Ovulation is timed by neural signals originating at the suprachiasmatic nucleus (SCN) that trigger ovulation when converge with high estradiol levels, which indicates the maturation of ovarian follicles. We have shown that the hypothalamic regulation of ovulation is asymmetrical and we hypothesized that the paired SCN could contribute to such symmetries. We unilaterally lesioned the SCN of rats at each stage of the estrous cycle and evaluated the acute effects on the progression of their estrous cycle, follicular development and ovulation. Lesions disrupted the estrous cycle when performed in estrus/metestrus but not in diestrus/proestrus. Abnormalities in follicular development were observed in the non-ovulating lesioned rats and this was independent of the side of the SCN destroyed and the stage of the cycle when surgery was performed. Groups of lesioned rats were then hormonally primed with GnRH or estradiol to assess the neuroendocrine pathway altered by the treatment. GnRH restored ovulation, suggesting that both SCN are needed for proper triggering of the preovulatory surge of GnRH and that unilateral lesion does not impair the sensitivity of the pituitary or the ovary to GnRH and gonadotropins, respectively. Estradiol was asymmetrically effective to restore ovulation in rats lesioned in estrous, partially effective on rats operated at diestrus and ineffective on metestrus. Our results indicate that the SCN regulates the activity of the hypothalamic-pituitary-ovarian axis not only by modulating the preovulatory surge of GnRH/gonadotropins, but also by promoting the hypothalamic integration of estrogenic signals from the ovaries in an asymmetric and stage-dependent fashion.

In brief Fertility has decreased due to advanced maternal age and the rising prevalence of the metabolic syndrome. Using quantitative image analysis methods, we show that these factors are associated with delayed preimplantation embryo development in a mouse model. Abstract Delayed maternal age, obesity and diabetes are associated with reduced fertility. We investigated how age and obesity/metabolic syndrome impact fertility and hypothesized that its decrease is due to defects in preimplantation embryo development. Three groups of female C57Bl6 mice (12 weeks, 9 months and 1 year old) were fed either a high-fat diet for 8 weeks, to induce obesity and the metabolic syndrome, or a control chow diet. Body weight and composition, glucose tolerance and insulin resistance were assessed. Fecundity was evaluated by mating and pregnancy rates, as well as by the number of embryos. Embryo quality was assessed morphologically, and cell fate composition was analysed in preimplantation embryos by state-of-the-art single-cell quantitative confocal image analysis. The high-fat diet was associated with increased adiposity, glucose intolerance and insulin resistance, especially in the older mice. Fecundity was affected by age more than by the diet. Both age and high-fat diet were associated with reduced cell fate allocation, indicating a delay in the preimplantation embryo development, and with increased expression of GATA3, an inhibitor of placentation. These results support that age and the metabolic syndrome reduce fertility through mechanisms which are present at conception or very early in pregnancy.

Adverse trends in reproductive function are a concern in humans, companion, livestock, and wildlife species. This study indicates that equine populations are at risk of a comparable decline in sperm progressive motility. There is increasing evidence reporting geographically sensitive adverse trends in human semen quality, with parallel trends observed in the dog sentinel. Despite significant economic and welfare complications associated with poor testicular function, trends in current equine populations are undetermined. Given the predictive value of sperm progressive motility (PMOT) in male factor infertility and fertilisation potential, research determining trends in this parameter is warranted. This research analysed trends in stallion sperm PMOT through systematic review and meta-regression. Using a comprehensive search strategy, Scopus, Embase (Ovid), Medline (Ovid), and VetMed (CAB direct) were scoped for eligible data. Using best practices, 230 meta-data points from 229 articles published from 1991 to 2021 were collated for meta-regression analysis. Sperm PMOT declined significantly between 1984 and 2019 (simple linear regression: b -0.340, P = 0.017; meta-regression: b -0.610, P ≤ 0.001). Overall and yearly PMOT declines were predicted at 33.51 and 0.96%, respectively (1984: 63.69 ± 5.07%; 2019: 42.35 ± 3.69%). Trends remained consistent irrespective of sensitivity analyses. Yearly and overall declines were stronger in western (yearly: 0.75%, overall: 26.29%) compared to non-western (yearly: 0.46%, overall: 10.65%) populations. Adverse trends contribute vital data to the debate surrounding declining semen quality, supporting the use of equines as novel comparative models for human reproduction. Results could have significant economic, health, and welfare consequences for equine breeding sectors. A comparable decline in human, dog, and horse sperm quality is indicative of a common environmental aetiology, indicating the need for a holistic One Health approach in determining causes and developing preventative strategies.

The appropriate growth and functions of Sertoli cells are crucial to testis development and spermatogenesis in mammals. This study reveals a novel mechanism of follicle-stimulating hormone in immature porcine Sertoli cell proliferation. Follicle-stimulating hormone (FSH) is a major Sertoli cell mitogen that binds to the FSH receptor. Sertoli cells are indispensable for testis development and spermatogenesis. However, the regulatory mechanisms of FSH in immature Sertoli cell proliferation have not been determined, particularly in domestic animals. In the present study, we identified the regulatory mechanisms of FSH during immature porcine Sertoli cell proliferation. Transcriptome analysis revealed 114 differentially expressed genes that were induced by FSH treatment, which contains 68 upregulated and 46 downregulated genes. These differentially expressed genes were enriched in multiple pathways, including the Ras signaling pathway. Knockdown of the CC-chemokine receptor 7 (CCR7) gene, which was upregulated by FSH, inhibited cell cycle progression by arresting cells in the G1 phase and reduced the cell proliferation and ERK1/2 phosphorylation. In addition, Kobe0065 inhibited Ras signaling in a similar manner as CCR7 knockdown. Furthermore, FSH abolished the effects of Ras signaling pathway inhibition and CCR7 knockdown. Collectively, FSH promotes immature porcine Sertoli cell proliferation by activating the CCR7/Ras-ERK signaling axis. Our results provide novel insights into the regulatory mechanism of FSH in porcine testis development and spermatogenesis by deciding the fate of immature porcine Sertoli cells.

Developmental programming refers to the long-term programming of gene expression during fetal and postnatal development, resulting in altered organ function even into adulthood. This review describes how maternal and paternal sustenance and stress, as well as fetal sex, all matter in large animal models and affect developmental programming of the offspring. Developmental programming is the concept that certain health outcomes throughout life can be linked to early fetal or postnatal development. Progress in understanding concepts and mechanisms surrounding developmental programming is heavily leveraged by the use of large animal models. Numerous large animal models have been developed that apply a host of different maternal stressors and, more recently, paternal stressors. Maternal nutrition is the most researched maternal stressor applied during gestation and includes both global nutrient supply and models that target specific macro- or micro- nutrients. The focus of this review is to provide an overview of the many large animal models of developmental programming and to discuss the importance of sex effects (including paternal contributions) in study design and data interpretation.

Sperm cryopreservation has been recognised as a tool for preventing loss of genetic diversity in amphibians; however, the combined effect of penetrative and non-penetrative cryoprotectants in cryodiluents is poorly understood. We demonstrate a clear benefit of using low concentrations of non-penetrative cryoprotectants when cryopreserving sperm of Australian tree frogs. Sperm cryopreservation protocols have been developed for an increasing number of amphibian species since the recognition of a global amphibian decline. Yet, the development of these protocols has neglected to elucidate the combined effect of the penetrative(PCP) and non-penetrative cryoprotectant (NPCP) on the recovery of live, motile sperm. The two-factor hypothesis of cryoinjury recognises a trade-off between cooling cells slowly enough to allow osmotic dehydration and therefore avoid intracellular ice formation, but fast enough to minimise effects from increasing extracellular osmolality as the frozen fraction of the media increases during freezing. We tested the effect of two concentrations of a PCP (10 and 15% v/v dimethyl sulfoxide (Me2SO)) and two concentrations of an NPCP (1 and 10% w/v sucrose) in various combinations on the sperm of six pelodryadid frogs. In all species, 15% v/v Me2SO with 1% w/v sucrose provided superior post-thaw recovery with high proportions of forward progressive motility, live cells and intact acrosomes (typically >50% for each). Theoretically, it has been suggested that increased NPCP concentration should improve cell survival by increasing the rate and extent of cell dehydration. We suggest, however, that the elevated osmolality in the unfrozen water fraction when 10% sucrose is used may be causing damage to cells via excessive cell shrinkage and solute effects as proposed in the two-factor hypothesis of cryoinjury. We showed this response in sperm across a range of frog species, providing compelling evidence for this hypothesis. We suggest protocol development using the PCP/NPCP ratios demonstrated in our study will be broadly applicable to many amphibian species.

IFN-λs participate in the fetal-maternal immune interaction, involving in immune regulation, uterine receptivity, cell migration and adhesion, and endometrium apoptosis. Our study helps to elucidate the underlying causes of the IFN-λs deficiency to spontaneous pregnancy loss in women. Immunotherapy has been commonly used to prevent recurrent pregnancy loss in women with inadequate uterus receptivity or immunological imbalance. Many immune regulators are now identified as having crucial roles at the embryo-maternal interface. However, the clinical efficacy of immunity-related markers during the peri-implantation period remains to be explored in depth. Here, we demonstrated that endometrial expression of interferon-λ (IFN-λ), regarded as a newer class of interferons, is aberrantly lower in women who suffered from recurrent implantation failure than that in fertile control. We further uncovered genetic and biochemical evidence that IFN-λ is induced directly by estrogen in the endometrial cells, and IFN-λ pathway may play multiple roles involving the inflammatory response, uterine receptivity, cell migration, and blastocyst adhesion. Furthermore, we indicated IFN-λ lessens the sensitivity of endometrium to FASL-mediated apoptosis. In addition to uncovering this IFN-λ as a novel nonredundant regulator that participates in the fetal-maternal immune interaction, our study helps to elucidate the underlying causes of spontaneous pregnancy loss in women.

Bull fertility is an important economic trait, this study identified some DNA methylation biomarkers that are associated with bull fertility. Subfertile bulls may cause huge economic losses in dairy production since their semen could be used to inseminate thousands of cows by artificial insemination. This study adopted whole-genome enzymatic methyl sequencing and aimed to identify candidate DNA methylation markers in bovine sperm that correlate with bull fertility. Twelve bulls were selected (high bull fertility = 6; low bull fertility = 6) based on the industry's internally used Bull Fertility Index. After sequencing, a total of 450 CpG had a DNA methylation difference higher than 20% (q < 0.01) had been screened. The 16 most significant differentially methylated regions (DMRs) were identified using a 10% methylation difference cut-off (q < 5.88 × 10-16). Interestingly, most of the differentially methylated cytosines (DMCs) and DMRs were distributed on the X and Y chromosomes, demonstrating that the sex chromosomes play essential roles in bull fertility. Additionally, the functional classification showed that the beta-defensin family, zinc finger protein family, and olfactory and taste receptors could be clustered. Moreover, the enriched G protein-coupled receptors such as neurotransmitter receptors, taste receptors, olfactory receptors, and ion channels indicated that the acrosome reaction and capacitation processes are pivotal for bull fertility. In conclusion, this study identified the sperm-derived bull fertility-associated DMRs and DMCs at the whole genome level, which could complement and integrate into the existing genetic evaluation methods, increasing our decisive capacity to select good bulls and explain bull fertility better in the future.

The role of visfatin in ovarian granulosa cell tumor (GCT) invasion and glucose metabolism reprogramming is largely unexplored. These studies imply that visfatin or its inhibitor is involved in regulating ovarian granuloma invasion by reprogramming glucose metabolism and may be a potential candidate for the diagnosis and treatment of ovarian GCT. Visfatin is an adipokine with nicotinamide phosphoribosyltransferase (NAMPT) activity, the concentration of which is higher in ascitic fluid than in serum, and is associated with ovarian cancer peritoneal dissemination. Potentially important effects of visfatin on glucose metabolism have been previously reported. However, the mechanism underlying the effects of visfatin on ovarian cancer cell invasion, and whether this involves altered glucose metabolism, has not been elucidated. Here, we tested the hypothesis that visfatin, which can reprogram cancer metabolism, promotes invasion by ovarian cancer spheroids. Visfatin increased glucose transporter (GLUT)1 expression and glucose uptake in adult granulosa cell tumor-derived spheroid cells (KGN) and also increased the activities of hexokinase 2 and lactate dehydrogenase. We showed a visfatin-induced increase in glycolysis in KGN cells. Moreover, visfatin increased the potential invasiveness of KGN spheroid cells by upregulating MMP2 (matrix metalloproteinase 2) and downregulating CLDN3 and CLDN4 (claudin 3 and 4) gene expression. Interestingly, an inhibitor of GLUT1 and lactate dehydrogenase (LDHA) abolished the stimulatory effect of visfatin on the potential invasiveness of KGN cells. More importantly, silencing expression of the NAMPT gene in KGN cells demonstrated its important effect on glycolysis and invasiveness in adult granulosa cell tumor cells (AGCTs). In summary, visfatin appears to increase AGCT invasiveness through effects on glucose metabolism and to be an important regulator of glucose metabolism in these cells.