caa a22 4500 469120886 CHVBK 20180323133138.0 cr unu---uuuuu 170328e19920601xx s 000 0 eng 10.1007/BF02245273 doi (NATIONALLICENCE)springer-10.1007/BF02245273 Clonidine and yohimbine modulate the effects of naloxone on novelty-induced hypoalgesia [Elektronische Daten] [Joseph Rochford, Patricia Dawes] Previous research has shown that repeated daily pretreatment with the opiate receptor blocker naloxone retards the development of habituation to novelty-induced hypoalgesia. The present experiments were conducted in order to determine whether noradrenergic substrates mediate this effect. Animals in the NAL condition were administered 10 mg/kg naloxone prior to assessment of pain sensitivity on a 48.5° C hot plate. Control animals (SAL condition) were administered saline prior to pain assessment, and naloxone 2-4 h later. Paw lick latencies declined over repeated tests in SAL animals, suggesting the habituation of novelty hypoalgesia. Naloxone pretreatment attenuated this decline. The longer paw lick latencies observed in NAL condition animals were reduced by administration of 2 µg/kg clonidine, a specific noradrenergic alpha-2 receptor agonist, and enhanced in a dose dependent (0.5-4.0 mg/kg) fashion by the alpha-2 antagonist yohimbine. Clonidine and yohimbine either failed to alter pain reactivity in control animals, or produced less marked effects than those observed in naloxone-exposed animals. These results suggest that noradrenergic substrates mediate naloxone's effects on novelty hypoalgesia. Springer-Verlag, 1992 Novelty hypoalgesia nationallicence Noradrenaline nationallicence Naloxone nationallicence Alpha-2 receptor nationallicence Rat nationallicence Rochford Joseph Department of Psychology, Concordia University, Center for Studies in Behavioral Neurobiology, 1455 deMaisonneuve Boulevard, W., H3G 1M8, Montreal, Quebec, Canada aut Dawes Patricia Department of Psychology, Concordia University, Center for Studies in Behavioral Neurobiology, 1455 deMaisonneuve Boulevard, W., H3G 1M8, Montreal, Quebec, Canada aut Psychopharmacology Springer-Verlag 107/4(1992-06-01), 575-580 0033-3158 107:4<575 1992 107 213 https://doi.org/10.1007/BF02245273 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02245273 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rochford Joseph Department of Psychology, Concordia University, Center for Studies in Behavioral Neurobiology, 1455 deMaisonneuve Boulevard, W., H3G 1M8, Montreal, Quebec, Canada aut NATIONALLICENCE 700 1- Dawes Patricia Department of Psychology, Concordia University, Center for Studies in Behavioral Neurobiology, 1455 deMaisonneuve Boulevard, W., H3G 1M8, Montreal, Quebec, Canada aut NATIONALLICENCE 773 0- Psychopharmacology Springer-Verlag 107/4(1992-06-01), 575-580 0033-3158 107:4<575 1992 107 213 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer