Loss of N-methyl--aspartate sensitivity of cerebellar Purkinje cells after climbing fiber deafferentation. An in vivo study in the rat

Abstract The sensitivity of cerebellar Purkinje cells to brief iontophoretic applications of excitatory amino acids has been studied in vivo in rats treated from 15 days to 4 months beforehand with 3-acetylpyridine in order to destroy the inferior olive. Responses of Purkinje cells (PCs) chronically deprived of climbing fibers were thus investigated using extracellular microelectrodes and compared to those of a group of control rats. No changes in the relative efficiencies of l -glutamate, l -aspartate, quisqualate and kainate have been observed. In contrast, the excitations induced by N- methyl- d -aspartate (NMDA) on most PCs in control animals, were no longer present after climbing fiber deprivation. These results show that both NMDA and non-NMDA receptors are present on PCs of adult rodents and that the NMDA responses are strongly depressed when PCs are deafferented of the climbing fibers.