A comprehensive study on the putative delta-opioid receptor (sub)types using the highly selective delta-antagonist, Tyr-Tic-(2S,3R)-beta-MePhe-Phe-OH

作者：Birkas Erika; Bakota Lidia; Gulya Karoly; Wen Ting; Pintar John; Toth Geza; Szucs Maria^*

来源：Neurochemistry International, 2011, 59(2): 192-201.

DOI：10.1016/j.neuint.2011.04.015

• delta-Opioid receptor subtypes
• delta-Opioid antagonist
• TIPP analog
• Mouse brain
• DOR-CHO
• delta-Opioid knock-out

The goal of our work was a throughout characterization of the pharmacology of the TIPP-analog, Tyr-Tic(2S,3R)-beta-MePhe-Phe-OH and see if putative delta-opioid receptor subtypes can be distinguished. Analgesic latencies were assessed in mouse tail-flick assays after intrathecal administration. In vitro receptor autoradiography, binding and ligand-stimulated [(35)S]GTP gamma S functional assays were performed in the presence of putative delta(1)-(DPDPE: agonist, BNTX: antagonist), delta(2)-(agonist: deltorphin II, IIe(5.6)-deltorphin II, antagonist: naltriben) and mu-(DAMGO: agonist) opioid ligands. The examined antagonist inhibited the effect of DPDPE by 60%, but did not antagonize delta(2)- and mu-agonist induced analgesia. The radiolabeled form identified binding sites with K(D) = 0.18 nM and receptor densities of 102.7 fmol/mg protein in mouse brain membranes. The binding site distribution of the [[(3)H]Tyr-Tic-(25,3R)-beta-MePhe-Phe-OH agreed well with that of [(3)H]Ile(5,6)-deltorphin 11 as revealed by receptor autoradiography. Tyr-Tic-(2S,3R)-beta-MePhe-Phe-OH displayed 2.49 +/- 0.06 and 0.30 +/- 0.01 nM potency against DPDPE and deltorphin 11 in the [(35)S]GTP gamma S functional assay, respectively. The rank order of potency of putative delta(1)- and delta(2)-antagonists against DPDPE and deltorphin was similar in brain and CHO cells expressing human delta-opioid receptors. Deletion of the DOR-1 gene resulted in no residual binding of the radioligand and no significant DPDPE effect on G-protein activation. Tyr-Tic-(2S,3R)-beta-MePhe-Phe-OH is a highly potent and delta-opioid specific antagonist both in vivo and in vitro. However, the putative delta(1)- and delta(2)-opioid receptors could not be unequivocally distinguished in vitro.

• 出版日期2011-8