Abstract
The aim of this study was to detect the mRNA expression levels of the dopamine D2 receptor (DRD2) and dopamine transporter (DAT) in peripheral blood leukocytes (PBLs) of schizophrenia patients and to explore the relationship between the mRNA expression levels and the clinical symptoms of schizophrenia. The research included 25 cases of acute schizophrenia patients, 27 cases of chronic schizophrenia patients, and 30 healthy controls. In every case, we measured the mRNA levels of DRD2 and DAT in PBLs by real-time quantitative reverse transcription-polymerase chain reaction (real-time RT-PCR), and we evaluated the patients’ clinical symptoms using the Positive and Negative Syndrome Scale (PANSS). DRD2 mRNA levels in PBLs of acute schizophrenia patients, chronic schizophrenia patients, and healthy controls were 0.32±0.13, 0.37±0.19, and 0.34±0.09, respectively, and the difference was not significant. DAT mRNA levels in PBLs of the abovementioned groups were 0.48±0.24, 0.58±0.21 and 0.39±0.24, respectively (F = 4.330, P = 0.017), and comparisons between every group showed that DAT mRNA levels in PBLs of chronic schizophrenia patients were significantly higher than those in healthy controls (MS interclass = 0.198, p = 0.005). The correlation between DRD2 mRNA levels in PBLs and the positive symptom points of PANSS in acute schizophrenia patients was significant (r = 0.443, p = 0.044). In conclusion, DRD2 mRNA levels in PBLs are correlated with positive symptoms in acute schizophrenia patients, and DAT mRNA levels in PBLs of chronic schizophrenia patients are over-expressed.
Highlights
Schizophrenia is a severe, chronic mental disorder, and it affects approximately 1% of the world’s population [1]
The Standard Curves of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), DRD2 and dopamine transporter (DAT) The DAT and DRD2 humanized full length transcription cDNA clones were diluted in gradient 10-fold as templates, and the standard curves were drawn with the slope and intercept calculated by the corresponding Ct value in the amplification
There was no significant difference in the DAT mRNA levels between the acute schizophrenia patients and the healthy controls, or between the acute schizophrenia patients and the NS*: Not statistically significant. doi:10.1371/journal.pone.0075259.t005
Summary
Schizophrenia is a severe, chronic mental disorder, and it affects approximately 1% of the world’s population [1]. The etiology and pathophysiology of schizophrenia remain obscure, and its current diagnosis is based on complex clinical symptoms. The application of detectable peripheral molecular markers could substantially help the diagnosis of psychiatric disorders [3]. Many of the signs and symptoms of schizophrenia can be reproduced in humans or animal models with dopaminergic drugs [7,8]. A recent meta-analysis was performed that was based on over 1000 association studies on schizophrenia, and this study highlighted 16 genes, which were mostly dopamine-related, including catechol-O-methyltransferase (COMT) and dopamine receptors D1, D2, and D4 (DRD1, DRD2 and DRD4) [9]
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