title: Selectivity of d[Cha4]AVP and SSR149415 at human vasopressin and oxytocin receptors: evidence that SSR149415 is a mixed vasopressin V1b/oxytocin receptor antagonist.
abstract: 1 A possible role of arginine vasopressin (AVP) V(1b) receptor subtype in stress-related disorders has been recently highlighted by the discovery of the agonist [1-deamino-4-cyclohexylalanine] AVP (d[Cha(4)]AVP) and the antagonist SSR149415. Both compounds have been proposed to target specifically V(1b) receptors, since the reported affinities for the related V(1a), V(2) and oxytocin receptors are in the micromolar or submicromolar range. In the present study, we further investigated the binding affinities of d[Cha(4)]AVP and SSR149415 at recombinant human vasopressin V(1b) (hV(1b)) and oxytocin (hOT) receptors expressed in Chinese hamster ovary (CHO) cells and functional properties of both compounds at hV(1b), hV(1a), hV(2) and hOT receptors. 2 d[Cha(4)]AVP bound to hV(1b) receptors and hOT receptors with pK(i) values of 9.68+/-0.06 and 7.68+/-0.09, respectively. SSR149415 showed pK(i) values of 9.34+/-0.06 at hV(1b) and 8.82+/-0.16 at hOT receptors. 3 d[Cha(4)]AVP stimulated [Ca(2+)](i) increase in hV(1b)-CHO cells with a pEC(50) value of 10.05+/-0.15. It showed pEC(50) values of 6.53+/-0.17 and 5.92+/-0.02 at hV(1a) and hV(2) receptors, respectively, and behaved as a weak antagonist at hOT receptors (pK(B)=6.31+/-0.12). SSR149415 inhibited the agonist-induced [Ca(2+)](i) increase with pK(B) values of 9.19+/-0.07 in hV(1b)-CHO and 8.72+/-0.15 in hOT-CHO cells. A functional pK(i) value of 7.23+/-0.10 was found for SSR1494151 at hV(1a) receptors, whereas it did not inhibit 20 nM AVP response at hV(2) receptors up to 3 microM. 4 Data obtained confirmed the high potency and selectivity of d[Cha(4)]AVP at hV(1b) receptors, but revealed that SSR149415, in addition to the high potency at hV(1b) receptors, displays a significant antagonism at hOT receptors.
authors.affiliation: Psychiatry Centre of Excellence for Drug Discovery, GlaxoSmithKline Group, Medicines Research Centre, Verona, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Griffante
authors.forename: Andrew
authors.initials: A
authors.lastname: Green
authors.forename: Ornella
authors.initials: O
authors.lastname: Curcuruto
authors.forename: Carl P
authors.initials: CP
authors.lastname: Haslam
authors.forename: Bryony A
authors.initials: BA
authors.lastname: Dickinson
authors.forename: Roberto
authors.initials: R
authors.lastname: Arban
mesh_terms: D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000031:analogs & derivatives* / Q000494:pharmacology; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D006224:Cricetinae; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D011759:Pyrrolidines / Q000494:pharmacology*; D018045:Receptors, Oxytocin / Q000037:antagonists & inhibitors*
chemical_list: C456029:1-(5-chloro-1-((2,4-dimethoxyphenyl)sulfonyl)-3-(2-methoxyphenyl)-2-oxo-2,3-dihydro-1H-indol-3-yl)-4-hydroxy-N,N-dimethyl-2-pyrrolidinecarboxamide; D065092:Antidiuretic Hormone Receptor Antagonists; D007211:Indoles; D011759:Pyrrolidines; D018045:Receptors, Oxytocin; C469699:argipressin, dCha(4)-; D001127:Arginine Vasopressin; D002118:Calcium