Wahba Z Z, Miller M S, Waalkes M P
Laboratory of Comparative Carcinogenesis, National Cancer Institute, Frederick Cancer Research and Development Center, MD 21702-1201.
Hum Exp Toxicol. 1994 Jan;13(1):65-7. doi: 10.1177/096032719401300110.
Testicular toxicity and interstitial cell tumours induced by cadmium are prevented by zinc or by low dose cadmium pretreatments. The mechanism of this tolerance is unknown, though metallothionein (MT) is thought to play a role in tissue resistance to cadmium toxicity. Thus, the possible involvement of the testicular MT gene in metal-induced tolerance to cadmium toxicity was studied. Rats were pretreated with zinc (1.0 mmol kg-1, s.c.). Histological examination of the testes indicated such pretreatments prevented the necrotizing effects of subsequent doses of cadmium (20 mumol kg-1, s.c.) administered 24 h later. RNA was extracted from testes or liver 24 h after zinc pretreatment, and analysed by the slot blot technique using the p2A10 cDNA probe to the MT gene. Zinc pretreatment had little effect on MT RNA in the testes, and such pretreatments did not alter testicular cadmium-binding protein capacity. In contrast, RNAs derived from livers of zinc pretreated rats showed marked increases in MT RNA and MT protein. Hence, the testicular MT gene does not appear to play a major role in the induced tolerance to cadmium toxicity and carcinogenesis generated by zinc.
锌或低剂量镉预处理可预防镉诱导的睾丸毒性和间质细胞瘤。尽管金属硫蛋白（MT）被认为在组织对镉毒性的抗性中起作用，但这种耐受性的机制尚不清楚。因此，研究了睾丸MT基因在金属诱导的对镉毒性耐受性中的可能作用。用锌（1.0 mmol kg-1，皮下注射）对大鼠进行预处理。对睾丸的组织学检查表明，这种预处理可预防24小时后给予的后续剂量镉（20 μmol kg-1，皮下注射）的坏死作用。在锌预处理24小时后从睾丸或肝脏中提取RNA，并使用针对MT基因的p2A10 cDNA探针通过狭缝印迹技术进行分析。锌预处理对睾丸中的MT RNA影响很小，并且这种预处理不会改变睾丸镉结合蛋白的能力。相反，来自锌预处理大鼠肝脏的RNA显示MT RNA和MT蛋白显著增加。因此，睾丸MT基因似乎在锌诱导的对镉毒性和致癌作用的耐受性中不起主要作用。
