Chronic manganese intake induces changes in the motor activity of rats

Abstract

Two groups of adult male Sprague-Dawley rats were treated with manganese added to the drinking water in concentrations of 0.1 and 5.0 mg Mn2+/ml. Age-matched controls received distilled demineralized water. Spontaneous motor activity, measured in 60-min weekly sessions during 8 months, showed a significant increase during the 1st month. Further exposure did not affect the motor activity to 6 months. But, on months 7 and 8 a significant reduction was observed compared with controls. Both hyper- and hypoactivity were not dose-dependent as the results obtained in both groups of manganese-exposed rats were similar. These findings should make health authorities aware of the potential involvement of low doses of manganese in the development of early behavioral problems long before the irreversible neurologic damage is established.