Subcortical changes in the regional uptake of [3H]-2-deoxyglucose in the brain of the monkey during experimental choreiform dyskinesia elicited by injection of a gamma-aminobutyric acid antagonist into the subthalamic nucleus.

Abstract

Hemichorea/hemiballismus was induced in monkeys by localized injections of a gamma-aminobutyric acid antagonist into the contralateral subthalamic nucleus. During active dyskinesia, [3H]-2-deoxyglucose was administered and, subsequently, regional cerebral metabolic activity was examined by autoradiographic exposure of brain sections. The results indicate that during dyskinesia there was an overall decrease in local cerebral glucose utilization in a number of structures on the side of the brain contralateral to the abnormal movements (ipsilateral to the drug injection). These structures included the injected subthalamic nucleus, both medial and lateral segments of the globus pallidus, the substantia nigra, and the ventral anterior and ventral lateral nuclei of the thalamus. On the basis of evidence that changes in the energy requirement of neurons are due mainly to changes in synaptic activity, the autoradiographic findings are interpreted as indicating that during experimental hemichorea/hemiballismus there was an overall decrease in synaptic activity of subthalamopallidal, subthalamonigral and pallidothalamic pathways on the side of the brain contralateral to the dyskinesia. This interpretation is discussed in relation to current theories of the pathophysiology of choreiform dyskinesias.