The role of Melatonin receptor MTNR1A in the action of Melatonin on bovine granulosa cells

Abstract

Granulosa cells (GCs) play an important role in ovarian follicle growth, development, and follicular atresia. In the present study, we investigated the effects of Melatonin on bovine GCs, and asked if MTNR1A was involved in their response to this indole hormone. Our results indicated that Melatonin inhibited GC apoptosis by up-regulating the expression of BCL2, BCL-XL, GPX4, and SOD1, and down-regulating the expression of BAX, CASP3, and TP53. Moreover, Melatonin modulated bovine GC function by decreasing the expression of INHA, INHBB, FSHR, and TGFBR3, and the abundance of Inhibin β and Activin B, while increasing the expression of LHR, INHBA, and secretion of progesterone by GCs. In contrast, knockdown of MTNR1A significantly increased the expression of BAX, CASP3, TP53, INHA, FSHR, and TGFBR3, as well as Inhibin β abundance, while decreasing the expression of BCL2, GPX4, SOD1, and LHR, and production of progesterone and estradiol; no effect was observed on the expression of BCL-XL, INHBA, or INHBB. These results suggest that Melatonin and MTNR1A play an important role in modulating bovine GC function by regulating cellular progression, apoptosis, hormones secretion, and reproduction-related genes. Furthermore, altered expression of MTNR1A could affect how bovine GCs respond to Melatonin.

Effect of melatonin on regulation of apoptosis and steroidogenesis in cultured buffalo granulosa cells

“…The outcome of this study revealed the presence of melatonin receptors, MT1 and MT2 in buffalo GCs, although MT2 appeared to be quiescent compared to MT1. The results are supportive to a previous study which reported higher consistency of MT1 amplification than MT2 in cultured bovine GCs (Wang et al., ). In this study, melatonin treatment resulted in significant increase in mRNA level of MT1 receptor which provides evidence of its homologous regulation in buffalo ovaries.…”

“…From one side, it stimulates ovarian functions via its ovarian receptors; whereas on the other hand, it extends its role as free radical scavenger that is helpful in oocyte maturation and nourishment of delicate embryos (Reiter, Paredes, Manchester, & Tan, 2009). Previous studies elaborated the expression of its receptors in human and bovine ovaries (Michelle et al, 2001;Wang et al, 2017), but no efforts have been made to define its role in buffalo GCs.…”

“…Approximately 150 ovaries were used in the three experiments. Granulosa cells were isolated according to previously described methods (Monga et al., ; Wang et al., ). Briefly, healthy follicles were assessed by the presence of vascularized theca externa and clear follicular fluid with no debris.…”

“…Melatonin was found to affect cellular fate in many cell models; however, no consistent reports on its effect on GCs growth in buffaloes are present. In a recent study, melatonin inhibited GC apoptosis in bovine GCs (Wang, Liu, Wang, Pang, & Yang, 2017), whereas, both melatonin receptors were associated with blastocycst cleavage and growth (Fang et al, 2018). In mammals, a direct link between follicular selection and GC maturation was described (Johnson & Woods, 2009), and the balance between cell proliferation and apoptosis was found to be critical for normal follicular growth (Denkova et al, 2004).…”

RNAi-mediated knockdown of MTNR1B without disrupting the effects of melatonin on apoptosis and cell cycle in bovine granulose cells

“…Granulosa cells collection was performed as previously described elsewhere ( Wang et al, 2012a , 2017b ). A total of 50–60 bovine ovaries were obtained from Bengbu abattoir (Anhui, China), washed three times by 70% alcohol and sterile 0.9% NaCl.…”