Beta-funaltrexamine disrupts the day-night rhythm of nociception in mice.
Determinations were made of the effects of beta-funaltrexamine (beta-FNA), an irreversible mu-opioid receptor antagonist, on the day-night rhythm of nociception in male mice. Peripheral administration of beta-FNA (20 and 40 mg/kg) disrupted the day-night rhythm of foot-licking response to aversive thermal (50 degrees C) stimulation. The peak nocturnal response latency was attenuated and the marked increases and decreases in response latency present at the light-dark and dark-light transitions, respectively, were suppressed. These results suggest that mu opioids are associated with the generation and expression of the day-night rhythm of this particular measure of nociception in mice.
Kavaliers
M
M
Division of Oral Biology, Faculty of Dentistry, University of Western Ontario, London, Canada.
D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects*; D008297:Male; D051379:Mice; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D017450:Receptors, Opioid, mu
D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D009271:Naltrexone; C024524:beta-funaltrexamine