[Dalargin--an opioid-like peptide with peripheral action]

Hexapeptide dalargin (Tyr-Dala-Gly-Phe-Leu-Arg) and its N-terminal penta- and tetrapeptide fragments significantly differed by the peripheral opioid activity "spectra" on three models of isolated organs: the guinea pig ileum, the mouse vas deferens and the mouse large intestine. N-terminal tripeptide and tyrosine-free fragment of Dala-Gly-Phe-Leu possessed no opioid properties. Dalargin and its opioid-like fragments exerted the analgesic effect according to the hot plate and tail flick tests in mice. When administered intracisternally they were inferior in the activity to a stable analogue of enkephalins FK 33-824 by 1-3 orders, at intravenous administration by tens of times. The data obtained suggest that dalargin is an opioid-like peptide with the peripheral action.