Involvement of sulfhydryl metabolism in tolerance to cadmium in testicular cells

Cadmium (Cd)-induced acute testicular toxicity and testicular interstitial cell (IC) tumors can be prevented by low-dose Cd pretreatment. The mechanism of this self-tolerance is unknown. In this regard glutathione (GSH) may play a role in protecting cells from damage by Cd. Therefore, possible mechanisms of self tolerance to Cd in ICs were investigated with emphasis on sulfhydryl metabolism. Rats were pretreated with low-dose Cd (3.0 μmol/kg, sc). Such low-dose Cd pretreatment prevented the necrotizing effects of normally testopathic doses of Cd (20.0 μmol/kg, sc) given 24 hr later. ICs were isolated by collagenase dispersion 24 hr after pretreatment and incubated with Cd (1.0 m m) for 1 hr. In vivo Cd-pretreatment alone increased GSH levels (as determined by HPLC) of whole cells (17%) and cytosol (17%) compared to nonpretreated control. When ICs from nonpretreated rats were exposed to Cd in vitro, GSH in whole cells declined 8% compared to nonpretreated control and 21% compared to cells from in vivo Cd-pretreated rats. In ICs isolated from pretreated rats and exposed to Cd in vitro, GSH levels were normal in whole cells and slightly increased in cytosol. In whole testes low-dose Cd reduced GSH overall, both in cytosol (34%) and in nuclei (14%). Changes in cysteine levels were also seen, similar to those of GSH in whole ICs and cytosol. Neither low-dose in vivo Cd-pretreatment nor in vitro Cd exposure greatly altered levels of the low M r testicular Cd-binding proteins as assessed by electrophoresis. These results indicate that sulfhydryl metabolism, specifically increased GSH, may be a factor in self tolerance to Cd in ICs.