The effect of 3-week daily injection of 5 or 15 mg enkephalin-like tetrapeptides (TP) into the rostral neostriatum was studied in chronic experiments on rats with implanted microcannulas. According to the type of TP, hyperkinesia or a pathological cataleptic status was registered in disorder of conditioned reflex behavior of rats. Myoclonus of the muscles of the face and the muscles of the front limbs was encountered from the 10th till the 120th minute after the injection and was characterized by dynamic changes during chronic administration of the agent and clearly defined stage of generalization. A pathologic cataleptic status (rigidity) in an animal kept in a suspended position occurred 120-140 minutes after the microinjection and lasted for up to 100 sec. The effect of the agent depended on the dose and stage of its chronic injection. The results of the study allow the conclusion on the principal possibility of the striatal enkephalinergic system being involved in the genesis of neuromotor dyskinesia and dysfunction of the basal ganglia, which is manifested by disorders of conditioned reflex behavior and motor extrapyramidal deviations.
Animals Corpus Striatum