Low doses of ethanol activate dopaminergic neurons in the ventral tegmental area

In unanesthetized rats the intravenous administration of low doses of ethanol (0.125-0.5 g/kg) produced a dose-dependent increase (30-80%) in the firing rate of dopaminergic (DA) neurons in the Ventral Tegmental Area (VTA). In agreement with previous observations, a dose range between 0.5 and 2 g/mg of ethanol was needed to produce comparable stimulant responses in DA neurons of the Substantia Nigra Pars Compacta. However, in anesthetized rats, doses of ethanol up to 1 g/kg failed to activate VTA-DA neurons. The high sensitivity of VTA-DA neurons to ethanol activation suggests that they might be involved in the reinforcing properties of the drug.