Different types of opioid receptors mediating analgesia induced by morphine, DAMGO, DPDPE, DADLE and ?-endorphin in mice
- 1 July 1990
- journal article
- Published by Springer Nature in Naunyn-Schmiedebergs Archiv für experimentelle Pathologie und Pharmakologie
- Vol. 342 (1)
- https://doi.org/10.1007/bf00178974
Abstract
The effects of intracerebroventricular (i.c.v.) administration of d-Phe-Cys-Tyr-d-Try-Orn-Thr-Pen-Thr-NH2 (CTOP), a selective mu-opioid receptor antagonist, (Allyl)2-Tyr-Aib-Aib-Phe-Leu-OH (ICI 174864) and (N,N-Bisallyl-Tyr-Gly-Gly-ψ-(CH2S)-Phe-Leu-OH (ICI 154129), selective delta-opioid receptor antagonists on blocking analgesia induced by β-endorphin, morphine, d-Ala2-NMePhe4-Gly-ol-enkephalin (DAMGO), d-Ala2-d-Leu5-enkephalin (DADLE) and d-Pen2-enkephalin (DPDPE) administered i.c.v. were studied in male ICR mice. The analgesia was assessed by the tail-flick and paw-licking (hot-plate) tests. The potencies of opioid agonists injected i.c.v. for producing analgesia were DAMGO > DADLE > β-endorphin > morphine > DPDPE. Intracerebroventricular administration of CTOP (0.05 μg) selectively antagonized inhibition of the tail-flick and paw-licking response induced by morphine, DAMGO or DADLE but not β-endorphin or DPDPE. ICI 174864 (5 μg) and ICI 154129 (5 μg) injected i.c.v. selectively antagonized analgesia induced by DPDPE or DADLE but not β-endorphin, morphine or DAMGO injected i.c.v. These results indicate that analgesia induced by morphine and DAMGO is mediated by the stimulation of mu-opioid receptors while analgesia induced by DPDPE is mediated by the stimulation of delta-opioid receptors. DADLE-induced analgesia is mediated by the stimulation of both mu- and delta-opioid receptors. Analgesia induced by β-endorphin is mediated by neither munor delta-opioid receptors.Keywords
This publication has 0 references indexed in Scilit: