Acta dermato-venereologica
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Acta Derm. Venereol. · Sep 2012
Opioid modulation of facial itch- and pain-related responses and grooming behavior in rats.
Intradermal facial injections of pruritogens or algogens elicit distinct behavioral hindlimb scratch or forelimb wiping responses in rodents. We systematically investigated the parameters and opioid modulation of these evoked behaviors and spontaneous facial grooming in rats. Serotonin (5-HT) elicited hindlimb scratch bouts with few wipes. ⋯ These data validate that the rodent "cheek" model discriminates between itch- and pain-related behaviors. Naltrexone sensitivity of facial grooming and 5-HT-evoked scratch-ing suggests a common functionality. Forelimb wipes may represent a nocifensive response akin to rubbing an injury to relieve pain.