SB-224289--a novel selective (human) 5-HT1B receptor antagonist with negative intrinsic activity.
1. Human 5-HT1B (h5-HT1B) and human 5-HT1D (h5-HT1D) receptors show remarkably similar pharmacology with few compounds discriminating the receptors. We report here on a novel compound, SB-224289 (1'-Methyl-5-[[2'-methyl-4'-(5-methyl- 1,2,4-oxadiazol-3-yl)biphenyl-4-yl]carbonyl]-2,3,6,7-tetrahydro spiro [furo [2,3-f]indole-3,4'-piperidine] oxalate), which has high affinity for h5-HT1B receptors (pK1=8.16+/-0.06) and displays over 75 fold selectivity for the h5-HT1B receptor over all other 5-HT receptors including the h5-HT1D receptor and all other receptors tested thus far. 2. Functional activity of SB-224289 was measured in a [15S]GTPgammaS binding assay on recombinant h5-HT1B and h5-HT1D receptors expressed in Chinese Hamster Ovary (CHO) cells. SB-224289 displayed negative intrinsic activity at both receptors with higher potency at h5-HT1B receptors. SB-224289 caused a rightward shift of agonist concentration response curves consistent with competitive antagonism and generated affinities comparable with those obtained from competition radioligand receptor binding studies. 3. SB-224289 potentiated [3H]5-HT release from electrically stimulated guinea-pig cerebral cortical slices to the same extent as as the non-selective 5-HT1 antagonist methiothepin. SB-224289 also fully reversed the inhibitory effect of exogenously superfused 5-HT on electrically stimulated release. 4. Using SB-224289 as a tool compound, we confirm that in guinea-pig cerebral cortex the terminal 5-HT autoreceptor is of the 5-HT1B subtype.
Department of Neurosciences, SmithKline Beecham Pharmaceuticals, Harlow, Essex.
J V
JV
Selkirk
C
C
Scott
M
M
Ho
M J
MJ
Burton
J
J
Watson
L M
LM
Gaster
L
L
Collin
B J
BJ
Jones
D N
DN
Middlemiss
G W
GW
Price
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D010881:Piperidones / Q000737:chemistry / Q000494:pharmacology*; D011869:Radioligand Assay; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D012702:Serotonin Antagonists / Q000737:chemistry / Q000494:pharmacology*; D013141:Spiro Compounds / Q000737:chemistry / Q000494:pharmacology*; D013462:Sulfur Radioisotopes / Q000378:metabolism
C470302:HTR1B protein, human; D010881:Piperidones; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin; D011994:Recombinant Proteins; C108518:SB 22489G; D012702:Serotonin Antagonists; D013141:Spiro Compounds; D013462:Sulfur Radioisotopes; D012701:Serotonin; D016244:Guanosine 5'-O-(3-Thiotriphosphate)