DIFFERENTIAL RESPONSES OF EXTRACELLULAR GABA TO INTRASTRIATAL PERFUSIONS OF 3-NITROPROPIONIC ACID AND QUINOLINIC ACID IN THE RAT

Although both quinolinic acid and 3-nitropropionic acid destroy medium sized, GABAergic, spiny projection neurons after direct perfusion of neurotoxin into the rat striatum, changes in extracellular GABA concen tration in the striatum within the first 90 min reflect different toxi c mechanisms in these two animal models for Huntington's disease. Sinc e quinolinic acid acts as a potent excitotoxin, the early depolarizing response in GABAergic neurons results in an early increase in extrace llular GABA activity (peak at 40 min) whereas the mon indirect action of 3-nitropropionic acid on mitochondrial energy metabolism results in a delayed increase in extracellular GABA activity (peak at 60 min) wi th a pattern of gradual increase and decline. The localized delivery o f cytotoxin provides an opportunity for kinetic comparisons of direct and indirect cytotoxic mechanisms that can be useful in developing neu roprotective treatment strategies in Huntington's disease. (C) 1997 El sevier Science B.V.