RELEASE OF N-ACETYLASPARTYLGLUTAMATE FROM SLICES OF RAT CEREBELLUM, STRIATUM, AND SPINAL-CORD, AND THE EFFECT OF CLIMBING FIBER DEPRIVATION

The release of endogenous N-acetylaspartyl-glutamate (NAAG) from slice s of rat cerebellum, striatum, and spinal cord upon depolarization wit h 50 mM K+ was investigated. NAAG in superfusates was prepurified usin g an ion exchanger, esterified, and then quantified by gas chromatogra phy-mass spectrometry. Deuterated NAAG was used as internal standard. A depolarization-induced release of NAAG was found in all three region s. The release was Ca2+ dependent to over 85% in cerebellum and striat um, but only to approximately 70% in spinal cord. In addition, the eff ect of lesions of the olivocerebellar pathway on the K+-induced releas e of NAAG was studied: Treatment of the animals with 3-acetylpyridine reduced the release of NAAG from cerebellar hemispheres significantly, by about 40% compared with controls. These results suggest that part of the NAAG released from cerebellar slices on depolarization is relat ed to climbing fibers. Implications of these findings concerning possi ble physiological roles of NAAG in the three CNS regions are discussed .