Colonic inflammation decreases thermal sensitivity of the forepaw and hindpaw in the rat.
Noxious stimulation at one site on the body can inhibit noxious stimulation at distal body sites. This has been extensively demonstrated for somatic stimuli, but less so for visceral stimuli. In the present study we present a model for visceral inflammatory stimuli inhibiting somatic thermal sensitivity in awake rats. Colonic inflammation induced by mustard oil increases the hindpaw and forepaw withdrawal latency from a noxious radiant heat source by 35-50% compared to baseline responses. The duration of the effect is dose-dependent. The withdrawal latency in control rats (mineral oil in colon, mustard oil on skin) was not affected. Rotarod performance was not affected by 5% mustard oil indicating that colonic inflammation did not produce a general malaise or decrease in motor performance. These data suggest that visceral inflammation in the rat decreases somatic sensitivity similar to that reported by patients with colonic hypersensitivity from irritable bowel syndrome or inflammatory bowel diseases.
Traub
Richard J
RJ
Department of Biomedical Sciences, Dental School and Program in Neurosciences, University of Maryland, 666 W. Baltimore St., Baltimore, MD 21201, USA. rjt001@dental.umaryland.edu
Wang
Gexin
G
D000818:Animals; D003092:Colitis / Q000139:chemically induced / Q000503:physiopathology*; D005552:Forelimb / Q000473:pathology / Q000502:physiology*; D006614:Hindlimb / Q000473:pathology / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects*; D008297:Male; D017288:Pain Threshold / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology