Age difference in the susceptibility to cadmium-induced testicular damage in rats

Abstract

Since the concentration of cadmium in the testes after cadmium administration to 4-day-old rats is five times that of adults, the objective of this study was to determine if there is an age difference in the susceptibility of Cd-induced testicular damage. Adult rats treated with Cd (1 mg Cd/kg, iv) at 10 weeks of age developed testicular damage and atrophy which persisted for at least 12 weeks. These rats were found to be sterile at the seventh week after injection. For rats treated at 4 days of age, there was no difference in testicular weight, morphology, and fertility between the saline- and Cd-treated groups during 12 weeks after injection. When rats of various ages were examined, it was found that Cd produced no detectable changes in the testes of rats that are 2 weeks of age and younger but slight degenerative changes were observed in rats 3 to 5 weeks of age. However, in rats 6 weeks of age and older, cadmium produced necrosis and atrophy of the testes. Testicular metallothioneins have been proposed to be involved in the protection against Cd-induced testicular damage after cadmium pretreatment in the adult. However, the testicular concentration of metallothioneins in 4-day-old rats was not higher than that of 10-week-old rats, indicating that the age difference in susceptibility to Cd-induced testicular damage is not due to age differences in testicular metallothionein levels. In conclusion, immature rats are resistant to testicular injury produced by Cd and it appears that testicular levels of metallothionein or cadmium do not play an important role in the difference in sensitivity of various aged rats to Cd.