Abstract: OBJECTIVE: To explore the mechanism of spermatogenesis inhibition induced by chronic alcohol consumption, and to examine the apotosis and proliferation of spermatogenic cells. METHODS: 40 healthy Sprague_Dawley adult male rats were randomly divided into four groups. Different doses of alcohol(0,2.7,4.5 and 7.5 g/kg) were administrated to the rats for 13 weeks by a gastric tube. The histological changes of rat testicular tissue were examined by light microscopy. The apoptosis and count of germ cells were evaluated by Flow Cytometry(FCM) and TUNEL, respectively.The expression of Caspase_3 and proliferating cell nuclear antigen (PCNA) in testes were detected by western blot. RESULTS: Light microscopic evaluation of testes demonstrated typical morphological changes of germ cell apoptosis including nuclear degeneration, condensation, and increased sloughed cellular element in tubular lumina especially in 7.5 g/kg alcohol_treated rats. Furthermore, the degree of testicular injury was associated with the dose of alcohol. Compared with control group , the apoptosis index in alcohol 7.5 g/kg group was higher(P<0.05). There was a marked decrease in haploid and tetraploid cells and significantly down_regulated expression of PCNA in alcohol 7.5 g/kg group(P<0.05). Western blot analysis showed that the expression of Caspase_3 increased markedly and the expression of PCNA significantly decreased in alcohol_treated group(P<0.05). CONCLUSION: Chronic alcohol intake could lead to an enhancement of germ cell apoptosis and a reduction of cell proliferation in rat testes, which may at least partly contribute to spermatogenesis inhibition.

Key words: alcohol, germ cell, rat, apoptosis, proliferating cell nuclear antigen, testes