Due to evidence suggesting that brain reinforcement systems are engaging in allostatic processes to combat the chronic effects of ethanol administration, the present series of experiments are designed to identify changes in basal and ethanol administration-contingent endogenous opioid and dopamine levels in the rat brain during acute and protracted withdrawal in ethanol dependent and non-dependent animals. Furthermore, non-selective and selective opioid receptor antagonists/agonists will be used to pharmacologically study the role of opioids within specific regions of the extended amygdala during acute withdrawal in ethanol dependent and non-dependent rats. These series of experiments will help to classify allostatic changes in brain reinforement systems that could contribute to addiction and dependence and possibly help to identify appropriate pharmacotherapeutics for use in the treatment of alcoholism.