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. accu mbens were examined in both anesthetized and unanesthetized rats using either in vivo voltammetry or microdialysis. In the voltammetry studi es, ethanol was microinjected directly into the accumbens. For the mic rodialysis studies, the ethanol was injected systemically. The voltamm etry studies failed to find any direct effect of local ethanol on extr acelular dopamine levels. However, exposure to high ethanol concentrat ions 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 extracellul ar dopamine in the n. accumbens were found in unanesthetized rats, sim ilar 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 togethe r, the data suggest that the actions of ethanol to increase extracellu lar 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 in creases neural activity within the mesoaccumbens pathway, perhaps via actions at the ventral tegmental area. (C) 1997 Elsevier Science Inc.