[125I][D-Ala2]deltorphin-I: a high affinity, delta-selective opioid receptor ligand

Peptides. 1991 Jul-Aug;12(4):825-30. doi: 10.1016/0196-9781(91)90141-b.

Abstract

The selective delta opioid agonist [D-Ala2]deltorphin-I was radioiodinated and the product purified using reverse phase HPLC. The binding characteristics and distribution profile of [125I][D-Ala2]deltorphin-I were assessed in mouse brain using homogenate binding techniques and quantitative autoradiography. [125I][D-Ala2]deltorphin-I bound with high affinity to a single class of sites (KD = 0.5 nM) in brain membrane preparations and striatal sections. Competition studies indicated that [125I][D-Ala2]deltorphin-I was selectively labeling delta opioid receptors as shown by the ratio of apparent affinities for mu and delta receptors (KI mu/KI delta = 1388). The autoradiographical distribution profile of [125I][D-Ala2]deltorphin-I binding sites was also consistent with that of other delta-selective radioligands. The data indicate that [125I][D-Ala2]deltorphin-I binds to delta opioid receptors with high affinity and selectivity. Because of its very high specific activity, it can be detected rapidly with high sensitivity by autoradiographic emulsion.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Autoradiography
  • Brain / metabolism
  • Chromatography, High Pressure Liquid
  • D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / antagonists & inhibitors
  • D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / metabolism
  • Enkephalins / pharmacology
  • Iodine Radioisotopes
  • Ligands
  • Male
  • Mice
  • Molecular Sequence Data
  • Oligopeptides / metabolism*
  • Receptors, Opioid / metabolism*
  • Receptors, Opioid, delta
  • Substrate Specificity

Substances

  • Enkephalins
  • Iodine Radioisotopes
  • Ligands
  • Oligopeptides
  • Receptors, Opioid
  • Receptors, Opioid, delta
  • deltorphin I, Ala(2)-
  • D-Ala(2),MePhe(4),Met(0)-ol-enkephalin