína quinase C (PKC) e fosfolipase A2 citosólica (cPLA2). Assim, objetivou-se analisar o efeito dos inibidores de Proteína G, PKC e PLA2 na síntese de PGF2 induzida pelo 17-estradiol e CI em células endometriais bovinas BEND (Experimento 1), e avaliar as proteínas PKC e PLA2 e ERK 1/2, pela técnica de Western Blotting, em explantes endometriais obtidos de fêmeas bovinas abatidas 2 horas após a administração de 17-estradiol no 17o dia do ciclo estral (Experimento 2). No Experimento 1, células endometriais bovinas (BEND) foram submetidas a ausência ou presença de um inibidor de proteína G - 10µM de Guanosine 5- {B-thio) difosfato trilitium (Experimento 1A), inibidor de PKC - 10µM de C25H24N4O2 Bisindolimaleimide I (Experimento 1B) ou inibidor de PLA2 - 20µM de AACOCF3 (Experimento 1C), sendo posteriormente tratadas ou não com 17-estradiol e CI. Os tratamentos foram realizados em triplicata em um total de três repetições. As concentrações de PGF2 no meio de cultivo foram mensuradas por radioimunoensaio. No Experimento 2, novilhas Nelore cíclicas receberam os tratamentos, com 0mg (n=5) ou 3mg de 17-estradiol (n=6), ia endovenosa, 17° dia do ciclo estral e foram abatidas 2 horas após. Os explantes endometriais foram avaliados por Western Blotting para as proteínas PKC, PLA2 e ERK1/2. As análises estatísticas dos experimentos foi realizada no programa SAS (SAS Institute, 1988). No experimento 1A, observou-se efeito de repetição (P<0,001) e inibidor (P<0,01), onde os grupos tratados com inibidor da proteina G (Inibidor de Proteína G e Inibidor de Proteína G+CI+ E2 ) apresentaram DIF 12 (concentração de PGF2 com 12 horas após o tratamento subtraída da concentração de PGF2 com 0 hora) maior (P<0,01) que os grupos não tratados com o inibidor da proteína G (controle e CI+ E2 ). No experimento 1B, houve efeito de repetição (<0,001) e não houve efeito do inibidor (P=0,2709). No experimento 1C, verificou-se efeito de repetição (P<0,001) e inibidor (P<0,05). As células tratadas com o inibidor de PLA2 (grupo inibidor de PLA2 e Inibidor de PLA2 + CI + E2) apresentaram uma DIF 12 menor (P<0,05) que os grupos não tratados com o inibidor de PLA2 (controle e CI + + E2). No experimento 2, não houve efeito significativo do estradiol no aumento da proteína PKC (P=0,08), PLA2 (P=0,56) e ERK1/2 (P=0,26). Concluiu-se que, no presente estudo, o E2 não estimulou a síntese das proteínas PKC e cPLA2.

In bovine females the release of endometrial prostaglandin F2 (PGF2) can be induced in vivo by estradiol (E2), however, its role has not yet been clarified. In previous studies conducted by the group, treatment with E2 in vivo two hours before cows were slaughtered on the 17th day of the estrous cycle, associated with the addition of ionophore calcium (IC) in vitro in endometrial explants, exacerbated PGF2 synthesis when compared to group of cows not treated with E2 and CI. The same was observed in bovine endometrial cells (BEND) exposed to E2 and IC simultaneously. Considering that plasma concentrations of PGF2 increase from 3.5 hours after the application of E2 in vivo, possibly such actions involve the synthesis of proteins. E2 has been hypothesized to stimulate the expression and / or activity of calcium dependent enzymes, specifically protein kinase C (PKC) and cytosolic phospholipase A2 (cPLA2). The objective of this study was to analyze the effect of Protein G, PKC and PLA2 inhibitors on the synthesis of PG2 induced by 17-estradiol and IC in BEND bovine endometrial cells (Experiment 1), and to evaluate the proteins PKC and PLA2 and ERK 1/2 by Western Blotting technique in endometrial explants obtained from bovine females slaughtered 2 hours after administration of 17-estradiol on the 17th day of the estrous cycle (Experiment 2). In Experiment 1, bovine endometrial cells (BEND) were subjected to the absence or presence of a G-10M inhibitor of Guanosine 5'- {B-thio) diphosphate trilitium (Experiment 1A), PKC inhibitor - 10M C25H24N4O2 - Bisindolimaleimide I (Experiment 1B) or inhibitor of PLA2 - 20M AACOCF3 (Experiment 1C), and subsequently treated with or without 17-estradiol and IC. Treatments were performed in triplicate for a total of three replicates. The concentrations of PGF2 in the culture medium were measured by radioimmunoassay. In Experiment 2, cyclic Nelore heifers were treated with 0mg (n = 5) or 3mg of 17-estradiol (n = 6), intravenous at day 17 of the estrous cycle and slaughtered 2 hours later. Endometrial explants were evaluated by Western blotting for PKC, PLA2 and ERK1 / 2 proteins. Statistical analysis of the experiments was performed in the SAS program (SAS Institute, 1988). In the experiment 1A, a repetitive effect (P <0.001) and inhibitor (P <0.01) were observed, where the G protein inhibitor (Protein G Inhibitor and Protein G Inhibitor + CI + E2) treated groups showed DIF 12 (concentration of PGF 2 at 12 hours post treatment subtracted from PGF 2 concentration with 0 hour) higher (P <0.01) than the groups not treated with the G protein inhibitor (control and CI + E2). In experiment 1B, there was a repetition effect (<0.001) and there was no inhibitor effect (P = 0.2709). In the experiment 1C, there was a repetition effect (P <0.001) and inhibitor (P <0.05). The cells treated with the PLA2 inhibitor (PLA2 inhibitor group and PLA2 + CI + E2 inhibitor) had a lower DIF 12 (P <0.05) than the groups not treated with the PLA2 inhibitor (control and CI + E2). In Experiment 2, there was no significant effect of estradiol on the increase of PKC (P = 0.08), PLA2 (P = 0.56) and ERK1 / 2 (P = 0.26). It was concluded that, in the present study, E2 did not stimulate the synthesis of PKC and cPLA2 proteins.