Effect of manganese on synthesis of brain catecholamines in growing rats

The effect of short-term exposure of manganese on the synthesis of brain catecholamines in growing rats has been investigated by using two methods, 1) measuring the amount of conversion of 3,5-3H-tyrosine to 3H-labelled dopamine and norepinephrine, and 2) measuring the rate of decline of endogenous dopamine and norepinephrine following inhibition of their synthesis with alpha-methyl-p-tyrosine. The magnitude of conversion of 3,5-3H-tyrosine to 3H-dopamine and 3H-norepinephrine in the brain at 60 min after the administration of labelled amino acid to the manganese treated rats (1 mg MnCl2.4H2O/ml of water for 30 days) was significantly greater than observed in control rats. Manganese also increased turnover of dopamine and norepinephrine to a greater extent in the brains of treated animals.