5-Hydroxytryptamine3 receptor modulation of excitatory amino acid release in the rat nucleus tractus solitarius.
In vivo microdialysis was employed to measure release of endogenous L-glutamate (GLU) and L-aspartate (ASP) in the medial nucleus tractus solitarius of urethane anaesthetised rats. Basal extracellular levels of these amino acids were stable following a 90 min equilibration period (6.3 +/- 0.24 and 3.4 +/- 0.6 pmol/20 microliters sample of GLU and ASP, respectively). Basal levels of endogenous extracellular GLU and ASP were increased over 2-fold and 3-fold, respectively, following local administration of the selective 5-hydroxytryptamine (5-HT3) receptor agonist phenylbiguanide (300 microM). Intracerebral administration of the selective 5-HT3 receptor antagonist ondansetron (30 microM) blocked the effect of phenylbiguanide on GLU release whilst the effect on ASP was variable and complex. These data suggest that 5-HT3 receptor activation in the rat nucleus tractus solitarius can affect excitatory amino acid neurotransmission in this region of the medulla oblongata.
Ashworth-Preece
M A
MA
Department of Pharmacology, Monash University, Clayton, Victoria, Australia.
Jarrott
B
B
Lawrence
A J
AJ
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001645:Biguanides / Q000494:pharmacology; D018846:Excitatory Amino Acids / Q000378:metabolism* / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D017551:Microdialysis; D017294:Ondansetron / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D011985:Receptors, Serotonin / Q000378:metabolism*; D017552:Solitary Nucleus / Q000187:drug effects / Q000378:metabolism*
D001645:Biguanides; D018846:Excitatory Amino Acids; D007004:Hypoglycemic Agents; D011985:Receptors, Serotonin; D001224:Aspartic Acid; D018698:Glutamic Acid; D017294:Ondansetron; C008846:phenyl biguanide