Perfusate serotonin increases extracellular dopamine in the nucleus accumbens as measured by in vivo microdialysis.
The effects of local application of serotonin (5-HT) on extracellular levels of dopamine (DA) in the nucleus accumbens (N. ACC) were assessed using in vivo microdialysis. At a perfusate flow rate of 0.3 microliter/min the baseline dialysate concentration of DA was 2.1 +/- 0.7 nM (mean +/- S.E.M.; n = 5) and significantly increased to 142 +/- 18%, 220 +/- 47% and 332 +/- 35% of baseline when 0.1 microM, 0.2 microM and 0.4 microM concentrations of 5-HT were included in the perfusate. Perfusate 5-HT concentrations below 0.1 microM had no effect on dialysate DA. The in vivo dialysis efficiency for 5-HT was found to be 39 +/- 12%, and thus the concentrations of 5-HT reaching the extracellular space at the surface of the dialysis membrane were estimated to be 40, 80 and 160 nM for the 0.1, 0.2 and 0.4 microM 5-HT perfusates, respectively. The serotonin-induced increase in dialysate DA was attenuated by co-perfusion of 0.4 microM 5-HT with 4 microM concentrations of pindolol (a relatively non-specific 5-HT1 antagonist; 151 +/- 7% vs. 332 +/- 35% baseline dialysate DA for 5-HT/antagonist and 5-HT-only perfusates, respectively), LY 53,857 (a specific 5-HT2 antagonist; 130 +/- 17% vs. 332 +/- 35%) and MDL 7222 (a specific 5-HT3 antagonist; 143 +/- 19% vs. 332 +/- 35%).(ABSTRACT TRUNCATED AT 250 WORDS)
Parsons
L H
LH
Emory University, Department of Chemistry, Atlanta, GA 30322.
Justice
J B
JB
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D003956:Dialysis / Q000379:methods; D004298:Dopamine / Q000378:metabolism*; D004873:Ergolines / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism*; D008297:Male; D009714:Nucleus Accumbens / Q000378:metabolism*; D009994:Osmolar Concentration; D010477:Perfusion; D010869:Pindolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D014326:Tropanes / Q000494:pharmacology
D004873:Ergolines; D012702:Serotonin Antagonists; D014326:Tropanes; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D010869:Pindolol; C032663:LY 53857; C042253:bemesetron; D004298:Dopamine