ETHANOL AS A NEUROCHEMICAL SURROGATE OF CONVENTIONAL REINFORCERS - THE DOPAMINE-OPIOID LINK

Various lines of evidence support the view that ethanol is a neurochem ical surrogate of conventional reinforcers, such as food and sex. In f act, ethanol activates central neuronal systems that utilize dopamine, opioids, and gamma-aminobutyric acid (GABA) as neurotransmitters and also are activated by conventional reinforcers. These neurotransmitter systems are likely to mediate specific aspects of ethanol's reinforci ng properties. Activation of the mesolimbic dopamine and endogenous op ioid systems might be the substrate of the incentive and rewarding (er gotropic) properties of ethanol (arousal, euphoria, motor stimulation) and of the process of acquiring ethanol-related secondary reinforcers (incentive learning) and ethanol self-administration habits. Stimulat ion of the endogenous GABAergic system might mediate the sedative and drive-reducing (trophotropic) properties of ethanol. The dopamine and opioid systems are largely interconnected. Thus, pharmacological block ade of the endogenous opioid system by mu- or delta-opioid receptor an tagonists prevents ethanol's activation of the dopamine system and red uces ethanol consumption. This interaction might contribute to naltrex one's effectiveness in reducing alcohol craving in humans.