gamma-Aminobutyric acid receptors in normal human brain and Huntington disease

GABA receptor binding curves were measured in well-washed membrane homogenates from eleven regions of normal human brain and four regions from brains of Huntington disease patients. Computer analysis suggested two populations of receptor sites of different affinity (KD = 10 nM and 240 nM) present in all brain regions but in variable quantity (cerebellar cortex and cerebral cortex greater than basal ganglia greater than deeper brain structures). The number of GABA receptor sites in the caudate-putamen region of Huntington brain was less than normal, but the number of sites was increased in Huntington disease substantia nigra. No differences from normal were found in cerebellar cortex or frontal cortex from Huntington disease, and no significant changes in binding affinity were observed for any of the four regions tested under the conditions used.