Enkephalin mydriasis in mice

Amos D. Korczyn*, Yechiel Eshel, Ora Keren

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Morphine is known to produce mydriasis in mice. We have found that enkephalins caused a similar effect. Morphine was twice as active as D-Ala-D-Leu-enkephalin (BW-180C), 5 times as active as Met-enkephalin and 7 times as active as Leu-enkephalin. The time course of the effect was shortest for the enkephalins (t1/2 = 8–12 min), intermediate for BW-180C (60 min) and longest for morphine (80 min). Naloxone antagonised the effect of all agents to a similar extent. The question whether enkephalins are involved in the physiological regulation of pupillary diameter was investigated by administering either naloxone or D-phenylalanine to mice. None of these agents changed pupillary size, thus making such an involvement unlikely.

Original languageEnglish
Pages (from-to)285-287
Number of pages3
JournalEuropean Journal of Pharmacology
Issue number2-3
StatePublished - 1980


  • D-Phenylalanine
  • Enkephalins
  • Morphine
  • Mydriasis
  • Naloxone
  • Opiate receptors


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