Melatonin facilitates oocyte growth in goats and mice through increased nutrient reserves and enhanced mitochondrial function.

Oogenesis involves two phases: initial volumetric growth driven by nutrient accumulation and subsequent nuclear maturation. While melatonin (MLT) has been employed as a supplement to enhance the quality of fully grown oocytes during nuclear maturation phase, its impact on oocyte growth remains poorly studied. Here, we provide in vivo evidence demonstrating that follicle-stimulating hormone increases MLT content in ovary. Administration of MLT improves oocyte growth and quality in mice and goats by enhancing nutrient reserves and mitochondrial function. Conversely, MLT-deficient mice have smaller oocytes and dysfunctional mitochondria. Exploring the clinical implications of MLT in promoting oocyte growth, we observe that a brief 2-day MLT treatment enhances oocyte quality and reproductive performance in older mice. These findings highlight the role of MLT in regulating oocyte growth and provide a specific treatment window for optimizing oocyte quality and reproductive performance in female animals.

Role of L-glutamine in the regulation of rat Sertoli cell proliferation by FSH.

In brief: FSH leads to glutamine dependence, which is required for mTORC1 activation and in consequence Sertoli cell proliferation. Abstract: The spermatogenic capacity of adult individuals depends on, among other factors, the number of Sertoli cells (SCs) that result from the proliferative waves during development. FSH upregulates SC proliferation at least partly, through the activation of the PI3K/Akt/mTORC1 pathway, among other mechanisms. It is widely known that mTORC1 is a sensor of amino acids. Among amino acids, glutamine acquires relevance since it might contribute to cell cycle progression through the modulation of mTORC1 activity. It has not been studied yet whether glutamine intervenes in FSH-mediated regulation of SC proliferation and cell cycle progression, or if FSH has any effect on glutamine metabolism. Eight-day-old rat SCs were incubated in culture media without glutamine or with glutamine in the absence or presence of a glutamine transporter inhibitor or a glutaminase activity inhibitor under basal conditions or stimulated with FSH. The results obtained show that FSH does not promote SC proliferation and mTORC1 activation in the absence of glutamine. Also, FSH modulates glutamine metabolism increasing glutaminase isoform 2 and reducing glutamine synthetaseexpression. FSH did not promote SC proliferation and mTORC1 activation when glutaminase activity was inhibited. The results suggest that glutamine or its metabolites might cooperate with FSH in the upregulation of SC proliferation through mTORC1. In addition, as FSH modulates glutamine metabolism through the induction of glutaminase isoform 2, the hormonal control of glutamine metabolism might be part of the intricate signaling network triggered by FSH, which is crucial to establish the population of mature SCs that supports the reproductive function.

SFRP4 promotes autophagy and blunts FSH responsiveness through inhibition of AKT signaling in ovarian granulosa cells.

BACKGROUND: Secreted frizzled-related proteins (SFRPs) comprise a family of WNT signaling antagonists whose roles in the ovary are poorly understood. Sfrp4-null mice were previously found to be hyperfertile due to an enhanced granulosa cell response to gonadotropins, leading to decreased antral follicle atresia and enhanced ovulation rates. The present study aimed to elucidate the mechanisms whereby SFRP4 antagonizes FSH action. METHODS: Primary cultures of granulosa cells from wild-type mice were treated with FSH and/or SFRP4, and effects of treatment on gene expression were evaluated by RT-qPCR and RNAseq. Bioinformatic analyses were conducted to analyse the effects of SFRP4 on the transcriptome, and compare them to those of FSH or a constitutively active mutant of FOXO1. Additional granulosa cell cultures from wild-type or Sfrp4-null mice, some pretreated with pharmacologic inhibitors of specific signaling effectors, were used to examine the effects of FSH and/or SFRP4 on signaling pathways, autophagy and apoptosis by western blotting and TUNEL. RESULTS: Treatment of cultured granulosa cells with recombinant SFRP4 was found to decrease basal and FSH-stimulated mRNA levels of FSH target genes. Unexpectedly, this effect was found to occur neither via a canonical (CTNNB1-dependent) nor non-canonical WNT signaling mechanism, but was found to be GSK3ß-dependent. Rather, SFRP4 was found to antognize AKT activity via a mechanism involving AMPK. This lead to the hypophosphorylation of FOXO1 and a decrease in the expression of a portion of the FSH and FOXO1 transcriptomes. Conversely, FSH-stimulated AMPK, AKT and FOXO1 phosphorylation levels were found to be increased in the granulosa cells of Sfrp4-null mice relative to wild-type controls. SFRP4 treatement of granulosa cells also induced autophagy by signaling via AKT-mTORC1-ULK1, as well as apoptosis. CONCLUSIONS: This study identifies a novel GSK3ß-AMPK-AKT signaling mechanism through which SFPR4 antagonizes FSH action, and further identifies SFRP4 as a novel regulator of granulosa cell autophagy. These findings provide a mechanistic basis for the phenotypic changes previously observed in Sfrp4-null mice, and broaden our understanding of the physiological roles of WNT signaling processes in the ovary.

The Protective Effect of Gallic Acid Against Bisphenol A-Induced Ovarian Toxicity and Endocrine Disruption in Female Rats.

Purpose: This study aimed to investigate the protective effects of gallic acid (GA) against ovarian damage induced by bisphenol A (BPA) exposure in female rats. We evaluated whether GA can mitigate the adverse effects of BPA on ovarian structure, inflammatory markers, oxidative stress, apoptosis, and reproductive hormone levels. Methods: Thirty-two female rats were categorized into four groups: control, GA, BPA, and GA+BPA. Histopathological evaluations of ovarian tissue were performed using hematoxylin-eosin staining. The immunohistochemical analysis was conducted for inflammatory, oxidative DNA damage, and apoptotic markers (Tumor necrosis factor alpha [TNFα], cyclooxygenase-2 [COX2], interleukin-1 beta [IL-1ß], 8-hydroxydeoxyguanosine [8-OHdG], and caspase 3). Oxidative stress was assessed by measuring malondialdehyde and superoxide dismutase levels. Furthermore, follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone levels were quantified using enzyme-linked immunosorbent assay. Results: Histopathological outcomes revealed that BPA significantly induced follicular degeneration, which was effectively mitigated by GA treatment (P < 0.05). Immunohistochemical analysis highlighted the exacerbation of inflammatory responses and oxidative DNA damage and apoptosis (TNFα, COX-2, IL-1ß, 8-OHdG, and caspase 3) in BPA-exposed tissues, which were reduced in the presence of GA (P < 0.05). The assessment of oxidative stress demonstrated that GA could significantly decrease lipid peroxidation and partially restore antioxidant defense mechanisms disrupted by BPA (P < 0.05). Hormonal profiling indicated that BPA exposure altered the levels of FSH, LH, estrogen, and progesterone, with GA treatment showing a capacity to modulate these changes, especially in progesterone levels (P < 0.05). Conclusions: The findings suggest that GA exhibits protective properties against BPA-induced ovarian damage through its antioxidative and anti-inflammatory activities, alongside its ability to modulate hormonal imbalances. This research underscores the therapeutic potential of GA in safeguarding reproductive health against environmental toxicants.