Striatal dopamine turnover and L-dopa treatment after short-term exposure of rats to manganese.

The turnover rate of striatal dopamine (DA) and the effect of L-dopa treatment was investigated in rats after the daily oral administration of MnCl2 . 4H20 for a period of 30 days. The turnover rate of striatal DA, as determined by the administration of alpha-methyl-p-tyrosine, increased significantly in manganese-exposed rats. L-Dopa administration resulted in a significant elevation in the levels of DA and its metabolite, homovanillic acid, in manganese-exposed rats, but these neurochemical changes could not be correlated with the concentration of manganese in the striatum. We therefore advise the L-dopa therapy should not be tried in early manganese intoxication, as it may aggravate manic symptoms due to marked increase in brain DA.