Increased GABA receptor binding in dominantly-inherited cerebellar ataxias.

We measured gamma-aminobutyric acid (GABA) receptor binding in the cerebellar cortex of 14 patients with dominantly-inherited cerebellar ataxias. Most of these patients had moderate to marked Purkinje cell loss as judged from the subnormal dentate nucleus GABA levels. Mean GABA receptor binding (at 25 nM GABA concentration) was elevated significantly by 37% in the total group of 14 patients studied and by 60% in the largest subgroup (n=6) analyzed. Possible explanations for the enhanced binding include glial proliferation, exposure of normally unexposed receptor sites consequent to neuronal degeneration, and/or denervation supersensitivity.