Peripheral Administration of Ethanol Results in a Correlated Increase in Dopamine and Serotonin Within the Posterior Ventral Tegmental Area.
OBJECTIVE
Two critical neurotransmitter systems regulating ethanol (EtOH) reward are serotonin (5-HT) and dopamine (DA). Within the posterior ventral tegmental area (pVTA), 5-HT receptors have been shown to regulate DA neuronal activity. Increased pVTA neuronal activity has been linked to drug reinforcement. The current experiment sought to determine the effect of EtOH on 5-HT and DA levels within the pVTA.


METHODS
Wistar rats were implanted with cannula aimed at the pVTA. Neurochemical levels were determined using standard microdialysis procedures with concentric probes. Rats were randomly assigned to one of the five groups (n = 41; 7-9 per group) that were treated with 0-3.0 g/kg EtOH (intraperitoneally).


RESULTS
Ethanol produced increased extracellular DA levels in the pVTA that resembled an inverted U-shape dose-response curve with peak levels (~200% of baseline) at the 2.25 g/kg dose. The increase in DA levels was observed for an extended period of time (~100 minutes). The effects of EtOH on extracellular 5-HT levels in the pVTA also resembled an inverted U-shape dose-response curve. However, increased 5-HT levels were only observed during the initial post-injection sample. The increases in extracellular DA and 5-HT levels were significantly correlated.


CONCLUSIONS
The data indicate intraperitoneal EtOH administration stimulated the release of both 5-HT and DA within the pVTA, the levels of which were significantly correlated. Overall, the current findings suggest that the ability of EtOH to stimulate DA activity within the mesolimbic system may be modulated by increases in 5-HT release within the pVTA.


OBJECTIVE
Two critical neurotransmitter systems regulating ethanol reward are serotonin and dopamine. The current experiment determined that intraperitoneal ethanol administration increased serotonin and dopamine levels within the pVTA (levels were significantly correlated). The current findings suggest the ability of EtOH to stimulate serotonin and dopamine activity within the mesolimbic system.
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA gdeehan@iupui.edu.
Gerald A
GA
Deehan
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Christopher P
CP
Knight
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
R Aaron
RA
Waeiss
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Eric A
EA
Engleman
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Jamie E
JE
Toalston
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
William J
WJ
McBride
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Sheketha R
SR
Hauser
Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Zachary A
ZA
Rodd
D000818:Animals; D004298:Dopamine / Q000032:analysis*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D007263:Infusions, Parenteral; D008297:Male; D017551:Microdialysis; D051381:Rats; D017208:Rats, Wistar; D012201:Reward; D012701:Serotonin / Q000032:analysis*; D017557:Ventral Tegmental Area / Q000737:chemistry / Q000187:drug effects*
D012701:Serotonin; D000431:Ethanol; D004298:Dopamine