Effect of Epimedium flavonoids on decreasing secretion function of Sertoli cells in testis of natural aging rats / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE To investigate the effect of total flavonoids of Epimedium (TFE) on the decline of secretion function of senile testis-supporting cells (Sertoli cells), and to explore their molecular mechanism from inositol-requiring enzyme 1α(IRE1α)/X-box- binding protein 1(XBP1) signaling pathway. METHODS Thirty-six SPF 18-month-old SD male rats were randomly divided into natural aging group, low and high dose TFE groups, with 12 rats in each group. Another ten 2-month-old rats were used as a youth control group. TFE was ig given once a day, and the ig administration was continued every five days after a two-day interval, and the administration lasted for 4 months. Then, the testicular index was calculated. The testicular histomorphology was observed by HE staining; while quantitative-PCR (qPCR) and Western blotting were used to detect the mRNA and protein expression levels of glial cell derived neurotrophic factor (GDNF), bone morphogenetic protein 4 (BMP4) and stem cell factor (SCF), and Western blotting protein expression levels of p-IRE1α and XBP1 in testes. The number of Sertoli cells in the testis and the localization of p-IRE1α in the testis were detected by immunofluorescence. RESULTS Compared with the young control group, the testicular index decreased significantly in the natural aging group (P<0.01), but was significantly up-regulated after TFE 40 m g · k g- 1 (P<0.05). The results of HE showed that the morphological structure of the testicular seminiferous tubules in the natural aging group were disorderly, and some spermatogenic cells were shed. The TFE group could improve the morphological structure of the seminiferous tubules of the testis. qPCR and Western blotting results showed that compared with the young control group, the mRNA and protein expression levels of GDNF, BMP4 and SCF in Sertoli cells in the natural aging group were significantly down-regulated (P< 0.01). However, the expression of secretory factors in TFE group was significantly up-regulated (P< 0.05, P<0.01). Western blotting results showed that compared with the young control group, the expression of p-IRE1α and XBP1 protein in the testis of the natural aging group was significantly down-regulated (P<0.01), but the expression of p-IRE1α and XBP1 protein in the TFE group was significantly up-regulated (P<0.01). The results of immunofluorescence also showed that there was no significant difference in the number of Sertoli cells between the natural aging group and the TFE group compared with the young control group, while the expression of p-IRE1α was localized both in cytoplasm of Sertoli cells and spermatogenic cells. CONCLUSION TFE can significantly improve the decline of secretion function of testicular Sertoli cells induced by aging, and the mechanism may be related to the regulation of IRE1α/XBP1 signaling pathway.