Evidence for motivational effects elicited by activation of GABA-A or dopamine receptors in the nucleus accumbens shell

• Published in: Pharmacology, biochemistry and behavior biochemistry and behavior, 2010-09, Vol.96 (3), p.342-346
• Main Authors: Wirtshafter, David, Stratford, Thomas R.
• Format: Article
• Language: English
• Subjects: Amphetamine; Animals; Behavior, Animal - drug effects; Biological and medical sciences; Brain; Conditioning, Operant - drug effects; Dextroamphetamine - administration & dosage; Dextroamphetamine - pharmacology; Dopamine; Dopamine Agonists - administration & dosage; Dopamine Agonists - pharmacology; Dopamine Uptake Inhibitors - administration & dosage; Dopamine Uptake Inhibitors - pharmacology; Feeding behavior; Food; Food intake; Food motivation; GABA Agonists - administration & dosage; GABA Agonists - pharmacology; Ingestion; Injections; Male; Medical sciences; Motivation - drug effects; Muscimol; Muscimol - administration & dosage; Muscimol - pharmacology; Neuropharmacology; Nucleus Accumbens - anatomy & histology; Nucleus Accumbens - drug effects; Operant behavior; Pharmacology. Drug treatments; Progressive ratio; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Rats; Rats, Sprague-Dawley; Receptors, Dopamine - drug effects; Receptors, GABA-A - drug effects; Reinforcement (Psychology); Reinforcement Schedule
• ISSN: 0091-3057; 1873-5177
• DOI: 10.1016/j.pbb.2010.06.004

Microinjections of the inhibitory GABA-A receptor agonist muscimol into the shell region of the nucleus accumbens (AcbSh) have been reported to induce large increases in food intake, but the effect of these injections on motivational processes is less clear. In the current study, bilateral injections of saline, muscimol (50 ng/side) or d-amphetamine (10 μg/side) were made into the AcbSh of rats trained to lever press on a progressive ratio schedule for food reward. Injections of both muscimol and amphetamine were found to produce a large increase in the breaking point relative to saline injections. This result suggests that inactivation of the AcbSh does not simply drive ingestive behavior, but also affects motivational processes assessed by the progressive ratio schedule. Breaking points were also increased by injections of amphetamine into the AcbSh. ►Injections of muscimol into the AcbSh increase responding on a PR schedule. ►Injections of amphetamine into the AcbSh have a similar effect. ►Intra-AcbSh muscimol does not simply activate feeding pattern generators. ►Inhibition of AcbSh neurons influences motivational factors.