Biochemical and behavioural effects of tyrosine hydroxylase inhibition

Observations give additional support to the view that the brain CA play a role in the maintenance of CAR, and a small subthreshold dose of l-DOPA given after (+)-amphetamine, restored the activity of amphetamine.

Abstract

Selective depletion of the brain catecholamines (CA) was induced in cat and rat by administration of 3, α-dimethyl tyrosine methylester-HCl (H 59/64), a specific inhibitor of tyrosine hydroxylase. A concomitant decrease of conditioned avoidance responses (CAR) was observed. The observations give additional support to the view that the brain CA play a role in the maintenance of CAR. The functional significance of the CA synthesis inhibition was further demonstrated in reserpine pretreated cats. In these animals the CAR was restored by (+)-amphetamine but the behavioural restoration failed to appear after the combined reserpine and H 59/64 pretreatment. A small subthreshold dose of l-DOPA given after (+)-amphetamine, restored the activity of amphetamine.