Presynaptic localization of the carboxy-terminus epitopes of the μ opioid receptor splice variants MOR-1C and MOR-1D in the superficial laminae of the rat spinal cord Journal Article

  

Authors:	Abbadie, C.; Pasternak, G. W.; Aicher, S. A.
Article Title:	Presynaptic localization of the carboxy-terminus epitopes of the μ opioid receptor splice variants MOR-1C and MOR-1D in the superficial laminae of the rat spinal cord
Abstract:	Opioids inhibit nociceptive transmission at the level of the spinal cord, possibly through inhibition of neurotransmitter release by presynaptic μ opioid receptors (MORs) thus preventing the activation of ascending pathways and the perception of pain. Most nociceptive primary afferents are unmyelinated fibers containing peptides such as substance P and/or calcitonin gene-related peptide. However, few terminals contain both substance P and MOR. Recently, we identified new carboxy-terminal MOR splice variants that are localized in the superficial laminae of the dorsal horn. We now report the precise cellular distribution of two of these MOR-1 variants, MOR-1C (exon 7/8/9 epitope) and MOR-1D (exon 8/9 epitope), at the ultrastructural level. In the superficial laminae of the dorsal horn, the majority of the labeling of MOR-1C and MOR-1D was found in unmyelinated axons. This distribution contrasts with that of MOR-1 (exon 4 epitope), in which labeling is equally found in dendrites and soma, as well as in axons. The presence of dense core vesicles in many of the MOR-1C-like immunoreactive terminals implies that this splice variant might be involved in presynaptic inhibition of transmitter release from peptide-containing afferents to the dorsal horn. Consistent with this finding, confocal microscopy analyses showed that many MOR-1C profiles in laminae I-II also contained calcitonin gene-related peptide, whereas fewer MOR-1 profiles contained either substance P or calcitonin gene-related peptide in this same region. From these findings we suggest that there are differential distributions of MOR-1 splice variants as well as distinct peptide colocalizations in the dorsal horn. © 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.
Keywords:	immunohistochemistry; controlled study; unclassified drug; exon; nonhuman; protein localization; electron microscopy; animals; microscopy, electron; animal tissue; pain; confocal microscopy; carboxy terminal sequence; immunoreactivity; nerve fiber; presynaptic inhibition; presynaptic terminals; epitope; rat; alternative splicing; protein structure, tertiary; rats; rats, sprague-dawley; ultrastructure; mu opiate receptor; mu opiate receptor 1c; receptors, opioid, mu; protein isoforms; dendrite; afferent pathways; nociceptors; epitopes; substance p; synaptic transmission; nerve fibers; neurotransmitter release; spinal cord dorsal horn; perikaryon; calcitonin gene related peptide; posterior horn cells; splice variant; μ opioid receptor; male; priority journal; article; dorsal horn; double labeling; mu opiate receptor 1d; nonmyelinated nerve; calcitonin gene-related peptide
Journal Title:	Neuroscience
Volume:	106
Issue:	4
ISSN:	0306-4522
Publisher:	Pergamon-Elsevier Science Ltd
Date Published:	2001-10-31
Start Page:	833
End Page:	842
Language:	English
DOI:	10.1016/s0306-4522(01)00317-7
PUBMED:	11682168
PROVIDER:	scopus
DOI/URL:	http://www.scopus.com/inward/record.url?eid=2-s2.0-0035980488&partnerID=40&md5=05e8adcb23286c593d24801bf4cda04c
Notes:	Export Date: 21 May 2015 -- Source: Scopus

https://synapse.mskcc.org/synapse/works/has_related_data_chk/73999