Opioid mydriasis: cross-tolerance between morphine and enkephalins.

Abstract

The occurrence of cross-tolerance between morphine and met-enkephalin, and between morphine and DADL (D-Ala-D-Leu-enkephalin) in causing mydriasis in mice was studied. Morphine-tolerant mice treated with met-enkephalin or DADL intracerebroventricularly (ICV) showed marked reduction of the pupillary effect of the endopioids. Maximal mydriasis in tolerant animals was only about 30% for met-enkephalin and 50% for DADL, compared to levels in nontolerant animals. These results are among the first to demonstrate cross-tolerance between morphine and enkephalins in intact animals and may suggest involvement of multiple opiate receptor systems in producing mydriasis.

Cite this paper

@article{BenAm1986OpioidMC, title={Opioid mydriasis: cross-tolerance between morphine and enkephalins.}, author={Monique Ben-Am and Amos D. Korczyn}, journal={Pharmacology}, year={1986}, volume={32 5}, pages={278-82} }