Serotonin depresses excitatory amino acid-induced excitation of cerebellar Purkinje cells in the adult rat in vivo.
The modulatory effects of serotonin (5-HT) on excitatory amino acid (EAA)-induced excitations of Purkinje cells (PCs) were examined in urethane-anesthetized adult male rats using microiontophoresis and extracellular recordings. Application of 5-HT had minimal effects on the spontaneous firing rates of PCs but depressed excitations elicited by glutamate (Glu), aspartate (Asp), kainate (KA), and quisqualate (QA), and to a lesser extent those of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA). Excitations induced by the metabotropic EAA agonist, (+-)-1-aminocyclopentane-trans-1,3-dicarboxylate (t-ACPD), were unaffected by 5-HT. In summary, 5-HT depressed EAA-mediated excitations with the following rank order of effectiveness: Glu = Asp = KA = QA > AMPA >> t-ACPD. These findings suggest that 5-HT shows some selectivity in its modulation of EAA-mediated excitations of PCs and thus may serve an important neuromodulatory role in the cerebellum.
Department of Physiology, Texas Tech University Health Sciences Center, School of Medicine, Lubbock 79430.
J G
JG
Netzeband
L B
LB
Weathers
H K
HK
Strahlendorf
J C
JC
Strahlendorf
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000596:Amino Acids / Q000037:antagonists & inhibitors*; D000818:Animals; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D008838:Microcomputers; D009420:Nervous System / Q000187:drug effects; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology*
D000596:Amino Acids; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D012701:Serotonin