Gonadotropin-inhibiting hormone promotes apoptosis of bovine ovary granulosa cells

Gonadotropin inhibitory hormone (GnIH) induces glucose metabolism disorders and ovarian dysfunction in ovarian white follicles of hens

Energy metabolism is crucial for reproduction, and disturbances in glucose metabolism are closely associated with reproductive disorders. The gonadotropin inhibitory hormone (GnIH) plays a crucial role in reproduction and glucose homeostasis in both birds and mammals. However, its specific effects on glucose metabolism-associated ovarian dysfunction in hens remain uncharacterized. In this study, we investigated the effects of GnIH on ovarian function and glucose homeostasis in hens using combined in vivo and in vitro approaches. Our results showed that GnIH and its receptor, GPR147, are predominantly expressed in white follicles. Continuous GnIH injection significantly reduced the ovarian index and the number of prehierarchical follicles, concurrently suppressing Fshr and LHr expression in white follicles. Additionally, metabolomic analyses indicate changes in key glucose metabolism pathways, indicating a regulatory role of GnIH in glucose metabolism. To validate our metabolomics findings, the effects of GnIH on glucose homeostasis in ovarian white follicles and granulosa cells (GCs) were further investigated through in vivo and in vitro studies. The results demonstrated that GnIH enhanced glucose transport, glycolysis and glycogen synthesis, but concurrently induced insulin resistance, oxidative stress, and mitochondrial dysfunction, ultimately leading to reduced energy levels and apoptosis in ovarian tissues. In summary, our study reveals that GnIH contributes to ovarian dysfunction via glucose metabolism dysregulation in hens, suggesting its potential as a therapeutic target for metabolic disorder-associated ovarian impairment in chickens.

Cuproptosis is involved in decabromodiphenyl ether-induced ovarian dysfunction and the protective effect of melatonin

Decabromodiphenyl ether (BDE-209) has been universally detected in environmental media and animals, but its damage to ovarian function and mechanism is still unclear, and melatonin has been shown to improve mammalian ovarian function. This study aimed to investigate the toxic effects of BDE-209 on the ovary and tried to improve ovarian function with melatonin. Herein, BDE-209 was administered orally to female SD rats for 60 days. Enzyme-linked immunosorbent assay, HE staining, transcriptome analysis, qPCR and immunohistochemical staining were used to explore and verify the potential mechanism. We found that BDE-209 exposure had effects on the ovary, as shown by abnormal changes in the estrous cycle, hormone levels and ovarian reserve function in rats, while increasing the proportion of collagen fibres in ovarian tissue. In terms of mechanism, cuproptosis, a form of cell death, was identified to play a crucial role in BDE-209-induced ovarian dysfunction, with the phenotype manifested as copper salt accumulation in ovary, downregulation of glutathione pathway metabolism and copper transfer molecule (ATP7A/B), and upregulation of FDX1, lipoic acid pathway (LIAS, LIPT1), pyruvate dehydrogenase complex components (DLAT, PDHB, PDHA1), and copper transfer molecule (SLC31A1). Furthermore, possible interventions were explored. Notably, a supplement with melatonin has a repair effect on the damage to ovarian function by reversing the gene expression of cuproptosis-involved molecules. Overall, this study revealed that cuproptosis is involved in BDE-209-induced ovarian damage and the beneficial effect of melatonin on ovarian copper damage, providing evidence for the prevention and control of female reproductive damage induced by BDE-209.

The possibly role of GnIH in stress and gut dysfunction in chicken

Stress is known to disrupt the intestinal barrier and induce intestinal dysfunction. A critical role for gonadotropin inhibitory hormone (GnIH) in stress has emerged. However, whether GnIH mediates stress-induced intestinal dysfunction remains unknown. The present study explored this question through in vivo and in vitro experiments in hens. Our in vivo experiments showed that continuous intraperitoneal injection of GnIH not only significantly increased the concentration of stress hormones in serum, but also significantly elevated the mRNA expression of glucocorticoid receptor (GR) in the duodenum and jejunum. Moreover, morphological and molecular analyses revealed that GnIH disrupted the physical and chemical barriers of the intestine and dramatically increased inflammatory factor levels in the intestine and serum of hens. Interestingly, the microbiomics results showed that GnIH altered the structure and composition of the gut flora in the cecum, revealing an increased abundance of harmful intestinal bacteria such as Desulfovibrionaceae. Similar results were found in in vitro studies in which the GnIH-induced intestinal mucosal barrier was disrupted, and inflammation increased in jejunal explants, although no significant difference was found in the expression of GR between the control and GnIH groups. Our results demonstrated that GnIH not only directly damaged intestinal barriers and elevated intestinal inflammation but also mediated stress and microflora imbalance-induced intestinal function disorder, suggesting that GnIH is a potential therapeutic target for gut dysfunction, stress-induced intestinal function disorder, and inflammatory bowel disease in animals and humans.

Rfamide-related peptide-3(RFRP-3) receptor gene is expressed in mouse ovarian granulosa cells: Potential role of RFRP-3 in steroidogenesis and apoptosis

RFRP-3 is a functional ortholog of avian GnIH and regulates reproductive activities in the gonads of animals. However, the role of RFRP-3 in the function of ovarian granulosa cells in mice remains unclear. First, we detected the expression of the RFRP-3 receptor (GPR147) in the ovarian granulosa cells of mice. Second, the effect of RFRP-3 treatment on estradiol and progesterone secretions from granulosa cells was tested by ELISA. Meanwhile, the expression of genes and proteins regulating steroid hormone synthesis was respectively examined by qPCR and western blot. Furthermore, the effect of RFRP-3 treatment on the apoptosis of granulosa cells was analyzed. The results revealed that the GPR147 protein (a RFRP-3 receptor) was expressed in the ovarian granulosa cells of mice. Low and medium doses RFRP-3 treatment significantly reduced progesterone secretion in the granulosa cells (P < 0.05), while RFRP-3 suppressed p450scc, 3β-HSD, StAR, and FSHR expression in a non-dose-dependent manner. Moreover, RFRP-3 treatment might induce the apoptosis of granulosa cells. Additionally, low doses RFRP-3 significantly reduced p-ERK1/2 protein expression (P < 0.05) in the ovarian granulosa cells. We here, for the first time, confirmed that GPR147 was expressed in the ovarian granulosa cells of mice. Our findings suggested that and RFRP-3 regulates the granulosa cell function through the ERK signaling pathway, which will lay the foundation for uncovering molecular mechanisms by which RFRP-3 regulates follicle development in future.

Melatonin Protects the Apoptosis of Sheep Granulosa Cells by Suppressing Oxidative Stress via MAP3K8 and FOS Pathway

Melatonin is not only a highly effective active oxygen scavenger but also an important reproductive hormone. Melatonin has a regulatory effect on animal reproduction, especially on the ovaries. It can affect the proliferation and apoptosis of cells in follicles. However, the mechanisms of the dual antioxidation and anti-apoptosis effects of melatonin on granulosa cells are still not clear, especially in sheep. Therefore, we investigated the mechanisms of the protective effect of melatonin against oxidative damage in granulosa cells. At a concentration of 250 µmol/L, H₂O₂ promoted granulosa cell apoptosis; however, 10 ng/mL melatonin effectively alleviated the pro-apoptotic effect of H₂O₂. Furthermore, through the application of high-throughput sequencing technology, we identified 109 significantly differentially expressed genes (35 upregulated and 74 downregulated genes) involved in the protective effect of melatonin against apoptosis. The expression levels of nine related genes, i.e., ATF3, FIBIN, FOS, HSPA6, MAP3K8, FOSB, PET117, DLX2, and TRIB1, changed significantly. MAP3K8 and FOS gene overexpression impacted the protective effect of melatonin in granulosa cells; the two genes exhibited an upstream and downstream regulatory relationship. Our findings indicated that melatonin alleviated H₂O₂-induced apoptosis in sheep granulosa cells through the MAP3K8-FOS pathway.

Recombinant HBsAg-S and RFRP-3 DNA vaccine promotes reproduction hormone secretion in sheep

RF-amide related peptides (RFRP) have been proposed as critical regulators of gonadotropin secretion in mammals. This study was designed to construct a DNA vaccine and investigate the effect of vaccine encoding RFRP-3 on reproduction physiology in ewe. A recombinant vaccine was constructed using two copies of the RFRP-3 gene and HBsAg-S that generate a fusion protein to induce an immunology response. Results showed this recombinant vaccine could produce a significant antibody titer in the treated animals (P < 0.05). The specific RFRP-3 antibody response induced by the vaccine was detected at week 2 with a peak at week 6 after the initial immunization. Furthermore, we found that ewes inoculated with pVAX-tPA-HBsAg-S-2RFRP-asd vaccine significantly raised the concentration of GnRH, LH and E₂ in serum compared to the control group. LH and E2 concentration in the treated ewes (Group T) was significantly higher than that in control ewes (Group C) at weeks 10, 12 and 14 after the initial immunization, respectively (P < 0.05). Therefore, RFRP-3 can be used as a target for DNA immunization to promote reproductive hormone secretion in ewes and RFRP-3 gene immunization might be a candidate tool to regulate mammal reproduction.

RFRP-3 Influences Apoptosis and Steroidogenesis of Yak Cumulus Cells and Compromises Oocyte Meiotic Maturation and Subsequent Developmental Competence

RF amide-related peptide 3 (RFRP-3), a mammalian ortholog of gonadotropin-inhibitory hormone (GnIH), is identified to be a novel inhibitory endogenous neurohormonal peptide that regulates mammalian reproduction by binding with specific G protein-coupled receptors (GPRs) in various species. Herein, our objectives were to explore the biological functions of exogenous RFRP-3 on the apoptosis and steroidogenesis of yak cumulus cells (CCs) and the developmental potential of yak oocytes. The spatiotemporal expression pattern and localization of GnIH/RFRP-3 and its receptor GPR147 were determined in follicles and CCs. The effects of RFRP-3 on the proliferation and apoptosis of yak CCs were initially estimated by EdU assay and TUNEL staining. We confirmed that high-dose (10^-6 mol/L) RFRP-3 suppressed viability and increased the apoptotic rates, implying that RFRP-3 could repress proliferation and induce apoptosis. Subsequently, the concentrations of E₂ and P₄ were significantly lower with 10^-6 mol/L RFRP-3 treatment than that of the control counterparts, which indicated that the steroidogenesis of CCs was impaired after RFRP-3 treatment. Compared with the control group, 10^-6 mol/L RFRP-3 treatment decreased the maturation of yak oocytes efficiently and subsequent developmental potential. We sought to explore the potential mechanism of RFRP-3-induced apoptosis and steroidogenesis, so we observed the levels of apoptotic regulatory factors and hormone synthesis-related factors in yak CCs after RFRP-3 treatment. Our results indicated that RFRP-3 dose-dependently elevated the expression of apoptosis markers (Caspase and Bax), whereas the expression levels of steroidogenesis-related factors (LHR, StAR, 3β-HSD) were downregulated in a dose-dependent manner. However, all these effects were moderated by cotreatment with inhibitory RF9 of GPR147. These results demonstrated that RFRP-3 adjusted the expression of apoptotic and steroidogenic regulatory factors to induce apoptosis of CCs, probably through binding with its receptor GPR147, as well as compromised oocyte maturation and developmental potential. This research revealed the expression profiles of GnIH/RFRP-3 and GPR147 in yak CCs and supported a conserved inhibitory action on oocyte developmental competence.

Effect of RFRP-3, the mammalian ortholog of GnIH, on apoptosis and autophagy in porcine ovarian granulosa cells via the p38MAPK pathway

RFamide-related peptide-3 (RFRP-3) has been proposed as a key inhibitory regulator of mammalian reproduction. Our previous studies demonstrated that RFRP-3 mediated apoptosis and autophagy of the epididymis in rats and inhibited porcine granulosa cell (GC) proliferation. However, the molecular mechanisms of the RFRP-3 effect on porcine GC apoptosis and autophagy have not been studied before. Herein, we first investigated the role of RFRP-3 in apoptosis and autophagy in cultured porcine GCs in vitro. Our results showed that different doses of RFRP-3 dose-dependently elevated the expression of autophagy markers at both the mRNA and protein levels, whereas the expression of apoptosis markers exhibited a bidirectional, dose-dependent effect. Because the p38MAPK signaling pathway plays essential roles in apoptosis and autophagy, we subsequently evaluated the effect of RFRP-3 on p38MAPK activation. The results showed that 10^-6 M RFRP-3 treatment not only significantly decreased p38MAPK phosphorylation but also inhibited the p38MAPK activator U-46619 to promote p38MAPK activation in porcine GCs. Finally, we applied U-46619 to investigate the role of the p38MAPK signaling pathway in apoptosis and autophagy in RFRP-3-treated porcine GCs. The results showed that all doses of RFRP-3 significantly inhibited the U-46619-induced increase in apoptosis in a dose-dependent manner. However, except for the U-46619-induced Beclin-1 expression increase, which was significantly suppressed in high-dose RFRP-3-treated porcine GCs, other doses of RFRP-3 treatment strengthened the U-46619-induced increase in other autophagy markers. In summary, our data demonstrate a critical role for the p38MAPK signaling pathway in the porcine GC cellular response to RFRP-3 by controlling the balance between apoptosis and autophagy.