Successful treatment with risperidone increases 5‐HT 3A receptor gene expression in patients with paranoid schizophrenia – data from a prospective study

INTRODUCTION The relationship between peripheral 5-HT3A receptor mRNA level and risperidone efficiency in paranoid schizophrenia patients is still unknown. METHODS A total 52 first-episode and drug-naive paranoid schizophrenia patients who were treated with risperidone and 53 matched healthy controls were enrolled. Patients were naturalistically followed up for 8 weeks. Positive and Negative Syndrome Scale (PANSS) was applied to assess symptom severity of the patients at baseline and at the end of 8th week. RESULTS There was no difference in 5-HT3A receptor mRNA level between paranoid schizophrenia patients and healthy controls at baseline (p = .24). Among 47 patients who completed 8-week naturalistic follow-up, 37 were responders to risperidone treatment. 5-HT3A receptor mRNA level of paranoid schizophrenia patients did not change in overall patients after 8-week treatment with risperidone (p = .29). However, 5-HT3A receptor mRNA level in responders increased significantly (p = .04), but not in nonresponders (p = .81). CONCLUSIONS Successful treatment with risperidone increases 5-HT3A receptor gene expression in patients with paranoid schizophrenia, indicating that 5-HT3A receptor may be involved in the mechanism of risperidone effect.