Differential effect of NMDA on extracellular serotonin in rat midbrain raphe and forebrain sites.
The contribution of NMDA receptors to regulation of serotonin (5-HT) release was assessed by in vivo microdialysis in freely behaving rats. During infusion of NMDA (30, 100, and 300 microM) into the dorsal raphe nucleus (DRN), 5-HT was increased by approximately 25, 100, and 280%, respectively. Competitive and noncompetitive NMDA-receptor antagonists blocked this effect on DRN 5-HT. Infusion of NMDA (300 microM) into the DRN also produced an 80% increase in extracellular 5-HT in the nucleus accumbens. During infusion of NMDA (100 and 300 microM) into the median raphe nucleus (MRN), 5-HT was increased by approximately 15 and 80%, respectively. NMDA-receptor antagonists blocked this effect on MRN 5-HT. Infusion of NMDA into the MRN also produced a significant increase in hippocampal 5-HT. In contrast, infusion of NMDA into the nucleus accumbens, frontal cortex, or hippocampus produced small decreases in 5-HT in these forebrain sites. Taken together, these results suggest that NMDA receptors in the midbrain raphe, but not the forebrain, can have an excitatory influence on 5-HT neurons and, thus, produce increased 5-HT release in the forebrain. Furthermore, in comparison with the MRN, DRN 5-HT neurons were more sensitive to the excitatory effect of NMDA.
Tao
R
R
Department of Biological Sciences, Rutgers University, New Brunswick, New Jersey, USA.
Auerbach
S B
SB
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000287:Administration, Topical; D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism*; D008297:Male; D008636:Mesencephalon / Q000187:drug effects / Q000378:metabolism*; D017551:Microdialysis; D016202:N-Methylaspartate / Q000008:administration & dosage / Q000494:pharmacology*; D016548:Prosencephalon / Q000187:drug effects / Q000378:metabolism*; D011903:Raphe Nuclei / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D016202:N-Methylaspartate; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin