Artificially produced meteorological changes aggravate pain in adjuvant-induced arthritic rats.
To examine the effects of change in meteorological parameters on pain-related behaviors in a simulated arthritic condition, rats with an injection of complete Freund's adjuvant into the tibio-tarsal joint were exposed to low barometric pressure (20 mmHg below the natural atmospheric pressure) and low ambient temperature (7 degrees C lower than 22 degrees C) in a climate-controlled room. When the arthritic rats were exposed to these environments, the already increased number of hindpaw withdrawals in response to noxious mechanical stimulation (hyperalgesia) was further increased, and a hindpaw withdrawal response to innocuous mechanical stimulation (allodynia) began to occur. Such exposures did not influence any of the pain-related behaviors of the control rats. These results show that lowering barometric pressure and ambient temperature within the range of natural environmental fluctuation intensify pain in arthritic rats.
Sato
Jun
J
Department of Neural Regulation, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan. jun@riem.nagoya-u.ac.jp
Aoyama
Morihiko
M
Yamazaki
Masahiro
M
Okumura
Satoshi
S
Takahashi
Ken
K
Funakubo
Megumi
M
Mizumura
Kazue
K
D000818:Animals; D001169:Arthritis, Experimental / Q000503:physiopathology*; D001274:Atmospheric Pressure; D003080:Cold Temperature; D006930:Hyperalgesia / Q000503:physiopathology*; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D014887:Weather