Work

Inflated reward value in early opiate withdrawal

Year: 2014

Type: article

Abstract: Through incentive learning, the emotional experience of a reward in a relevant need state (e.g. hunger for food) sets the incentive value that guides the performance of actions that earn that reward when the need state is encountered again. Opiate withdrawal has been proposed as a need state in which, through experience, opiate value can be increased, resulting in escalated opiate self-administration. Endogenous opioid transmission plays anatomically dissociable roles in the positive emotional experience of reward consumption and incentive learning. We, therefore, sought to determine if chronic opiate exposure and withdrawal produces a disruption in the fundamental incentive learning process such that reward seeking, even for non-opiate rewards, can become maladaptive, inconsistent with the emotional experience of reward consumption and irrespective of need. Rats trained to earn sucrose or water on a reward-seeking chain were treated with morphine (10-30 mg/kg, s.c.) daily for 11 days prior to testing in withdrawal. Opiate-withdrawn rats showed elevated reward-seeking actions, but only after they experienced the reward in withdrawal, an effect that was strongest in early (1-3 days), as opposed to late (14-16 days), withdrawal. This was sufficient to overcome a negative reward value change induced by sucrose experience in satiety and, in certain circumstances, was inconsistent with the emotional experience of reward consumption. Lastly, we found that early opiate withdrawal-induced inflation of reward value was blocked by inactivation of basolateral amygdala mu opioid receptors. These data suggest that in early opiate withdrawal, the incentive learning process is disrupted, resulting in maladaptive reward seeking.

Source: Addiction Biology

DOI: 10.1111/adb.12172

Authors: Kate M. Wassum, Venuz Y. Greenfield, Kay E. Linker, Nigel T. Maidment, Sean B. Ostlund

Institution: University of California, Los Angeles

Language: English

Topic: Neurotransmitter Receptor Influence on Behavior

Subfield: Cellular and Molecular Neuroscience

Field: Neuroscience

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: green

Funders: National Institutes of Health, National Institute on Drug Abuse, Life Sciences, University of California, Los Angeles