Anandamide suppresses pain initiation through a peripheral endocannabinoid mechanism

Article metrics



Peripheral cannabinoid receptors exert a powerful inhibitory control over pain initiation, but the endocannabinoid signal that normally engages this intrinsic analgesic mechanism is unknown. To address this question, we developed a peripherally restricted inhibitor (URB937) of fatty acid amide hydrolase (FAAH), the enzyme responsible for the degradation of the endocannabinoid anandamide. URB937 suppressed FAAH activity and increased anandamide levels outside the rodent CNS. Despite its inability to access brain and spinal cord, URB937 attenuated behavioral responses indicative of persistent pain in rodent models of peripheral nerve injury and inflammation and prevented noxious stimulus–evoked neuronal activation in spinal cord regions implicated in nociceptive processing. CB1 cannabinoid receptor blockade prevented these effects. These results suggest that anandamide-mediated signaling at peripheral CB1 receptors controls the access of pain-related inputs to the CNS. Brain-impenetrant FAAH inhibitors, which strengthen this gating mechanism, might offer a new approach to pain therapy.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: URB937 is a peripherally restricted FAAH inhibitor.
Figure 2: URB937 suppressed pain responses elicited by intraperitoneal injections of acetic acid in Swiss Webster mice.
Figure 3: URB937 suppressed pain behavior elicited by neural injury in mice.
Figure 4: URB937 attenuated pain behavior elicited by inflammation in mice.
Figure 5: URB937 attenuated formalin-induced pain behavior and spinal cord Fos protein expression in rats.


  1. 1

    Stein, C., Schafer, M. & Machelska, H. Attacking pain at its source: new perspectives on opioids. Nat. Med. 9, 1003–1008 (2003).

  2. 2

    Calignano, A., La Rana, G., Giuffrida, A. & Piomelli, D. Control of pain initiation by endogenous cannabinoids. Nature 394, 277–281 (1998).

  3. 3

    Nackley, A.G., Suplita, R.L. II & Hohmann, A.G. A peripheral cannabinoid mechanism suppresses spinal fos protein expression and pain behavior in a rat model of inflammation. Neuroscience 117, 659–670 (2003).

  4. 4

    Dziadulewicz, E.K. et al. Naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone: a potent, orally bioavailable human CB1/CB2 dual agonist with antihyperalgesic properties and restricted central nervous system penetration. J. Med. Chem. 50, 3851–3856 (2007).

  5. 5

    Anand, P., Whiteside, G., Fowler, C.J. & Hohmann, A.G. Targeting CB2 receptors and the endocannabinoid system for the treatment of pain. Brain Res. Rev. 60, 255–266 (2009).

  6. 6

    Agarwal, N. et al. Cannabinoids mediate analgesia largely via peripheral type 1 cannabinoid receptors in nociceptors. Nat. Neurosci. 10, 870–879 (2007).

  7. 7

    Kaufmann, I. et al. Enhanced anandamide plasma levels in patients with complex regional pain syndrome following traumatic injury: a preliminary report. Eur. Surg. Res. 43, 325–329 (2009).

  8. 8

    Richardson, D. et al. Characterization of the cannabinoid receptor system in synovial tissue and fluid in patients with osteoarthritis and rheumatoid arthritis. Arthritis Res. Ther. 10, R43 (2008).

  9. 9

    Mitrirattanakul, S. et al. Site-specific increases in peripheral cannabinoid receptors and their endogenous ligands in a model of neuropathic pain. Pain 126, 102–114 (2006).

  10. 10

    Schlosburg, J.E., Kinsey, S.G. & Lichtman, A.H. Targeting fatty acid amide hydrolase (FAAH) to treat pain and inflammation. AAPS J. 11, 39–44 (2009).

  11. 11

    Kathuria, S. et al. Modulation of anxiety through blockade of anandamide hydrolysis. Nat. Med. 9, 76–81 (2003).

  12. 12

    Piomelli, D. et al. Pharmacological profile of the selective FAAH inhibitor KDS-4103 (URB597). CNS Drug Rev. 12, 21–38 (2006).

  13. 13

    Clapper, J.R. et al. A second generation of carbamate-based fatty acid amide hydrolase inhibitors with improved activity in vivo. ChemMedChem 4, 1505–1513 (2009).

  14. 14

    Alexander, J.P. & Cravatt, B.F. Mechanism of carbamate inactivation of FAAH: implications for the design of covalent inhibitors and in vivo functional probes for enzymes. Chem. Biol. 12, 1179–1187 (2005).

  15. 15

    Löscher, W. & Potschka, H. Blood–brain barrier active efflux transporters: ATP-binding cassette gene family. NeuroRx 2, 86–98 (2005).

  16. 16

    Imai, Y. et al. Breast cancer resistance protein exports sulfated estrogens, but not free estrogens. Mol. Pharmacol. 64, 610–618 (2003).

  17. 17

    LoVerme, J., La Rana, G., Russo, R., Calignano, A. & Piomelli, D. The search for the palmitoylethanolamide receptor. Life Sci. 77, 1685–1698 (2005).

  18. 18

    Cravatt, B.F. et al. Supersensitivity to anandamide and enhanced endogenous cannabinoid signaling in mice lacking fatty acid amide hydrolase. Proc. Natl. Acad. Sci. USA 98, 9371–9376 (2001).

  19. 19

    Starowicz, K., Nigam, S. & Di Marzo, V. Biochemistry and pharmacology of endovanilloids. Pharmacol. Ther. 114, 13–33 (2007).

  20. 20

    LoVerme, J. et al. Rapid broad-spectrum analgesia through activation of peroxisome proliferator-activated receptor alpha. J. Pharmacol. Exp. Ther. 319, 1051–1061 (2006).

  21. 21

    Russo, R. et al. Synergistic antinociception by the cannabinoid receptor agonist anandamide and the PPAR alpha receptor agonist GW7647. Eur. J. Pharmacol. 566, 117–119 (2007).

  22. 22

    Bennett, G.J. & Xie, Y.K. A peripheral mononeuropathy in rat that produces disorders of pain sensation like those seen in man. Pain 33, 87–107 (1988).

  23. 23

    Russo, R. et al. The fatty acid amide hydrolase inhibitor URB597 (cyclohexylcarbamic acid 3′-carbamoylbiphenyl-3-yl ester) reduces neuropathic pain after oral administration in mice. J. Pharmacol. Exp. Ther. 322, 236–242 (2007).

  24. 24

    Coderre, T.J. & Melzack, R. The contribution of excitatory amino acids to central sensitization and persistent nociception after formalin-induced tissue injury. J. Neurosci. 12, 3665–3670 (1992).

  25. 25

    Puig, S. & Sorkin, L.S. Formalin-evoked activity in identified primary afferent fibers: systemic lidocaine suppresses phase-2 activity. Pain 64, 345–355 (1996).

  26. 26

    Kunos, G., Osei–Hyiaman, D., Batkai, S., Sharkey, K.A. & Makriyannis, A. Should peripheral CB(1) cannabinoid receptors be selectively targeted for therapeutic gain? Trends Pharmacol. Sci. 30, 1–7 (2009).

  27. 27

    Ahluwalia, J., Yaqoob, M., Urban, L., Bevan, S. & Nagy, I. Activation of capsaicin-sensitive primary sensory neurones induces anandamide production and release. J. Neurochem. 84, 585–591 (2003).

  28. 28

    Liu, J. et al. A biosynthetic pathway for anandamide. Proc. Natl. Acad. Sci. USA 103, 13345–13350 (2006).

  29. 29

    Hohmann, A.G. & Herkenham, M. Localization of central cannabinoid CB1 receptor messenger RNA in neuronal subpopulations of rat dorsal root ganglia: a double-label in situ hybridization study. Neuroscience 90, 923–931 (1999).

  30. 30

    Hohmann, A.G. & Herkenham, M. Cannabinoid receptors undergo axonal flow in sensory nerves. Neuroscience 92, 1171–1175 (1999).

  31. 31

    Richardson, J.D., Kilo, S. & Hargreaves, K.M. Cannabinoids reduce hyperalgesia and inflammation via interaction with peripheral CB1 receptors. Pain 75, 111–119 (1998).

  32. 32

    Guindon, J. & Hohmann, A.G. Cannabinoid CB2 receptors: a therapeutic target for the treatment of inflammatory and neuropathic pain. Br. J. Pharmacol. 153, 319–334 (2008).

  33. 33

    Sagar, D.R., Kendall, D.A. & Chapman, V. Inhibition of fatty acid amide hydrolase produces PPAR alpha–mediated analgesia in a rat model of inflammatory pain. Br. J. Pharmacol. 155, 1297–1306 (2008).

  34. 34

    Cravatt, B.F. et al. Functional disassociation of the central and peripheral fatty acid amide signaling systems. Proc. Natl. Acad. Sci. USA 101, 10821–10826 (2004).

  35. 35

    Lever, I.J. et al. Localization of the endocannabinoid-degrading enzyme fatty acid amide hydrolase in rat dorsal root ganglion cells and its regulation after peripheral nerve injury. J. Neurosci. 29, 3766–3780 (2009).

  36. 36

    Stein, C. & Zollner, C. Opioids and sensory nerves. Handb. Exp. Pharmacol. 194, 495–518 (2009).

  37. 37

    Tegeder, I. et al. Peripheral opioid analgesia in experimental human pain models. Brain 126, 1092–1102 (2003).

  38. 38

    Mor, M. et al. Cyclohexylcarbamic acid 3′- or 4′-substituted biphenyl-3-yl esters as fatty acid amide hydrolase inhibitors: synthesis, quantitative structure–activity relationships, and molecular modeling studies. J. Med. Chem. 47, 4998–5008 (2004).

  39. 39

    King, A.R. et al. URB602 inhibits monoacylglycerol lipase and selectively blocks 2-arachidonoylglycerol degradation in intact brain slices. Chem. Biol. 14, 1357–1365 (2007).

  40. 40

    Astarita, G., Ahmed, F. & Piomelli, D. Identification of biosynthetic precursors for the endocannabinoid anandamide in the rat brain. J. Lipid Res. 49, 48–57 (2008).

  41. 41

    Calignano, A., La Rana, G. & Piomelli, D. Antinociceptive activity of the endogenous fatty acid amide, palmitylethanolamide. Eur. J. Pharmacol. 419, 191–198 (2001).

  42. 42

    Tjølsen, A., Berge, O.G., Hunskaar, S., Rosland, J.H. & Hole, K. The formalin test: an evaluation of the method. Pain 51, 5–17 (1992).

Download references


We thank E. Dotsey for help with experiments. This research was supported by grants from the National Institutes on Drug Abuse (D.P. and A.G.H.), the University of Parma (M.M.) and the Italian Ministry for Public Education, University and Research (G.T., A.D and A.T.). G.M.-S. was partially supported by the Fulbright Commission and the Exchange Abroad Program, University of California. The support of the Agilent Foundation is gratefully acknowledged.

Author information

J.R.C., G.M.-S., R.R., A.G., N.R.S., J.M.S., F.V., A.D., A.T. and S.S. participated in the design, performance and interpretation of the experiments and chemical syntheses. A.G.H., A.C., M.M., G.T. and D.P. participated in the design and interpretation of the experiments and chemical syntheses. D.P. oversaw the project and wrote the manuscript with help from J.R.C., G.M.-S., A.G.H., A.D., M.M. and G.T.

Correspondence to Daniele Piomelli.

Ethics declarations

Competing interests

A patent application covering URB937 and allied compounds has been filed on behalf of the inventors (D.P., J.R.C., G.M.-S., A.D., A.T., M.M. and G.T.) by the University of California, Irvine, the Italian Institute of Technology, and the Universities of Urbino and Parma.

Supplementary information

Supplementary Text and Figures

Supplementary Figures 1–10, Supplementary Table 1 and Supplementary Methods (PDF 6178 kb)

Rights and permissions

Reprints and Permissions

About this article

Further reading