Sunshine-exposure variation of human striatal dopamine D2/D3 receptor availability in healthy volunteers

Background: In addition to the serotonergic system, the central dopaminergic system has been reported to be correlated with seasonality. The aim of this study was to explore the difference in striatal dopamine D-2/D-3 receptor availability between healthy volunteers who had a high-sunshine exposure and those who had a low exposure. Methods: Sixty-eight participants were enrolled, and those in the upper and lower quartiles in terms of sunshine exposure were categorized into high- (n = 17) and low-sunshine-exposure (n = 18) subgroups. Single photon emission computed tomography with [I-123] iodo-benzamide was used to measure striatal dopamine D-2/D-3 receptor availability. Results: Striatal dopamine D-2/D-3 receptor availability was significantly greater in the subjects with high-sunshine exposure than in those with low-sunshine exposure (F = 7.97, p = 0.01) after controlling for age, sex, and smoking status. Limitations: Different subjects were examined at different time points in our study. In addition, the sex and tobacco use distributions differed between groups. Conclusion: The central dopaminergic system may play a role in the neurobiological characteristics of sunshine-exposure variation. (C) 2010 Elsevier Inc. All rights reserved.