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: Ildiko Racz, Xavier Nadal, Judith Alferink, Josep E Baños, Jennifer Rehnelt, Miquel Martín, Belén Pintado, Alfonso Gutierrez-Adan, Elena Sanguino, Jorge Manzanares, Andreas Zimmer, Rafael Maldonado
• Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience (J Neurosci) Vol. 28 Issue 46 Pg. 12125-35 (Nov 12 2008) ISSN: 1529-2401 [Electronic] United States
• PMID: 19005077 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Receptor, Cannabinoid, CB2

Topics

• Animals
• Astrocytes (immunology, metabolism)
• Bone Marrow Transplantation
• Disease Models, Animal
• Female
• Gliosis (immunology, metabolism, physiopathology)
• Hematopoietic Stem Cells (immunology)
• Hyperalgesia (immunology, metabolism, physiopathology)
• Male
• Mice
• Mice, Knockout
• Microglia (immunology, metabolism)
• Neuralgia (immunology, metabolism, physiopathology)
• Peripheral Nervous System Diseases (immunology, metabolism, physiopathology)
• Posterior Horn Cells (immunology, pathology, physiopathology)
• Receptor, Cannabinoid, CB2 (genetics, immunology, metabolism)
• Sciatic Neuropathy (immunology, metabolism, physiopathology)
• Spinal Cord (immunology, metabolism, physiopathology)