Role of the cannabinoid signaling in the brain orexin- and ghrelin-induced visceral antinociception in conscious rats

Publication date: Available online 7 June 2018Source: Journal of Pharmacological SciencesAuthor(s): Toshikatsu Okumura, Tsukasa Nozu, Shima Kumei, Masumi OhhiraAbstractWe hypothesized that the cannabinoid (CB) system may mediate the brain orexin- or ghrelin-induced visceral antinociception. Intraperitoneal injection of either CB1/2 agonist, WIN 55212 or O-Arachidonoyl ethanolamine increased the threshold volume of colonic distension-induced abdominal withdrawal reflex in rats, suggesting CB could induce visceral antinociception. Pretreatment with either the CB1 or CB2 antagonist potently blocked the centrally injected orexin-A-induced antinociceptive action against colonic distension while CB2 but not CB1 antagonist blocked the brain ghrelin-induced visceral antinociception. These results suggest that the cannabinoid signaling may be involved in the central orexin- or ghrelin-induced antinociceptive action in a different mechanistic manner.
Source: Journal of Pharmacological Sciences - Category: Drugs & Pharmacology Source Type: research