Modulation of morphine antinociception by swim-stress in the mouse: involvement of supraspinal opioid delta-2 receptors.

摘要: The present study evaluated the effect of a brief exposure mice to cold-water swim-stress (CWSS) on antinociceptive potency i.c.v. given morphine. No significant response could be demonstrated in warm-water tail-flick test, 10 min after 30-sec water at 5 degrees C. However, morphine dose-response curve exposed CWSS was displaced significantly left when compared that obtained control (i.e., non-CWSS-exposed) mice. Although coadministration delta antagonist, N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH 1 (ICI 174,864), with did not produce antagonism action this mu opiate, leftward displacement seen CWSS-exposed blocked ICI 174,864-treated suggesting involvement opioid receptors modulatory effect. Pretreatment delta-1 [D-Ala2, Leu5, Cys6] enkephalin, antagonize antinociception and further produced by CWSS. delta-2 5'-isothiocyanate, also effects but associated CWSS, an receptor beta-funaltrexamine, as rightward dose-effect curve.(ABSTRACT TRUNCATED AT 250 WORDS)