Document Detail

An examination of the effects of subthalamic nucleus inhibition or μ-opioid receptor stimulation on food-directed motivation in the non-deprived rat.
MedLine Citation:
PMID:  22391117     Owner:  NLM     Status:  MEDLINE    
The subthalamic nucleus (STN) serves important functions in regulating movement, cognition, and motivation and is connected with cortical and basal ganglia circuits that process reward and reinforcement. In order to further examine the role of the STN on motivation toward food in non-deprived rats, these experiments studied the effects of pharmacological inhibition or μ-opioid receptor stimulation of the STN on the 2-h intake of a sweetened fat diet, the amount of work exerted to earn sucrose on a progressive ratio 2 (PR-2) schedule of reinforcement, and performance on a differential reinforcement of low-rate responding (DRL) schedule for sucrose reward. Separate behavioral groups (N=6-9) were tested following bilateral inhibition of the STN with the GABA(A) receptor agonist muscimol (at 0-5 ng/0.5 μl/side) or following μ-opioid receptor stimulation with the agonist D-Ala², N-MePhe⁴, Gly-ol-enkephalin (DAMGO; at 0, 0.025 or 0.25 μg/0.5 μl/side). Although STN inhibition increased ambulatory behavior during 2-h feeding sessions, it did not significantly alter intake of the sweetened fat diet. STN inhibition also did not affect the breakpoint for sucrose pellets during a 1-h PR-2 reinforcement schedule or impact the number of reinforcers earned on a 1-h DRL-20s reinforcement schedule in non-deprived rats. In contrast, STN μ-opioid receptor stimulation significantly increased feeding on the palatable diet and reduced the reinforcers earned on a DRL-20 schedule, although DAMGO microinfusions had no effect on PR-2 performance. These data suggest that STN inhibition does not enhance incentive motivation for food in the absence of food restriction and that STN μ-opioid receptors play an important and unique role in motivational processes.
Wayne E Pratt; Eugene Choi; Elizabeth G Guy
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-02-25
Journal Detail:
Title:  Behavioural brain research     Volume:  230     ISSN:  1872-7549     ISO Abbreviation:  Behav. Brain Res.     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-04-09     Completed Date:  2012-08-28     Revised Date:  2014-03-25    
Medline Journal Info:
Nlm Unique ID:  8004872     Medline TA:  Behav Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  365-73     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 Elsevier B.V. All rights reserved.
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MeSH Terms
Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / pharmacology*
Feeding Behavior / drug effects*
GABA-A Receptor Agonists / pharmacology*
Motivation / drug effects*
Muscimol / pharmacology*
Rats, Sprague-Dawley
Receptors, Opioid, mu / agonists*,  drug effects
Subthalamic Nucleus / drug effects*
Grant Support
R15 DA030618/DA/NIDA NIH HHS; R15 DA030618-01/DA/NIDA NIH HHS
Reg. No./Substance:
0/GABA-A Receptor Agonists; 0/Receptors, Opioid, mu; 100929-53-1/Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; 2763-96-4/Muscimol

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