Effects of satiety on operant responding in rats raised in enrichment

Rats reared in enriched environmental conditions (EC) show altered responding for visual novelty and psychostimulants compared with rats reared in isolated conditions (IC). This study investigated whether response rate was altered in EC and IC rats when a visual stimulus was or was not paired with sucrose delivery in food-deprived and free-fed rats. Male Sprague-Dawley rats were reared in EC, IC, or social conditions (SC) before training to lever press for liquid sucrose on a fixed ratio 5 schedule. Food-deprived EC rats responded significantly more than IC rats during acquisition and when cue lights were removed, these results were reversed in free-fed rats. In the absence of the cue light, IC food-deprived rats took more time to extinguish responding and showed greater reinstatement compared with EC rats. These results reveal differences between EC and IC rats in response to incentive value and learning abilities. During all phases, responding for SC rats was generally between EC and IC rats. These studies suggest that differences in the incentive value of the stimulus contribute to differential responding in EC, IC, and SC rats for sucrose paired with a cue-light reinforcer. Behavioural Pharmacology 22: 40-48 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.