title: Activation of cannabinoid receptor 2 inhibits experimental cystitis.
abstract: Cannabinoids have been shown to exert analgesic and anti-inflammatory effects, and the effects of cannabinoids are mediated primarily by cannabinoid receptors 1 and 2 (CB1and CB2). Both CB1 and CB2 are present in bladders of various species, including human, monkey, and rodents, and it appears that CB2 is highly expressed in urothelial cells. We investigated whether treatment with the CB2 agonist GP1a alters severity of experimental cystitis induced by acrolein and referred mechanical hyperalgesia associated with cystitis. We also investigated whether the mitogen-activated protein kinases (MAPK), ERK1/2, p38, and JNK are involved in the functions of CB2. We found that treatment with the selective CB2 agonist GP1a (1-10 mg/kg, ip) inhibited the severity of bladder inflammation 3 h after intravesical instillation of acrolein in a dose-dependent manner, and inhibition reached significance at a dose of 10 mg/kg (P < 0.05). Treatment with GP1a (10 mg/kg) inhibited referred mechanical hyperalgesia associated with cystitis (P < 0.05). The inhibitory effects of the CB2 agonist were prevented by the selective CB2 antagonist AM630 (10 mg/kg, sc). We further demonstrated the inhibitory effects of CB2 appear to be at least partly mediated by reducing bladder inflammation-induced activation of ERK1/2 MAPK pathway. The results of the current study indicate that CB2 is a potential therapeutic target for treatment of bladder inflammation and pain in patients.
authors.affiliation: Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA. wangz@svm.vetmed.wisc.edu
authors.forename: Zun-Yi
authors.initials: ZY
authors.lastname: Wang
authors.forename: Peiqing
authors.initials: P
authors.lastname: Wang
authors.forename: Dale E
authors.initials: DE
authors.lastname: Bjorling
mesh_terms: D000171:Acrolein; D000818:Animals; D063386:Cannabinoid Receptor Agonists / Q000494:pharmacology / Q000627:therapeutic use*; D063387:Cannabinoid Receptor Antagonists / Q000494:pharmacology; D003556:Cystitis / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D007192:Indenes / Q000494:pharmacology / Q000627:therapeutic use*; D007211:Indoles / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010147:Pain Measurement; D011720:Pyrazoles / Q000494:pharmacology / Q000627:therapeutic use*; D043885:Receptor, Cannabinoid, CB2 / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism; D012720:Severity of Illness Index
chemical_list: D063386:Cannabinoid Receptor Agonists; D063387:Cannabinoid Receptor Antagonists; D007192:Indenes; D007211:Indoles; C553580:N-(piperidin-1-yl)-1-(2,4-dichlorophenyl)-1,4-dihydro-6-methylindeno(1,2-c)pyrazole-3-carboxamide; D011720:Pyrazoles; D043885:Receptor, Cannabinoid, CB2; D000171:Acrolein; D020928:Mitogen-Activated Protein Kinases; C094023:iodopravadoline
keywords: GP1a; cannabinoid receptor 2; cystitis; hyperalgesia; mice