Nucleus accumbens corticotropin-releasing factor increases cue-triggered motivation for sucrose reward: paradoxical posi
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BioMed Central
Open Access
Research article
Nucleus accumbens corticotropin-releasing factor increases cue-triggered motivation for sucrose reward: paradoxical positive incentive effects in stress? Susana Peciña*1, Jay Schulkin2 and Kent C Berridge1 Address: 1Department of Psychology, University of Michigan, Ann Arbor, MI 48109, USA and 2Department of Physiology and Biophysics, Georgetown University, CNE Branch, National Institute of Mental Health, USA Email: Susana Peciña* - [email protected]; Jay Schulkin - [email protected]; Kent C Berridge - [email protected] * Corresponding author
Published: 13 April 2006 BMC Biology2006, 4:8
doi:10.1186/1741-7007-4-8
Received: 16 July 2005 Accepted: 13 April 2006
This article is available from: http://www.biomedcentral.com/1741-7007/4/8 © 2006Peciña et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract Background: Corticotropin-releasing factor (CRF) is typically considered to mediate aversive aspects of stress, fear and anxiety. However, CRF release in the brain is also elicited by natural rewards and incentive cues, raising the possibility that some CRF systems in the brain mediate an independent function of positive incentive motivation, such as amplifying incentive salience. Here we asked whether activation of a limbic CRF subsystem magnifies the increase in positive motivation for reward elicited by incentive cues previously associated with that reward, in a way that might exacerbate cue-triggered binge pursuit of food or other incentives? We assessed the impact of CRF microinjections into the medial shell of nucleus accumbens using a pure incentive version of Pavlovian-Instrumental transfer, a measure specifically sensitive to the incentive salience of reward cues (which it separates from influences of aversive stress, stress reduction, frustration and other traditional explanations for stress-increased behavior). Rats were first trained to press one of two levers to obtain sucrose pellets, and then separately conditioned to associate a Pavlovian cue with free sucrose pellets. On test days, rats received microinjections of vehicle, CRF (250 or 500 ng/0.2 µl) or amphetamine (20 µg/0.2 µl). Lever pressing was assessed in the presence or absence of the Pavlovian cues during a half-hour test. Results: Microinjections of the highest dose of CRF (500 ng) or amphetamine (20 µg) selectively enhanced the ability of Pavlovian reward cues to trigger phasic peaks of increased instrumental performance for a sucrose reward, each peak lasting a minute or so before decaying after the cue. Lever pressing was not enhanced by CRF microinjections in the baseline absence of the Pavlovian cue or during the presentation without a cue, showing that the CRF enhancement could not be explained as a result of generalized motor arou
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