NE-19550 AND NE-21610, ANTINOCICEPTIVE CAPSAICIN ANALOGS - STUDIES ON NOCICEPTIVE FIBERS OF THE NEONATAL RAT TAIL INVITRO

When applied to peripheral fibres in a neonatal rat tail/spinal cord preparation in vitro, capsaicin (0.2-50 μM) induced an activation, selective desensitization and reduced responses to other noxious stimuli (heat, bradykin). Similar concentrations of the antinociceptive analogues NE-19550 and NE-21610, did not affect peripheral fibre responsiveness but induced cross desensitization to capsaicin. At 500 μM both analogues produced similar effects to capsaicin. Capsaicin analogues may induce analgesia without initial activation of nociceptors. © 1990.