Characterization of new iodinated peptide radioligand for delta opioid receptors
AuthorFang, Lei, 1966-
KeywordsHealth Sciences, Pharmacology.
AdvisorYamamura, Henry I.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractNew radioligand [4'-¹²⁵I-[Phe⁴]DPDPE ([¹²⁵I] DPDPE) was prepared from [4'-NH₂-Phe⁴] DPDPE. Its binding characteristics were determined using rat brain membranes. Saturation studies showed one binding site with K(d) = 421 ± 67 pM and B(max) = 36.4 ± 2.7 fmol/mg protein. Kinetic studies showed association rate constant k₊₁ = 5.80 ± 0.88 x 10⁷ M⁻¹ min⁻¹ and dissociation rate constant k-1 = 0.917 ± 0.117 x 10⁻² min⁻¹. Competitive inhibition studies showed high selectivity for delta opioid receptors. Distribution of [¹²⁵I] DPDPE labeled sites in rat brain (autoradiography) is consistent with previous results using other radioligands. The inhibition constants of [¹²⁵I] DPDPE binding by delta selective ligands were similar in mouse brain and mouse vas deferens, and no significantly different values were determined in rat brain. These data indicate that [¹²⁵I] DPDPE due to high specific activity is valuable for characterization of delta opioid receptors.