Regional cerebral glucose utilization reveals widespread abnormalities in the motor system of the rat mutant dystonic

Abstract

Rats with an inherited movement disorder (dystonic, dt), their phenotypically normal littermates, and normal unrelated controls were studied using a metabolic mapping technique, 2-deoxyglucose autoradiography. This approach was used to identify potential sites of abnormality underlying the movement disorder, as no morphological abnormalities using light and electron microscopic techniques have been identified in this mutation. There was a significant overall glucose utilization (GU) reduction in the dt rats and their littermate controls when they were at rest and not displaying abnormal movements. Conversion of GU values to standard scores showed abnormalities in dt compared with both control groups in the following areas: deep cerebellar nuclei, locus coeruleus, pontine gray, ventrolateral-ventromedial thalamic complex, nucleus of the third nerve, lateral habenula, and basolateral amygdala. Littermates were different from nonlittermates in several regions, including the dentate and red nuclei. A study of relative GU performed in animals displaying dystonic movements also showed abnormalities in the deep cerebellar nuclei and locus coeruleus, and in the red nucleus, external cuneate, and medial septum. Correlations computed for GU in pairs of regions with known anatomical connections suggested that cerebellar, substantia nigra, and basal ganglia efferents may be abnormal. These studies complement existing biochemical and neuropharmacological data which show abnormalities in the cerebellum of the dt rat. Additionally, the function of brain stem and even basal ganglia nuclei is affected in this mutant, perhaps as a consequence of abnormal cerebellar activity. The partial effects in the littermates suggest that abnormalities in only a few regions are not sufficient to produce the movement disorder, and a gene dose effect may exist.(ABSTRACT TRUNCATED AT 250 WORDS)