Yangjing Capsule Increases Testosterone Production through SET/PI3K/Akt Pathway in Leydig Cell

Background. Our previous works revealed Yangjing capsule (YC) could inhibit cell apoptosis and promote testosterone production in Leydig cells. SET protein has been reported to be important in regulating testosterone synthesis and apoptosis. The purpose of this study was to investigate whether the steroidogenic and antiapoptotic effects of YC are mediated in part by the SET/PI3K/Akt pathway in Leydig cells. Methods. MLTC-1 cells were treated with YC-medicated serum. si-RNA was used to knockdown SET expression in MLTC-1 cells. The elderly BALB/c mice were treated with different doses of YC extract. Flow cytometry and TUNEL staining were used to assess apoptosis in MLTC-1 cells and mouse testes. HE staining was conducted to detect the morphological changes in mouse testes. Testosterone levels in cell culture medium and serum were measured by ELISA kit. Quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) and Western blot were used to detect the expression levels of key molecules. Results. YC-medicated serum could significantly increase the expression of SET and StAR, P450scc, HSD17B, and testosterone production in MLTC-1 cells. YC-medicated serum could increase Akt phosphorylation and Bcl-2/Bax ratio to suppress apoptosis in MLTC-1 cells. SET knockdown significantly inhibited YC-medicated serum-induced steroidogenic and antiapoptotic effects in MLTC-1 cells. In vivo experiments revealed the YC extract could enhance SET expression, trigger Akt phosphorylation, and suppress apoptosis in mouse testis to raise serum testosterone levels. Conclusions. A possible mechanism of promoting testosterone production induced by YC in Leydig cell was by triggering SET/PI3K/Akt pathway.