Article date: 2003/11/5
PubMed ID: 1350665
Journal name: Psychopharmacology (ISSN: 0033-3158)
These findings suggest that pharmacological stimulation of any of these neurochemical systems in isolation is insufficient to enable acquisition of a food-reinforced operant task. Thus, these selective processes, while likely involved in control of food intake and food-seeking behavior, appear unable to recapitulate the conditions necessary to mimic the state of negative energy balance.
All animals were given the opportunity to learn an instrumental response (a lever press) to obtain a food pellet. Prior to training, ad lib-fed rats were infused with the gamma-aminobutyric acid (GABA)A agonist muscimol (100 ng/0.5 microl per side) or the mu-opioid receptor agonist D-Ala2, N-me-Phe4, Gly-ol5-enkephalin (DAMGO, 0.25 microg/0.5 microl per side), or saline into the nucleus accumbens shell (AcbSh). The indirect dopamine agonist amphetamine (10 microg/0.5 microl per side) was infused into the AcbSh or nucleus accumbens core (AcbC) of ad lib-fed rats. An additional group was food deprived and infused with saline in the AcbSh. Chow and sugar pellet intake responses after drug treatments were also evaluated in free-feeding tests.
Muscimol, DAMGO, or amphetamine did not facilitate acquisition of lever pressing for food, despite clearly increasing food intake in free-feeding tests. In contrast, food-deprived animals rapidly learned the task.
Author List: Hanlon Erin C, Baldo Brian A, Sadeghian Ken, Kelley Ann E
Publication Types: Journal Article; Research Support, U.S. Gov't, P.H.S.
Article Date: 2003/11/04
Substances mentioned in the article: Analgesics, Opioid; Dopamine Agents; GABA Agonists; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Muscimol; Amphetamine;
Mesh terms: Amphetamine/pharmacology; Analgesics, Opioid/pharmacology; Animals; Conditioning, Operant/drug effects; Dopamine Agents/pharmacology; Eating/drug effects; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology; GABA Agonists/pharmacology; Male; Muscimol/pharmacology; Nucleus Accumbens/drug effects; Rats; Rats, Sprague-Dawley;