N-methyl-4-phenylpyridinium and an endogenously formed analog, N-methylated beta-carbolinium, inhibit striatal tyrosine hydroxylation in freely moving rats.

The effects of N-methyl-4-phenylpyridinium (MPP+) and its endogenous analog, 2,9-di-methyl-norharmanium (2,9-Me2NH+), on in vivo tyrosine hydroxylation were evaluated in freely moving rats. MPP+ gradually but almost completely reduced tyrosine hydroxylation, even at a dose as low as 0.05 mM. This effect was considered to be caused by the inhibition of… CONTINUE READING