title: Acute stress worsens the deficits in appetitive behaviors for social and sexual stimuli displayed by rats after long-term withdrawal from morphine.
abstract: BACKGROUND
  Negative affective states, e.g., anhedonia, are suggested to be involved in the long-lasting motivational processes associated with relapse. Here, we investigated whether anhedonic behaviors could be elicited by an acute stress after protracted abstinence from morphine.
  
  
  OBJECTIVE
  The behavioral responses to natural stimuli following exposure to an acute stress were examined after 14 days of withdrawal from morphine. Male rats were pretreated with either a binge-like morphine regimen or daily saline injections for 5 days. The motivation for two natural stimuli, i.e., a social stimulus (male rat) and a sexual stimulus (estrous female rat), was measured, following exposure to an acute stress (intermittent foot shock, 0.5 mA * 0.5 s * 10 min; mean inter-shock interval 40 s), under three conditions: free approach and effort- and conflict-based approaches.
  
  
  RESULTS
  Foot-shock-induced stress did not influence free-approach behavior (sniffing time) towards the social or sexual stimulus. However, in the effort-based approach task, the stressed morphine-withdrawn rats demonstrated an attenuated motivation to climb over a partition to approach the social stimulus while the stressed saline-pretreated rats showed an increased motivation to approach the social stimulus. When an aversive stimulus (pins) was introduced in order to induce an approach-avoidance conflict, both drug-withdrawn and drug-naïve groups exhibited a bimodal distribution of approach behavior towards the sexual stimulus after the stress was introduced, i.e., the majority of rats had low risky appetitive behaviors but a minority of them showed rather highly "risky" approach behavior.
  
  
  CONCLUSIONS
  The acute stress induces differential motivational deficits for social and sexual rewards in protracted drug-abstinent rats.
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, 100101, Beijing, China. baiyj@psych.ac.cn.|Department of Psychology, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, 100049, Beijing, China. baiyj@psych.ac.cn.
authors.forename: Yunjing
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Department of Psychology, University of Cambridge, Downing Street, Cambridge, CB3 2EB, UK.
authors.forename: David
authors.initials: D
authors.lastname: Belin
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, 100101, Beijing, China.|Department of Psychology, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, 100049, Beijing, China.
authors.forename: Xigeng
authors.initials: X
authors.lastname: Zheng
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, 100101, Beijing, China.|Department of Psychology, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, 100049, Beijing, China.
authors.forename: Zhengkui
authors.initials: Z
authors.lastname: Liu
authors.affiliation: CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, 16 Lincui Road, Chaoyang District, 100101, Beijing, China.|Department of Psychology, University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, 100049, Beijing, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007398:Interpersonal Relations; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D009021:Morphine Dependence / Q000523:psychology; D051381:Rats; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D013315:Stress, Psychological / Q000523:psychology*; D013375:Substance Withdrawal Syndrome / Q000523:psychology*; D013997:Time Factors
chemical_list: D009020:Morphine
keywords: Anhedonia; Appetitive behavior; Protracted morphine withdrawal; Sexual reward; Social reward; Stress