title: Crucial role of CB(2) cannabinoid receptor in the regulation of central immune responses during neuropathic pain.
abstract: Neuropathic pain is a clinical manifestation of nerve injury difficult to treat even with potent analgesic compounds. Here, we used different lines of genetically modified mice to clarify the role played by CB(2) cannabinoid receptors in the regulation of the central immune responses leading to the development of neuropathic pain. CB(2) knock-out mice and wild-type littermates were exposed to sciatic nerve injury, and both genotypes developed a similar hyperalgesia and allodynia in the ipsilateral paw. Most strikingly, knock-outs also developed a contralateral mirror image pain, associated with an enhanced microglial and astrocytic expression in the contralateral spinal horn. In agreement, hyperalgesia, allodynia, and microglial and astrocytic activation induced by sciatic nerve injury were attenuated in transgenic mice overexpressing CB(2) receptors. These results demonstrate the crucial role of CB(2) cannabinoid receptor in modulating glial activation in response to nerve injury. The enhanced manifestations of neuropathic pain were replicated in irradiated wild-type mice reconstituted with bone marrow cells from CB(2) knock-outs, thus demonstrating the implication of the CB(2) receptor expressed in hematopoietic cells in the development of neuropathic pain at the spinal cord.
authors.affiliation: Institute of Molecular Psychiatry, University of Bonn, 53105 Bonn, Germany.
authors.forename: Ildiko
authors.initials: I
authors.lastname: Racz
authors.forename: Xavier
authors.initials: X
authors.lastname: Nadal
authors.forename: Judith
authors.initials: J
authors.lastname: Alferink
authors.forename: Josep E
authors.initials: JE
authors.lastname: Baños
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rehnelt
authors.forename: Miquel
authors.initials: M
authors.lastname: Martín
authors.forename: Belén
authors.initials: B
authors.lastname: Pintado
authors.forename: Alfonso
authors.initials: A
authors.lastname: Gutierrez-Adan
authors.forename: Elena
authors.initials: E
authors.lastname: Sanguino
authors.forename: Jorge
authors.initials: J
authors.lastname: Manzanares
authors.forename: Andreas
authors.initials: A
authors.lastname: Zimmer
authors.forename: Rafael
authors.initials: R
authors.lastname: Maldonado
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000276:immunology / Q000378:metabolism; D016026:Bone Marrow Transplantation; D004195:Disease Models, Animal; D005260:Female; D005911:Gliosis / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D006412:Hematopoietic Stem Cells / Q000276:immunology; D006930:Hyperalgesia / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D017628:Microglia / Q000276:immunology / Q000378:metabolism; D009437:Neuralgia / Q000276:immunology* / Q000378:metabolism / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000276:immunology* / Q000378:metabolism / Q000503:physiopathology; D020671:Posterior Horn Cells / Q000276:immunology / Q000473:pathology / Q000503:physiopathology; D043885:Receptor, Cannabinoid, CB2 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D020426:Sciatic Neuropathy / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D013116:Spinal Cord / Q000276:immunology* / Q000378:metabolism / Q000503:physiopathology
chemical_list: D043885:Receptor, Cannabinoid, CB2