Effect of manganese and copper interaction on behavior and biogenic amines in rats fed a 10% casein diet.

Manganese chloride (1 mg manganese/ml drinking water) and copper sulphate (250 mg copper/kg diet) were administered daily for 30 days to growing rats maintained on a 10% casein diet. Manganese in combination with copper produced impairment in the learning ability and memory of rats in either dietary group, with greater alterations in those receiving a 10% casein diet. Hyperactivation due to the combined effects of the metal ions was identical in both dietary groups. The behavioral aberrations were associated with a marked accumulation of Cu in the brain of rats receiving the 10% casein diet. Combined exposure of Mn and Cu also produced a greater elevation in the levels of dopamine (DA) and norepinephrine (NE) and a depression of 5-hydroxytryptamine (5-HT) in the brain of animals fed with a 10% casein diet compared to the animals receiving the 21% casein diet. Thus the animals receiving the 10% casein diet appear to be more vulnerable to the neurotoxic effects of a combined exposure to manganese and copper. However rats maintained on the 21% casein diet and receiving both manganese and copper showed almost identical changes to those observed after manganese administration alone.