AUTHOR=Li Canye , Cai Qiming , Su Zuanjun , Chen Zhicong , Cao Jinming , Xu Feng 

TITLE=Could peripheral 5-HT level be used as a biomarker for depression diagnosis and treatment? A narrative minireview

JOURNAL=Frontiers in Pharmacology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2023.1149511

DOI=10.3389/fphar.2023.1149511

ISSN=1663-9812

ABSTRACT=The serotonin hypothesis of depression is still influential, but the relationship between peripheral 5-
HT levels and depression is still unknown. This review aimed to verify whether peripheral 5-HT 
levels could be used as a gold biomarker for depression diagnosis and treatment. PubMed and 
EMBASE were searched using terms appropriate to the area of research. Clinical trials and animal 
experiments from 1957 to 2022 in the following areas were identified: depression, 5-HT, serotonin 
and peripheral. 69 clinical trials and 404 animal experiments were searched. 54 studies were
included: 6 clinical trials about periphery 5-HT levels in depressive patients compared to normal 
subjects, 16 clinical trials about changes of peripheral 5-HT levels in patients with depression after 
drug treatment, 19 animal experiments about CNS 5-HT levels with depression in animal models 
and 13 animal experiments about peripheral 5-HT levels with depression in animal models. 
Peripheral 5-HT levels presented three different outcomes before and after antidepressant treatments: 
increased, decreased and no significant change. In conclusion, changes in peripheral 5-HT levels 
did not show consistent results among these studies. Peripheral 5-HT level could not be used as a 
biomarker both for depression diagnosis and for antidepressant efficacy evaluation.