Increased spontaneous motor activity in offspring after maternal cadmium exposure during lactation

Lactating rats were exposed to 0, 5 or 25 ppm cadmium as cadmium chloride in the drinking water. A battery of neurobehavioural tests was applied to the male offspring after weaning at 5 weeks until 4 months of age. The mean cadmium levels in exposed pup kidneys ranged from 0.006 to 0.030 mg/kg wet weight at weaning, with the corresponding maternal kidney cadmium levels ranging from 4 to 13 mg/kg wet weight. Significantly increased activity during the initial 20 min of the spontaneous motor activity test was observed in the highest-dose group compared to the control group. The activity outcome was significantly positively correlated with cadmium levels in the pup kidneys. No cadmium-related changes in performance were observed in the Morris water maze, the E-shaped maze or the elevated plus-maze. The results indicate that neurobehavioural effects during development may be a more sensitive parameter for Cd toxicity than renal dysfunction.