Decreased plasma neuroactive amino acids and increased nitric oxide levels in melancholic major depressive disorder.
BACKGROUND
Amino acid neurotransmitters and nitric oxide (NO) are involved in the pathogenesis of major depressive disorder (MDD). Here we want to establish whether changes in their plasma levels may serve as biomarker for the melancholic subtype of this disorder.


METHODS
Plasma levels of glutamic acid (Glu), aspartic acid (Asp), glycine (Gly), gamma-aminobutyric acid (GABA), and NO were determined in 27 medicine-naïve melancholic MDD patients and 30 matched controls. Seven of the MDD patients participated also in a follow-up study after 2 months' antidepressant treatment. The relationship between plasma and cerebral-spinal fluid (CSF) levels of these compounds was analyzed in an additional group of 10 non-depressed subjects.


RESULTS
The plasma levels of Asp, Gly and GABA were significantly lower whereas the NO levels were significantly higher in melancholic MDD patients, also after 2 months of fluoxetine treatment. In the additional 10 non-depressed subjects, no significant correlation was observed between plasma and CSF levels of these compounds.


CONCLUSIONS
These data give the first indication that decreased plasma levels of Asp, Gly and GABA and increased NO levels may serve as a clinical trait-marker for melancholic MDD. The specificity and selectivity of this putative trait-marker has to be investigated in follow-up studies.
Yun-Rong
YR
Lu
Xin-Yan
XY
Fu
Li-Gen
LG
Shi
Yan
Y
Jiang
Juan-Li
JL
Wu
Xiao-Juan
XJ
Weng
Zhao-Pin
ZP
Wang
Xue-Yan
XY
Wu
Zheng
Z
Lin
Wei-Bo
WB
Liu
Hui-Chun
HC
Li
Jian-Hong
JH
Luo
Department of Neurobiology; Key Laboratory of Medical Neurobiology of Ministry of Health of China; Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, 866 Yuhangtang Road, Hangzhou 310058, Zhejiang, P, R, China. baoaimin@zju.edu.cn.
Ai-Min
AM
Bao
D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000097:blood*; D000928:Antidepressive Agents / Q000627:therapeutic use; D001224:Aspartic Acid / Q000097:blood; D015415:Biomarkers / Q000097:blood; D003865:Major Depressive Disorder / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy; D005260:Female; D005500:Follow-Up Studies; D018698:Glutamic Acid / Q000097:blood; D005998:Glycine / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood*; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000097:blood
D000596:Amino Acids; D000928:Antidepressive Agents; D015415:Biomarkers; D001224:Aspartic Acid; D009569:Nitric Oxide; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005998:Glycine