Lipopolysaccharide induces fever and decreases tail flick latency in awake rats.
In humans, somatic aches and pains are frequently reported during fever. To determine whether exogenous pyrogen administration increases nociceptive responsiveness in rats, the tail flick reflex evoked by noxious heat was compared in animals that received an intraperitoneal injection of exogenous pyrogen (lipopolysaccharide) or vehicle (saline). There were no differences in skin temperature between lipopolysaccharide- and vehicle-injected rats. Awake rats injected with lipopolysaccharide exhibited an increase in colonic temperature and a decrease in tail flick latency when compared to vehicle-injected rats. Neural events that trigger fever may therefore also modulate nociceptive responsiveness.
Mason
P
P
Department of Pharmacological and Physiological Sciences, University of Chicago, IL 60637.
D000818:Animals; D005334:Fever / Q000139:chemically induced*; D006358:Hot Temperature; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D009619:Nociceptors / Q000187:drug effects; D010146:Pain / Q000139:chemically induced*; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D012881:Skin Temperature / Q000187:drug effects
D008070:Lipopolysaccharides