Interference Of Environmental Estrogen Effect Of Cadmium On The Testicular Differentiation And Development Of Male Rats

Objective: To investigate the interference and mechanism of environmental estrogen effect of cadmium on the testicular differentiation and development of off-spring male rats.Methods: 32 pregnant SD rats were randomly divided into the normal control group, two CdCl2 treated groups and positive control group, 8 each group. On the 9th, 11th, 13th day during the pregnant period and every other day during lactation respectively, the two CdCl2 treated groups were intraperitoneally injected with CdCl2[1.2 or 1.5 mg/(kg·d)], the posivive control group were subcutaneously injected with DES[100μg/(kg·d)] on the 9th-17th during the pregnant period and every other day during lactation respectively, the normal control group was given equivalent normal saline. On the 18th day during the pregnant, 4 pregnant SD rats of each group were uterine-incision deliveried, fetal testes were obtained for immunohistochemistry of Cytochrome P450 side chain cleavage enzyme (P450scc) and estrogen receptor alpha (ERα), light microscope and ultrastructrue observation. On the 30th day after parturition,the testes of off-spring male rats from the rest pregnant SD rats were obtained for related morphological measure, immunohistochemistry of P450scc and ERα, light and electron microscope observation. Meanwhile, Serum sex hormone were determined by radioimmunity.Results: (1) Differentiated initial stage seminiferous tubule were observed in GD18 fetal rats from normal control group by light microscope. Monoptychial Sertoli cells tightly stuck to the basal lamina, and near to some gonocytes. Sertoli cells were disordered arranged in 1.5 mg/(kg·d) Cd group and positive control group, whereas 1.2 mg/(kg·d) Cd group had no obvious changes compared with nomal control group. Abnomal ultrastructual alternations of seminiferous tubules and Leydig cells were also observed in both Cd groups, showing swelling of mitochondria and dilatation of endoplasmic reticulum in gonocytes, Sertoli cells and Leydig cells, cumulation of lipid droplets in Leydig cells. The positive products of P450scc in cytoplasm of Leydig cells were significant decreased in both Cd groups and positive control group compared with normal control group(P<0.05). Whereas the positive products of ERαin nucleus of gonocytes and Leydig cells were increased in both Cd groups and positive control group (P<0.05).(2) On PND30, the weight and volume of testes were both decreased in 1.5 mg/(kg·d) Cd group(P<0.05). MSTD and TBS were also decreased in both Cd groups and positive control group. In addition, the histological changes of seminiferous tubule were observed in both Cd groups, including vacuoles among the cells tightly stuck to the basal lamina, sparse arranged spermatogenic cells, caducous spermatogenic cells clumping in some seminiferous tubule, and hyperplastic fibroblasts and collagen fibers. Furthermore, wide gaps between spermatogonia and Sertoli cells, swollen mitochondria and /or dilatate endocytoplasmic reticulum in spermatogonia, Sertoli cells and Leydig cells, as well as increased lysosomes and myelinfigure in some cells were observed by electron microscope. Meanwhile, serum T and LH were significant down regulation corresponding in both Cd groups and positive control group compared with normal control group(P<0.001), and the positive products of P450scc were significant decreased, accordingly (P<0.05). Whereas the positive products of ERαwere increased in spermatogonia and Leydig cells of 1.5 mg/(kg·d) Cd group and positive control group (P<0.05).Conclusion: Our experiments demonstrated that cadmium exposure during gestation and lactation could cause the histomorphology disorder of testicular differentiation and development on off-spring male rats. It influenced the expressions of P450scc and ERαsignificantly, and down regulated serum T and LH accordingly. The disturbing effect could be continued from embryonic period to impuberal. It presumed that cadmium could play a environmental estrogen effect on male testicular differentiation and development through anti-androgenic actitivity, estrogenic activity as well as feedback regulation of hypothalamic-pituitary-gonadal axis which influence hormones metabolism.