Immunofluorescent identification of a delta (delta)-opioid receptor on primary afferent nerve terminals

Neuroreport. 1993 Dec 13;5(3):341-4. doi: 10.1097/00001756-199312000-00041.


Antisera were produced against synthetic peptides predicted from the recent cloning of a delta opioid receptor, DOR-1. Confocal microscopic examination of immunostained spinal cord sections revealed that DOR-1 immunoreactive (-ir) nerve fibers and terminals form a moderately dense plexus within the superficial dorsal horn of rats and mice. These fibers decreased dramatically following dorsal rhizotomy and consistent with these observations a population of small diameter neurons in ganglia exhibited DOR-1-ir. DOR-1-ir ganglion neurons were also immunoreactive for calcitonin gene-related peptide (CGRP), and their terminals in the spinal cord contained both CGRP- and DOR-1-ir, the latter presumably located as a 'presynaptic' receptor. Interestingly, terminals containing DOR-1-ir appeared to be closely apposed by fibers and terminals containing enkephalin (ENK)-ir, which suggests that ENK may be a physiologically relevant ligand for the receptor encoded by DOR-1, and that DOR-1 may act to regulate the release of transmitters from small diameter primary afferent neurons.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Enkephalins / immunology
  • Enkephalins / metabolism
  • Fluorescent Antibody Technique
  • Ganglia, Spinal / immunology
  • Ganglia, Spinal / metabolism
  • Immunoblotting
  • Male
  • Mice
  • Nerve Endings / immunology
  • Nerve Endings / metabolism*
  • Nerve Fibers / metabolism
  • Neurons, Afferent / immunology
  • Neurons, Afferent / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Opioid, delta / immunology
  • Receptors, Opioid, delta / metabolism*
  • Spinal Cord / cytology
  • Spinal Cord / metabolism


  • Enkephalins
  • Receptors, Opioid, delta