Naunyn-Schmiedeberg's Archives of Pharmacology

, Volume 379, Issue 4, pp 371–378 | Cite as

Positive allosteric modulatory effects of ajulemic acid at strychnine-sensitive glycine α1- and α1β-receptors

  • Jörg AhrensEmail author
  • Martin Leuwer
  • Reyhan Demir
  • Klaus Krampfl
  • Jeanne de la Roche
  • Nilufar Foadi
  • Matthias Karst
  • Gertrud Haeseler
Original Article


The synthetic cannabinoid ajulemic acid (CT-3) is a potent cannabinoid receptor agonist which was found to reduce pain scores in neuropathic pain patients in the absence of cannabis-like psychotropic adverse effects. The reduced psychotropic activity of ajulemic acid has been attributed to a greater contribution of peripheral CB receptors to its mechanism of action as well as to non-CB receptor mechanisms. Loss of inhibitory synaptic transmission within the dorsal horn of the spinal cord plays a key role in the development of chronic pain following inflammation or nerve injury. Inhibitory postsynaptic transmission in the adult spinal cord involves mainly glycine. As we hypothesised that additional non-CB receptor mechanisms of ajulemic acid might contribute to its effect in neuropathic pain, we investigated the interaction of ajulemic acid with strychnine-sensitive α1- and α1β-glycine receptors by using the whole-cell patch clamp technique. Ajulemic acid showed a positive allosteric modulating effect in a concentration range which can be considered close to clinically relevant concentrations (EC50 values: α1 = 9.7 ± 2.6 μM and α1β = 12.4 ± 3.4 μM). Direct activation of glycine receptors was observed at higher concentrations above 100 μM (EC50 values: α1 = 140.9 ± 21.5 μM and α1β = 154.3 ± 32.1 μM). These in vitro results demonstrate that ajulemic acid modulates strychnine-sensitive glycine receptors in clinically relevant concentrations.


Glycine receptor Neuropathic pain Cannabinoids Ajulemic acid (CT-3) 



We are grateful to J. Kilian and A. Niesel, Dept. of Neurology, Hannover, for technical support and Prof. Dr. Sumner Burstein, Dept. of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, USA, for his kind supply of AJA.

Conflict of interest statement

The authors declare that they have no conflict of interest.


  1. Agarwal N, Pacher P, Tegeder I, Amaya F, Constantin CE, Brenner GJ, Rubino T, Michalski CW, Marsicano G, Monory K, Mackie K, Marian C, Batkai S, Parolaro D, Fischer MJ, Reeh P, Kunos G, Kress M, Lutz B, Woolf CJ, Kuner R (2007) Cannabinoids mediate analgesia largely via peripheral type 1 cannabinoid receptors in nociceptors. Nat Neurosci 10(7):870–879PubMedCrossRefGoogle Scholar
  2. Ahmadi S, Lippross S, Neuhuber WL, Zeilhofer HU (2002) PGE(2) selectively blocks inhibitory glycinergic neurotransmission onto rat superficial dorsal horn neurons. Nat Neurosci 5(1):34–40PubMedCrossRefGoogle Scholar
  3. Ahrens J, Haeseler G, Leuwer M, Mohammadi B, Krampfl K, Dengler R, Bufler J (2004) 2,6 Di-tert-butylphenol, a nonanesthetic propofol analog, modulates alpha1beta glycine receptor function in a manner distinct from propofol. Anesth Analg 99(1):91–96PubMedCrossRefGoogle Scholar
  4. Ahrens J, Leuwer M, Stachura S, Krampfl K, Belelli D, Lambert JJ, Haeseler G (2008) A transmembrane residue influences the interaction of propofol with the strychnine-sensitive glycine α1 and α1β receptor. Anesth Analg 107, (in press)Google Scholar
  5. Ashton JC (2007) Cannabinoids for the treatment of inflammation. Curr Opin Investig Drugs 8(5):373–384PubMedGoogle Scholar
  6. Batista C, Berisha M, Karst M, Salim K, Schneider U, Brenneisen R (2005) Determination of ajulemic acid and its glucuronide in human plasma by gas chromatography–mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 820(1):77–82PubMedCrossRefGoogle Scholar
  7. Betz H, Laube B (2006) Glycine receptors: recent insights into their structural organization and functional diversity. J Neurochem 97(6):1600–1610PubMedCrossRefGoogle Scholar
  8. Bolay H, Moskowitz MA (2002) Mechanisms of pain modulation in chronic syndromes. Neurology 59(5 Suppl 2):S2–S7PubMedGoogle Scholar
  9. Brooks TA, Hawkins BT, Huber JD, Egleton RD, Davis TP (2005) Chronic inflammatory pain leads to increased blood–brain barrier permeability and tight junction protein alterations. Am J Physiol Heart Circ Physiol 289(2):H738–H743PubMedCrossRefGoogle Scholar
  10. Burstein S (2005) Ajulemic acid (IP-751): synthesis, proof of principle, toxicity studies, and clinical trials. AAPS J 7(1):E143–E148PubMedCrossRefGoogle Scholar
  11. Burstein SH, Karst M, Schneider U, Zurier RB (2004) Ajulemic acid: a novel cannabinoid produces analgesia without a “high”. Life Sci 75(12):1513–1522PubMedCrossRefGoogle Scholar
  12. Chen Y, Dai TJ, Zeng YM (2007) Strychnine-sensitive glycine receptors mediate the analgesic but not hypnotic effects of emulsified volatile anesthetics. Pharmacology 80(2–3):151–157PubMedCrossRefGoogle Scholar
  13. Costa B (2007) On the pharmacological properties of Delta9-tetrahydrocannabinol (THC). Chem Biodivers 4(8):1664–1677PubMedCrossRefGoogle Scholar
  14. Coull JA, Boudreau D, Bachand K, Prescott SA, Nault F, Sik A, De Koninck P, De Koninck Y (2003) Trans-synaptic shift in anion gradient in spinal lamina I neurons as a mechanism of neuropathic pain. Nature 424(6951):938–942PubMedCrossRefGoogle Scholar
  15. Dyson A, Peacock M, Chen A, Courade JP, Yaqoob M, Groarke A, Brain C, Loong Y, Fox A (2005) Antihyperalgesic properties of the cannabinoid CT-3 in chronic neuropathic and inflammatory pain states in the rat. Pain 116(1–2):129–137PubMedCrossRefGoogle Scholar
  16. Fox A, Bevan S (2005) Therapeutic potential of cannabinoid receptor agonists as analgesic agents. Expert Opin Investig Drugs 14(6):695–703PubMedCrossRefGoogle Scholar
  17. Franke C, Hatt H, Dudel J (1987) Liquid filament switch for ultra-fast exchanges of solutions at excised patches of synaptic membrane of crayfish muscle. Neurosci Lett 77(2):199–204PubMedCrossRefGoogle Scholar
  18. Froh M, Thurman RG, Wheeler MD (2002) Molecular evidence for a glycine-gated chloride channel in macrophages and leukocytes. Am J Physiol Gastrointest Liver Physiol 283(4):856–863Google Scholar
  19. Geiman EJ, Zheng W, Fritschy JM, Alvarez FJ (2002) Glycine and GABA(A) receptor subunits on Renshaw cells: relationship with presynaptic neurotransmitters and postsynaptic gephyrin clusters. J Comp Neurol 444(3):275–289PubMedCrossRefGoogle Scholar
  20. Gordh T, Chu H, Sharma HS (2006) Spinal nerve lesion alters blood–spinal cord barrier function and activates astrocytes in the rat. Pain 124(1–2):211–221PubMedCrossRefGoogle Scholar
  21. Grudzinska J, Schemm R, Haeger S, Nicke A, Schmalzing G, Betz H, Laube B (2005) The beta subunit determines the ligand binding properties of synaptic glycine receptors. Neuron 45(5):727–739PubMedCrossRefGoogle Scholar
  22. Guindon J, Hohmann AG (2008) Cannabinoid CB2 receptors: a therapeutic target for the treatment of inflammatory and neuropathic pain. Br J Pharmacol 153(2):319–334PubMedCrossRefGoogle Scholar
  23. Haeseler G, Ahrens J, Krampfl K, Bufler J, Dengler R, Hecker H, Aronson JK, Leuwer M (2005) Structural features of phenol derivatives determining potency for activation of chloride currents via alpha(1) homomeric and alpha(1)beta heteromeric glycine receptors. Br J Pharmacol 145(7):916–925PubMedCrossRefGoogle Scholar
  24. Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch 391(2):85–100PubMedCrossRefGoogle Scholar
  25. Hejazi N, Zhou C, Oz M, Sun H, Ye JH, Zhang L (2006) Delta9-tetrahydrocannabinol and endogenous cannabinoid anandamide directly potentiate the function of glycine receptors. Mol Pharmacol 69(3):991–997PubMedGoogle Scholar
  26. Iatsenko NM, Tsintsadze T, Lozova NO (2007) The synthetic cannabinoid analog WIN 55,212-2 potentiates the amplitudes of glycine-activated currents. Fiziol Zh 53(3):31–37PubMedGoogle Scholar
  27. Jentsch TJ, Stein V, Weinreich F, Zdebik AA (2002) Molecular structure and physiological function of chloride channels. Physiol Rev 82(2):503–568PubMedGoogle Scholar
  28. Karst M, Salim K, Burstein S, Conrad I, Hoy L, Schneider U (2003) Analgesic effect of the synthetic cannabinoid CT-3 on chronic neuropathic pain: a randomized controlled trial. JAMA 290(13):1757–1762PubMedCrossRefGoogle Scholar
  29. Knabl J, Witschi R, Hosl K, Reinold H, Zeilhofer UB, Ahmadi S, Brockhaus J, Sergejeva M, Hess A, Brune K, Fritschy JM, Rudolph U, Mohler H, Zeilhofer HU (2008) Reversal of pathological pain through specific spinal GABAA receptor subtypes. Nature 451(7176):330–334PubMedCrossRefGoogle Scholar
  30. Langosch D, Thomas L, Betz H (1988) Conserved quaternary structure of ligand-gated ion channels: the postsynaptic glycine receptor is a pentamer. Proc Natl Acad Sci U S A 85(19):7394–7398PubMedCrossRefGoogle Scholar
  31. Laube B, Maksay G, Schemm R, Betz H (2002) Modulation of glycine receptor function: a novel approach for therapeutic intervention at inhibitory synapses? Trends Pharmacol Sci 23(11):519–527PubMedCrossRefGoogle Scholar
  32. Lynch JW, Callister RJ (2006) Glycine receptors: a new therapeutic target in pain pathways. Curr Opin Investig Drugs 7(1):48–53PubMedGoogle Scholar
  33. McCarberg BH, Barkin RL (2007) The future of cannabinoids as analgesic agents: a pharmacologic, pharmacokinetic, and pharmacodynamic overview. Am J Ther 14(5):475–483PubMedCrossRefGoogle Scholar
  34. Mihic SJ, Ye Q, Wick MJ, Koltchine VV, Krasowski MD, Finn SE, Mascia MP, Valenzuela CF, Hanson KK, Greenblatt EP, Harris RA, Harrison NL (1997) Sites of alcohol and volatile anaesthetic action on GABA(A) and glycine receptors. Nature 389(6649):385–389PubMedCrossRefGoogle Scholar
  35. Mitrirattanakul S, Ramakul N, Guerrero AV, Matsuka Y, Ono T, Iwase H, Mackie K, Faull KF, Spigelman I (2006) Site-specific increases in peripheral cannabinoid receptors and their endogenous ligands in a model of neuropathic pain. Pain 126(1–3):102–114PubMedCrossRefGoogle Scholar
  36. Moore KA, Kohno T, Karchewski LA, Scholz J, Baba H, Woolf CJ (2002) Partial peripheral nerve injury promotes a selective loss of GABAergic inhibition in the superficial dorsal horn of the spinal cord. J Neurosci 22(15):6724–6731PubMedGoogle Scholar
  37. Pribilla I, Takagi T, Langosch D, Bormann J, Betz H (1992) The atypical M2 segment of the beta subunit confers picrotoxinin resistance to inhibitory glycine receptor channels. EMBO J 11(12):4305–4311PubMedGoogle Scholar
  38. Rhee MH, Vogel Z, Barg J, Bayewitch M, Levy R, Hanus L, Breuer A, Mechoulam R (1997) Cannabinol derivatives: binding to cannabinoid receptors and inhibition of adenylylcyclase. J Med Chem 40(20):3228–3233PubMedCrossRefGoogle Scholar
  39. Salim K, Schneider U, Burstein S, Hoy L, Karst M (2005) Pain measurements and side effect profile of the novel cannabinoid ajulemic acid. Neuropharmacology 48(8):1164–1171PubMedCrossRefGoogle Scholar
  40. Shan Q, Nevin ST, Haddrill JL, Lynch JW (2003) Asymmetric contribution of alpha and beta subunits to the activation of alphabeta heteromeric glycine receptors. J Neurochem 86(2):498–507PubMedCrossRefGoogle Scholar
  41. Tao Q, McAllister SD, Andreassi J, Nowell KW, Cabral GA, Hurst DP, Bachtel K, Ekman MC, Reggio PH, Abood ME (1999) Role of a conserved lysine residue in the peripheral cannabinoid receptor (CB2): evidence for subtype specificity. Mol Pharmacol 55(3):605–613PubMedGoogle Scholar
  42. Todd AJ, Watt C, Spike RC, Sieghart W (1996) Colocalization of GABA, glycine, and their receptors at synapses in the rat spinal cord. J Neurosci 16(3):974–982PubMedGoogle Scholar
  43. Weir CJ, Ling AT, Belelli D, Wildsmith JA, Peters JA, Lambert JJ (2004) The interaction of anaesthetic steroids with recombinant glycine and GABAA receptors. Br J Anaesth 92(5):704–711PubMedCrossRefGoogle Scholar
  44. Yamamoto I, Kimura T, Kamei A, Yoshida H, Watanabe K, Ho IK, Yoshimura H (1998) Competitive inhibition of delta8-tetrahydrocannabinol and its active metabolites for cannabinoid receptor binding. Biol Pharm Bull 21(4):408–410PubMedGoogle Scholar
  45. Zeilhofer HU (2005) The glycinergic control of spinal pain processing. Cell Mol Life Sci 62(18):2027–2035PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Jörg Ahrens
    • 1
    Email author
  • Martin Leuwer
    • 3
  • Reyhan Demir
    • 1
  • Klaus Krampfl
    • 2
  • Jeanne de la Roche
    • 1
  • Nilufar Foadi
    • 1
  • Matthias Karst
    • 1
  • Gertrud Haeseler
    • 1
  1. 1.Clinic for Anaesthesia and Critical Care Medicine, OE 8050Hannover Medical SchoolHannoverGermany
  2. 2.Department of Neurology and NeurophysiologyHannover Medical SchoolHannoverGermany
  3. 3.Division of Clinical SciencesThe University of LiverpoolLiverpoolUK

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