title: Subtype selectivity and antagonistic profile of the nonpeptide Y1 receptor antagonist BIBP 3226.
abstract: In the present study, the subtype specificity and species selectivity of the nonpeptide BIBP 3226, as well as its in vitro antagonism of neuropeptide Y (NPY)-mediated second messengers have been investigated. Radiolabeled NPY is potently displaced by BIBP 3226 [(R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenylmethyl]-D- arginine amide] on human Y1 receptor expressing Chinese hamster ovary-K1 cells (Ki = 0.47 +/- 0.07 nM). SK-N-MC human neuroblastoma cells (Ki = 5.1 +/- 0.5 nM) and the rat parietal cortex membranes (Ki = 6.8 +/- 0.7 nM). The interaction of BIBP 3226 with the Y1 receptor is stereoselective, because the (S)-enantiomer of the (R)-configured BIBP 3226 displays almost no affinity (Ki > 10,000 nM). In contrast, concentrations up to 10 microM BIBP 3226 do not displace [125I]NPY from the human Y2 receptor (neuroblastoma cell line SMS-KAN), the rabbit Y2 receptor (kidney) and the rat Y2 receptor (hippocampus). Functional antagonism could be shown for the human Y1 receptor: 0.1 microM BIBP 3226 antagonizes the NPY induced Ca++ mobilization (pKb = 7.5 +/- 0.17) as well as the NPY-mediated inhibition of cyclic AMP synthesis (pKb = 8.2 +/- 0.24) in SK-N-MC cells. In contrast, none of the formerly described putative antagonists PYX-2, [D-Trp32]NPY and benextramine could be characterized as high affinity Y1 receptor antagonists. The 18 amino acid NPY analog EXBP 68 Ile-Glu-Pro-Orn-Tyr-Arg-Leu-Arg-Tyr-NH2, cyclic (2,4'), (2',4')-diamide] displayed Y1-selective affinity with in vitro antagonistic properties (Ki = 0.33 +/- 0.04 nM and pKb = 8.4 +/- 0.07) in SK-N-MC cells. Therefore, BIBP 3226 is the first potent and subtype-selective nonpeptide Y1 receptor antagonist.
authors.affiliation: Preclinical Research Department, Dr. Karl Thomae GmbH, Biberach, Germany.
authors.forename: H A
authors.initials: HA
authors.lastname: Wieland
authors.forename: K D
authors.initials: KD
authors.lastname: Willim
authors.forename: M
authors.initials: M
authors.lastname: Entzeroth
authors.forename: W
authors.initials: W
authors.lastname: Wienen
authors.forename: K
authors.initials: K
authors.lastname: Rudolf
authors.forename: W
authors.initials: W
authors.lastname: Eberlein
authors.forename: W
authors.initials: W
authors.lastname: Engel
authors.forename: H N
authors.initials: HN
authors.lastname: Doods
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D006224:Cricetinae; D004285:Dogs; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000378:metabolism / Q000648:ultrastructure; D009478:Neuropeptide Y / Q000031:analogs & derivatives / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors* / Q000145:classification / Q000378:metabolism; D013237:Stereoisomerism; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: C092926:BIBP 3226; C096170:EXBP 68; D009478:Neuropeptide Y; D010446:Peptide Fragments; D017476:Receptors, Neuropeptide Y; C079216:PYX 2; D001120:Arginine; D002118:Calcium