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Diester CM, Lichtman AH, Negus SS. Behavioral Battery for Testing Candidate Analgesics in Mice. II. Effects of Endocannabinoid Catabolic Enzyme Inhibitors and ∆9-Tetrahydrocannabinol. J Pharmacol Exp Ther 2021; 377:242-253. [PMID: 33622769 PMCID: PMC8058502 DOI: 10.1124/jpet.121.000497] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 02/22/2021] [Indexed: 12/19/2022] Open
Abstract
Enhanced signaling of the endocannabinoid (eCB) system through inhibition of the catabolic enzymes monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH) has received increasing interest for development of candidate analgesics. This study compared effects of MAGL and FAAH inhibitors with effects of ∆9-tetrahydrocannabinol (THC) using a battery of pain-stimulated, pain-depressed, and pain-independent behaviors in male and female mice. Intraperitoneal injection of dilute lactic acid (IP acid) served as an acute visceral noxious stimulus to stimulate two behaviors (stretching, facial grimace) and depress two behaviors (rearing, nesting). Nesting and locomotion were also assessed in the absence of IP acid as pain-independent behaviors. THC and a spectrum of six eCB catabolic enzyme inhibitors ranging from MAGL- to FAAH-selective were assessed for effectiveness to alleviate pain-related behaviors at doses that did not alter pain-independent behaviors. The MAGL-selective inhibitor MJN110 produced the most effective antinociceptive profile, with 1.0 mg/kg alleviating IP acid effects on stretching, grimace, and nesting without altering pain-independent behaviors. MJN110 effects on IP acid-depressed nesting had a slow onset and long duration (40 minutes to 6 hours), were blocked by rimonabant, and tended to be greater in females. As inhibitors increased in FAAH selectivity, antinociceptive effectiveness decreased. PF3845, the most FAAH-selective inhibitor, produced no antinociception up to doses that disrupted locomotion. THC decreased IP acid-stimulated stretching and grimace at doses that did not alter pain-independent behaviors; however, it did not alleviate IP acid-induced depression of rearing or nesting. These results support further consideration of MAGL-selective inhibitors as candidate analgesics for acute inflammatory pain. SIGNIFICANCE STATEMENT: This study characterized a spectrum of endocannabinoid catabolic enzyme inhibitors ranging in selectivity from monoacylglycerol lipase-selective to fatty acid amide hydrolase-selective in a battery of pain-stimulated, pain-depressed, and pain-independent behaviors previously pharmacologically characterized in a companion paper. This battery provides a method for prioritizing candidate analgesics by effectiveness to alleviate pain-related behaviors at doses that do not alter pain-independent behaviors, with inclusion of pain-depressed behaviors increasing translational validity and decreasing susceptibility to motor-depressant false positives.
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Affiliation(s)
- C M Diester
- Department of Pharmacology and Toxicology (C.M.D., A.H.L., S.S.N.), School of Pharmacy (A.H.L.), Virginia Commonwealth University, Richmond, Virginia
| | - A H Lichtman
- Department of Pharmacology and Toxicology (C.M.D., A.H.L., S.S.N.), School of Pharmacy (A.H.L.), Virginia Commonwealth University, Richmond, Virginia
| | - S S Negus
- Department of Pharmacology and Toxicology (C.M.D., A.H.L., S.S.N.), School of Pharmacy (A.H.L.), Virginia Commonwealth University, Richmond, Virginia
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Leonard MZ, Alapafuja SO, Ji L, Shukla VG, Liu Y, Nikas SP, Makriyannis A, Bergman J, Kangas BD. Cannabinoid CB 1 Discrimination: Effects of Endocannabinoids and Catabolic Enzyme Inhibitors. J Pharmacol Exp Ther 2017; 363:314-323. [PMID: 28947487 DOI: 10.1124/jpet.117.244392] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/14/2017] [Indexed: 11/22/2022] Open
Abstract
An improved understanding of the endocannabinoid system has provided new avenues of drug discovery and development toward the management of pain and other behavioral maladies. Exogenous cannabinoid type 1 (CB1) receptor agonists such as Δ9-tetrahydrocannabinol are increasingly used for their medicinal actions; however, their utility is constrained by concern regarding abuse-related subjective effects. This has led to growing interest in the clinical benefit of indirectly enhancing the activity of the highly labile endocannabinoids N-arachidonoylethanolamine [AEA (or anandamide)] and/or 2-arachidonoylglycerol (2-AG) via catabolic enzyme inhibition. The present studies were conducted to determine whether such actions can lead to CB1 agonist-like subjective effects, as reflected in CB1-related discriminative stimulus effects in laboratory subjects. Squirrel monkeys (n = 8) that discriminated the CB1 full agonist AM4054 (0.01 mg/kg) from vehicle were used to study, first, the inhibitors of fatty acid amide hydrolase (FAAH) or monoacylglycerol lipase (MGL) alone or in combination [FAAH (URB597, AM4303); MGL (AM4301); FAAH/MGL (JZL195, AM4302)] and, second, the ability of the endocannabinoids AEA and 2-AG to produce CB1 agonist-like effects when administered alone or after enzyme inhibition. Results indicate that CB1-related discriminative stimulus effects were produced by combined, but not selective, inhibition of FAAH and MGL, and that these effects were nonsurmountably antagonized by low doses of rimonabant. Additionally, FAAH or MGL inhibition revealed CB1-like subjective effects produced by AEA but not by 2-AG. Taken together, the present data suggest that therapeutic effects of combined, but not selective, enhancement of AEA or 2-AG activity via enzyme inhibition may be accompanied by CB1 receptor-mediated subjective effects.
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Affiliation(s)
- Michael Z Leonard
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Shakiru O Alapafuja
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Lipin Ji
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Vidyanand G Shukla
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Yingpeng Liu
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Spyros P Nikas
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Alexandros Makriyannis
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Jack Bergman
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
| | - Brian D Kangas
- Harvard Medical School, Department of Psychiatry, Boston, Massachusetts (J.B., B.D.K.); McLean Hospital, Preclinical Pharmacology Laboratory, Belmont, Massachusetts (M.Z.L., J.B., B.D.K.); MakScientific LLC, Burlington, Massachusetts (S.O.A.); and Center for Drug Discovery, Northeastern University, Boston, Massachusetts (L.J., V.G.S., Y.L., S.P.N., A.M.)
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Owens RA, Mustafa MA, Ignatowska-Jankowska BM, Damaj MI, Beardsley PM, Wiley JL, Niphakis MJ, Cravatt BF, Lichtman AH. Inhibition of the endocannabinoid-regulating enzyme monoacylglycerol lipase elicits a CB 1 receptor-mediated discriminative stimulus in mice. Neuropharmacology 2017; 125:80-86. [PMID: 28673548 DOI: 10.1016/j.neuropharm.2017.06.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 06/17/2017] [Accepted: 06/29/2017] [Indexed: 10/19/2022]
Abstract
Substantial challenges exist for investigating the cannabinoid receptor type 1 (CB1)-mediated discriminative stimulus effects of the endocannabinoids, 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide; AEA), compared with exogenous CB1 receptor agonists, such as Δ9-tetrahydrocannabinol (THC) and the synthetic cannabinoid CP55,940. Specifically, each endocannabinoid is rapidly degraded by the respective hydrolytic enzymes, monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH). Whereas MAGL inhibitors partially substitute for THC and fully substitute for CP55,940, FAAH inhibitors do not substitute for either drug. Interestingly, combined FAAH-MAGL inhibition results in full THC substitution, and the dual FAAH-MAGL inhibitor SA-57 serves as its own discriminative training stimulus. Because MAGL inhibitors fully substitute for SA-57, we tested whether the selective MAGL inhibitor MJN110 would serve as a training stimulus. Twelve of 13 C57BL/6J mice learned to discriminate MJN110 from vehicle, and the CB1 receptor antagonist rimonabant dose-dependently blocked its discriminative stimulus. CP55,940, SA-57, and another MAGL inhibitor JZL184, fully substituted for MJN110. In contrast, the FAAH inhibitor PF-3845 failed to substitute for the MJN110 discriminative stimulus, but produced a 1.6 (1.1-2.2; 95% confidence interval) leftward shift in the MJN110 dose-response curve. Inhibitors of other relevant enzymes (i.e., ABHD6, COX-2) and nicotine did not engender substitution. Diazepam partially substituted for MJN110, but rimonabant failed to block this partial effect. These findings suggest that MAGL normally throttles 2-AG stimulation of CB1 receptors to a magnitude insufficient to produce cannabimimetic subjective effects. Accordingly, inhibitors of this enzyme may release this endogenous brake producing effects akin to those produced by exogenously administered cannabinoids.
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Affiliation(s)
- Robert A Owens
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Mohammed A Mustafa
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Bogna M Ignatowska-Jankowska
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Patrick M Beardsley
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA
| | - Jenny L Wiley
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC, 27709-2194, USA
| | - Micah J Niphakis
- The Skaggs Institute for Chemical Biology, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Benjamin F Cravatt
- The Skaggs Institute for Chemical Biology, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Aron H Lichtman
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA.
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Wilkerson JL, Ghosh S, Mustafa M, Abdullah RA, Niphakis MJ, Cabrera R, Maldonado RL, Cravatt BF, Lichtman AH. The endocannabinoid hydrolysis inhibitor SA-57: Intrinsic antinociceptive effects, augmented morphine-induced antinociception, and attenuated heroin seeking behavior in mice. Neuropharmacology 2016; 114:156-167. [PMID: 27890602 DOI: 10.1016/j.neuropharm.2016.11.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 10/11/2016] [Accepted: 11/21/2016] [Indexed: 12/18/2022]
Abstract
Although opioids are highly efficacious analgesics, their abuse potential and other untoward side effects diminish their therapeutic utility. The addition of non-opioid analgesics offers a promising strategy to reduce required antinociceptive opioid doses that concomitantly reduce opioid-related side effects. Inhibitors of the primary endocannabinoid catabolic enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) show opioid-sparing effects in preclinical models of pain. As simultaneous inhibition of these enzymes elicits enhanced antinociceptive effects compared with single enzyme inhibition, the present study tested whether the dual FAAH-MAGL inhibitor SA-57 [4-[2-(4-chlorophenyl)ethyl]-1-piperidinecarboxylic acid 2-(methylamino)-2-oxoethyl ester] produces morphine-sparing antinociceptive effects, without major side effects associated with either drug class. SA-57 dose-dependently reversed mechanical allodynia in the constriction injury (CCI) of the sciatic nerve model of neuropathic pain and carrageenan inflammatory pain model. As previously reported, SA-57 was considerably more potent in elevating anandamide (AEA) than 2-arachidonyl glycerol (2-AG) in brain. Its anti-allodynic effects required cannabinoid (CB)1 and CB2 receptors; however, only CB2 receptors were necessary for the anti-edematous effects in the carrageenan assay. Although high doses of SA-57 alone were required to produce antinociception, low doses of this compound, which elevated AEA and did not affect 2-AG brain levels, augmented the antinociceptive effects of morphine, but lacked cannabimimetic side effects. Because of the high abuse liability of opioids and implication of the endocannabinoid system in the reinforcing effects of opioids, the final experiment tested whether SA-57 would alter heroin seeking behavior. Strikingly, SA-57 reduced heroin-reinforced nose poke behavior and the progressive ratio break point for heroin. In conclusion, the results of the present study suggest that inhibition of endocannabinoid degradative enzymes represents a promising therapeutic approach to decrease effective doses of opioids needed for clinical pain control, and may also possess therapeutic potential to reduce opioid abuse.
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Affiliation(s)
- Jenny L Wilkerson
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA.
| | - Sudeshna Ghosh
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Mohammed Mustafa
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Rehab A Abdullah
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Micah J Niphakis
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Roberto Cabrera
- Laboratory of Neuropharmacology. Department de Ciencies Experimentals i de la Salut, Pompeu Fabra University, PRBB, C/ Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Rafael L Maldonado
- Laboratory of Neuropharmacology. Department de Ciencies Experimentals i de la Salut, Pompeu Fabra University, PRBB, C/ Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Benjamin F Cravatt
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Aron H Lichtman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
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