Dietary supplementation with metformin improves testis function and semen quality and increases antioxidants and autophagy capacity in goats.

ATP is essential for mammalian sperm to maintain fertilizing capacity. Metformin (Met) can activate 5'-AMP-activated protein kinase (AMPK) to maintain energy homeostasis. Thus, the aim of the present study was to investigate whether Met can improve testis function, semen quality, antioxidant and autophagy capacity through AMPK mediation of energy metabolism in goats. Twelve adult goats were randomly divided into three dietary treatments. All goats were fed a basal diet for 3 weeks and then assigned to a Met supplementation diet containing 0, 150, or 300 mg/kg for 8 weeks. The results showed that sperm viability, sperm membranal functional integrity, and acrosome integrity increased (P < 0.05) relative to the other treatments in the 300 mg/kg Met group. Growth hormone (GH) and insulin-like growth factor (IGF-1) in the 300 mg/kg Met group significantly decreased (P < 0.05) relative to the control group. Estrogen levels (E2) in the 300 mg/kg Met group remarkably improved (P < 0.05) compared with the control group. The activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GSH-px), and superoxide dismutase (SOD) significantly increased (P < 0.05) in the 300 mg/kg Met group relative to the control group. A significant increase in AMPK and p-AMPK protein expression in the 300 mg/kg Met group was observed relative to the control group (P < 0.05). Belicin-1 and LC3II/I protein expression was significantly increased by adding Met to the diet (P < 0.05) and reached a maximum in the 300 mg/kg Met group. In addition, differentially expressed genes (DEGs) of goat testis were confirmed by RNA-seq. GO enrichment analysis revealed that DEGs were enriched in testicular metabolism and sperm development-related functional pathways. Overall, the results indicate that Met may play an important role in the regulation of testis function, semen quality, antioxidant, and autophagy capacity. These findings will help elucidate the role of Met in goat testis development.

γ-Linolenic Acid Prevents Lipid Metabolism Disorder in Palmitic Acid-Treated Alpha Mouse Liver-12 Cells by Balancing Autophagy and Apoptosis via the LKB1-AMPK-mTOR Pathway.

Excessive fat deposition is the main character in nonalcoholic fatty liver disease (NAFLD), while γ-linolenic acid (GLA) is a polyunsaturated fatty acid that can reduce lipid deposition. This study investigated the effect and regulatory mechanism of GLA (100 µM) on lipid metabolism in alpha mouse liver 12 (AML-12) cells treated by 400 µM palmitic acid (PA). GLA reduced lipid content and increased fatty acid ß oxidation, as indicated by decreasing triglyceride and cholesterol contents and increasing mRNA and protein expressions of CPT1α and PPARα. GLA relieved oxidative stress caused by PA, upregulated mRNA levels of superoxide dismutase and glutathione peroxidase, and decreased reactive oxygen species content. GLA reduced apoptosis, as indicated by decreases in the BAX/BCL2 expression level and apoptosis percentage. GLA activated autophagy, autophagosome-lysosome fusion, and LKB1-AMPK-mTOR signaling and upregulated mRNA and protein expressions of Beclin-1, autophagy-related 5, and liver kinase B1 (LKB1). These effects of GLA on lipid metabolism disorders of PA-treated hepatocytes were reversed by autophagy inhibitor 3MA and AMPK inhibitor compound C, confirming our conclusions. Overall, GLA can protect AML-12 cells from lipid metabolism disorder caused by PA via balancing autophagy and apoptosis mediated by the LKB1-AMPK-mTOR pathway. Consequently, GLA, as a dietary supplement, can help to prevent and treat NAFLD by regulating lipid metabolism and autophagy.

Arginine infusion rescues ovarian follicular development in feed-restricted Hu sheep during the luteal phase.

The aim of this study was to investigate the molecular mechanisms of arginine (Arg) on follicular development of acute feed-restricted ewes during the luteal phase. From day 6 of the estrous cycle, 24 multiparous Hu sheep were randomly assigned into three groups: control group (a maintenance diet; n = 6), feed restriction group (0.5 maintenance diet, saline infusion; n = 9) and Arg treatment group (0.5 maintenance diet, infusion with 155 µmol of Arg-HCl/kg body weight; n = 9). The intravenous administrations were performed three times per day from day 6 to day 15 of the estrous cycle. At the end of treatment, the hypothalamus and pituitary were collected, as well as the follicular fluid (FF) and granulose cells (GCs) in the ≥2.5 mm follicles. The transcription level of NPVF was significantly increased, and the expression level of GNRH was significantly decreased in the hypothalamus with feed restriction. In addition, feed restriction significantly decreased the number of ≥2.5 mm follicles in the ovaries. In the ≥2.5 mm follicles, feed restriction significantly increased estradiol (E2) level in FF and the expression levels of steroidogenesis related genes (STAR, 3BHSD and CYP19A1) in GCs, while significantly decreased the expressions of FSHR and cell proliferation related genes (YAP1, CCND1 and PCNA) in GCs. Moreover, the activities of glucose metabolism enzymes (PFKP and G6PDH) were significantly decreased in GCs of the ≥2.5 mm follicles with feed restriction. Interestingly, as a precursor of nitric oxide, Arg supplementation can rescue the effects of feed restriction on follicular development by enhancing glucose metabolism and cell proliferation of GCs, and alleviating the abnormal E2 secretion in the ≥2.5 mm follicles, accompanied with recovering the expressions of NPVF and GNRH in the hypothalamus. These findings will be helpful for understanding the role of nutrition and Arg in sheep follicular development.

Roles of vitamin D and its receptor in the proliferation and apoptosis of luteinised granulosa cells in the goat.

The objective of this study was to investigate the dose-dependent effect of 1α,25-(OH)2VD3 (Vit D3) on invitro proliferation of goat luteinised granulosa cells (LGCs) and to determine the underlying mechanisms of its action by overexpressing and silencing vitamin D receptor (VDR) in LGCs. Results showed that VDR was prominently localised in GCs and theca cells (TCs) and its expression increased with follicle diameter, but was lower in atretic follicles than in healthy follicles. The proliferation rate of LGCs was significantly higher in the Vit D3-treated groups than in the control group, with the highest proliferation rate observed in the 10nM group; this was accompanied by changes in the expression of cell cycle-related genes. These data indicate that Vit D3 affects LGC proliferation in a dose-dependent manner. Contrary to the VDR knockdown effects, its overexpression upregulated and downregulated cell cycle- and apoptosis-related genes respectively; moreover, supplementation with 10nM of Vit D3 significantly enhanced these effects. These results suggest that changes in VDR expression patterns in LGCs may be associated with follicular development by regulation of cell proliferation and apoptosis. These findings will enhance the understanding of the roles of Vit D3 and VDR in goat ovarian follicular development.