The relationship between feeding and drug-seeking behaviors

This chapter focuses on the relationship between avidity for sweet substances and drug abuse using rats that were selectively bred for high (HiS) vs. low (LoS) saccharin intake. These rats serve as genetic models for several aspects of drug abuse such as initiation, maintenance, escalation, and relapse to drug seeking. Neurobiological differences in brain areas associated with drug and food reward underlie the behavioral differences. In addition to dietary compulsions, animal models of high vs. low novelty reactivity (HR vs. LR), novelty preference (HNP vs. LNP), impulsive choice (HiI vs. LoI), impulsive action (HI vs. LI), avidity for exercise (HiR vs. LoR), and attention to reward-related stimuli, such as sign- (reward-associated stimuli) vs. goal-tracking (reward) (ST vs. GT), also predict high vs. low drug seeking, respectively. The high-performing traits have some overlap in predicting addictive behavior, but in many respects they appear to be independent predictors of addictive behavior. In contrast, rats selected for low reward seeking are more reactive to stressful or aversive events associated with drugs and less likely to engage in drug seeking. These traits provide a model of resilience to drug abuse. Segregating individual differences into reward sensitive and aversion reactive may allow for customized addiction treatment. It is hypothesized that reward-sensitive individuals would be responsive to reward-replacement therapy, such as exercise, while aversion-reactive individuals may react more to negative outcomes for drug use. Initial data indicate better treatment success in the LoS (vs. HiS) and LoI (vs. HiI) rats, yet higher drug-seeking females respond better to treatment than males. Knowledge of specific vulnerability factors is important to designing maximally effective prevention and treatment strategies.