Combined effects of systemic alcohol and nicotine on dopamine release in the nucleus accumbens shell.
This study was undertaken to determine whether simultaneous administration of both alcohol and nicotine systemically would result in an additive dopamine release in the nucleus accumbens (NACC). Moreover, to also investigate whether nicotinic receptors may be mediating these effects of alcohol and nicotine, the effects of mecamylamine, a nicotinic receptor antagonist was also evaluated. Microdialysis was applied to measure the dopamine overflow in the shell region of NACC. All drugs were administered intraperitoneally. The doses of alcohol ranged from 0.5-2.0 g/kg, and nicotine and mecamylamine 0.25-1.0 mg/kg. An additive effect of combined alcohol and nicotine on dopamine release was obtained. This effect of alcohol and nicotine was dose-dependently blocked by mecamylamine pre-treatment. These findings further support the hypothesis that an additive effect of alcohol and nicotine on the mesolimbic 'reward pathway' may contribute to the high incidence of smoking in alcoholics. Furthermore, nicotinic antagonists can block such effects of combined alcohol and nicotine.