Peri-conceptional under-nutrition alters transcriptomic profile in the endometrium during the peri-implantation period-The study in domestic pigs.

Female under-nutrition during early pregnancy may affect the physiological pattern of the transcriptomic profile in the endometrium. We aimed to determine if restricted diet applied to females during peri-conceptional period, that is, from the onset of the oestrus until day nine of pregnancy, alters transcriptomic profile in the endometrium during the peri-implantation period. The restricted diet gilts were fed forage, in which the dose of proteins and energy had been reduced by 30% compared to normal diet. Microarray analysis revealed that approximately 4% of transcripts, that is 1690 of 43803 probes from The Porcine (V2) Gene Expression Microarray 4 × 44 (Agilent Technologies, Santa Clara, CA, USA) were consistently altered (p ≤ .05) in the endometrium harvested from pigs fed restricted diet. In pigs fed restricted diet out of 1690 genes, 714 genes were upregulated and 976 genes were downregulated versus in pigs fed normal diet. From 1690 genes, 510 (30%) were genes with known biological functions in the KEGG database. The proportions of the differentially expressed transcripts were organized into six major categories and 39 subcategories containing 259 pathways associated with the differentially expressed genes. The largest amount of differentially expressed genes was involved in metabolism category. The most relevant genes were involved in gene ontology (GO) cellular component (CC) term. These findings suggest that females under-nutrition during peri-conceptional period may create changes in endometrial transcriptome during the peri-implantation period creating the potential changes in physiological functions of peri-implantation endometrium.

Expression of 17ß-hydroxysteroid dehydrogenase and the effects of LH, FSH and prolactin on oestrone and 17ß-oestradiol secretion in the endometrium of pigs during early pregnancy and the oestrous cycle.

The endometrium of pregnant and cyclic pigs is a source of oestrone (E1) and 17ß-oestradiol (E2). However, the roles of LH, FSH and prolactin (PRL) as regulators of endometrial steroidogenesis, and the presence of 17ß-hydroxysteroid dehydrogenase (17ß-HSD) in the porcine endometrium, remain unknown. Therefore, in the present study we examined 17ß-HSD expression and the effects of LH, FSH and PRL on E1 and E2 release in vitro in endometrial explants harvested from gravid pigs on Days 10-11 (embryo migration within the uterus), 12-13 (maternal recognition of pregnancy) and 15-16 (beginning of implantation) and compared them with results obtained in non-gravid pigs. The results show that: (1) endometrial 17ß-HSD activity was decreased on Days 15-16 in pregnant and cyclic pigs compared with the preceding days; (2) LH, FSH and PRL increased endometrial E1 secretion on Days 10-11 and 15-16 of pregnancy and on Days 12-13 and 15-16 of the oestrous cycle; and (3) LH, FSH and PRL increased endometrial E2 secretion on Days 15-16 of pregnancy and during the days studied in the oestrous cycle. In conclusion, data suggest that LH, FSH and PRL affect endometrial secretion of estrogens in pigs.

Periconceptional undernutrition affects in utero methyltransferase expression and steroid hormone concentrations in uterine flushings and blood plasma during the peri-implantation period in domestic pigs.

Female undernutrition during early pregnancy may affect the physiological pattern of genomic DNA methylation. We hypothesised that in utero DNA methylation may be impaired in females fed a restrictive diet in early pregnancy. In this study we evaluated whether poor maternal nutritional status, induced by applying a restricted diet during the peri-conceptional period, may influence: (1) the potential for in utero DNA methylation, expressed as changes in the mRNA expression and protein abundance of methyltransferases: DNA methyltransferase 1 (DNMT1) and DNMT3a in the endometrium and the myometrium, (2) the intrauterine microenvironment, measured as oestradiol 17ß (E2) and progesterone (P4) concentrations in uterine flushings and (3) plasma concentration of E2 and P4 during the peri-implantation period. Our results indicate that maternal peri-conceptional undernutrition affects maintenance and de novo DNA methylation in the endometrium, de novo methylation in the myometrium and a results in a decrease in intrauterine E2 concentration during the peri-implantation period. The intrauterine concentration of P4 and plasma concentrations of E2 and P4 did not change. These findings suggest that undernutrition during the earliest period of pregnancy, and perhaps the pre-pregnancy period, may create changes in epigenetic mechanisms in the uterus and intrauterine milieu of E2 during the peri-implantation period.

Effect of neonatal or adult heat acclimation on plasma fT3 level, testicular thyroid receptors expression in male rats and testicular steroidogenesis in vitro in response to triiodothyronine treatment.

This study aimed to evaluate the effect of heat acclimation of neonatal and adult rats on their testes response to in vitro treatment with triiodothyronine (T3). Four groups of rats were housed from birth as: 1) control (CR) at 20°C for 90 days, 2) neonatal heat-acclimated (NHA) at 34°C for 90 days, 3) adult heat-acclimated (AHA) at 20°C for 45 days followed by 45 days at 34°C and 4) de-acclimated (DA) at 34°C for 45 days followed by 45 days at 20°C. Blood plasma and both testes were harvested from 90-day old rats. Testicular slices were then submitted to in vitro treatment with T3 (100 ng/ml) for 8 h. Plasma fT3 level was lower in AHA, NHA and DA groups than in CR group. Basal thyroid hormone receptor α1 (Thra1) expression was higher in testes of NHA and DA and ß1 receptor (Thrb1) in DA rats vs. other groups. In the in vitro experiment, T3: 1) decreased Thra1 expression in all groups and Thrb1 in DA group, 2) increased Star expression in CR, NHA and DA groups, and Hsd17b3 expression in NHA group, 3) decreased the expression of Cyp11a1 in NHA and DA groups, and Cyp19a1 in all the groups, 4) did not affect the activity of steroidogenic enzymes and steroid secretion (A4, T, E2) in all the groups. These results indicate, that heat acclimation of rats, depending on their age, mainly affects the testicular expression of steroidogenic enzymes in response to short-lasting treatment with T3.

Transcriptomic profile of the porcine oviductal epithelial cells during the peri-conceptional period.

The optimal environment in the oviduct is created by adjusting its ultrastructure and secretory activity to serve the most suitable protection of gametes and to support embryo development. Through gametes/embryo's presence inside the oviduct, the oviductal transcriptomic profile may be altered, and these changes may be caused by DNA methylation. The results of the present study documented that in the epithelial cells of the ampulla and isthmus of the oviducts collected from pigs during the peri-conceptional period, the most differentially expressed genes (DEGs) were down-regulated. Identified DEGs were classified into gene ontology categories as well as annotated into different biological pathways. From evaluated DEGs, genes important for embryo development were selected and the level of DNA methylation was determined. It was documented CLDN18, MUC1, CYP19A3, SOCS1, and ESR1 methylation level have been altered. The presence of embryos in the oviduct changed the transcriptomic profile and the level of DNA methylation in the epithelial cells of ampulla and isthmus during the peri-conceptional period.

The effect of progesterone on oxytocin-stimulated intracellular Ca2+ mobilisation and prostaglandin secretion in porcine endometrium.

We have studied in the porcine endometrium the expression of oxytocin receptor (OTR) mRNA and the effect of progesterone (P4) on oxytocin/oxytocin receptor (OT/OTR) function concerning intracellular Ca2+ mobilisation ([Ca2+]i), prostaglandin F2alpha (PGF2alpha) and E2 (PGE2; PG) secretion. Tissue was taken from cyclic and early pregnant pigs (days 14-16). A higher expression of OTR mRNA (P < 0.05) was observed in the endometrium of cyclic than pregnant pigs. The stimulatory (P < 0.05) effect of OT (10(-7) M) on [Ca2+]i mobilisation was noticed within 15-60 s and 30-60 s in endometrial stromal cells of cyclic and pregnant pigs, respectively. In the presence of P4 (10(-5) M) basal and OT-stimulated [Ca2+]i concentrations decreased in stromal cells during luteolysis and pregnancy. In stromal cells P4 delayed mobilisation of [Ca2+]i in response to OT by 15 s during luteolysis and had no effect during pregnancy. In cyclic and pregnant epithelial cells OT stimulated mobilisation of [Ca2+]i in 45 s and 60 s, respectively. Oxytocin increased (P < 0.05) PGF2alpha secretion during luteolysis and pregnancy and PGE2 during luteolysis from endometrial slices. Progesterone did not inhibit this stimulatory effect. During luteolysis OT increased (P < 0.05) PGF2alpha in epithelial and stromal cells and PGE2 secretion in epithelial cells. In the presence of P4 this effect of OT was reduced only in stromal cyclic cells (6 h culture). The presence of P4 decreased the effect of OT on [Ca2+]i mobilisation only in stromal cells. We found that, in most conditions, P4 did not inhibit the OT-stimulated secretion of PG in the porcine endometrium.

Effect of warm-rearing and heat acclimation on pituitary-gonadal axis in male rats.

Plasma gonadotrophic and testicular hormones concentrations in both immature and adult male rats exposed to 34 degrees C of ambient temperature were determined. In vitro steroidogenic ability of interstitial cells from experimental rats was also studied. Four groups of rats (n = 45) were used. Warm-reared (WR) males were housed in 34 degrees C and control-reared rats in 20 degrees C from birth to adulthood. The other groups were acclimated to 34 degrees C [warm-acclimated (WA) group] or 20 degrees C [deacclimated (DA) group] as adults. Decreased body weight and testis weight (p < 0.05) was found in heat-exposed groups, but relative testis weight was unchanged in WA and increased (p < 0.05) in WR and DA males. Plasma luteinizing hormone (LH) concentration increased in WA and DA males. Increased (p < 0.05) follicle-stimulating hormone (FSH) and prolactin plasma levels were found in DA and WR groups respectively. WA males had decreased testosterone (T) and WR rats androstenedione (A(4)) plasma concentration (p < 0.05). Interstitial cells (43% of them were Leydig cells by 3beta-hydroxysteroid dehydrogenase activity) from heat-exposed males secreted less (p < 0.05) T compared with the control group when incubated without LH (basal conditions). Androstenedione secretion decreased (p < 0.05) in WA rats. Secretion of estradiol-17beta (E(2)) was higher in WR and lower in DA cells under basal conditions. Weaker responsiveness to LH was observed in WR cells. Androgen synthesis from pregnenolone by interstitial cells increased (p < 0.05) in the WA group. We concluded that heat exposure of neonatal and adult male rats caused different pituitary-testicular axis adjustments. It seemed that long-term heat exposure of neonatal rats is less deleterious concerning the activity of pituitary-testicular axis than heat acclimation of adults.

Secretion of estradiol-17beta by porcine endometrium and myometrium during early pregnancy and luteolysis.

Past studies of the source of estrogens secreted during maternal recognition of pregnancy in pigs have focused on embryonic rather than uterine origin of these steroids. The present study documents: (1) the expression of the gene CYP 17, encoding cytochrome P450 17alpha-hydroxylase/C(17-20) lyase and (2) the synthesis and secretion of estradiol-17 beta (E(2)) in endometrial and myometrial tissues in gilts. The expression of CYP 17 gene was shown in porcine endometrium and myometrium. Basal endometrial secretion of E(2) was higher in pregnant gilts than in cyclic gilts (days 14-16). The myometrium secreted more E(2) during the expected time of luteolysis compared to early pregnancy. Basal secretion of E(2) during pregnancy was higher from the endometrium than from the myometrium. Conversely, during luteolysis E(2) secretion was higher from the myometrium and lower from the endometrium. In pregnant and cyclic gilts (days 14-16), progesterone (P(4), 10(-5)M) in vitro significantly increased E(2) secretion regardless of reproductive status. Oxytocin (OT, 10(-7)M) had no influence on E(2) secretion and did not change the stimulatory effect of P(4) in both tissues examined. In conclusions: (1) the CYP 17 gene transcript is present in porcine endometrium and myometrium; (2) porcine endometrium and myometrium release E(2) in vitro; (3) the endometrium releases more E(2) than the myometrium during early pregnancy; (4) the myometrium releases E(2) mainly during luteolysis; (5) the endometrium and myometrium can increase E(2) release in vitro if substrate (P(4)) is provided during early pregnancy and luteolysis. These data suggest active estrogen production by the myometrium and endometrium as an alternative source for this signal for recognition of pregnancy in the pig.

Interleukin-1ß system in the oviducts of pigs during the oestrous cycle and early pregnancy.

Interleukin-1ß (IL-1ß) acts throughout the IL-1ß system, which contains IL-1ß and the IL-1ß receptor (IL-1R), accessory protein (IL-1RacP), and receptor antagonist (IL-1Ra). In pigs, the expression of the members of the IL-1ß system was documented in uterine tissues during the oestrous cycle and early pregnancy, as well as in embryos harvested during the peri-implantation period. In the oviducts of non-gravid and gravid pigs, the expression of the IL-1ß system is unknown. Thus, in this study, the expression of the IL-1ß system was examined in porcine oviducts harvested on days 2-3 to 18-20 of the oestrous cycle and on days 2-3 to 15-16 of pregnancy. The expression of IL-1ß, IL-1R and IL-1RacP mRNAs in oviducts increased during the mid-luteal phase of the oestrous cycle, whereas the expression of IL-1Ra mRNA increased only during the early luteal phase, e.g., on days 2-3 of the oestrous cycle. Low expression of IL-1ß and IL-1Ra mRNAs was observed during the follicular phase of the oestrous cycle. In gravid pigs, the expression of IL-1ß, IL-1Ra and IL-1R mRNAs decreased (P < 0.05) from days 2-3 to 15-16 of pregnancy, whereas IL-1RacP mRNA expression did not change in pregnant pigs (P > 0.05). Significantly greater expression of the IL-1ß system mRNAs was demonstrated in oviducts harvested on days 2-3 of pregnancy vs. the respective days of the oestrous cycle. On days 2-3 of pregnancy, compared to respective days of the oestrous cycle, the quantity of IL-1ß protein was decreased (P < 0.05) in the ampulla and isthmus, while the quantity of IL-1Ra (only in the ampulla) and IL-1RacP proteins (in the ampulla and isthmus) were increased. The concentration of IL-1ß in oviductal flushings did not change (P > 0.05) in non-pregnant pigs, and it was greater (P < 0.05) on days 2-3 of pregnancy vs. the respective days of the oestrous cycle. Therefore, the presence of embryos in oviducts on days 2-3 after mating may influence the oviductal expression of the members of the IL-1ß system, determining the action of IL-1ß, which may be considered to be the earliest sign of pregnancy in pigs.

The effect of progesterone on oxytocin-stimulated intracellular mobilization of Ca2+ and prostaglandin E2 and F2alpha secretion from porcine myometrial cells.

UNLABELLED: Our past studies have shown that porcine myometrium produce prostaglandins (PG) during luteolysis and early pregnancy and that oxytocin (OT) and its receptor (OTr) support myometrial secretion of prostaglandins E2 and F2alpha (PGE2 and PGF2alpha) during luteolysis. This study investigates the role of intracellular Ca2+ [Ca2+]i as a mediator of OT effects on PG secretion from isolated myometrial cells in the presence or absence of progesterone (P4). Basal [Ca2+]i was similar in myometrial cells from cyclic and pregnant pigs (days 14-16). OT (10(-7)M) increased [Ca2+]i in myometrial cells of cyclic and pregnant pigs, although this effect was delayed in myometrium from pregnant females. After pre-incubation of the myocytes with P4 (10(-5)M) the influence of OT on [Ca2+]i)was delayed during luteolysis and inhibited during pregnancy. Myometrial cells in culture produce more PGE2 than PGF2alpha regardless of reproductive state of the female. OT (10(-7)M) increased PGE2 secretion after 6 and 12 h incubation for the tissue harvested during luteolysis and after 12 h incubation when myometrium from gravid females was used. In the presence of P4 (10(-5)M), the stimulatory effect of OT on PG secretion was diminished. IN CONCLUSION: (1) porcine myometrial cells in culture secrete PG preferentially during early pregnancy and produce more PGE2 than PGF2alpha, (2) OT controls myometrial PGF2alpha secretion during luteolysis, (3) release of [Ca2+]i is associated with the influence of OT on PG secretion, and (4) the effects of OT on PG secretion and Ca2+ accumulation are delayed by P4 during luteolysis and completely inhibited by P4 during pregnancy.

Expression of enzymes of cyclooxygenase pathway and secretion of prostaglandin E2 and F2alpha by porcine myometrium during luteolysis and early pregnancy.

UNLABELLED: Past studies of uterine prostaglandin (PGs) and pig reproduction have focused on endometrial rather than myometrial PGs. This study documents the synthesis and secretion of myometrial prostaglandins (PGs) in pigs and the involvement of oxytocin (OT) in these processes. Cyclooxygenase-2 (COX-2) expression was similar in myometrial explants from cyclic and pregnant pigs (days 14-16) and OT (10(-7) M) in vitro significantly increased COX-2 protein regardless of reproductive state. Basal expression of prostaglandin E2 synthase (PGES) was higher during pregnancy than during luteolysis. Conversely, prostaglandin F synthase (PGFS) was highest during luteolysis and lower in myometrium from gravid animals. OT had no influence on the expression of PGES and PGFS. In another tissue culture experiment, myometrial slices produced more PGE2 than PGF2alpha regardless of reproductive state of the female. OT stimulated PGE2 production in myometrium harvested during luteolysis and increased PGF2alpha production in all tissues examined. Progesterone (P4; 10(-5) M) blocked stimulatory effect of OT on myometrial PG release. Myometrial OTr mRNA was higher (P=0.03) during luteolysis than during pregnancy. IN CONCLUSION: (1) oxytocin increases myometrial COX-2 expression, but does not influence the expression of terminal enzymes of PGs synthesis (PGES and PGFS); (2) porcine myometrium preferentially produces PGs during early pregnancy and secretes more PGE2 than PGF2alpha; (3) myometrial OT and OTr support secretion of PGs from myometrium during luteolysis.

Oxytocin (OT) action in uterine tissues of cyclic and early pregnant gilts: OT receptors concentration, prostaglandin F(2)alpha secretion, and phosphoinositide hydrolysis.

Oxytocin (OT) is involved in the regulation of luteolysis in pigs. However, it is still not clear if OT is responsible for initiation of luteal regression in this species. The objectives of the study were: (1) to compare OT receptors (OTr) concentrations in endometrium and myometrium of cyclic and early pregnant pigs, (2) to examine the effect of OT on plasma PGF(2)alpha secretion during the progressive luteal regression, (3) to ascertain the effect of OT on inositol phosphates (IPs) accumulation in endometrial and myometrial cells of cyclic and early pregnant pigs. Concentrations of OTr on the endometrium and myometrium of cyclic (n = 33) (days 2-4; 11-13; 14-16; 18-20; day 21) and early pregnant (n = 4) (days 14-16) gilts were determined and they ranged from 7 +/- 3 (days 11-13) to 377 +/- 113 fmol/mg protein (day 21) in the endometrium and from 33 +/- 11 (days 2-4) to 167 +/- 28 fmol/mg protein (days 18-20) in the myometrium. In both tissues, concentrations of OTr were low during the luteal phase and increased (P < 0.01) during the follicular phase. In contrast to myometrial OTr, endometrial OTr during pregnancy were undetectable. In next experiment, mature gilts (n = 12) were injected with OT (20IU; i.v.) for three consecutive days starting on days 14 and 15 of the oestrous cycle and plasma PGF(2)alpha metabolite-13,14-dihydro-16-keto PGF(2)alpha (PGFM) concentration was determined. On days 15-16 and 16-17, OT increased plasma PGFM level. This effect was not observed on days 14-15 of the estrous cycle. A negative correlation was noticed between plasma concentrations of PGFM and progesterone (r = -0.3; P < 0.05). In last experiment, OT (100 nM) augmented (P < 0.01) an accumulation of inositol phosphates (IPs) in isolated myometrial cells on days 14-16 (n = 4) and 18-20 (n = 3) of the estrous cycle and on days 14-16 (n = 4) of pregnancy. Oxytocin-stimulated accumulation of IPs was not observed in endometrial cells. In summary: (1) concentrations of OTr on both the endometrium and myometrium were the highest during perioestrus-period in pigs, (2) myometrium of early pregnant sows possessed functional OTr, (3) oxytocin increased plasma PGFM concentration after initiation of luteolysis; and (4) OT-stimulated accumulation of IPs in myometrial, but not in endometrial cells. In conclusion, OT appears to not be involved in the initiation of luteal regression in sows and functional OTr are still present in the myometrium during early pregnancy (days 14-16).

Effect of neonatal or adult heat acclimation on testicular and epididymal morphometry and sperm production in rats.

The accessory gland weight, testicular and epididymal morphometry and sperm production were analyzed in four groups of rats housed at 20 or 34°C: (1) control rats (CR) kept at 20°C from birth to day 90; (2) adult heat-acclimated rats (AHA) kept at 20°C from birth to day 45 followed by 34°C to day 90; (3) neonatal heat-acclimated rats (NHA) kept at 34°C from birth to day 90 and (4) de-acclimated rats (DA) kept at 34°C from birth to day 45 followed by 20°C to day 90. In NHA and DA rats, accessory gland weight was higher than in controls. Despite the lack of differences in testicular and epididymal morphometry, curvilinear velocity of spermatozoa was lower in the NHA group compared to controls. Areas of seminiferous tubules were lower in the DA than in CR and NHA groups, however, sperm concentration and motility were not affected by the treatment in this group. In AHA rats, epithelium of approximately 20% of seminiferous tubules was degenerated and Sertoli cell number was lower in the remaining tubules. In contrast to sperm motility, epididymal duct area, area of the duct occupied by spermatozoa and cauda epididymis sperm concentration were lower in AHA rats than in the other groups. In conclusion, neonatal heat acclimation did not affect the testicular morphometry and epididymal sperm concentration, suggesting adjustment to high ambient temperature. On the contrary, adult heat acclimation of rats affected the examined parameters, leading to decreased sperm concentration.

Involvement of gonadotropins in induction of luteolysis in pigs.

In our previous study we have demonstrated that treatment of endometrial explants with LH increased 13,14-dihydro-15-ketoprostaglandin F(2alpha) (PGFM) accumulation in pigs. This was particularly visible on Days 14-16 of the estrous cycle. Action of gonadotropin in porcine endometrium appears to be mediated by LH/hCG receptors whose number is dependent on the day of the estrous cycle. In the current study i.v. infusion (1 hour) of hCG (200 IU) performed on Days 10 (n=4) and 12-14 (n=4) of the porcine estrous cycle did not affect plasma PGFM (ng/ml+/-SEM) concentrations. In contrast, administration of hCG on Days 15-17 produced, depending on plasma PGFM level before the infusion period, three different types of response: I. plasma PGFM surge of amplitude 0.62+/-0.15 was observed when the mean basal pre-infusion PGFM plasma level was 0.23+/-0.05 (n=6 gilts); II. the delayed PGFM surge of amplitude 0.62+/-0.15 was determined when basal pre-infusion PGFM level was 0.80+/-0.20 (n=6); and III. lack of PGFM response to hCG was found when basal pre-infusion PGFM level was 1.09+/-0.61 (n=6). Concentrations of plasma PGFM before and after saline infusion did not differ on Days 12-14 and 16 of the estrous cycle. In the next experiment blood samples were collected every 1 hour on Days 12-19 of the estrous cycle to determine concentrations of LH, PGFM and progesterone in four gilts. In particular gilts, plasma peaks of LH closely preceded surges of PGFM in 72.7, 84.6, 75.0 and 66.6 percent, respectively. The highest PGFM surges followed a decline in plasma progesterone concentration. We conclude that the increased PGF(2alpha) metabolite production after hCG infusion during the late luteal phase of the estrous cycle as well as the relationship between plasma LH and PGFM peaks suggest the LH involvement in the elevation of endometrial PGF(2alpha) secretion in pigs, and, in consequence, induction of luteolysis.

Secretion of estradiol-17beta by porcine mammary gland of ovariectomized steroid-treated sows.

Although the mammary gland of many species secretes estradiol (E(2)), nothing is known of E(2) secretion in the porcine gland. The present study was designed to investigate whether porcine mammary gland was a source of E(2), and to test the influence of individual and combined effects of exogenous progesterone and estradiol benzoate (EB) on the secretion of E(2). Immature crossbred gilts were ovariectomized at 7 months of age followed by 4 weeks later by steroid hormone replacement therapy to produce estradiol and progesterone (P(4)) blood concentrations similar to those observed during a normal estrous cycle. Arterial and venous blood plasma (from carotid artery and anterior mammary vein, respectively) were sampled for 2h at 10 min intervals. Plasma concentrations of progesterone, androstenedione (A(4)), testosterone (T), estrone (E(1)) and estradiol were determined by RIA. In all gilts treated with progesterone alone or in combination with EB, concentrations of P(4), A(4) and E(1) in blood collected from venous outflow were lower compared to concentrations in arterial blood, whereas concentrations of E(2) were higher in blood plasma from the anterior mammary vein compared to plasma from the carotid artery. The results indicated that the porcine mammary gland secreted E(2). Increased concentrations of plasma E(2) collected only from P(4)-treated animals suggested that progesterone activated enzymes involved in steroidogenesis in porcine mammary gland, or those utilized in its metabolism.

Prolactin, progesterone and luteinizing hormone secretion after bromocriptine (CB-154) treatment in cyclic sows.

The effect of bromocriptine (CB-154) on prolactin, progesterone and luteinizing hormone (LH) secretion was studied in cyclic sows. Four sows were given subcutaneous injections of bromocriptine on Day 14 of the estrous cycle (70 mg CB-154) and again on Day 16 of the cycle (50 mg CB-154). Two control sows were injected with vehicle at similar time intervals. Blood samples were taken four times daily (0700, 1100, 1500 and 1900 h) from Day 11 of the estrous cycle to Day 2 of the following estrous cycle. Prolactin peaks during the estrous cycle were not observed after CB-154 treatment. CB-154 treatment had no effect on plasma LH concentration, but plasma progesterone concentrations appeared to fluctuate more and slowly decreased.

The concentrations of catecholamines and oxytocin receptors in the oviduct and its contractile activity in cows during the estrous cycle.

UNLABELLED: In vitro experiments on oviducts of cyclic cows were undertaken to study: (1) the content of dopamine (DA), noradrenaline (NA) and adrenaline (A) in infundibulum, ampulla and isthmus, (2) the concentration of oxytocin receptors (OTR) in oviductal tissues and (3) the motility of ampulla and isthmus. Changes of DA content were observed in the infundibulum and the ampulla with maximal values occurring on Days 6-10 of the estrous cycle. The mean NA content was greatest in infundibulum

Effect of an oxytocin antagonist on prostaglandin F2 alpha secretion and the course of luteolysis in sows.

The role of oxytocin (OT) in the regulation of prostaglandin F2 alpha (PGF2 alpha) secretion during luteolysis in gilts was studied using a highly specific OT antagonist (CAP-581). In Experiment 1 gilts on Days 14 to 19 of the oestrous cycle in Latin square design were used, to determine the dose and time of application of OT and CAP. In Group I (n = 6) gilts were treated intravenously with saline or with 10, 20 and 30 IU of OT. Concentrations of the main PGF2 alpha metabolite i.e. 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were measured in blood samples as uterine response to the treatment. Twenty IU of OT was the most effective to stimulate PGFM release and this dose was used after CAP treatment in gilts of Groups II, III and IV. Gilts of Group II (n = 3) were injected into the uterine horns (UH) with saline (5 ml/horn) or CAP (2 mg, 3 mg and 4 mg; half dose/horn) and OT was injected (i.v.) 30 min thereafter. Any of the CAP doses given into the UH affected PGFM plasma concentrations stimulated by OT. In Group III (n = 4) gilts were infused (i.v.) for 30 min with CAP (9 mg, 14 mg and 18 mg/gilt) followed by 20 IU of OT. All doses of CAP effectively inhibited OT-stimulated PGF2 alpha release, therefore 9 mg was selected for the further studies. Gilts of Group IV (n = 4) received OT 4, 6 and 8 h after CAP to define how long CAP blocks the OT receptors. Concentrations of PGFM increased after any of this period of time. Thus, we concluded that 9 mg of CAP infused every 4 h will effectively block OT receptors. In Experiment 2, gilts (n = 4) received CAP as a 30-min infusion every 4 h on Days 12-20 of the oestrous cycle. Control gilts (n = 3) were infused with saline. CAP infusions diminished the height of PGFM peaks (P < 0.05). Frequency of the PGFM (P < 0.057) and OT (P < 0.082) peaks only tended to be lower in the CAP-treated gilts. Peripheral plasma concentrations of progesterone (P4) and oestradiol-17 beta (E2) and the time of luteolysis initiation as measured by the decrease of P4 concentration were the same in CAP- and saline-treated gilts. The macroscopic studies of the ovaries in gilts revealed lack of differences between groups. We conclude that OT is involved in the secretion of luteolytic PGF2 alpha peaks but its role is limited to controlling their height and frequency. Blocking of OT receptors did not prevent luteolysis in sows.

The effect of interleukin-1ß, interleukin-6, and tumor necrosis factor-α on estradiol-17ß release in the myometrium: the in vitro study on the pig model.

Estradiol-17ß (E2) is a potent regulator of early pregnancy and the estrous cycle in pigs. Production of E2 occurs in the porcine myometrium, but the factors involved in its regulation are unknown. In this in vitro study, it was investigated whether interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α affect the release of E2 from the porcine myometrium on Days 10 to 11, 12 to 13, and 15 to 16 of pregnancy and the estrous cycle. The expression of the cytochrome P450 family 19 (CYP19) gene and the presence of the aromatase cytochrome P450 protein in the myometrium confirmed the ability of the tissue to produce E2. In gravid pigs, the expression of IL1RI mRNA and IL6R mRNA was markedly increased on Days 15 to 16 of gestation, whereas TNFRI mRNA was increased on Days 10 to 11 of gestation. In cyclic pigs, the expression of myometrial IL1RI mRNA did not differ among the studied days, although the expression of IL6R and TNFRI mRNAs was increased on Days 15 to 16. In gravid pigs, IL-1ß, IL-6, and TNF-α increased myometrial E2 secretion on Days 15 to 16 but did not affect E2 release on Days 10 to 11 and 12 to 13 of pregnancy. In cyclic pigs, IL-1ß, IL-6, and TNF-α did not increase myometrial E2 release. In conclusion, IL-1ß, IL-6, and TNF-α affected myometrial E2 release in a manner that is dependent on the physiologic status of the female. The porcine myometrium expresses IL1RI, IL6R, and TNFRI genes and is the target tissue for IL-1ß, IL-6, and TNF-α. In gravid pigs, IL-1ß, IL-6, and TNF-α may increase myometrial release of E2 in vitro specifically on Days 15 to 16 of pregnancy. These findings may be of interest to researchers using pigs as an animal model for fetal programming.