Protein phosphorylation in rat caudate homogenate: stimulatory effects of dopamine and enhancement of dopamine response following 6-hydroxydopamine treatment.

Dopamine (3-hydroxytyramine) stimulates the incorporation of 32P into proteins endogenous to a homogenate of rat caudate nucleus when 10 microM [gamma-32P]-ATP is used as a substrate following preincubation with 400 microM ATP. The increase in 32P incorporation has pharmacological characteristics similar to caudate tissue. Chronic depletion of striatal dopamine in vivo by stereotaxic injection of 6-hydroxydopamine in the nigrostriatal pathway results in a significant enhancement of the dopamine stimulation of 32 p incorporation in vitro. Cyclic AMP-stimulated phosphorylation of caudate proteins remains unchanged following 6-hydroxydopamine treatment.