RESUMEN
BACKGROUND AND PURPOSE: Compound LASSBio-881 is an orally effective antinociceptive that binds to cannabinoid receptors and is active mainly on the neurogenic component of pain models. We investigated whether transient receptor potential vanilloid subfamily type 1 (TRPV1) channels are involved in the effects of LASSBio-881. EXPERIMENTAL APPROACH: Modulation of capsaicin (CAP)- and low pH-induced currents was evaluated in TRPV1-expressing Xenopus oocytes. In vivo effects were evaluated in CAP-induced acute and inflammatory changes in nociception, as well as in partial sciatic ligation-induced thermal hypernociception. KEY RESULTS: LASSBio-881 inhibited TRPV1 currents elicited by CAP with an IC(50) of 14 microM, and inhibited proton-gated currents by 70% at 20 microM. Functional interaction with CAP was surmountable. Locally applied LASSBio-881 decreased time spent in CAP-elicited nocifensive behaviour by 30%, and given orally it reduced measures of CAP- or carrageenan-evoked thermal hypernociception by 60 and 40% respectively. In addition, LASSBio-881 decreased the paw withdrawal responses to thermal stimuli of animals with sciatic neuropathy 7-11 days after nerve ligation, at a dose of 300 micromol*kg(-1)*day(-1) p.o. At this dose, hyperthermia was not observed within 4 h following oral administration. CONCLUSIONS AND IMPLICATIONS: LASSBio-881 is a TRPV1 antagonist that apparently competes with CAP. Accordingly, LASSBio- 881 inhibited nociception in models of acute, inflammatory and neuropathic pain presumed to involve TRPV1 signalling. These in vivo actions were not hindered by hyperthermia, a common side effect of other TRPV1 antagonists. We propose that the antinociceptive properties of LASSBio-881 are due to TRPV1 antagonism, although other molecular interactions may contribute to the effects of this multi-target drug candidate.