Celastrol induced the autophagy of spermatogonia cells contributed to tripterygium glycosides-related testicular injury

Tripterygium glycosides (TG) is extracted from the roots of Chinese herbal medicine named Tripterygium wilfordii Hook F (TwHF). TG tablets are the representative TwHF-based agents with anti-inflammatory and immunomodulatory activities for treating rheumatoid arthritis. Although the curative effect of TG is remarkable, the clinical application is limited by a variety of organ toxicity. One of the most serious side-effects induced by TG is damage of the male reproductive system and the toxic mechanism is still not fully elucidated. TG-induced testicular injury was observed in male mice by treated with different concentrations of TG. The results showed that TG induced a significant decrease in testicular index. Pathological observation showed that spermatogenic cells were obviously shed, arranged loosely, and the spermatogenic epithelium was thin compared with control mice. In addition, the toxic effect of TG on mouse spermatogonia GC-1 cells was investigated. The results displayed that TG induced significant cytotoxicity in mouse GC-1 cells. To explore the potential toxic components that triggered testicular injury, the effects of 8 main components of TG on the viability of GC-1 cells were detected. The results showed that celastrol was the most toxic component of TG to GC-1 cells. Western blot analysis showed that LC3-II and the ratio of LC3-II/LC3-I were significantly increased and the expression level of p62 were decreased in both TG and celastrol treated cells, which indicated the significant activation of autophagy in spermatogonia cells. Therefore, autophagy plays an important role in the testicular injury induced by TG, and inhibition of autophagy is expected to reduce the testicular toxicity of TG.