Decreased platelet 5-hydroxytryptamin (5-HT) levels: A response to antidepressants

Abstract Background Platelet 5-hydroxytryptamin (serotonin, 5-HT) has been examined for its use as a peripheral biomarker for depression or other mental disorders; however, it remains unclear whether blood 5-HT levels can reflect the brain's levels of serotonin. Methods Platelet 5-HT levels in 45 drug-naive, 32 citalopram-treated patients with major depression and 32 healthy control were assayed, Hamilton Depression scale (HAMD) and Hamilton Anxiety Scale (HAMA) were assessed. We then measured 5-HT in platelet, in platelet-poor plasma and in the nuclei of brain tissues obtained from chronic unpredictable mild stress (CUMS) rats with or without citalopram treatment, and from the controls rats that were treated with vehicle. Toward this end, we analyzed whether correlations exist between platelet and brain. Results No differences were observed among drug-naive patients, citalopram-treated patients and health control according to gender and age ( p >0.05). Drug-naive depressed patients had highest scores in HAMD and HAMA among the three groups ( F =223.3, p F =70.7, p 9 versus 558.0±199.4 ng/10 9 , p 9 versus 646.4±259.0 ng/10 9 , p p >0.05). Consistent with clinical results, in comparison with control (1473.4±391.0 ng/10 9 ) and drug-naive CUMS rats (1559.0±424.4 ng/10 9 ), the citalopram-treated CUMS rats (684.2±335.6 ng/10 9 ) demonstrated a significant reduction in platelet 5-HT levels ( p F =0.11, p >0.05). Hippocampal 5-HT levels were higher among CUMS rats treated with saline (98.2±59.0 ng/g) than vehicle animals (31.9±18.3 ng/g, p p p >0.05). Furthermore, the levels of platelet 5-HT did not correlate with neuronal 5-HT levels ( p >0.05). Limitations Dosages was fix for citalopram-treat rats, and the citalopram-treated vehicle arm did not set up. Conclusions Our study suggests that platelet 5-HT levels might respond to SSRI treatment, but this peripheral index is not a direct reflector of central 5-HT levels.