[Zinc deficiency induces exfoliation of round spermatids by decreasing the expressions of TGF-β1 and FAK in the mouse testis].

OBJECTIVE

To investigate the mechanisms of zinc deficiency inducing spermatogenic disorders.

METHODS

Forty 4-week-old CD-1 male mice were randomly divided into two groups of equal number: experimental and control, the former fed on a low-zinc diet and the latter on a normal diet, both for 5 weeks. Then all the mice were sacrificed and their testes and epididymides harvested for detection of the concentration of zinc ion in the testis by atomic absorption spectrophotometry, observation of the histopathological changes in the testis and epididymis by HE staining, examination of the properties of the exfoliated cells by dual immunofluorescence staining and determination of the expressions of ZO-1, FAK, TGF-β1, TGF-β2, TNF-α and Par6 proteins in the testicular tissue by Western blot.

RESULTS

The concentration of zinc ion in the testis was significantly lower in the experimental than in the control group (［140.59 ± 16.22］ vs ［218.44 ± 31.29］ μg/g, P < 0.05). HE staining showed normal testicular tissue structure, dense seminiferous tubules and intact seminiferous epithelium, with clear and orderly arrangement of spermatogenic cells at all levels in the control group. The ratio of the abnormal seminiferous tubules to the total number was 0.01 ± 0.01. The mice in the experimental group, however, exhibited degeneration of seminiferous epithelium, reduced number of spermatids, vacuolated cytoplasm of Sertoli cells, occluded seminiferous tubules, and a remarkably larger number of abnormal seminiferous tubules than that in the control (0.75 ± 0.04 vs 0.25 ± 0.04, P < 0.01). Exfoliated cells were observed in the abnormal tubules and the caput, corpus and cauda of the epididymis in the experimental group, which were shown to be immature round spermatids in H1T2 and TRA54 dual-immunofluore-scence staining. Western blot manifested that the protein expression of ZO-1 was 0.904 ± 0.052 vs 1.130 ± 0.054 in the experimental and control groups, that of Par6 was 0.129 ± 0.049 vs 0.145 ± 0.047, that of TGF-β2 was 0.116 ± 0.047 vs 0.142 ± 0.048, and that of TNF-α was 0.469 ± 0.022 vs 0.458 ± 0.023, with significant decreases in the former group as compared with the latter in the levels of FAK (0.144 ± 0.047 vs 0.219 ± 0.048, P < 0.05) and TGF-β1 (0.024 ± 0.058 vs 0.586 ± 0.048, P < 0.01).

CONCLUSIONS

Zinc deficiency can induce histopathological changes in the testis of the mouse, leading to exfoliation of round spermatids, in which FAK and TGF-β1 may play an essential contributive role.