title: Severe dopaminergic neuron loss in rhesus monkey brain impairs morphine-induced conditioned place preference.
abstract: It is well known that dopamine (DA) is critical for reward, but the precise role of DA in reward remains uncertain. The aim of this study was to determine what percentage of dopaminergic neurons in the primate brain is required for the expression of conditioned reward by measuring the performance of DA-deficient rhesus monkeys in a morphine-induced conditioned place preference (CPP) paradigm. Animals with mild Parkinsonian symptoms successfully developed and retained a morphine preference that was equivalent to control monkeys. However, these monkeys could not maintain the preference as well as controls when they retained severe Parkinsonian symptoms. On the other hand, monkeys initially in a severe Parkinsonian state developed a preference for morphine, but this preference was weaker than that of the controls. Histological results showed that the loss of dopaminergic neurons in monkeys that had severe Parkinsonian symptoms was about 80% in comparison to the control monkeys. All these data suggest that a severely impaired DA system alters rewarding-seeking behavior in non-human primates.
authors.affiliation: Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China ; University of Chinese Academy of Sciences Beijing, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Yan
authors.affiliation: Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China ; University of Chinese Academy of Sciences Beijing, China.
authors.forename: Joshua Dominic
authors.initials: JD
authors.lastname: Rizak
authors.affiliation: Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China.
authors.forename: Shangchuan
authors.initials: S
authors.lastname: Yang
authors.affiliation: Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China ; Kunming Primate Research Center, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China ; Yunnan Key Laboratory of Primate Biomedical Research Kunming, Yunnan, China.
authors.forename: Yuanye
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China ; Kunming Primate Research Center, Kunming Institute of Zoology, Chinese Academy of Sciences Kunming, Yunnan, China ; Yunnan Key Laboratory of Primate Biomedical Research Kunming, Yunnan, China.
authors.forename: Xintian
authors.initials: X
authors.lastname: Hu
keywords: dopamine; morphine; place preference; reward; rhesus monkey