DIFFERENTIAL ABUNDANCE OF SUPEROXIDE-DISMUTASE IN INTERNEURONS VERSUSPROJECTION NEURONS AND IN MATRIX VERSUS STRIOSOME NEURONS IN MONKEY STRIATUM

To investigate whether differences in vulnerability to free radicals m ight underlie differences among striatal neurons in their vulnerabilit y to neurodegenerative processes such as occur in ischemia and Hunting ton's disease, we have analyzed the localization of superoxide free ra dical scavengers in different striatal neuron types in normal rhesus m onkey. Single- and double-label immunohistochemical experiments were c arried out using antibodies against the enzymes copper, zinc superoxid e dismutase (SOD1), or manganese superoxide dismutase (SOD2), and agai nst markers of various striatal cell types. Our results indicate that the striatal cholinergic and parvalbumin interneurons are enriched in SOD1 and/or SOD2, whereas striatal projection neurons and neuropeptide Y/somatostatin (NPY+/SS+) interneurons express only low levels of bot h SOD1 and SOD2. We also found that projection neurons of the matrix c ompartment express significantly higher levels of SOD than those in th e striosome compartment. Since projection neurons have been reported t o be more vulnerable than interneurons and striosome neurons more vuln erable than matrix neurons to neurodegenerative processes, our results are consistent with the notion that superoxide free radicals are at l east partly involved in producing the differential neuron loss observe d in the striatum following global brain ischemia or in Huntington's d isease.