Background: Abnormal serotonin (5-HT) activity has been implicated in schizophrenia. However, the role of 5-HT receptors and transporter (5-HTT) in male and female schizophrenia remains largely unknown. Recent studies suggest that 5-HT system expressed in the peripheral leukocyte could be a marker of the illness.
Methods: 46 acute schizophrenic patients (male=35, female=11) that were antipsychotic-naïve or antipsychotic-free for at least three months (average=27.3 months) and 44 age- and sex-matched healthy subjects (male=24, female=20) were included for blood leukocytes expression of 5-HT(1A), 5-HT(2A) and 5-HT(7) receptor and 5-HTT mRNA, using real-time PCR technique.
Results: ANOVA analysis showed a significant increase of 5HT(2A) mRNA and 5-HTT mRNA (each >2-fold, P<0.01) and a trend increase of 5HT(1A) mRNA (P<0.15) and 5-HT(7) mRNA (P<0.09) level in blood leukocytes of pooled schizophrenic patients than in the healthy subjects. The elevation was mainly found in the male patients. Within-sex analysis showed that the male antipsychotic-free schizophrenic patients exhibited greater 5-HT(1A) and 5-HT(7) mRNA expression (P<0.05, each ) whereas female antipsychotic-free patients showed decreased 5-HT(1A) mRNA expression (P<0.05) when compared with the male and female healthy subjects, respectively. The correlations between 5-HT mRNA and clinical symptoms (PANSS scales) were calculated.
Conclusions: The present findings showed an abnormal expression of leukocyte 5-HT system in antipsychotic-free and antipsychotic-naïve schizophrenia especially in the male patients. Because of the greater accumulative dose of antipsychotics in the relatively smaller number of the female patients of the study, further study is needed to confirm the present findings. If replicated, blood serotonergic markers could add to the diagnosis and individualized pharmacotherapy of schizophrenic patients, especially the male patients.
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