The opioid activities of tetrapeptide-amide analogues of enkephalin /H-Tyr-D-Met-Gly-Phe-NH2; H-Tyr-D-Nle-Gly-Phe-NH2/ were studied in isolated, electrically stimulated longitudinal muscle strip of guinea-pig ileum and mouse vas deferens preparations in vitro and in vivo in the rat tail-flick test. Their effects were compared to those of the parent L-Pro5-NH2 containing analogues, and to other enkephalin derivatives substituted with D-Met in position 2 and L-amino/imino acids of different character in position 5. It was found that whilst the opioid receptor in mouse vas deferens preferred aliphatic residues of acidic character at the C-terminus of pentapeptides and was highly sensitive to the removal of C-terminal amino acid, the other systems were either much less responsive to these changes, or the effects were opposite to those found in mouse vas deferens.
|Number of pages||11|
|Journal||Biochemical and biophysical research communications|
|Publication status||Published - Dec 28 1979|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology