Excitatory effect of L-aspartate and L-glutamate on Purkinje cells in rat cerebellum.
L-aspartate and L-glutamate were microiontophoretically applied onto Purkinje cells and unidentified cerebellar neurons of urethane-anesthetized rats. Both amino acids produced a dose-dependent increase in the spontaneous firing rate of all cells tested. Fifty-three percent (8 of 15 cells) of the dose-response relationships for L-aspartate as compared to those for L-glutamate on Purkinje cells were not parallel, implying different mechanisms of action (suggesting different receptors). On these 8 Purkinje cells, L-glutamate was three times more potent than L-aspartate. Only thirty-three percent of the dose-response relationships (8 of 24 cells) for the two agents on the unidentified cerebellar cells were not parallel. There was no statistical difference in the potency of L-aspartate as compared to L-glutamate on these particular cells. Tests for antagonism on Purkinje cells revealed L-glutamic acid diethyl ester (GDEE) to be a more effective blocker of L-aspartate than of L-glutamate while DL-alpha-aminoadipic acid (DL alpha AA)) was not selective in antagonizing the action of either amino acid. These data are discussed in terms for L-aspartate functioning as a neurotransmitter in the cerebellum of rat and possessing receptor sites distinct from those for L-glutamate.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology*; D002531:Cerebellum / Q000502:physiology; D004553:Electric Conductivity; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats
D005971:Glutamates; D001224:Aspartic Acid; D018698:Glutamic Acid