Peripheral administration of urocortin suppresses operant responding for food reward.

The effects of peripheral systemic administration of urocortin on operant responding to obtain food were investigated using three separate concentrations. The drug was administered intraparitoneally at a concentration of 10 microg/ml/Kg, 5 microg/ml/Kg, and 0 microg/ml/Kg suspended in saline at a volume of 1 ml/Kg to Sprague-Dawley rats fifteen minutes prior to being exposed to an operant bar press task. Eleven subjects were used, each receiving a single injection of each concentration on separate days with the order of treatment counterbalanced. The results indicated that the administration of urocortin in a dose dependent manner reduced responding of food deprived subjects for a food reward in a thirty minute session. These data indicated that the peripheral administration of urocortin reduced the motivation of food deprived subjects to respond.