STRIATAL EXTRACELLULAR DOPAMINE LEVELS ARE NOT INCREASED BY HYPERGLYCEMIC EXACERBATION OF ISCHEMIC BRAIN-DAMAGE IN RATS

We tested the hypothesis that hyperglycemic exacerbation of incomplete forebrain ischemia is mediated by increased extracellular dopamine le vels. Normoglycemic and hyperglycemic Sprague-Dawley rats (eight each) with previously placed coaxial striatal microdialysis probes underwen t 12 min of forebrain ischemia produced by bilateral carotid artery oc clusion and trimethaphan-induced hypotension. Microdialysis was perfor med before, during, and for 6 h after ischemia, then perfusion-fixatio n was performed. Hyperglycemic rats had more severe postischemic damag e in the caudate-putamen, neocortex, and hippocampus. Extracellular st riatal dopamine levels were increased by ischemia, but were unaffected by hyperglycemia. These data show that hyperglycemic exacerbation of ischemic striatal damage does not depend on elevated extracellular dop amine levels.