Reproductive effects of low acute doses of cadmium chloride in adult male rats

Adult male Sprague-Dawley rats were injected sc with cadmium (Cd, as cadmium chloride) in doses ranging from 1.6 to 152 μmol Cd/kg body weight (body wt). Fourteen days after dosing, animals were evaluated for reproductive damage. Evaluations for each animal included testes, seminal vesicles, and epididymides weights, vas deferens sperm concentration, and human chorionic gonadotropin (hCG) -stimulated serum testosterone concentration. Since 10 to 60% mortality occurred in the two highest dose groups (74 and 152 μmol/kg), no additional evaluations were conducted in these groups. The weights of the testes, seminal vesicles, and epididymides were reduced at least 40 to 50% in groups receiving 16 or 33 μmol Cd/kg while vas deferens sperm concentrations and hCG-stimulated serum testosterone concentrations were essentially zero. Significant depressions in the sperm concentrations and in the hCG-stimulated serum testosterone concentrations were found in animals receiving the two lowest doses (1.6 and 7.4 μmol Cd/kg) although no changes in tissue weights were observed in these animals. Curve-linear regression analyses for the dose responsiveness of these parameters demonstrated that serum testosterone concentration initially decreased at a rate of 19%/μmol Cd/kg, respectively, and was the most sensitive to Cd exposure. The initial rates of decrease for sperm concentrations and for seminal vesicles, testes, and epididymides weight were 6.45, 5.30, 4.19, and 2.45%/μmol Cd/kg, respectively, and were less responsive to Cd exposure than serum testosterone levels.