CHRONIC INTRASTRIATAL QUINOLINIC ACID PRODUCES REVERSIBLE CHANGES IN PERIKARYAL CALBINDIN AND PARVALBUMIN IMMUNOREACTIVITY

We recently reported the use of a chronic dialytic delivery system for intrastriatal administration of quinolinic acid in the rat.(3,4) This system produces neurodegeneration with some characteristics similar to post mortem brain tissue from Huntington's disease patients, including reduced cytochrome oxidase staining, a decreased number of Nissl-stained neurons, and relative spacing of striatal NADPH-diaphorase containing neurons.(4) The present findings show that chronic dialytic delivery of quinolinic acid also produces a Huntington's disease-like pattern of reduced calbindin and parvalbumin perikaryal immunoreactivity that is reversed in rats allowed four to eight weeks' recovery after cessation of quinolinic acid. Furthermore, cytochrome oxidase staining and the number of Nissl-stained cells were unchanged in the region of transient calbindin and parvalbumin immunoreactive perikaryal staining alterations. These results suggest that changes in calbindin and parvalbumin perikaryal immunoreactivity provide a relatively sensitive measure of quinolinic acid induced neurotoxicity. The reversible nature of reduced perikaryal immunoreactivity suggests a premorbid state of neurotoxicity, possibly marked by cellular redistribution of calbindin and parvalbumin.