Distribution of phosphate-activated glutaminase, succinic dehydrogenase, pyruvate dehydrogenase and gamma-glutamyl transpeptidase in post-mortem brain from Huntington's disease and agonal cases.

The activity of phosphate-activated glutaminase was reduced throughout the brain of cases with longstanding illnesses (agonal controls) compared to cases dying suddenly. The reduction was less marked in cortical than sub-cortical areas, with the caudate nucleus occupying an intermediate position. In control brains succinic dehydrogenase and pyruvate dehydrogenase were little affected by the ante-mortem clinical state. Of 9 brain areas studied, only the caudate nucleus showed a reduction of phosphate-activated glutaminase and succinic dehydrogenase in Huntington's disease greater than in agonal controls. The levels of succinic dehydrogenase and pyruvate dehydrogenase were highly correlated in frontal cortex and in caudate nucleus of Huntington's disease and control brains. There was a significant reduction in pyruvate dehydrogenase mean activity and a significant increase in gamma-glutamyl transpeptidase mean activity in Huntington's disease caudate nucleus. The level of pyruvate dehydrogenase significantly decreased and the level of gamma-glutamyl transpeptidase significantly increased with increasing duration of illness, possibly due to a progressive loss of neurons and increase in the density of glia in Huntington's disease caudate nucleus.