Optimal dose of zinc supplementation for preventing aluminum-induced neurotoxicity in rats.

Zinc supplementation can help maintain learning and memory function in rodents. In this study, we hypothesized that zinc supplementation could antagonize the neurotoxicity induced by aluminum in rats. Animals were fed a diet containing different doses of zinc (50, 100, 200 mg/kg) for 9 weeks, and orally administered aluminum chloride (300 mg/kg daily) from the third week for 7 consecutive weeks. Open-field behavioral test results showed that the number of rearings in the group given the 100 mg/kg zinc supplement was significantly increased compared with the group given the 50 mg/kg zinc supplement. Malondialdehyde content in the cerebrum was significantly decreased, while dopamine and 5-hydroxytryptamine levels were increased in the groups given the diet supplemented with 100 and 200 mg/kg zinc, compared with the group given the diet supplemented with 50 mg/kg zinc. The acetylcholinesterase activity in the cerebrum was significantly decreased in the group given the 100 mg/kg zinc supplement. Hematoxylin-eosin staining revealed evident pathological damage in the hippocampus of rats in the group given the diet supplemented with 50 mg/kg zinc, but the damage was attenuated in the groups given the diet supplemented with 100 and 200 mg/kg zinc. Our findings suggest that zinc is a potential neuroprotective agent against aluminum-induced neurotoxicity in rats, and the optimal dosages are 100 and 200 mg/kg.