The effects of local application of ethanol in the n. accumbens on dopamine overflow and clearance

The actions of ethanol on extracellular dopamine levels in the n. accumbens were examined in both anesthetized and unanesthetized rats using either in vivo voltammetry or microdialysis. In the voltammetry studies, ethanol was microrejected directly into the accumbens. For the microdialysis studies, the ethanol was injected systemically. The voltammetry studies failed to find any direct effect of local ethanol on extracelular dopamine levels. However, exposure to high ethanol concentrations directly injected into the n. accumbens slowed the rise rate and the return to baseline rate to a n. accumbens KCl-stimulated dopamine release. In the microdialysis studies, increased levels of extracellular dopamine in the n. accumbens were found in unanesthetized rats, similar to those reported in the literature. However, in the anesthetized rats, the extracellular dopamine levels were not increased, even with similar local ethanol levels measured in the dialysate. Taken together, the data suggest that the actions of ethanol to increase extracellular dopamine levels in the n. accumbens are most likely not an effect of ethanol at the level of the accumbens but rather an action which increases neural activity within the mesoaccumbens pathway, perhaps via actions at the ventral tegmental area.