Selective labeling of κ2 opioid receptors in rat brain by [ 125I]IOXY: Interaction of opioid peptides and other drugs with multiple κ2a binding sites
Recent studies from our laboratory resolved two subtypes of the κ 2 binding site, termed κ 2a and κ 2b, using guinea pig, rat, and human brain membranes depleted of μ and δ receptors by pretreatment with the site-directed acylating agents BIT (μ-selective) and FIT (δ-selective). 6β-Iodo-3,14-dihydro...
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Published in | Peptides (New York, N.Y. : 1980) Vol. 14; no. 6; pp. 1279 - 1293 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
New York, NY
Elsevier Inc
1993
Elsevier Science |
Subjects | |
Online Access | Get full text |
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Summary: | Recent studies from our laboratory resolved two subtypes of the
κ
2 binding site, termed
κ
2a and
κ
2b, using guinea pig, rat, and human brain membranes depleted of μ and δ receptors by pretreatment with the site-directed acylating agents BIT (μ-selective) and FIT (δ-selective). 6β-Iodo-3,14-dihydroxy-17-cyclopropylmethyl-4,5α-epoxymorphinan (IOXY), an opioid antagonist that has high affinity for
κ
2 sites, was radioiodinated to maximum specific activity (2200 Ci/mmol) and purified by high pressure liquid chromotography and used to characterize multiple
κ
2 binding sites. The results indicated that [
125I]IOXY, like [
3H]bremazocine, selectively labels
κ
2 binding sites in rat brain membranes pretreated with BIT and FIT. Using 100 n
M [
d-Ala
2-MePhe
4,Gly-ol
5]enkephalin to block [
125I]IOXY binding to the
κ
2b site, two subtypes of the
κ
2a binding site were resolved, both in the absence and presence of 50 μ
M 5′-guanylyimidodiphosphate. Viewed collectively, these results provide further evidence for heterogeneity of the κ opioid receptor, which may provide new targets for drug design, synthesis, and therapeutics. |
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ISSN: | 0196-9781 1873-5169 |
DOI: | 10.1016/0196-9781(93)90188-M |