Differential effects of endocannabinoid catabolic inhibitors on morphine withdrawal in mice. (1st January 2015)

• Record Type: Journal Article
• Authors: Gamage, Thomas F.; Ignatowska-Jankowska, Bogna M.; Muldoon, Pretal P.; Cravatt, Benjamin F.; Damaj, M. Imad; Lichtman, Aron H.
• Is Part Of: Drug and alcohol dependence. Volume 146(2015)
• Page Start: 7
• Page End: 16
• Publication Date: 2015-01-01
• Subjects: Morphine -- Withdrawal -- Cannabinoid -- Fatty acid amide hydrolase (FAAH) -- Monoacylglycerol lipase -- Conditioned place aversion (CPA); Drug abuse -- Periodicals; Alcoholism -- Periodicals; 616.86
• DOI: 10.1016/j.drugalcdep.2014.11.015
• Languages: English
• ISSNs: 0376-8716

Abstract

Highlights: Morphine or clonidine reduces the development of conditioned place aversions of withdrawal in morphine-dependent mice. THC and endocannabinoid degradative enzyme inhibitors reduce somatic signs of morphine withdrawal, but not the development of conditioned place aversions of withdrawal. Endocannabinoid degradative enzymes inhibitors do not elicit rewarding effects on their own, as assessed in the conditioned place preference paradigm. 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.