Modification of Receptor Selectivity and Functional Activity in Cholecystokinin Peptoid Ligands
作者:Milana Dezube、Elizabeth E. Sugg、Larry S. Birkemo、Dallas K. Croom、Robert W. Dougherty、Gregory N. Ervin、Mary K. Grizzle、Michael K. James、Michael F. Johnson
DOI:10.1021/jm00017a022
日期:1995.8
Hybrid analogs of the cholecystokinin A (CCK-A) receptor selective tetrapeptide agonist Boc-Trp-Lys(Tac)-Asp-MePhe-NH2 (1, A-71623) and the CCK-B receptor selective antagonists PD-135118 (2) and CI-988 (3) were prepared. Incorporation of the Lys(Tac) side chain into 2 produced a moderately potent antagonist of CCK-8 in the isolated guinea pig gallbladder (GPGB). Incorporation of the Lys(Tac) side chain into 3 produced the novel agonist analog 7 (EC(50) = 28 nM in the GPGB) with excellent affinity for both human CCK-A (IC50 = 12 nM) and CCK-B (IC50 = 17 nM) receptors. Analog 7 was a full agonist (EC(50) = 3.5 nM) for calcium mobilization on CHO-K1 cells expressing hCCK-A receptors but a partial agonist on CHO-K1 cells expressing hCCK-B receptors, eliciting a weak agonist reponse (EC(50) = 2800 nM) and antagonizing CCK-8-induced calcium mobilization (K-B = 20 nM). Despite this unusual in vitro profile, analog 7 was a potent anorectic agent in rats (ED(50) = 30 nmol/kg) following intraperitoneal administration.