the observations that dopamine and apomorphine can block forskolin activation of tyrosine hydroxylase , that this blockade can in turn be prevented by preincubation with haloperidol or chlorpromazine , and that the amount of dopamine required for blockade of forskolin activation in synaptosomes has no effect on tyrosine hydroxylase when added to the enzyme assay constitute the first clear evidence of a presynaptic dopamine receptor ( autoreceptor ) .
C0206129
presynaptic
C0206128
autoreceptor