title: Haloperidol and nucleus accumbens dopamine depletion suppress lever pressing for food but increase free food consumption in a novel food choice procedure.
abstract: 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.
authors.affiliation: Department of Psychology, University of Connecticut, Storrs 06269-1020.
authors.forename: J D
authors.initials: JD
authors.lastname: Salamone
authors.forename: R E
authors.initials: RE
authors.lastname: Steinpreis
authors.forename: L D
authors.initials: LD
authors.lastname: McCullough
authors.forename: P
authors.initials: P
authors.lastname: Smith
authors.forename: D
authors.initials: D
authors.lastname: Grebel
authors.forename: K
authors.initials: K
authors.lastname: Mahan
mesh_terms: D000818:Animals; D002404:Catheterization; D002851:Chromatography, High Pressure Liquid; D003216:Conditioning, Operant / Q000187:drug effects*; D004298:Dopamine / Q000378:metabolism*; D005247:Feeding Behavior / Q000187:drug effects*; D005502:Food; D005518:Food Preferences / Q000187:drug effects; D006220:Haloperidol / Q000494:pharmacology*; D008297:Male; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D016627:Oxidopamine / Q000494:pharmacology; D051381:Rats; D012055:Reinforcement Schedule; D013238:Stereotaxic Techniques
chemical_list: D016627:Oxidopamine; D006220:Haloperidol; D004298:Dopamine