Neurotoxic effects of cadmium in young rats

Abstract

This study examined the effects of cadmium on the brain of male, Sprague-Dawley rats of different ages. Cadmium was more toxic in 4-day-old than in adult rats, thus 2 and 4 mg/kg were given sc to the younger rats and 4 and 6 mg/kg to the older rats. The lower doses resulted in no mortality and the higher dose about 10% mortality in both groups. Four days after a sc injection of cadmium chloride (4 mg Cd/kg) to 4-day-old rats, lesions were evident in the corpus callosum, caudate-putamen, and cerebellum, while 2 mg/kg of cadmium produced only slight cerebellar damage. Nineteen days after injection of 4 mg Cd/kg to 4-day-old rats, a large cystic cavity was evident where the corpus callosum is normally located. In contrast, cadmium did not produce any observable brain damage in adult rats at 4 or 6 mg/kg, either 4 or 19 days after injection. Eighteen days after treatment, hyperactivity was evident in newborn rats exposed to 4 mg/kg of cadmium, but not in newborn rats exposed to 2 mg/kg of cadmium or in adult rats treated with 4 or 6 mg/kg of cadmium. Thus, cadmium at a dose that produces only a few deaths is toxic to the brain of newborn rats, as evident by hyperactivity and lesions.