Changes in Nine Enzyme Markers for Neurons, Glia, and Endothelial Cells in Agonal State and Huntington's Disease Caudate Nucleus

Enzymes considered to be markers for neurons (angiotensin converting enzyme, thermolysin-like metalloendopeptidase, alanine aminopeptidase, and glutamate-oxaloacetate transaminase), glia (glutamine synthetase, pyruvate carboxylase, and beta-glucuronidase), and endothelial cells (alkaline phosphatase and plasminogen activator) were measured in caudate nucleus from 10 sudden death controls, eight agonal state controls, and 16 Huntington's disease patients. Glutamate-oxaloacetate transaminase was slightly reduced by agonal state. The four enzymes with a neuronal distribution were all correlatively reduced in Huntington's disease caudate nucleus. Glutamine synthetase activity was reduced and beta-glucuronidase mean activity increased over twofold in Huntington's disease caudate nucleus, with the two enzyme activities being inversely related. Pyruvate carboxylase was markedly affected by agonal state and was very variable in Huntington's disease caudate nucleus. The two endothelial enzymes were unaltered in Huntington's disease caudate nucleus. The findings are indicative of neuronal loss, an increased proportion of altered glia, and also of maintained vasculature in Huntington's disease caudate nucleus. Measurement of enzyme activities can help to delineate the types of cell altered in Huntington's disease.