title: Differential effects of serotonin on the spontaneous discharge and on the excitatory amino acid-induced responses of deep cerebellar nuclei neurons in rat cerebellar slices.
abstract: The effects of steady iontophoretic applications of serotonin on the spontaneous discharge and on the excitatory responses induced in deep cerebellar nuclei neurons by iontophoretic pulse applications of L-glutamate, L-aspartate, N-methyl-D,L-aspartate and quisqualate were studied in rat cerebellar slices maintained in vitro. Serotonin increased the spontaneous firing rate of deep cerebellar nuclei neurons in 91% of the tested cells by 109% on the average and had no effect on the remaining recorded neurons. Conversely, the monoamine induced a depression of the excitatory responses induced by four agonists tested and the depressant potency of serotonin was in the order quisqualate, glutamate, aspartate, N-methyl-D,L-aspartate. These effects persisted in low calcium high magnesium solution, suggesting that the serotonin receptors involved in these phenomena were, at least partially, postsynaptically located. The serotonin-induced increase in the cell firing rate appeared to be methysergide-resistant whereas the serotonin-induced decrease in the responses elicited by excitatory amino acids was depressed by this antagonist, which could indicate that these differential effects of serotonin are mediated via different mechanisms and/or serotonin receptor subtypes.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000596:Amino Acids / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002529:Cerebellar Nuclei / Q000187:drug effects / Q000502:physiology*; D004347:Drug Interactions; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D066298:In Vitro Techniques; D016202:N-Methylaspartate; D010069:Oxadiazoles / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D016318:Quisqualic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000493:pharmacokinetics / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D005971:Glutamates; D010069:Oxadiazoles; D001224:Aspartic Acid; D012701:Serotonin; D018698:Glutamic Acid; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D011188:Potassium; D002118:Calcium