Relationship between dopamine deficit and the expression of depressive behavior resulted from alteration of serotonin system

Minkyung Lee, Young Hoon Ryu, Won Gil Cho, Yeo Wool Kang, Soo Jin Lee, Tae Joo Jeon, Chul Hyoung Lyoo, Chul Hoon Kim, Dong Goo Kim, Kyochul Lee, Tae Hyun Choi, Jae Yong Choi

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23 Citations (Scopus)


Depression frequently accompanies in Parkinson's disease (PD). Previous research suggested that dopamine (DA) and serotonin systems are closely linked with depression in PD. However, comprehensive studies about the relationship between these two neurotransmitter systems are limited. Therefore, the purpose of this study is to evaluate the effect of dopaminergic destruction on the serotonin system. The interconnection between motor and depression was also examined. Two PET scans were performed in the 6-hydroxydopamine (6-OHDA) lesioned and sham operated rats: [18F]FP-CIT for DA transporters and [18F]Mefway for serotonin 1A (5-HT1A) receptors. Here, 6-OHDA is a neurotoxin for dopaminergic neurons. Behavioral tests were used to evaluate the severity of symptoms: rotational number for motor impairment and immobility time, acquired from the forced swim test for depression. Region-of-interests were drawn in the striatum and cerebellum for the DA system and hippocampus and cerebellum for the 5-HT system. The cerebellum was chosen as a reference region. Nondisplaceable binding potential in the striatum and hippocampus were compared between 6-OHDA and sham groups. As a result, the degree of DA depletion was negatively correlated with rotational behavior (R2=0.79, P=0.003). In 6-OHDA lesioned rats, binding values for 5-HT1A receptors was 22% lower than the sham operated group. This decrement of 5-HT1A receptor binding was also correlated with the severity of depression (R2=0.81, P=0.006). Taken together, this research demonstrated that the destruction of dopaminergic system causes the reduction of the serotonergic system resulting in the expression of depressive behavior. The degree of dopaminergic dysfunction was positively correlated with the impairment of the serotonin system. Severity of motor symptoms was also closely related to depressive behavior.

Original languageEnglish
Pages (from-to)453-460
Number of pages8
Issue number9
Publication statusPublished - 2015 Sept 1

Bibliographical note

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© 2015 Wiley Periodicals, Inc.

All Science Journal Classification (ASJC) codes

  • Cellular and Molecular Neuroscience


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