title: The consummatory and motivational behaviors for natural rewards following long-term withdrawal from morphine: no anhedonia but persistent maladaptive behaviors for high-value rewards.
abstract: The negative affective state, e.g., anhedonia, emerges after abstinence from abused drugs may be linked to the motivational processes of drug craving and relapse. Although anhedonia diminishes over time with drug abstinence, it is not yet rather explicit whether anhedonia exists or not following protracted withdrawal.
  
  
  
  The behavioral responses to natural rewards were examined after 2 to 3 weeks withdrawal from morphine. Male rats were pretreated with either a binge-like morphine paradigm or daily saline injection for 5 days. The consummatory and motivational behaviors for three natural rewards (sucrose solutions 4, 15, and 60%, social stimulus: male rat, and sexual stimulus: estrous female rat) were examined under varied testing conditions.
  
  
  
  The morphine-withdrawn rats significantly increased their intake of 15% sucrose solution during the 1-h consumption test and their operant responding for 15% sucrose solution under a progressive ratio (PR) schedule of reinforcement. When obtaining a reinforcer was associated with a 0.5 mA foot shock under a PR-punishment schedule, the morphine-withdrawn rats showed a higher performance for 60% sucrose solution. Meanwhile, the morphine-withdrawn rats displayed a higher motivation to sexual stimulus during the free-approach test and more approaching behaviors towards sexual stimulus in a conflict-based approach test (concurrent presence of reward and aversive stimulus).
  
  
  
  No anhedonia-like behavior but sensitized behaviors for natural rewards were found after long-term morphine withdrawal. Notably, the morphine-withdrawn rats displayed persistent motivated behaviors for high-value rewards (60% sucrose and sexual stimulus) in the conflict tests suggesting impairments in inhibitory control in morphine-treated rats.
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Xigeng
authors.initials: X
authors.lastname: Zheng
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Na
authors.initials: N
authors.lastname: Xu
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Zhengkui
authors.initials: Z
authors.lastname: Liu
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Beijing, China. baiyj@psych.ac.cn.|University of Chinese Academy of Sciences, Beijing, China. baiyj@psych.ac.cn.
authors.forename: Yunjing
authors.initials: Y
authors.lastname: Bai
mesh_terms: D059445:Anhedonia / Q000187:drug effects*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D008297:Male; D009020:Morphine / Q000009:adverse effects; D009021:Morphine Dependence / Q000523:psychology*; D009042:Motivation / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D013375:Substance Withdrawal Syndrome / Q000523:psychology*; D013395:Sucrose / Q000494:pharmacology
chemical_list: D013395:Sucrose; D009020:Morphine
keywords: Anhedonia; Consummatory behavior; Motivational behavior; Natural reward; Protracted abstinence