Effect of inhibin A on proliferation of porcine granulosa cells in vitro.

Inhibins regulate folliculogenesis, gametogenesis and hormone secretion via endocrine, paracrine and autocrine manners, and play roles in encouraging or suppressing proliferation of cells. In order to investigate the effects of inhibin A on proliferation and apoptosis of porcine granulosa cells (GCs), GCs were isolated from ovarian follicles (3-6 mm), treated with inhibin A at different concentrations. The cell viability, mitochondrial membrane potential (MMP), expression of proliferation-related genes and cell cycle were detected. Inhibin α subunit (INHA) gene was silenced to detect the effect of down-regulation of inhibin on expression of proliferation-related genes in GCs. The results showed that cell viability was associated with inhibin A concentration and significantly enhanced by inhibin A at high doses (50 and 100 ng/mL, P < 0.05) compared to control group (0 ng/mL). Meanwhile, the MMP boosted after treated with 100 ng/mL inhibin A for 48 h. Expression of proliferating cell nuclear antigen (PCNA) (200 ng/mL) and CyclinB1 (100 and 200 ng/mL) was promoted while Caspase-3(100 and 200 ng/mL) and BAX (200 ng/mL) was inhibited in dose dependent manner after the cells were incubated with inhibin A for 24 h (P < 0.05) compared to control group, thereby the transition from G1 phase to S phase was promoted and the number of S phase cells was increased. After silencing the INHA gene expression, expression of Caspase-3 was enhanced and CyclinB1 was inhibited (P < 0.05) compared to Ri-negative group. All the results pointed to the conclusion that inhibin A promotes the proliferation of GCs while inhibits apoptosis.