• David Cabañero, Angela Ramírez-López, Eva Drews, Anne Schmöle, David M Otte, Agnieszka Wawrzczak-Bargiela, Hector Huerga Encabo, Sami Kummer, Antonio Ferrer-Montiel, Ryszard Przewlocki, Andreas Zimmer, and Rafael Maldonado.
• Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain.
• Elife. 2020 Jul 20; 9.

AbstractCannabinoid CB2 receptor (CB2) agonists are potential analgesics void of psychotropic effects. Peripheral immune cells, neurons and glia express CB2; however, the involvement of CB2 from these cells in neuropathic pain remains unresolved. We explored spontaneous neuropathic pain through on-demand self-administration of the selective CB2 agonist JWH133 in wild-type and knockout mice lacking CB2 in neurons, monocytes or constitutively. Operant self-administration reflected drug-taking to alleviate spontaneous pain, nociceptive and affective manifestations. While constitutive deletion of CB2 disrupted JWH133-taking behavior, this behavior was not modified in monocyte-specific CB2 knockouts and was increased in mice defective in neuronal CB2 knockouts suggestive of increased spontaneous pain. Interestingly, CB2-positive lymphocytes infiltrated the injured nerve and possible CB2transfer from immune cells to neurons was found. Lymphocyte CB2depletion also exacerbated JWH133 self-administration and inhibited antinociception. This work identifies a simultaneous activity of neuronal and lymphoid CB2that protects against spontaneous and evoked neuropathic pain.© 2020, Cabañero et al.

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