The Studies Of Sub-Chronic Aluminum Exposure On Reproductive Toxicity In Male Rats

The toxicity mechanism of sub-chronic aluminum exposure on reproductive system in male rats was explored. In this experiment, 5-weeks rats (n=60) were randomly divided into four groups: the control group, the low dose group, the middle dose group and the high dose group, and orally exposed to 0, 25.67, 128.36 and 256.72 mg/kg aluminum trichloride (AlCl₃) by drinking water for 120 days. Physical condition, cutting inspection changes, microstructure and ultrastructure of the testis and epididymis, sperm count and abnormal sperm rate were observed. The activities of ACP,SDH,LDH,LDHx and ATPase were detected by spectrophotometry. The contests of Al, Zn, Cu and Fe in testis were measured using graphite furnace atomic absorption spectrophotometry and flame atomic absorption spectrophotometry. The levels of T, LH and FSH in serum were detected using 125I radioimmunoassay (RIA) kits. The protein expressions of AR, FSHR and LHR in testes were detected by immunohistochemistry. The mRNA expressions of AR in testes were detected by real-time Q-PCR. The mRNA expressions of FSHR and LHR in testes were detected by semiquantitative RT-PCR. The results were shown as follows:1 Under optical microscope, cell interstitial fibrosis of the epididymis in Al-treated rats was observed, and columnar epithelial cells dissolved and disappeared; Leydig eosinophils increased significantly, and testicular tubules seminiferous epithelium became thinning. Seminiferous tube was narrow, and sperm quantity within convoluted tubule was little or no. Under electron microscope, stereocilia of cell surface fusion, mitochondria swelling or empty bubble degeneration and rough surface tastes retinal sexual structure fusion were observed in the epididymis of Al-treated rats. Capsule of spermtail and acrosomal dissolved. Intercellular spaces of spermatogoniums and spermatocytes increased and nuclear membrane shrinked.2 Compared with the control group, the sperm counts in the middle and high groups were decreased (P<0.01), and the sperm abnormal rate was increased (P<0.01), which indicated that Al damaged sperms.3 The decreases of ACP, SDH, LDH, LDH-x and ATPase activities induced by sub-chronic Al exposure interfered with energy metabolism of reproductive system and then suppressed the function of germ cells.4 Compared with the control group, the contents of Al and Cu in the middle and high groups were increased (P<0.05, P<0.01), and the contents of Zn and Fe were decreased (P<0.05, P<0.01) in testes, which indicated that Al accumulated in the testes interfered with the metabolism of Zn, Cu, Fe, accordingly inhibited spermatogenesis.5 Compared with the control group, the serum levels of T and LH in the middle and high groups were decreased (P<0.05, P<0.01), while there was no significant difference in the levels of FSH between the Al-exposre groups and the control group. The results indicated that sub-chronic Al exposure decreased the serum levels of T, LH and the mRNA and protein expressions of AR, FSHR and LHR, which reduced the combination of the hormones and receptors, inhibited the effects of the hormones on testis development and spermatogenesis.