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Owens RA, Ignatowska-Jankowska B, Mustafa M, Beardsley PM, Wiley JL, Jali A, Selley DE, Niphakis MJ, Cravatt BF, Lichtman AH. Discriminative Stimulus Properties of the Endocannabinoid Catabolic Enzyme Inhibitor SA-57 in Mice. J Pharmacol Exp Ther 2016; 358:306-14. [PMID: 27307500 DOI: 10.1124/jpet.115.229492] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 05/18/2016] [Indexed: 12/15/2022] Open
Abstract
Whereas the inhibition of fatty acid amide hydrolase (FAAH) or monoacylglycerol lipase (MAGL), the respective major hydrolytic enzymes of N-arachidonoyl ethanolamine (AEA) and 2-arachidonoylglycerol (2-AG), elicits no or partial substitution for Δ(9)-tetrahydrocannabinol (THC) in drug-discrimination procedures, combined inhibition of both enzymes fully substitutes for THC, as well as produces a constellation of cannabimimetic effects. The present study tested whether C57BL/6J mice would learn to discriminate the dual FAAH-MAGL inhibitor SA-57 (4-[2-(4-chlorophenyl)ethyl]-1-piperidinecarboxylic acid 2-(methylamino)-2-oxoethyl ester) from vehicle in the drug-discrimination paradigm. In initial experiments, 10 mg/kg SA-57 fully substituted for CP55,940 ((-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol), a high-efficacy CB1 receptor agonist in C57BL/6J mice and for AEA in FAAH (-/-) mice. Most (i.e., 23 of 24) subjects achieved criteria for discriminating SA-57 (10 mg/kg) from vehicle within 40 sessions, with full generalization occurring 1 to 2 hours postinjection. CP55,940, the dual FAAH-MAGL inhibitor JZL195 (4-nitrophenyl 4-(3-phenoxybenzyl)piperazine-1-carboxylate), and the MAGL inhibitors MJN110 (2,5-dioxopyrrolidin-1-yl 4-(bis(4-chlorophenyl)methyl)piperazine-1-carboxylate) and JZL184 (4-[Bis(1,3-benzodioxol-5-yl)hydroxymethyl]-1-piperidinecarboxylic acid 4-nitrophenyl ester) fully substituted for SA-57. Although the FAAH inhibitors PF-3845 ((N-3-pyridinyl-4-[[3-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenyl]methyl]-1-piperidinecarboxamide) and URB597 (cyclohexylcarbamic acid 3'-(aminocarbonyl)-[1,1'-biphenyl]-3-yl ester) did not substitute for SA-57, PF-3845 produced a 2-fold leftward shift in the MJN110 substitution dose-response curve. In addition, the CB1 receptor antagonist rimonabant blocked the generalization of SA-57, as well as substitution of CP55,940, JZL195, MJN110, and JZL184. These findings suggest that MAGL inhibition plays a major role in the CB1 receptor-mediated SA-57 training dose, which is further augmented by FAAH inhibition.
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Affiliation(s)
- Robert A Owens
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Bogna Ignatowska-Jankowska
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Mohammed Mustafa
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Patrick M Beardsley
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Jenny L Wiley
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Abdulmajeed Jali
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Dana E Selley
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Micah J Niphakis
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Benjamin F Cravatt
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
| | - Aron H Lichtman
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia (R.A.O., B.I.J., M.M., P.M.B., A.J., D.E.S., A.H.L.); RTI International, Research Triangle Park, North Carolina (J.L.W.); and The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California (M.J.N.; B.F.C.)
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Winsauer PJ, Filipeanu CM, Bailey EM, Hulst JL, Sutton JL. Ovarian hormones and chronic administration during adolescence modify the discriminative stimulus effects of delta-9-tetrahydrocannabinol (Δ⁹-THC) in adult female rats. Pharmacol Biochem Behav 2012; 102:442-9. [PMID: 22705493 DOI: 10.1016/j.pbb.2012.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 05/12/2012] [Accepted: 06/09/2012] [Indexed: 02/04/2023]
Abstract
Marijuana abuse during adolescence may alter its abuse liability during adulthood by modifying the interoceptive (discriminative) stimuli produced, especially in females due to an interaction with ovarian hormones. To examine this possibility, either gonadally intact or ovariectomized (OVX) female rats received 40 intraperitoneal injections of saline or 5.6 mg/kg of Δ⁹-THC daily during adolescence, yielding 4 experimental groups (intact/saline, intact/Δ⁹-THC, OVX/saline, and OVX/Δ⁹-THC). These groups were then trained to discriminate Δ⁹-THC (0.32-3.2 mg/kg) from saline under a fixed-ratio (FR) 20 schedule of food presentation. After a training dose was established for the subjects in each group, varying doses of Δ⁹-THC were substituted for the training dose to obtain dose-effect (generalization) curves for drug-lever responding and response rate. The results showed that: 1) the OVX/saline group had a substantially higher mean response rate under control conditions than the other three groups, 2) both OVX groups had higher percentages of THC-lever responding than the intact groups at doses of Δ⁹-THC lower than the training dose, and 3) the OVX/Δ⁹-THC group was significantly less sensitive to the rate-decreasing effects of Δ⁹-THC compared to other groups. Furthermore, at sacrifice, western blot analyses indicated that chronic Δ⁹-THC in OVX and intact females decreased cannabinoid type-1 receptor (CB1R) levels in the striatum, and decreased phosphorylation of cyclic adenosine monophosphate response element binding protein (p-CREB) in the hippocampus. In contrast to the hippocampus, chronic Δ⁹-THC selectively increased p-CREB in the OVX/saline group in the striatum. Extracellular signal-regulated kinase (ERK) was not significantly affected by either hormone status or chronic Δ⁹-THC. In summary, these data in female rats suggest that cannabinoid abuse by adolescent human females could alter their subsequent responsiveness to cannabinoids as adults and have serious consequences for brain development.
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Affiliation(s)
- Peter J Winsauer
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
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Abstract
The recent discovery of arachidonylethanolamide (anandamide), an endogenous ligand for cannabinoid receptors, and the synthesis of SR141716A, a cannabinoid antagonist selective for brain cannabinoid (CB1) receptors, have provided new tools to explore the mechanisms underlying cannabis abuse and dependence. Drug discrimination is the animal model with the most predictive validity and specificity for investigation of the psychoactive effects of cannabinoids related to their abuse potential, because, unlike many other drugs of abuse, delta9-tetrahydrocannabinol (delta9-THC), the major psychoactive ingredient of marijuana, is not self-administered by animals. Results of delta9-THC discrimination studies have revealed that the subjective effects of cannabis intoxication are pharmacologically selective for centrally active cannabinoid compounds, and that cannabis action at CB1 receptors is involved in medication of these effects. Less clear is the role of endogenous cannabinoid system(s) in cannabis intoxication. Anandamide, named for a Sanskrit word for "internal bliss," unreliably substitutes for delta9-THC. Further, substitution, when it is observed, occurs only at doses that also significantly decrease response rates. In contrast, delta9-THC and other structurally diverse cannabinoids fully substitute for delta9-THC at doses that do not substantially affect response rates. Attempts to train animals to discriminate anandamide (or SR141716A) have so far been unsuccessful. Preliminary evidence from drug discrimination studies with more metabolically stable anandamide analogs have suggested that these differences in the discriminative stimulus effects of delta9-THC and anandamide-like cannabinoids are not entirely due to pharmacokinetic factors, but the exact role of "internal bliss" in cannabis intoxication and dependence is still not completely understood.
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Affiliation(s)
- J L Wiley
- Virginia Commonwealth University, Department of Pharamcology & Toxicology, Richmond 23298-0613, USA
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Abstract
Areas of neurobiological interest are identified towards which drug discrimination (DD) studies have made important contributions. DD allows ligand actions to be analyzed at the whole organism level, with a neurobiological specificity that is exquisite and often unrivalled. DD analyses have thus been made of a vast array of CNS agents acting on receptors, enzymes, or ion channels, including most drugs of abuse. DD uniquely offers access to the study of subjective drug effects in animals, using a methodology that also is transposable to humans and has generated unprecedented models of pathology (e.g., chronic pain, opiate addiction). Parametric studies of such independent variables as training dose and reinforcement provide refined insights into the dynamic psychophysiological mechanisms of both drug effects and behavior. Three different mechanisms have been identified by which discriminative, and perhaps other behaviors, can come about. DD also is superbly sensitive to small, partial activation of molecular substrates; this has enabled DD analyses to pioneer the unravelling of molecular mechanisms of drug action (attributing, f.ex., LSD's particular subjective effects to an unusual, partial activation of 5-HT, and perhaps other receptors). DD has both oriented and served as a tool to conduct drug discovery research (e.g., pirenperone-risperidone, loperamide). The DD response arguably constitutes a quantal, rather than graded, variable, and as such allows a comprehension of molecular, pharmacological, and behavioral mechanisms that would have been otherwise inaccessible. Perhaps most important are the following further contributions. One is the notion that particular, different levels of receptor activation are associated with qualities of neurobiological actions that also differ and are unique, this notion arguably constituting the most significant addition to affinity and intrinsic activity since the earliest theoretical conceptions of molecular pharmacology. Another contribution consists of studies that render redundant the notion of tolerance and identify fundamental mechanisms of signal transduction; these mechanisms account for apparent tolerance, dependence, addiction, and sensitization, and appear to operate ubiquitously in a bewildering array of biological systems.
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Affiliation(s)
- F C Colpaert
- Centre de Recerche Pierre Fabre, Castres, France
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Wiley JL, Ryan WJ, Razdan RK, Martin BR. Evaluation of cannabimimetic effects of structural analogs of anandamide in rats. Eur J Pharmacol 1998; 355:113-8. [PMID: 9760024 DOI: 10.1016/s0014-2999(98)00502-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Arachidonylethanolamide (anandamide), an endogenous ligand for the cannabinoid receptor, binds competitively to brain cannabinoid receptors and shares many, but not all, of the in vivo effects of delta9-tetrahydrocannabinol. In this study, the cannabinoid effects of anandamide analogs in which the anandamide molecule was altered were assessed in a drug discrimination model. Structural manipulations of the anandamide molecule included saturation of the arachidonyl moiety with fluorination (O-586), substitution for either the ethanolamide moiety (O-612 and O-595) or C2' hydroxyl (O-585), and addition of a methyl group at various positions (O-610, O-680, and O-689). Despite the low binding affinities of the non-methylated compounds (Ki values > 2000 nM), all of the analogs had previously shown cannabinoid activity in mice. In the present study, these analogs were tested in a more pharmacologically specific delta9-tetrahydrocannabinol discrimination procedure in rats. This animal model is predictive of the subjective effects of marijuana intoxication in humans. Whereas delta9-tetrahydrocannabinol and an aminoakylindole fully substituted for the training dose of 3 mg/kg delta9-tetrahydrocannabinol, anandamide and its non-methylated analogs were not cannabimimetic in this procedure. Methylation appeared to increase binding affinity (Ki values < 150 nM) and efficacy; however, the greatest substitution produced by the methylated analogs occurred only at doses that decreased overall rates of responding, suggesting that these analogs are not fully delta9-tetrahydrocannabinol-like. The rapid metabolism of anandamide and some of its analogs undoubtedly contribute to the differences between the pharmacological profiles of the anandamides and classical cannabinoids. These results support the prediction that the subjective effects of anandamide analogs that have been developed thus far would not be cannabimimetic except at high doses.
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Affiliation(s)
- J L Wiley
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0613, USA.
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Wiley JL, Barrett RL, Lowe J, Balster RL, Martin BR. Discriminative stimulus effects of CP 55,940 and structurally dissimilar cannabinoids in rats. Neuropharmacology 1995; 34:669-76. [PMID: 7566504 DOI: 10.1016/0028-3908(95)00027-4] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
CP 55,940 is a potent synthetic bicyclic cannabinoid analog that has been used in a number of studies as a radioligand for the cannabinoid receptor. This compound shares behavioral and biochemical properties with naturally occurring cannabinoids such as delta 9-THC. The purpose of the present study was 3-fold: to establish the ability of CP 55,940 to serve as a discriminative stimulus, to determine whether this discriminative stimulus is identical to that of delta 9-THC, and to examine whether a newly developed cannabinoid antagonist, SR141716A, would antagonize the discriminative stimulus effects of CP 55,940. Rats were trained to discriminate 0.1 mg/kg CP 55,940 from vehicle in standard 2-lever operant conditioning chambers. CP 55,940 produced dose-dependent generalization from the training dose in dose-effect determinations conducted before and after testing with other drugs. The effects of the training dose of CP 55,940 were dose-dependently antagonized by co-administration of SR141716A. Results of substitution tests showed that delta 9-THC, WIN 55,212-2, and cannabinol substituted completely for CP 55,940 in a dose-dependent manner; however, CP 55,940 was approx 10-fold more potent than any of the other drugs in producing CP 55,940-like discriminative stimulus effects. Several drugs with CNS depressant properties (phencyclidine, haloperidol and diazepam) failed to produce reliable substitution for CP 55,940. These results demonstrate that CP 55,940 has discriminative stimulus effects and that it shares these effects with structurally dissimilar compounds that, like CP 55,940, bind to the cannabinoid receptor. Further, these effects are blocked by SR141716A, a cannabinoid receptor antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J L Wiley
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0613, USA
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