Abstract

Transient receptor potential vanilloid 1 (TRPV1) activation in peripheral sensory nerve is known to be associated with various pain-related diseases, thus TRPV1 has been the focus as a target for drug discovery. In this study, we characterized the pharmacological profiles of (3S)-3-(hydroxymethyl)-4-(5-methylpyridin-2-yl)-N-[6-(2,2,2-trifluoroethoxy)pyridin-3-yl]-3,4-dihydro-2H-benzo[b][1,4]oxazine-8-carboxamide (JTS-653), a novel TRPV1 antagonist. JTS-653 displaced [³H]resiniferatoxin binding to human and rat TRPV1. JTS-653 competitively antagonized the capsaicin-induced activation of human TRPV1 with pA₂ values of 10.1. JTS-653 also inhibited proton-induced activation of human and rat TRPV1 with IC₅₀ values of 0.320 and 0.347 nM, respectively. Electrophysiological studies indicated that JTS-653 blocked heat-induced inward currents in rat TRPV1 with IC₅₀ values of 1.4 nM. JTS-653 showed weak or no inhibitory effects on other TRP channels, receptors, and enzymes. JTS-653 significantly prevented capsaicin-induced mechanical hyperalgesia at 1 mg/kg p.o. and attenuated carrageenan-induced mechanical hyperalgesia at 0.3 mg/kg p.o. JTS-653 significantly attenuated carrageenan-induced thermal hyperalgesia at 0.1 mg/kg p.o. and fully reversed at 0.3 mg/kg p.o. without affecting the volume of the carrageenan-treated paw. JTS-653 showed a transient increase of body temperature at 0.3 mg/kg p.o. These results indicated that JTS-653 is a highly potent and selective TRPV1 antagonist in vitro and in vivo and suggested that JTS-653 is one of the most potent TRPV1 antagonists. The profiles of JTS-653, high potency in vivo and transient hyperthermia, seem to be associated with polymodal inhibition of TRPV1 activation.