EFFECT OF ETHANOL ON EXTRACELLULAR DOPAMINE IN RAT STRIATUM BY DIRECTPERFUSION WITH MICRODIALYSIS

The concentration-related effects of ethanol on extracellular dopamine (DA) in rat striatum were studied by direct perfusion through microdi alysis probes in freely moving rats. Two sets of three ethanol concent rations were separately tested using a Latin square experimental desig n. Potassium stimulation with high potassium (50 mM) in artificial CSF (ACSF) preceding ethanol treatment confirmed the neuronal function of dopaminergic cells by increasing DA concentrations to 200-1,500% of b asal levels. The perfusion with calcium-free ACSF applied at the end o f each experiment confirmed the calcium dependency of the basal levels of extracellular DA by decreasing basal DA levels by 70%. The striata l volume measurement to examine the possible brain damage by direct et hanol perfusion suggested that ethanol did not increase the damage cau sed by the probe implantation at any ethanol concentration tested in t his study. The 30-min direct perfusion of 510 and 860 mM ethanol resul ted in a significant concentration-related stimulatory effect on the e xtracellular DA concentration in rat striatum (510 mM, 29% increase, p < 0.05; 860 mM, 66% increase, p < 0.05). However, there was no signif icant effect of ethanol al low concentrations, less than or equal to 1 70 mM. Considering the effective ethanol concentration in tissue areas in which DA is sampled, the data suggest that concentrations of ethan ol associated with moderate intoxication do not directly affect the ex tracellular concentration of DA in the striatum. Therefore, the system ic effects of ethanol on striatal DA found in previous studies may be caused by the interaction with sites other than the striatum.