Serotonin differentially modulates responses mediated by specific excitatory amino acid receptors in the rat locus coeruleus.
Microiontophoretic application of selective agonists for the three major excitatory amino acid receptors, N-methyl-D-aspartate (NMDA), quisqualate and kainate, increased the discharge rate of noradrenergic locus coeruleus (LC) neurons in vivo. NMDA activation was selectively attenuated by iontophoretic application of 2-amino-5-phosphonopentanoate (AP5), an antagonist at NMDA receptors, whereas kainate- and quisqualate-evoked responses were attenuated by both NMDA and non-NMDA antagonists iontophoresis. NMDA- and quisqualate-evoked responses were significantly decreased by co-iontophoresis of serotonin (5-HT). When the NMDA receptor-mediated component of the response to kainate was blocked with AP5 iontophoresis, 5-HT increased the response of LC neurons to kainate. These results revealed that 5-HT differentially modulates the responsiveness of LC neurons to excitatory amino acids, depending on the receptor subtypes responsible for the neuronal activation.
Charléty
P J
PJ
INSERM U171, Centre Hospitalier Lyon Sud, Pierre Bénite, France.
Chergui
K
K
Akaoka
H
H
Saunier
C F
CF
Buda
M
M
Aston-Jones
G
G
Chouvet
G
G
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000596:Amino Acids / Q000502:physiology; D000818:Animals; D004594:Electrophysiology; D007478:Iontophoresis; D007608:Kainic Acid / Q000494:pharmacology; D008125:Locus Coeruleus / Q000166:cytology / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D016318:Quisqualic Acid / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017459:Receptors, Amino Acid / Q000037:antagonists & inhibitors / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012701:Serotonin / Q000494:pharmacology*
D000596:Amino Acids; D017459:Receptors, Amino Acid; D016194:Receptors, N-Methyl-D-Aspartate; D012701:Serotonin; D015763:2-Amino-5-phosphonovalerate; D016318:Quisqualic Acid; D007608:Kainic Acid