Effect of fluoxetine on circadian rhythm of melatonin in patients with major depressive disorder.
OBJECTIVE
The purpose of this study is to explore the response of melatonin circadian rhythm to fluoxetine treatment and its relationship with clinical therapeutic effect.


METHODS
This study investigated salivary melatonin in 13 outpatients with major depressive disorder and age- and sex-matched healthy controls. Depressed patients received six weeks fluoxetine (20 mg/day) treatment, and saliva was collected before and four weeks after treatment. In sampling days, a total of 12 time-point salivary melatonin was measured over 24-hours. Multioscillator cosinor model was used to fit the rhythms.


RESULTS
There was no difference of circadian melatonin rhythms in depressed patients, and melatonin was not significantly lower after fluoxetine treatment. To our surprise, the melatonin amplitude (Before minus After) was positively correlated with the improvement in Hamilton Depression Rating Scale (HDRS) scores at day 42 whereas there was no such correlation at day 28.


CONCLUSIONS
Melatonin rhythms were similar between depressed patients and matched healthy controls. The interesting finding that the difference of salivary melatonin amplitude was correlated with the clinical improvement after six weeks fluoxetine treatment deserve further study.
Tan
Zhong-Lin
ZL
Hefei National Laboratory for Physical Sciences at Microscale and Department of Neurobiology, School of Life Science, University of Science and Technology of China, China.
Bao
Ai-Min
AM
Zhao
Guo-Qiu
GQ
Liu
Ya-Jing
YJ
Zhou
Jiang-Ning
JN
D000328:Adult; D018687:Antidepressive Agents, Second-Generation / Q000494:pharmacology* / Q000627:therapeutic use; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology; D003865:Major Depressive Disorder / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D005473:Fluoxetine / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D011569:Psychiatric Status Rating Scales; D012463:Saliva / Q000378:metabolism; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use
D018687:Antidepressive Agents, Second-Generation; D005473:Fluoxetine; D008550:Melatonin; D017367:Selective Serotonin Reuptake Inhibitors