Consequences of rearing feeding programme on the performance of rabbit females from 1st to 2nd parturition.

To evaluate how rearing programmes could affect resources allocation and reproductive performance of primiparous rabbit females, a total of 118 rabbit females were used to evaluate the effects of five rearing feeding programmes on their performance from 1st to 2nd parturition: CAL, fed ad libitum C diet (11.0 MJ digestible energy (DE), 114 g digestible protein (DP) and 358 g NDF/kg dry matter (DM) until 1st parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until 1st parturition; F, fed ad libitum with F diet (8.7 MJ DE, 88 g DP and 476 NDF/kg DM) until 1st parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until 1st parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until 1st parturition. From 1st parturition, C diet was ad libitum offered to all the experimental groups until 2nd parturition. CAL females presented lower feed intake than females of F, FC and FCF groups in the 1st week of lactation (on av. -16.6%; P<0.05). During 1st lactation, the perirenal fat thickness change in CAL females was not different from 0 (+0.02 mm), while in the other four groups it increased (on av. +0.44 mm; P<0.05). Plasma of females fed with F diet during rearing (F, FC and FCF) had lower non-esterified fatty acids content than those exclusively fed with C diet (-0.088 and -0.072 mmol/l compared to CAL and CR, respectively; P<0.05). FCF litters had higher weight than F litters at day 21 of lactation (+247 g; P<0.05), but FCF litter had significantly lower weight than FC litters at weaning (+170 g; P<0.05). CR females had the shortest average interval between the 1st and 2nd parturition (49 days) and FCF females the longest (+ 9 days compared to CR; P<0.05). At 2nd parturition, liveborn litters of F females were larger and heavier than litters of FCF females (+2.22 kits and +138 g; P<0.05), probably due to the lower mortality at birth of F litters (-16.5 percentage points; P<0.05). In conclusion, rearing females on fibrous diets seems to increase the ability of primiparous rabbit females to obtain resources, especially at the onset of lactation.

The different effects of linseed and fish oil supplemented diets on insulin sensitivity of rabbit does during pregnancy.

This study investigates the effects of linseed (rich in ɑ-linolenic acid (ALA)) and fish oil (rich in eicosapentaenoic (EPA) and docosahexaenoic acid (DHA)) supplementation on the insulin resistance of pregnant rabbits. Two months before insemination, the rabbits (15 animals/group) were fed different diets: commercial standard (group C), supplemented with 10% extruded linseed (group L), and 3% fish oil (group FO). The L group does showed both the highest feed intake before AI (P < 0.01) and the highest body weight (BW) throughout pregnancy (P < 0.001). The L does yielded less milk than the C does (P < 0.001); however, no differences were observed in either weight or size of litter at weaning. Regardless of diet, insulin concentrations and HOMA-IR values were higher during the first half of pregnancy (P < 0.001). Nevertheless, the L does showed higher mean insulin concentrations than FO rabbits (P < 0.01) and the lowest glucose clearance (P < 0.01) during pregnancy. On the other hand, pregnant FO rabbits showed the lowest glucose concentrations (P < 0.05) and the lowest Homeostasis model assessment values for insulin resistance (HOMA-IR, P < 0.05) as well as a faster restoration of baseline glucose levels following glucose load (P < 0.001). Before and during pregnancy, the BW of the rabbits was positively related to fasting sample- and tolerance test-derived indices of insulin resistance (P < 0.05) suggesting that a high pre-pregnancy BW predisposes to gestational insulin resistance. Linseed supplementation increased BW and predisposed to insulin resistance during pregnancy; whereas, fish oil improved insulin sensitivity without significant changes in BW.

The presence and distribution of cannabinoid type 1 and 2 receptors in the mandibular gland: The influence of different physical forms of diets on their expression in piglets.

We explored the expression and cell type distribution of cannabinoid receptors type 1 (CB1) and cannabinoid receptors type 2 (CB2) in the mandibular glands of pigs in relation to different physical forms of the diet. Thirty-two crossbred growing pigs (ages 5-6 weeks) were randomly allotted to four experimental groups (eight pigs/group) and fed four different physical types of the same diet for 4 weeks: finely ground pellet (FP), coarsely ground meal (CM), coarsely ground pellet (CP) and coarsely ground extruded (CE) with dMEAN of 0.46, 0.88, 0.84 and 0.66 mm respectively. At the end of the feeding trial, the pigs were euthanized and the mandibular gland was collected after dissection. By immunohistochemistry, positive signals for CB1 were found in the cytoplasm of duct epithelial cells of pigs fed CP, FP and CE diets and in the serous cells of mixed acini in pigs fed the coarser CM diet. Positive signals for CB2 were detected in duct epithelial cells and in neurons of ganglia close to major secretory ducts of all pigs. The differential expression and localization of these receptors in response to variable chewing activity due to the type of diet suggest that endocannabinoids may influence the functional activity of the mandibular gland by modifying qualitative and/or quantitative aspects of salivary secretion.

Serum concentration dynamic of energy homeostasis hormones, leptin, insulin, thyroid hormones, and cortisol throughout canine pregnancy and lactation.

Pregnancy and lactation represent critical periods of canine reproductive life and different hormones are required to maintain homeostasis and the correct energy requirements. The aim of this study was to evaluate leptin, insulin, triiodotyronine (T3), thyroxin (T4) and cortisol serum concentrations to better describe the canine maternal energy metabolism. Twelve Bloodhound bitches that had at least one litter and were considered to be healthy submitted blood samples every 15 days starting from day 0 (ovulation) throughout pregnancy up to the end of lactation (day 120). We found that leptin concentrations increased from day 0 to reach maximum value at day 45 (P < 0.001), decreased at day 60 (P < 0.05) and rose again at day 105 and day 120 (P < 0.05 and P < 0.01 respectively). Insulin concentrations significantly increased during pregnancy peaking at day 60 (P < 0.05). After parturition dropped and reached progressively lower values similar to those at day 0 at the end of lactation. During pregnancy Body Weight was in low correlation with leptin (r = 0.32, P < 0.01) and there was no correlation with insulin (r = 0.13, P > 0.1); moreover, no correlation was found during lactation. T3 concentrations showed a U-shaped trend with a significant reduction at day 75 (P < 0.05). T4 concentrations fluctuated without any significant change (ranging from 27.0 ± 1.6 nmol/l to 32.1 ± 1.9 nmol/l). Cortisol concentrations ranged within the reference values (minimal value at day 30 (49.8 ± 6.3 nm/L) and maximal value at day 45 (72.5 ± 16.1 nm/L)). Our study states that canine pregnancy and lactation evoke many hormonal changes necessary to mother and fetuses. In particular, this is the first report regarding the pattern of leptin during whole pregnancy and lactation. The present work lays the groundwork for further studies on endocrine homeostatic mechanisms using the dog as a model for human medicine.

Expression of nerve growth factor and its receptors in the uterus of rabbits: functional involvement in prostaglandin synthesis.

The aim of the present study was to evaluate: (1) the presence of nerve growth factor (NGF), neurotrophic tyrosine kinase receptor 1 (NTRK1), and nerve growth factor receptor (NGFR) in the rabbit uterus; and (2) the in vitro effects of NGF on PGF2α and PGE2 synthesis and on the PGE2-9-ketoreductase (PGE2-9-K) activity by the rabbit uterus. Nerve growth factor, NTRK1, and NGFR were immunolocalized in the luminal and glandular epithelium and stroma cells of the endometrium. reverse transcriptase polymerase chain reaction indicated the presence of messenger RNA for NGF, NTRK1, and NGFR in the uterus. Nerve growth factor increased (P < 0.01) in vitro secretions of PGF2α and PGE2 but coincubation with either NTRK1 or oxide nitric synthase (NOS) inhibitors reduced (P < 0.01) PGF2α production and blocked (P < 0.01) PGE2 secretion. Prostaglandins releases were lower (P < 0.01) than control when uterine samples were treated with NGF plus cyclooxygenase inhibitor. However, addition of NGFR inhibitor reduced (P < 0.01) PGF2α secretion less efficiently than NTRK1 or NOS inhibitors but had no effect on PGE2 yield. Nerve growth factor increased (P < 0.01) the activity of PGE2-9-K, whereas coincubation with NTRK1 or NOS inhibitors abolished (P < 0.01) this increase in PGE2-9-K activity. However, cotreatment with either cyclooxygenase or NGFR inhibitors had no effect on PGE2-9-K activity. This is the first study to document the distribution of NGF/NTRK1 and NGFR systems and their effects on prostaglandin synthesis in the rabbit uterus. NGF/NTRK1 increases PGF2α and PGE2 productions by upregulating NOS and PGE2-9-K activities, whereas NGF/NGFR augments only PGF2α secretion, through an intracellular mechanism that is still unknown.

Gene Expression and Localization of NGF and Its Cognate Receptors NTRK1 and NGFR in the Sex Organs of Male Rabbits.

Experiments were devised to characterize the expression of nerve growth factor, beta polypeptide (NGF), and its cognate receptors neurotrophic tyrosine kinase receptor type 1 (NTRK1) and nerve growth factor receptor (NGFR) in rabbit male sex organs, as well as the concentrations of NGF in both seminal and blood plasma of sexually mature male rabbits. Immunoreactivity and gene expression for NGF and cognate receptors were detected in testis, prostate gland and seminal vesicle. The highest levels of NGF and NTRK1 transcripts were found in the prostate, while intermediate expressions were found in the testis. NGFR transcripts were expressed at the same levels in both testis and prostate and were more abundant than in seminal vesicles. The widespread distribution of NGF in all prostate glandular cells, together with its relative high mRNA abundance, confirms that the prostate of rabbits is the main source of this neurotrophin. In conclusion, the present data suggest that the NGF system is involved in the testicular development and spermatogenesis of rabbits and that NGF may act as a potential ovulation-inducing factor being abundantly present in the seminal plasma.

Food restriction during pregnancy in rabbits: effects on hormones and metabolites involved in energy homeostasis and metabolic programming.

This study examined the effects of food restriction during rabbit pregnancy on hormones and metabolites involved in energy homeostasis and metabolic programming. Pregnant does were assigned to four groups: the control group was fed a standard ration while the others received a restricted amount of food (30% restriction) during early (0-9 days), mid (9-18 days), and late (19-28 days) pregnancy. The pregnancy induced a coordinated range of adaptations to fulfil energy requirements of both mother and foetus, such as hyperleptinaemia and hyperinsulinaemia, reduced insulin sensitivity, increased cortisol and non-esterified fatty acid. Food restriction altered leptin, insulin, T3, non-esterified fatty acids and glucose concentrations depending on the gestational phase in which it was applied. Collectively, present data confirm that the endocrinology of pregnancy and the adaptive responses to energy deficit make the rabbit an ideal model for studying nutritional-related disorders and foetal programming of metabolic disease.

Effects of a bacterial lipopolysaccharide on the reproductive functions of rabbit does.

Systemic and local infections and inflammations are known to cause infertility in humans and animals. However, the mechanisms by which infection/inflammation induces infertility are only partially known. The objectives of this study were: (i) to provide models of systemic (acute) and local (sub-acute) inflammation by intra-peritoneal injection or intra-cervical deposition of lipopolysaccharide (LPS) in the rabbit and (ii) to assess their effects on uterine tissues and sperm transport in the genital tract of rabbit does. Intra-peritoneal administration of different doses of LPS induced systemic effects such as fever, anorexia and changes in white blood cells (WBC) count. In our study, LPS inoculation (100µg/kg) produced an inflammation-like status that lasted for about 3 days, with minimal distress for the animals. Intra-peritoneal administration of LPS 60h before artificial insemination induced a rapid increase of IL-1ß concentrations. The intra-cervical inoculation of LPS did not show any systemic effects, as confirmed by the lack of changes in body temperature, feed intake and WBC count. Histological examination of uterine tissues showed an endometritis-like inflammation status in LPS-treated does, more severe in those inoculated intra-cervically. The number of spermatozoa recovered from uterine horns and oviducts of intra-cervically treated does was less than that retrieved from intra-peritoneally treated animals and controls. These results suggest (i) that sub-acute or acute inflammation may cause infertility by compromising the uterine environment and/or impairing sperm transport and (ii) that the LPS-induced -infection/inflammation experimental model is useful for studying the mechanisms involved in reproductive dysfunctions in the rabbit.

Ovarian hormones and fasting differentially regulate pituitary receptors for estrogen and gonadotropin-releasing hormone in rabbit female.

To investigate the mechanisms by which caloric restriction affects reproductive function in female rabbits, we measured, in animals intact or ovariectomized (OVX) estrogen-primed and fed ad libitum or fasted for 48 h, the adenohypophysial expression of estrogen receptor-alpha (ESR1) and gonadotropin releasing hormone receptor (GnRHR) and the dynamic secretion of LH following GnRH stimulation. Fasting increased the number of GnRHR-immunoreactive (-IR) cells in intact animals, whereas reduced the density of ESR1-IR cells in OVX rabbits. Estrogen priming decreased the number of ESR1-IR cells in fasted and OVX animals. Ovariectomy increased the number of ESR1-IR cells in fed rabbits, but caused an opposite effect in both fed and fasted animals treated with estrogen. Fasting down regulated the mRNA levels for ESR1 and GnRHR. Estrogen-priming reduced the abundance for ESR1 mRNA in both fed and fasted rabbits, and that for GnRHR in fasted rabbits. Ovariectomy halved ESR1 mRNA levels independently of treatment and feeding condition, whereas increased (P < 001) that for GnRHR in estrogen-primed rabbits. In all rabbits, an LH surge occurred 30 min after GnRH injection but the lowest levels were found in intact fasted rabbits and the highest in fasted, estrogen-primed animals. The LH profile was similar in intact and OVX rabbits and neither fasting nor estrogen priming modified it. In conclusion, fasting differentially modifies the ESR1 and GnRHR expression in the pituitary, depending on the presence of gonadal hormones, indicating complex interactions between metabolic signals and ovarian steroids.

Expression of the cannabinoid receptor type 1 in the pituitary of rabbits and its role in the control of LH secretion.

The aim of this study was to elucidate the possible direct regulatory role of the endocannabinoids in the modulation of LH secretion in rabbits, a reflex ovulator species. The cannabinoid receptor type 1 (CB1) was characterized by RT-PCR techniques in the anterior pituitary of intact and ovariectomized does treated with GnRH and primed with estrogen and CB1 antagonist, rimonabant. Cannabinoid receptor type 1 immune reaction was evidenced by immunohistochemistry in the cytoplasm of approximately 10% of the pituitary cells with a density of 8.5 ± 1.9 (per 0.01 mm(2)), both periodic acid-Schiff positive (30%) and negative (70%). All CB1-immunoreactive cells were also immune reactive for estrogen receptor type 1. Ovariectomy, either alone or combined with estrogen priming, did not modify the relative abundances of pituitary CB1 mRNA, but decreased (P < 0.01) the expression of estrogen receptor type 1 mRNA. Treatment with CB1 antagonist (rimonabant) inhibited (P < 0.01) LH secretory capacity by the pituitary after GnRH injection, and estrogen priming had no effect. The present findings indicate that the endocannabinoid system is a potential candidate for the regulation of the hypothalamic-pituitary-ovarian axis in reflex ovulatory species.

Orexin system expression in the gastrointestinal tract of pigs.

The aim of the present study was to characterize the expression of both proteins and gene transcripts for orexins (OXA and OXB) and their cognate receptors (OX1R and OX2R) in the different gastrointestinal sections of pigs. Using immunohistochemistry, OXA and OXB were found to be co-expressed in the same endocrine cells localized in the basal third of the glands of the body portion of the stomach. Using double immunostaining technique, these orexin-immunoreactive (IR) cells co-stored ghrelin and gastrin. Apparently, OX1R was also expressed within the same cells, forming the tubular gastric gland which displayed positive immunostaining for orexins and the other peptides. Neurons of the enteric nervous system of the stomach were not immunolabeled. We did not find any definite OXA- or OXB-IR cells as well as any immunosignal for orexin receptors in sections of the duodenum, ileum, cecum and rectum. PPOX, OX1R, OX2R mRNA were similarly expressed in all the gastrointestinal tracts. Gastrin and ghrelin showed the highest levels of expression in the gastric mucosa, but their abundance decreased along the subsequent tracts. Thus, in pigs, orexins do not play any role in the local control of intestinal motility and secretion but may rather be involved as endocrine modulators for the regulation of feeding and metabolic homeostasis. However, the co-localization of ghrelin and gastrin with both orexins in the same endocrine cells of the gastric glands suggests that these gut peptides may collaborate in the regulation of gastric secretion, energy homeostasis, body weight and food intake.

Clinical efficacy of the GnRH agonist (deslorelin) in dogs affected by benign prostatic hyperplasia and evaluation of prostatic blood flow by Doppler ultrasound.

In six German Shepherds dogs, GnRH agonist implants (Deslorelin) were inserted subcutaneously one month after histological confirmation of benign prostatic hyperplasia (BPH). Prostatic volume (PV), characteristics of ejaculate, serum testosterone concentrations and Doppler parameters of prostatic and subcapsular arteries were detected at different time intervals, for 6 month. The prostatic volume showed a significantly reduction starting at day 37. The decrease in sperm concentration, motility and increase in morphological abnormal sperm were observed from day 22 to day 37, when it was no longer possible to obtain the ejaculate. The values of peak systolic velocity and end-diastolic velocity in prostatic and subcapsular arteries showed from day 11 a gradual decrease, significant at day 22 until day 37 and reaching the lowest values at day 52 until the end of observation. The power Doppler pixel intensity of both arteries showed a gradual decrease from day 5 until day 52. In particular, a significant decrease was observed for both arteries from day 11. Testosterone serum concentration decreased to undetectable levels by day 11 until the end of the observations. All these Doppler parameters and testosterone values were positively correlated with the prostatic volume. Furthermore, testosterone values were positively correlated with peak systolic velocity, end diastolic velocity and pixel numbers. The use of implants containing GnRH analogues, even in asymptomatic subjects, is effective for the control of BPH and the application of Doppler exam of prostatic blood flow represent an non-invasive tool for monitoring the response of medical treatment.

Power and pulsed Doppler evaluation of ovarian hemodynamic changes during diestrus in pregnant and nonpregnant bitches.

The aim of the study was to further characterize the relationship between hemodynamic changes in the ovary and luteal function in pregnant and nonpregnant bitches. Fourteen German Shepherd bitches were monitored three times a week from the first day of cytological diestrus (D1) until parturition or the end of diestrus (progesterone <2 ng/mL) by color Doppler, pulsed wave spectral Doppler, and power Doppler (PD) ultrasonography. By means of PD the total number of color pixels were calculated. The Doppler parameters evaluated were: peak systolic velocity (PSV), end diastolic velocity (EDV), and both resistive and pulsatility indices. Blood samples were collected three times a week throughout the experiment to determine progesterone (P4) concentrations. The length of diestrus in pregnant versus nonpregnant group was significantly shorter (P < 0.01; 57 ± 1 vs. 63 ± 1, respectively). By means of pulsed wave spectral Doppler the waveform showed a typical pattern of a low-resistive vessel characterized by a rapid systolic peak followed by a slow telediastolic decrease with a relatively high end-diastolic velocity. Blood flow parameters did not differ between left and right ovary. In both groups PSV and EDV showed a gradual decrease with the progress of diestrus; however, the values of PSV and EDV were significantly higher (P < 0.05) in the pregnant group versus nonpregnant group from D31 to D61 and from D49 to D58 respectively. Moreover, a significantly decrease (P < 0.05) of PSV and EDV in the pregnant group was observed from D46 to D58 and from D49 to D55, respectively. The resistive and pulsatility indices showed an increase during diestrus and the values were significantly lower (P < 0.05) in the pregnant group from D49 to D61. By means of PD, the pixel number was significantly higher (P < 0.05) in the pregnant versus nonpregnant group from D40 to D61. In particular, a significant decrease (P < 0.05) in the pixel number in the pregnant group was observed from D46 to D61. The comparison of the P4 values with the ovarian pixel number in the pregnant and nonpregnant group showed a direct correlation (r = 0.792, N = 59 and r = 0.774, N = 59, respectively). In particular, the P4 values were higher (P < 0.05) in the pregnant than in the nonpregnant group from D37 to D52. In conclusion, significant physiological differences between pregnant and nonpregnant bitches in terms of P4 and ovarian blood supply are reported. In addition it was possible to define that blood flow pattern during diestrus in pregnant bitches is not always closely related with P4 production.

Effects of feeding programme on the performance and energy balance of nulliparous rabbit does.

A total of 190 rabbit females were used to evaluate five feeding programmes from 9 weeks of age to the first parturition: CAL, fed ad libitum with a control diet (C: 11.0 MJ digestible energy (DE) and 114 g digestible protein (DP)/kg dry matter (DM)) until first parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until first parturition; F, fed ad libitum with a low-energy, high-fibre diet (F: 8.7 MJ DE and 88 g DP/kg DM) until first parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until first parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until first parturition. The rabbits were artificially inseminated at 18 weeks of age. CAL group had a higher mortality rate compared with the other groups between 9 and 12 weeks of age (34% v. 3%; P < 0.05) and during the last 3 weeks of first pregnancy (14% v. 3%; P < 0.05). The CAL and FC females presented higher BW and perirenal fat thickness (PFT) than CR females at 11 days of pregnancy (+0.41 kg and +0.6 mm; P < 0.05), with F females showing medium values. The type of feeding procedure did not affect the fertility rate of young females at first artificial insemination. Differences in BW disappeared at parturition, when only CAL females presented a greater PFT than CR and FC females (+0.3 mm; P < 0.05). In comparison with FCF, CAL females had smaller and thinner live born litters (-2.5 kits and -139 g, respectively; P < 0.05), with CR, F and FC females showing medium values. The low number of kits born alive for CAL females was because of their lesser total number of kits born (-1.7 kits; P < 0.05) and the greater mortality of their litters at birth (+13.9%; P < 0.05) compared with FCF females. Non-esterified fatty acid was higher in the blood of females fed C diet (CAL and CR) than in others at partum day (on average +0.15 mmol/l; P < 0.05). In conclusion, the ad libitum use of diets for lactating rabbit does throughout the rearing period could lead young rabbit females to present a higher risk of early death and smaller litter size at first parturition. Feed restriction or earlier use of suitably fibrous diets led females to achieve the critical BW and fat mass at first mating to ensure reproduction.

Immunolocalization, gene expression, and enzymatic activity of cyclooxygenases, prostaglandin e2-9-ketoreductase, and nitric oxide synthases in Mediterranean buffalo (Bubalus bubalis) corpora lutea during diestrus.

Immunopresence, gene expression, and enzymatic activity of cyclooxygenase 1 (COX1), COX2, PGE2-9-ketoreductase (PGE2-9-K), endothelial (eNOS), and inducible nitric oxide synthases (iNOS), and hormone in vitro production were examined in early, mid, late, and regressive buffalo corpora lutea (CL). COX1 immunosignals were detected in the cytoplasm of small luteal cells, COX2 in large luteal cells, and PGE2-9-K in all luteal cells. COX2 and PGE2-9-K immunosignals were greater in late CL. Immunopresence of both NOS types were evidenced in the nuclei and cytoplasm of all luteal cells, as well as in the nuclei of endothelial cells, during all stages studied. The eNOS and iNOS immunosignals increased during the early stage. COX1 transcripts were lower in late and regressive CL, COX2 in late, PGE2-9-K higher in regressive, and iNOS higher in early and lower in regressive CL. COX1 enzymatic activity was lower in regressive CL, COX2 increased in mid and late stages, and PGE2-9-K was higher in late CL. Endothelial NOS activity was higher during mid and late stages and lower in regressive, whereas iNOS was greater in late and lower in early. Progesterone in vitro release was higher in mid and lower in late phase, while PGF2α synthesis was higher in late CL and lower in regressive, and PGE2 was higher during regressive stage. These results support the idea that COX, NOS, and PGE2-9-K regulate buffalo CL life span. In particular, regressive CL seems involved in the development of the contralateral early CL, through the production of the luteotrophic PGE2.

Immunohistochemical detection of the orexin system in the placenta of cats.

The aim of the present study was to investigate the presence and distribution of cells containing orexin A (OXA), and orexin type 1 and 2 receptors (OX1R and OX2R, respectively) in the feline placenta by means of immunohistochemical technique. OXA was identified in several decidual and syncytiotrophoblastic cells present in the lamellar portion of the placenta. In the same placental structures, few decidual and syncytiotrophoblastic cells showed the presence of OX1R-like immunoreactivity. Characteristically, immunopositivity for OX2R, but not for OX1R, was evidenced in the cells of the glandular layer. The orexinic system was not expressed in the uterine structures that were not engaged by the chorion. Our results provide the first evidence of the presence of a placental orexinic system in a mammalian species. Orexin A and both OX1R and OX2R are unequally distributed within the cat placenta. Local OXA production and the presence of specific receptors, differentially expressed in the placental structures of the cat, suggest that the orexinic system may participate in placental growth and development as well as in the regulation of its steroidogenic capacity via endocrine, paracrine and/or autocrine mechanisms.

Ovulation induction in rabbit does: current knowledge and perspectives.

The profitability of rabbit farms has increased in recent years due primarily to improvements in the management of reproduction and genetic selection. This review summarizes the most important scientific papers relating to ovulation in rabbit does dealing in particular with: (a) studies from 1905 to the present day relating to ovulatory mechanisms in rabbit does; (b) research on the primary gonadotrophin-releasing hormone (GnRH), its analogues and their functions; and (c) descriptions of parenteral and intravaginal (iv.) treatments for induction of ovulation in does and their reported efficacies. The addition of GnRH analogues via the seminal dose (iv.) fulfils the need for a welfare-orientated method of inducing ovulation in rabbits. The structure, tissues, secretions, contractions, and innervations of the vagina in rabbits that can affect absorption profiles are reviewed in the context of recent reports of the achievement of high ovulation rates obtained by adding GnRH analogues directly to the seminal dose. This review demonstrates the possibility of ovulation induction in rabbits by the addition of GnRH synthetic analogues to the seminal doses and provides new perspectives for simplifying the AI technique.

Acute fasting before conception affects metabolic and endocrine status without impacting follicle and oocyte development and embryo gene expression in the rabbit.

Food deprivation affects female reproduction. The goal of the present study was to elucidate in the rabbit model the effects of acute energy restriction on ovarian function (follicle development, atresia rate and in vitro oocyte maturation) and embryonic development and gene expression of some candidate genes. Serum metabolic parameters (non-esterified fatty acids (NEFA), triglycerides, glucose, insulin and leptin concentrations) and endocrine markers (oestradiol-17ß and progesterone concentrations) were also studied. A control group of nulliparous does fed ad libitum and a 72-h fasted group were used. At the end of the nutritional treatment, the ovaries of half of the animals were retrieved while the other animals were re-fed and artificially inseminated to recover embryos at 84 h after insemination, during the luteal phase. At the end of fasting, increased serum NEFA and decreased leptin concentrations were observed in the fasted group, but no differences appeared in serum steroid concentrations, follicle population and atresia rate or nuclear and cytoplasmic oocyte maturation. In the luteal phase, insulin concentrations increased notably in the fasted group. The number of recovered embryos per female and the speed of embryo development were reduced in the food-deprived group. Acute fasting altered both metabolic and endocrine markers and embryo development, but follicle and oocyte development and embryo gene expression were not affected.

In vitro effects of gonadotropin-releasing hormone (GnRH) on Leydig cells of adult alpaca (Lama pacos) testis: GnRH receptor immunolocalization, testosterone and prostaglandin synthesis, and cyclooxygenase activities.

The main objective of this study was to examine the modulatory in vitro effects of gonadotropin-releasing hormone (GnRH) on isolated Leydig cells of adult alpaca (Lama pacos) testis. We first evaluated the presence of GnRH receptor (GnRHR) and cyclooxygenase (COX) 1 and COX2 in alpaca testis. We then studied the in vitro effects of buserelin (GnRH analogue), antide (GnRH antagonist), and buserelin plus antide or inhibitor of phospholipase C (compound 48/80) and COXs (acetylsalicylic acid) on the production of testosterone, PGE(2), and PGF(2α) and on the enzymatic activities of COX1 and COX2. Immunoreactivity for GnRHR was detected in the cytoplasm of Leydig cells and in the acrosomal region of spermatids. COX1 and COX2 immunosignals were noted in the cytoplasm of spermatogonia, spermatocytes, spermatids, Leydig cells, and Sertoli cells. Western blot analysis confirmed the GnRHR and COX1 presence in alpaca testis. The in vitro experiments showed that buserelin alone increased (P < 0.01) and antide and buserelin plus acetylsalicylic acid decreased (P < 0.01) testosterone and PGF(2α) production and COX1 activity, whereas antide and compound 48/80 counteracted buserelin effects. Prostaglandin E(2) production and COX2 activity were not affected by buserelin or antide. These data suggest that GnRH directly up-regulates testosterone production in Leydig cells of adult alpaca testis with a postreceptorial mechanism that involves PLC, COX1, and PGF(2α).

Aglepristone (RU534) administration to non-pregnant bitches in the mid-luteal phase induces early luteal regression.

The effect of the antiprogestagen aglepristone (10 mg/kg bw), administered at days 29 and 30 following the estimated day of LH surge (day 0), on corpora lutea (CL) function was examined during the diestrus phase of non-pregnant bitches. Aglepristone shortened (P < 0.01) the luteal phase and complete luteolysis (progesterone <2 ng/mL) was observed at days 40.8 +/- 3.5 and 71.5 +/- 4.6 (means +/- SD; n = 9/group) in treated and control bitches, respectively. Peripheral estradiol-17beta concentrations declined from 91.5 +/- 14.3 pg/mL at day 9 to 50 pg/mL at day 18, remaining at approximately the same levels thereafter in both treated and control bitches. Intraluteal in vitro synthesis of progesterone and estradiol-17beta released by CL explanted at day 38 from control bitches (511.9 +/- 285.6 and 40.7 +/- 17.2 pg/mg protein, respectively) did not differ from that of treated. From day 38, intraovarian hemodynamic variables (arterial blood flow, systolic peak, and end-diastolic velocities), monitored by color-coded and pulsed Doppler, decreased more steeply (P < 0.01) in aglepristone-treated (n = 4) than in control (n = 4) bitches, whereas the resistance index increased (P < 0.01) in treated animals. All the blood flow parameters were undetectable at 60 +/- 3.6 and 68 +/- 2.0 days (medians +/- SD) after LH peak in treated and control bitches, respectively. In conclusion, aglepristone administration to dogs during the mid-luteal phase markedly accelerates the luteolytic process which is accompanied by a parallel decline in ovarian blood flow supply with a shift from approximately 8 to 10 days.