title: [The study of neuroendocrine mechanism of depression induced by chronic mild stress].
abstract: OBJECTIVE
  To elucidate the mechanism of depression induced by chronic unpredictable mild stress (CUMS), the effects of CUMS on serotonin (5-HT), tryptophan, stress hormones and behaviour were investigated in rats.
  
  
  METHODS
  Depression was induced by for 8 weeks CUMS and confirmed by behavioral tests, the brain and plasma levels of monoamine neurotransmitters were analyzed by HPLC-ECD techniques, the content of plasma corticosterone was evaluated by I125 cortisol radioactivity immunoassay and the serum tryptophan content was measured by HTTACHI L-8800 amino acid analyzer.
  
  
  RESULTS
  (1) Rats exposed to a series of mild, unpredictable stressors for 8 weeks displayed the decreased body weight, reduced scores of open-field test and preference of sucrose solution (P < 0.05). (2) Plasma and brain 5-HT contents in rats after exposure to CUMS 8 weeks decreased significantly (P < 0.05). While serum tryptophan content increased at the same time (P < 0.05). (3) Plasma norepinephrine and epinephrine in rats were increased after CUMS 8 weeks, but there was no difference between control and CUMS group in plasma corticosterone.
  
  
  CONCLUSIONS
  The behavioral changes induced by CUMS for 8 weeks are similar to the features of human depression, which may be related to the disturbances of tryptophan metabolism induced by increased norepinephrine and epinephrine in CUMS rat.
authors.affiliation: Institute of Health and Environmental Medicine, Academy of Military Medical Sciences, Tianjin 300050, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Ling-Jia
authors.initials: LJ
authors.lastname: Qian
authors.forename: Zhi-Hua
authors.initials: ZH
authors.lastname: Yang
authors.forename: Rui
authors.initials: R
authors.lastname: Zhan
authors.forename: Hong
authors.initials: H
authors.lastname: Feng
authors.forename: Lei
authors.initials: L
authors.lastname: Wu
mesh_terms: D000818:Animals; D003863:Depression / Q000378:metabolism*; D004837:Epinephrine / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D009490:Neurosecretory Systems / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D013315:Stress, Psychological / Q000378:metabolism*
chemical_list: D012701:Serotonin; D009638:Norepinephrine; D004837:Epinephrine