This study was carried out to investigate the effect of manganese on the brains of rats, and chronic exposure to manganese is known to induce Parkinsonism in human.

The rats were divided into three groups: the first group was a control group that was administrated normal saline, and the second group was subdivided into the low dose group (10 mg/kg) and the high dose group (40 mg/kg) according to the administered dose of manganese. The rats of each group received an injection of normal saline and manganese via a tail vein once a week for 4 weeks. The rats were sacraficed at 4 weeks after the first adminstration of manganese. Brain MR imaging was performed before the rats were killed. After the rats were killed, the concentration of blood manganese was measured, and pathologic examination of the brain was performed in all the groups.

The concentration of blood manganese was increased proportionally to the administered dose. The signal intensity of the basal ganglia on the T1-weighted imaging of brain MRI was increased in accordance with the administered dose. The ratio of neuron/glial cells in the basal ganglia was decreased in the experiment group as compared to that of the control group.

This study showed that the signal intensity and the damage of neurons in basal ganglia were increased according to the administered dose of manganese in rats.