Algogenic Peripheral Effects of RFa Peptides

Earlier, we showed on a nerve-skin preparation that FMRFa and other RFa-like peptides activate a considerable proportion of somatosensory nociceptive afferent units (C fibers). To check the algogenic effect of RFa peptides in vivo, we recorded the parameters of a few behavioral phenomena after subcutaneous injections of solutions of FMRFa and KNFLRFa into the hindlimb of mice. Introduction of the above peptides evoked intensive pain reactions of the animals manifested in long-lasting licking of the injected limb and an increase in the number of the cycles of licking of this limb. We hypothesize that interaction of RFa peptides with proton-activated ion channels (ASICs) in the membranes of sensory nociceptive neurons is one of the possible mechanisms of this nociceptive reaction. Neirofiziologiya/Neurophysiology, Vol. 37, No. 4, pp. 347–351, July–August, 2005.