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A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats
Published on: November 6, 2018
Dorsal Raphe Nucleus Serotoninergic Neurons Mediate Morphine Rewarding Effect and Conditioned Place Preference
Bo Fu1, Jun-Qi Yao2, Chang Lu3
1Laboratory of Occupational Medicine, Tianjin Institute of Environmental and Occupational Medicine, Tianjin 300050, China; State Key Laboratory of Proteomics and Department of Neurobiology, Institute of Military Cognitive and Brain Sciences, Academy of Military Medical Sciences, Beijing 100850, China.
Abstract:
Morphine rewarding properties are the main reasons for drug-craving in behaviors occurring during morphine addiction. It has been suggested that morphine addiction relies on signals to the mesolimbic dopamine system, although the mechanisms outside the dopaminergic system are still unclear. Notably, the role of the dorsal raphe nucleus (DRN) serotoninergic (5-hydroxytryptamine, 5-HT) system remains unexplored. Using in vivo electrophysiological and optogenetic approaches, we found that morphine treatment increased DRN 5-TH neurons firing rate and optogenetic activation of DRN 5-HT neurons induced a rewarding effect, indicating that morphine reward is related to DRN 5-HT neurons. Accordingly, optogenetic inhibition of DRN 5-HT neurons following morphine injection reversed conditioned place preference (CPP) during chronic morphine treatment. These findings aid our understanding of the new functions of the DRN 5-HT neurons for morphine rewarding effect and provide a potential approach for the treatment of morphine addiction.
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