Effect of testicular autophagy on spermatogenic cells in varicocele rats

Objective To study the effect of different levels of autophagy in the testis on the apoptosis of spermatogenic cells in the rat model of varicocele (VC). METHODS We randomly divided 54 SD male rats into six groups, blank control (n = 6), rapamycin control (n = 6), chloroquine control (n = 6), VC model control (n = 12), VC + rapamycin (n = 12), and VC + chloroquine (n = 12). We observed the histomorphological changes of the testis and epididymis by HE staining, obtained the scores on spermatogenesis in the testis and epididymis, calculated the apoptosis index (AI) of the testicular spermatogenic cells by TUNEL, and determined the expressions of LC3-Ⅱ, LC3-Ⅰ, p62, Bax and Bcl-2 proteins in the testis tissue by Western blot. RESULTS There were no significant morphological changes in the testis and epididymis of the rats in the blank control, rapamycin control and chloroquine control groups, or significant differences in the scores on testicular and epididymal spermatogenesis and AI of the testicular spermatogenic cells (P>0.05). The animals in the VC model control group exhibited significant pathological damage in the testicular and epididymal tissues, with remarkably decreased scores on spermatogenesis (P<0.01) and increased AI (P<0.01), which were markedly improved in the VC + rapamycin group and slightly aggravated in the VC + chloroquine group compared with the VC model controls. In comparison with the rats in the blank control group, those in the VC model control group showed significantly up-regulated expressions of the autophagy-related protein LC3 (including the LC3-Ⅱ/LC3-Ⅰ ratio) and the pro-apoptotic protein Bax in testicular tissue (P<0.01) but down-regulated expression of the anti-apoptotic protein Bcl-2 (P<0.01). The expressions of LC3 and Bcl-2 in the testis tissue were significantly higher in the VC + rapamycin (P<0.01) but lower in the VC + chloroquine group (P<0.01), while those of p62 and Bax remarkably lower in the VC + rapamycin (P<0.01) but higher in the VC + chloroquine group than in the VC model controls (P<0.01). CONCLUSIONS Varicocele induces autophagy in the testis and apoptosis of spermatogenic cells in rats. Up-regulating autophagy can inhibit while blocking autophagy can promote the apoptosis of spermatogenic cells.