title: Increased thermal and mechanical nociceptive thresholds in rats with depressive-like behaviors.
abstract: Clinical observations suggest that depressed patients were less sensitive to experimental pain than healthy subjects. However, few animal studies are reported concerning the association of depression and pain. The purpose of this study was to investigate the effects of unpredictable chronic mild stress (UCMS) induced depression on the perceived intensity of painful stimulation in rats. We measured the thermal and mechanical paw withdrawal thresholds (PWT) of normal and spinal nerve ligated (SNL) rats using hot plate test and von Frey test, respectively. The results showed that rats exposed to UCMS exhibited significantly higher thermal and mechanical pain thresholds in comparison to the non-depressed controls. In particular, the PWT of the SNL group was restored to nearly normal level after three weeks of UCMS, and even comparable to that of the control group. These results strongly suggest that the depressed subjects have decreased sensitivity to externally applied noxious stimulation, which is consistent with our previous findings.
authors.affiliation: Neuroscience Research Institute and Department of Neurobiology, Peking University Health Science, Beijing, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Shi
authors.forename: Wei-Jing
authors.initials: WJ
authors.lastname: Qi
authors.forename: Ge
authors.initials: G
authors.lastname: Gao
authors.forename: Jin-Yan
authors.initials: JY
authors.lastname: Wang
authors.forename: Fei
authors.initials: F
authors.lastname: Luo
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D003863:Depression / Q000503:physiopathology*; D004195:Disease Models, Animal; D006358:Hot Temperature / Q000009:adverse effects; D006930:Hyperalgesia / Q000503:physiopathology*; D008297:Male; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D013127:Spinal Nerves / Q000503:physiopathology; D013315:Stress, Psychological / Q000150:complications; D013395:Sucrose / Q000378:metabolism; D014868:Water Deprivation / Q000502:physiology
chemical_list: D013395:Sucrose