[3H]-2-deoxyglucose uptake study in mutant dystonic hamsters: abnormalities in discrete brain regions of the motor system.

The genetically dystonic (dtSZ) hamster, an animal model of idiopathic paroxysmal dystonia, displays attacks of generalized twisting movements and abnormal postures of limbs and trunk either spontaneously or in response to mild stress. This experimental model may be helpful to give insights into the pathophysiology of idiopathic dystonia in man. In the present study, the regional uptake of [3H]-2-deoxyglucose (2-DG) was examined in brains (75 brain regions) of dtSZ hamsters during the expression of severe dystonia. 2-DG autoradiography revealed significant changes of 2-DG uptake in discrete brain regions of dtSZ hamsters compared with age-matched, nondystonic control hamsters. In dystonic hamsters, a dramatic increase of 2-DG uptake was observed in the red nucleus (159% over control). Furthermore, enhanced 2-DG uptake was found in the ventromedial, ventrolateral, and anteroventral nuclei of the thalamus (19-42%) and in the medial vestibular nucleus (23%). A significant decrease in 2-DG uptake in deep cerebellar nuclei (-30%) may be the result of decreased synaptic activity of GABAergic neurons within these structures resulting in enhanced excitatory output to red nucleus, thalamic, and vestibular nuclei. In dtSZ hamsters, the 2-DG uptake was not significantly altered overall within the basal ganglia. Significant increases of 14% were, however, found in discrete parts of the caudate putamen in which recent studies revealed changes of dopamine receptors. Altered neural activity within the basal ganglia may therefore contribute to increased 2-DG uptake in the ventral thalamic nuclei as well as to decreased 2-DG uptake (-13%) found in the reticular thalamic nucleus. Although the present data are in line with the concept that abnormal thalamocortical activity seems to be critically involved in the dystonic syndrome, altered activities in other motor areas than output structures of the basal ganglia, such as in the red nucleus, may contribute to clinical manifestation of dystonia in mutant hamsters.