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Hypoalgesia Induced by Reward Devaluation in Rats
Ana María Jiménez-García1,2, Leandro Ruíz-Leyva1,2, Cruz Miguel Cendán1
1Department of Pharmacology, Biomedical Research Center (CIBM) and Institute of Neuroscience, Faculty of Medicine, University of Granada, Campus Ciencias de la Salud, 18016, Granada, Spain.
Plos One
|October 21, 2016
Summary
Experiencing reward devaluation, such as a decrease in sucrose concentration, can lead to reduced pain sensitivity (hypoalgesia) in rats. This effect was observed even after the first instance of reward loss.
Area of Science:
- Neuroscience
- Behavioral Science
- Pain Research
Background:
- Reduced sensitivity to physical pain (hypoalgesia) is linked to experiences of reward devaluation.
- The consummatory successive negative contrast (cSNC) task is a model for studying reward devaluation effects.
Purpose of the Study:
- To investigate the impact of reward devaluation on pain sensitivity in Wistar rats.
- To determine if hypoalgesia occurs after the first or second devaluation session and its duration.
Main Methods:
- Rats underwent a cSNC task involving changes in sucrose concentration.
- Pain sensitivity was assessed using mechanical (von Frey filaments) and thermal (Hargreaves stimuli) tests at various time points after devaluation.
- Control groups received consistent sucrose concentration throughout the study.
Main Results:
- Rats experiencing reward devaluation (downshifted groups) showed reduced sucrose consumption, confirming the cSNC effect.
- Hypoalgesia was observed 5 minutes after both the first and second devaluation sessions.
- Evidence of hypoalgesia persisted 300 minutes (5 hours) after the second devaluation session, but not the first.
Conclusions:
- Reward devaluation can induce hypoalgesia shortly after the initial experience of reward loss.
- Hypoalgesia following reward loss can be long-lasting, persisting for at least 5 hours after the second devaluation.
- The neurobehavioral mechanisms underlying this reward-pain interaction require further investigation.
