Effects of treatment with Astragalus Membranaceus on function of rat leydig cells

Background: Astragalus membranaceus (AM) is a Chinese traditional herb which has been reported to have broad positive effects on many diseases, including hepatitis, heart disease, diabetes and skin disease. AM can promote cell proliferation, increase the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), and inhibit apoptosis by regulating the transcription of proto-oncogenes controlling cell death. While AM is included in some commercially available "testosterone boosting supplements", studies directly testing ability of AM to modulate testosterone production are lacking. In the present study, we examined the effects of AM on Leydig cell function in vitro. Methods: Rat Leydig cells were purified and treated with AM at different concentrations (0 μg/mL, 10 μg/mL, 20 μg/mL, 50 μg/mL, 100 μg/mL and 150 μg/mL) and cell counting-8 (CCK-8) assay, Enzyme-linked immunosorbent assay, quantitative real time PCR and analysis of activities of SOD and GPx were done respectively. Results: Treatment with 100 μg/mL (P<0.05) and 150 μg/mL AM (P<0.01) significantly increased Leydig cell numbers. Treatment with AM (20 μg/mL, 50 μg/mL and 100 μg/mL) significantly increased testosterone production (P<0.01). In addition, increased Leydig cell SOD and GPx activities were observed in response to 20 μg/mL and 50 μg/mL AM treatment (P<0.01). Furthermore, expression of Bax mRNA was significantly decreased (P<0.01), and the ratio of Bcl-2/Bax mRNA was significantly increased in response to 20 μg/mL AM in the culture medium (P<0.05). Conclusions: Results supported a beneficial effect of AM on multiple aspects of rat Leydig cell function in vitro including testosterone production.