Haloperidol and nucleus accumbens dopamine depletion suppress lever pressing for food but increase free food consumption in a novel food choice procedure

Abstract:  Haloperidol and nucleus accumbens dopamine depletion suppress lever pressing for food but increase free food consumption in a novel food choice procedure. Salamone JD, Steinpreis RE, McCullough LD, Smith P, Grebel D, Mahan K. Department of Psychology, University of Connecticut, Storrs 06269-1020. An important aspect of motivated behavior is that organisms will perform complex instrumental behaviors to gain access to stimuli such as food. In the present study, food-deprived rats were tested in an operant chamber in which the animals had a choice between pressing a lever to obtain a more-preferred food (Bioserve pellets), or free feeding on a less-preferred food (lab chow). Typically, rats pressed the lever to obtain the preferred food pellets, and ate little of the less-preferred food even though it was freely available. Pre-fed rats showed suppression of both lever pressing and feeding. Systemic administration of 0.1 mg/kg haloperidol (HP) led to a dramatic shift in the behavior of these rats, such that the number of lever presses was substantially reduced, but the amount of less-preferred food consumed showed a significant increase. This result occurred if the rats pressed a lever on either a CRF or FR5 schedule. Injection of 3.5-7.0 micrograms HP directly into the nucleus accumbens, or intra-accumbens injections of 6-hydroxy-dopamine, also decreased lever pressing for food and increased feeding on laboratory chow. Thus, interference with brain dopamine suppressed a highly active instrumental response for food, although the behavior of the animal was still directed towards food acquisition and consumption. PMID: 1780422 [PubMed - indexed for MEDLINE]