European Journal of Pharmacology, 1986, Vol.130(3), pp.203-208
The antinociceptive effects obtained in arthritic rats with morphine, the opioid mu-agonist DAGO [D-Ala2,MePhe4,Gly-ol5]enkephalin, the delta-selective agonist DTLET [D-Thr2, Leu5]enkephalyl-Thr, and the kappa-agonist U-50,488H were compared to their corresponding effects in normal animals and morphine-pretreated arthritic rats, respectively, using a paw pressure test. The effects of the mu- and kappa-agonists were increased in arthritic rats. While morphine-treated rats were cross-tolerant to the mu- and kappa-agonists, no tolerance to the delta-selective agonist was found. The possibility that the potent action of morphine in this model for chronic inflammatory pain is mediated partly through kappa-mechanisms is discussed.
Arthritic Rats ; Opioid Receptors ; Analgesia ; Tolerance ; Pharmacy, Therapeutics, & Pharmacology
View record in ScienceDirect (Access to full text may be restricted)