title: Differential effects of endocannabinoid catabolic inhibitors on morphine withdrawal in mice.
abstract: BACKGROUND
  Inhibition of endocannabinoid catabolic enzymes fatty acid amide hydrolase (FAAH) and/or monoacylglycerol lipase (MAGL) reduces somatic morphine withdrawal signs, but its effects on aversive aspects of withdrawal are unknown. The present study investigated whether Δ(9)-tetrahydrocannabinol (THC), the MAGL inhibitor JZL184, the FAAH inhibitor PF-3845, or the dual FAAH/MAGL inhibitor SA-57 would reduce acquisition of morphine withdrawal-induced conditioned place avoidance (CPA) and jumping.
  
  
  METHODS
  Mice were implanted with placebo or 75 mg morphine pellets, 48 h later injected with naloxone or saline and placed in the conditioning apparatus, and assessed for CPA at 72 h. Subjects were also observed for jumping behavior following naloxone challenge.
  
  
  RESULTS
  Naloxone (0.056 mg/kg) produced robust CPA in morphine-pelleted, but not placebo-pelleted, mice. Morphine pretreatment prevented the occurrence of withdrawal CPA and withdrawal jumping, while clonidine (an α2 adrenergic receptor agonist) only blocked withdrawal CPA. THC, JZL184, and SA-57 significantly reduced the percentage of mice that jumped during the conditioning session, but did not affect acquisition of withdrawal CPA. PF-3845 did not reduce morphine withdrawal CPA or jumping. Finally, neither THC nor the endocannabinoid catabolic enzyme inhibitors in non-dependent mice elicited a conditioned place preference or aversion.
  
  
  CONCLUSIONS
  These findings suggest that inhibiting endocannabinoid catabolic enzymes reduces somatic morphine withdrawal signs, but not aversive aspects as inferred in the CPA paradigm. The observation that non-dependent mice administered inhibitors of endocannabinoid degradation did not display place preferences is consistent with the idea that that endocannabinoid catabolic enzymes might be targeted therapeutically, with reduced risk of abuse.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298, United States.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Gamage
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298, United States.
authors.forename: Bogna M
authors.initials: BM
authors.lastname: Ignatowska-Jankowska
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298, United States.
authors.forename: Pretal P
authors.initials: PP
authors.lastname: Muldoon
authors.affiliation: The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, 10550N. Torrey Pines Rd., La Jolla, CA 92037, United States.
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Cravatt
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298, United States.
authors.forename: M Imad
authors.initials: MI
authors.lastname: Damaj
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Kontos Medical Sciences Building, 1217 East Marshall Street, Richmond, VA, 23298, United States. Electronic address: alichtma@vcu.edu.
authors.forename: Aron H
authors.initials: AH
authors.lastname: Lichtman
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000581:Amidohydrolases / Q000037:antagonists & inhibitors; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D052117:Benzodioxoles / Q000494:pharmacology; D002219:Carbamates / Q000494:pharmacology; D003213:Conditioning, Psychological / Q000187:drug effects; D013759:Dronabinol / Q000494:pharmacology; D063388:Endocannabinoids / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008994:Monoacylglycerol Lipases / Q000037:antagonists & inhibitors; D009020:Morphine / Q000009:adverse effects*; D009270:Naloxone / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D013375:Substance Withdrawal Syndrome / Q000523:psychology*; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000081:Acetamides; D000581:Amidohydrolases; D052117:Benzodioxoles; D002219:Carbamates; D013759:Dronabinol; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D008994:Monoacylglycerol Lipases; D009020:Morphine; D009270:Naloxone; D010880:Piperidines; D011725:Pyridines; D000099252:Fatty Acid Amide Hydrolases; C000596174:4-(2-(4-chlorophenyl)ethyl)-1-piperidinecarboxylic acid 2-(methylamino)-2-oxoethyl ester; C534333:JZL 184; C557973:PF 3845
keywords: Cannabinoid; Conditioned place aversion (CPA); Fatty acid amide hydrolase (FAAH); Monoacylglycerol lipase; Morphine; Withdrawal