Effects of nutritional cues on the duration of the winter anovulatory phase and on associated hormone levels in adult female Welsh pony horses (Equus caballus)

<p>Abstract</p> <p>Background</p> <p>Mares have an annual reproductive rhythm, with a phase of inactivity in midwinter. The aim of this study was to determine the impact of food restriction on physiological and metabolic hallmarks of this rhythm.</p> <p>Methods</p> <p>Over three successive years, 3 groups of 10 mares were kept under natural photoperiod. A 'well-fed' group was fed to maintain the mares in good body condition; a 'restricted' group received a diet calculated to keep the mares thin and a 'variable' group was fed during some periods like the 'restricted' group and during some other periods like the 'well-fed' group, with the aim of mimicking the natural seasonal variation of pasture availability, but a few months in advance of this natural rhythm.</p> <p>Results</p> <p>Winter ovarian inactivity always occurred and was long in the restricted group. In contrast, in the 'well-fed' group, 40% of mares showed this inactivity, which was shorter than in the other groups. Re-feeding the 'variable' group in autumn and winter did not advance the first ovulation in spring, compared with the 'restricted' group. Measurements of glucose and insulin concentrations in mares from the 'restricted' group during two 24 h periods of blood sampling, revealed no post-prandial peaks. For GH (Growth hormone), IGF-1 and leptin levels, large differences were found between the 'well-fed' group and the other groups. The glucose, insulin, GH and leptin levels but not melatonin level are highly correlated with the duration of ovulatory activity.</p> <p>Conclusions</p> <p>The annual rhythm driven by melatonin secretion is only responsible for the timing of the breeding season. The occurrence and length of winter ovarian inactivity is defined by metabolic hormones.</p

FOXL2 is a Progesterone Target Gene in the Endometrium of Ruminants

Forkhead Box L2 (FOXL2) is a member of the FOXL class of transcription factors, which are essential for ovarian differentiation and function. In the endometrium, FOXL2 is also thought to be important in cattle; however, it is not clear how its expression is regulated. The maternal recognition of pregnancy signal in cattle, interferon-Tau, does not regulate FOXL2 expression. Therefore, in the present study, we examined whether the ovarian steroid hormones that orchestrate implantation regulate FOXL2 gene expression in ruminants. In sheep, we confirmed that FOXL2 mRNA and protein was expressed in the endometrium across the oestrous cycle (day 4 to day 15 post-oestrus). Similar to the bovine endometrium, ovine FOXL2 endometrial expression was low during the luteal phase of the oestrous cycle (4 to 12 days post-oestrus) and at implantation (15 days post-oestrus) while mRNA and protein expression significantly increased during the luteolytic phase (day 15 post-oestrus in cycle). In pregnant ewes, inhibition of progesterone production by trilostane during the day 5 to 16 period prevented the rise in progesterone concentrations and led to a significant increase of FOXL2 expression in caruncles compared with the control group (1.4-fold, p < 0.05). Ovariectomized ewes or cows that were supplemented with exogenous progesterone for 12 days or 6 days, respectively, had lower endometrial FOXL2 expression compared with control ovariectomized females (sheep, mRNA, 1.8-fold; protein, 2.4-fold; cattle; mRNA, 2.2-fold; p < 0.05). Exogenous oestradiol treatments for 12 days in sheep or 2 days in cattle did not affect FOXL2 endometrial expression compared with control ovariectomized females, except at the protein level in both endometrial areas in the sheep. Moreover, treating bovine endometrial explants with exogenous progesterone for 48h reduced FOXL2 expression. Using in vitro assays with COS7 cells we also demonstrated that progesterone regulates the FOXL2 promoter activity through the progesterone receptor. Collectively, our findings imply that endometrial FOXL2 is, as a direct target of progesterone, involved in early pregnancy and implantation

Nucleologenesis and the onset of transcription in the eight-cell bovine embryo : fine-structural autoradiographic study

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Perioestrous patterns of circulating LH, FSH, prolactin and oestradiol-17 beta in the gilt.

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Perioestrous patterns of circulating LH, FSH, prolactin and oestradiol-17 beta in the gilt.

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Patterns of circulating LH, FSH, prolactin and E2 17 β in the gilt during the follicular phase of the oestrus cycle

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Nutritional programming and the reproductive function of the offspring

International audienceThere is ample evidence on the importance of maternal nutrition during pregnancy on fetal and offspring development. In ruminant females, the pool of oocytes is complete and definitive before birth, based on the resting reserve of primordial follicles established during fetal life, which represent the lifespan supply for the female’s fertilisable oocytes, whereas in males, although the production of spermatozoa is a continuous process throughout post-pubertal life. Sertoli cells, which play a central role in the development of a functional testis, proliferate during pre- and post-natal life, coordinating testicular development. Both male and female fertility may, therefore, be affected by the maternal environment, but studies on the effects of developmental nutritional conditions on reproductive function and fertility, both in males and females, are relatively scarce. In humans, intrauterine growth retardation has been associated with abnormal ovarian development, characterised by a decreased volume of primordial follicles in the ovarian cortical tissue in girls, and a higher incidence of cryptorchidism in boys, with subsequent low sperm counts in adulthood. Age at puberty and gonadotropin and inhibin B plasma concentrations are also affected. Animal studies suggest both in males and females that maternal undernutrition during pregnancy may affect pituitary response to GnRH and gonadal development and function, depending on the timing and magnitude of the undernutrition. Excess nutrition, which is often associated with intrauterine growth retardation in domestic species, induces effects on the onset of puberty and both testicular and ovarian function, maybe through the observed reduction in fetal growth. This review addresses the influence of maternal nutrition on offspring reproductive function using examples in humans and animals, with particular focus on ruminants

Evolution des secretions hormonales (LH,FSH,prolactine,E2 17beta) pendant la phase folliculaire du cycle sexuel chez la truie.

National audienc

Le placenta

Chapitre 20National audienc