[The effect of chronic activation and block of the dopamin- and enkephalinergic systems of the neostriatum on conditioned-reflex behavior abd dopamine metabolism in the nigrostriatal system of rats].

Were studied the effects of bilateral daily intrastriatal microinjections in the course of two weeks of amphetamine (45 mcg), haloperidol (5 mcg), naloxone (5 mcg), and enkephalin synthetic tetrapeptide analogue (15 mcg) on behaviour and the level of dopamine and its metabolites in the striatum and substantia nigra of rats. Amphetamine improved but haloperidol impaired conditioned avoidance response realization in a shuttle-box and produced parkinsonian-like akinetic status. Naloxone was behaviourally uneffective but the tetrapeptide produced the obvious cataleptic status with plastic rigidity of the skeletal muscles. Both amphetamine and haloperidol lowered significantly striatal dopamine level and increased the level of its metabolites. The tetrapeptide produced the opposite neurochemical effect. Possible origin of discoordination between behavioural and neurotransmitter changes are discussed.