The role of withdrawal in heroin addiction: enhances reward or promotes avoidance?

The compulsive nature of heroin abuse has been attributed to the fact that drug self-administration enables an addict to escape from and avoid the severe withdrawal symptoms resulting from opiate dependence. However, studies of incentive learning under natural motivational states suggest an alternative hypothesis, that withdrawal from heroin functions as a motivational state that enhances the incentive value of the drug, thereby enabling it to function as a much more effective reward for self-administration. In support of this hypothesis, we show here that previous experience with heroin in withdrawal is necessary for subsequent heroin-seeking behavior to be enhanced when dependent rats once again experience withdrawal.