Extracellular dopamine and serotonin after ethanol monitored with 5-minute microdialysis

In order to determine potential rapid changes in extracellular dopamine (DA) and 5-hydroxytryptamine (serotonin, 5-HT) during the first 5-10 min after ethanol, intracerebral microdialysis coupled with microbore HPLC was used. Ethanol at the doses of 0.5, 1, and 2 g/kg was administered IP and extracellular DA and 5-HT in 5-min dialysates from the nucleus accumbens (NAC) of freely moving rats were determined. Ethanol at all doses significantly increased extracellular DA and 5-HT. DA and 5-HT peaked at 10, 15, 20 min and 20, 20, 55 min following 0.5, 1, and 2 g/kg, respectively. Based on previous reports showing that brain or blood ethanol levels peaked within 10-20 min after administration, the results indicate that peak increases in extracellular DA and 5-HT in the NAC occurred at approximately the same time, with the DA time course more temporally correlated with the blood or brain alcohol concentration curve reported in the literature. These results support the concept that the reinforcing properties of ethanol derive, at least in part, from its ability to stimulate DA release in the NAC. In addition, the present data are not in opposition with a role of 5-HT in the ethanol reinforcing effect.