[Estradiol benzoate induces abnormal proliferation of spermatogenic cells in the testis of infertile male mice].

Objective: To explore the change in the proliferation of spermatogenic cells in the male mouse with infertility induced by exogenous estradiol benzoate (EB).
Methods: Sixty male mice aged 4 weeks were randomly divided into a control, a low-dose EB, and a high-dose EB group to be injected intramuscularly with corn oil at 150 μl or EB at 5 or 10 mg/kg, respectively, every other day for 4 weeks. Then, we obtained the weight and indexes of the testis, performed HE staining of the paraffin sections of the testis tissue and epididymal cauda, counted the spermatozoa in the epididymal sperm suspension, and determined the expression of the proliferating cell nuclear antigen (PCNA), the mRNA expressions of CyclinA1, CyclinB1, VASA and p53, and the protein expressions of p53 and phosphorylated p53 in the testis by immunohistochemistry, qRT-PCR and Western blot, respectively.
Results: In comparison with the controls, the mice treated with EB showed significantly decreased testicular indexes (P <0.05), no sperm in the sperm suspension or epididymal tubes, remarkably reduced numbers of spermatogonia, primary spermatocytes and Sertoli cells (P <0.05), down-regulated expression of PCNA (P <0.05) and mRNA expressions of CyclinA1, CyclinB1, PCNA and VASA in the seminiferous tubules (P <0.05), but a dose-dependent increase of the p53 level (P <0.05). Western blot revealed markedly higher levels of p53 protein expression and phosphorylation in the EB than in the control group (P <0.05) and even higher in the 10 mg/kg than in the 5 mg/kg EB group (P <0.05).
Conclusions: EB inhibited the proliferation of spermatogenic cells by down-regulating the expressions of cell cycle-related factors in a dose-dependent manner, which might contribute to abnormal proliferation of spermatogenic cells in the testis of infertile male mice.