Whanger P D, Ridlington J W, Holcomb C L
Ann N Y Acad Sci. 1980;355:333-46. doi: 10.1111/j.1749-6632.1980.tb21351.x.
The administration of cadmium to rats by either oral or injection routes causes zinc to accumulate in the low molecular weight (MW) protein metallothionein (MT) of liver and kidney, but not in a low MW protein in the testis. Preliminary evidence indicates that the low MW cadmium-binding protein in testes is not MT. Feeding high levels of zinc to rats results in its accumulation with tissue MT, and the zinc is very labile. In contrast, the zinc that accumulates in MT as the result of cadmium exposure is not very labile. In the reverse situation, zinc does not cause cadmium to accumulate in MT. The turnover of MT is shorter when saturated with zinc than when cadmium is the predominant metal bound to it. Even though selenium will counteract testicular damage due to cadmium, it causes cadmium to accumulate in this organ at higher levels than in animals exposed to cadmium without selenium. Injection of selenate, and selenide--but not selenomethionine or selenocystine--diverts the binding of injected cadmium from low MW proteins to high MW ones in the testes. Selenium injections had only minor influences on the binding of zinc to testicular proteins. In contrast, very little diversion occurred in the binding of either cadmium or zinc in tissues of rats fed high levels of selenium. The data suggest that it is the selenide form of selenium that causes the diversion of cadmium binding in tissues, thus providing protection of testes against cadmium exposure.
通过口服或注射途径给大鼠施用镉会导致锌在肝脏和肾脏的低分子量（MW）蛋白质金属硫蛋白（MT）中积累，但不会在睾丸的低MW蛋白质中积累。初步证据表明，睾丸中的低MW镉结合蛋白不是MT。给大鼠喂食高水平的锌会导致其与组织MT积累，并且锌非常不稳定。相比之下，由于镉暴露而在MT中积累的锌不是很不稳定。在相反的情况下，锌不会导致镉在MT中积累。当MT被锌饱和时，其周转时间比以镉为主要结合金属时短。尽管硒会抵消镉对睾丸的损伤，但它会导致镉在该器官中的积累水平高于未接触硒的镉暴露动物。注射硒酸盐和硒化物——但不是硒代蛋氨酸或硒代胱氨酸——会使注射的镉在睾丸中的结合从低MW蛋白质转向高MW蛋白质。硒注射对锌与睾丸蛋白质的结合只有轻微影响。相比之下，在喂食高水平硒的大鼠组织中，镉或锌的结合几乎没有发生转移。数据表明，正是硒的硒化物形式导致组织中镉结合的转移，从而为睾丸提供了免受镉暴露的保护。
