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Opioid Peptides Endomorphin‐1 and Endomorphin‐2 in the Immune System in Humans and in a Rodent Model of Inflammation
Author(s) -
JESSOP DAVID S.,
RICHARDS LOUISE J.,
HARBUZ MICHAEL S.
Publication year - 2002
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2002.tb04247.x
Subject(s) - immune system , inflammation , spleen , opioid peptide , arthritis , chemistry , medicine , receptor , endocrinology , adjuvant , opioid , immunology , pharmacology
A bstract : Endomorphin (EM)‐1 and EM‐2 are tetrapeptides with high affinity and selectivity for the μ‐opioid receptor. We have utilized specific radioimmunoassays to characterize EM‐1 and EM‐2 in immune tissues from normal human subjects and from rats with adjuvant arthritis (AA). PBLs from three normal human subjects contained 248, 13, and 303 pg EM‐1 per 100 million cells, whereas EM‐2 was measured in two subjects at 69 and 588 pg per 100 million cells. In AA rats, EM‐1 (but not EM‐2) contents in the spleen and thymus were elevated compared with levels in tissues from non‐AA controls. EM‐1 was detectable in five of eight samples of synovial tissue from inflamed hind paws, whereas EM‐2 was detectable in two of eight synovial extracts. Neither EM‐1 nor EM‐2 were detectable in synovial tissue from non‐AA rats. To our knowledge, this is the first report of endomorphins in normal human immune cells. Increased endomorphin expression or uptake in peripheral tissues in a rodent model of chronic inflammation provides potential for endomorphins to selectively modulate chronic inflammation in mammals.