Immunoreactivity for endomorphin-2 occurs in primary afferents in rats and monkey.
Antisera were raised against endomorphin-2, a recently isolated endogenous opioid peptide that binds potently and selectively to the mu-opioid receptor. When sections of spinal cord were stained immunocytochemically, a dense plexus of fibres and varicosities was visualized in the superficial dorsal horn of rats and one monkey. Following unilateral multiple dorsal rhizotomy, labeling for endomorphin-2 was markedly reduced ipsilateral to the lesion. In sections stained for both endomorphin-2 and CGRP, double-labeling was observed. Taken together, these data suggest that endomorphin-2 occurs in small diameter primary afferent fibres in rodents and primates. It appears possible that the release of neurotransmitters from nociceptive primary afferents might be regulated by release of endomorphin-2 from primary afferent terminals.
Pierce
T L
TL
Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis 55455, USA.
Grahek
M D
MD
Wessendorf
M W
MW
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis; D007150:Immunohistochemistry; D008253:Macaca mulatta; D008297:Male; D009412:Nerve Fibers / Q000737:chemistry*; D009842:Oligopeptides / Q000032:analysis*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000819:agonists*; D013116:Spinal Cord / Q000737:chemistry*
D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105294:endomorphin 2; D015740:Calcitonin Gene-Related Peptide