Naltrexone alteration of the nicotine-induced EEG and mood activation response in tobacco-deprived cigarette smokers

Abstract

The neural mechanisms contributing to the arousal-eliciting actions of smoking and nicotine involve multiple neurotransmitter systems. The current study examined the role of opioid neurotransmission in modulating the neuroelectric- and mood-activating response to acute nicotine administration in overnight tobacco-deprived smokers. In a randomized, double-blind, placebo-controlled design involving 18 (10 male, 8 female) overnight tobacco-abstinent smokers, spectrally analyzed electroencephalographic (EEG) activity and subjective reports of mood, euphoria, and smoking withdrawal were assessed in response to nicotine gum (4 mg) after pretreatment with placebo or with 50 mg of the opioid antagonist naltrexone. In addition to reducing withdrawal symptoms and increasing euphoria ratings, as well as subjective alertness in male participants, nicotine induced an EEG arousal response consisting of diffuse slow wave (delta, theta) amplitude reductions, frontal fast alpha wave amplitude increments, and elevations in beta wave amplitude, which were greater in female than in male smokers. Naltrexone attenuated the alerting and euphoric actions of nicotine but did not affect nicotine's ameliorating effects on withdrawal symptoms. Nicotine-induced frontal reductions in delta and global reductions in theta were prevented by naltrexone pretreatment, as were increases in anterior recordings of relative fast alpha. These findings suggest that the opioid system is involved in nicotine-induced subjective and neuroelectric arousal and implicate opioid-cholinergic interactions in the elicitation of these arousal responses to nicotine.