title: Hyperalgesia by low doses of the local anesthetic lidocaine involves cannabinoid signaling: an fMRI study in mice.
abstract: Lidocaine is clinically widely used as a local anesthetic inhibiting propagation of action potentials in peripheral nerve fibers. Correspondingly, the functional magnetic resonance imaging (fMRI) response in mouse brain to peripheral noxious input is largely suppressed by local lidocaine administered at doses used in a clinical setting. We observed, however, that local administration of lidocaine at doses 100 × lower than that used clinically led to a significantly increased sensitivity of mice to noxious forepaw stimulation as revealed by fMRI. This hyperalgesic response could be confirmed by behavioral readouts using the von Frey filament test. The increased sensitivity was found to involve a type 1 cannabinoid (CB(1)) receptor-dependent pathway as global CB(1) knockout mice, as well as wild-type mice pretreated systemically with the CB(1) receptor blocker rimonabant, did not display any hyperalgesic effects after low-dose lidocaine. Additional experiments with nociceptor-specific CB(1) receptor knockout mice indicated an involvement of the CB(1) receptors located on the nociceptors. We conclude that low concentrations of lidocaine leads to a sensitization of the nociceptors through a CB(1) receptor-dependent process. This lidocaine-induced sensitization might contribute to postoperative hyperalgesia.
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zürich 8093, Switzerland Neuroscience Center, University and ETH Zurich, Switzerland, Zürich 8057, Switzerland Institute of Pharmacology and Toxicology, University of Zurich, Zürich 8057, Switzerland Institute of Pharmaceutical Sciences, ETH Zurich, Zürich 8093, Switzerland.
authors.forename: Simone C
authors.initials: SC
authors.lastname: Bosshard
authors.forename: Joanes
authors.initials: J
authors.lastname: Grandjean
authors.forename: Aileen
authors.initials: A
authors.lastname: Schroeter
authors.forename: Christof
authors.initials: C
authors.lastname: Baltes
authors.forename: Hanns U
authors.initials: HU
authors.lastname: Zeilhofer
authors.forename: Markus
authors.initials: M
authors.lastname: Rudin
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002186:Cannabinoids / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D006930:Hyperalgesia / Q000139:chemically induced*; D008012:Lidocaine / Q000494:pharmacology*; D008279:Magnetic Resonance Imaging; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009619:Nociceptors / Q000378:metabolism; D010146:Pain / Q000188:drug therapy / Q000503:physiopathology; D010147:Pain Measurement; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism
chemical_list: D000779:Anesthetics, Local; D002186:Cannabinoids; D043884:Receptor, Cannabinoid, CB1; D008012:Lidocaine