[3H]LY334370, a novel radioligand for the 5-HT1F receptor. I. In vitro characterization of binding properties.
[(3)H]LY334370 was developed as a radioligand to study the characteristics of this compound's interaction with the 5-HT(1F) receptor. Monovalent or divalent cations did not enhance the binding of [(3)H]LY334370 to the cloned human 5-HT(1F) receptor. In the presence of MgCl(2), the time to reach equilibrium was approximately 2 h, while in its absence equilibrium was reached in less than 1 h. [(3)H]LY334370 had high affinity for the cloned human 5-HT(1F) receptor (K(d)=0.446 nM) and the 5-HT(1F) receptor in rat brain (K(d)=0.388 nM). The expression density of 5-HT(1F) receptors, as determined by binding to homogenates of cortical regions from rat, was low (B(max)=79.1 fmol/mg protein). There was a statistically significant correlation between the apparent pK(i) for inhibition of [(3)H]LY334370 binding and the pEC(50) for stimulation of [(35)S]GTPgammaS binding to homogenates of cells expressing the cloned human 5-HT(1F) receptor. In addition, there was a statistically significant correlation between the apparent pK(i) for inhibition of [(3)H]LY334370 binding to the cloned human 5-HT(1F) receptor and the pID(50) for inhibition of trigeminal nerve stimulated dural plasma protein extravasation in the guinea pig. The conclusion from these studies is that [(3)H]LY334370 is a high affinity radioligand which can be used for the study of the 5-HT(1F) receptor in rat brain or in cells transformed with the human 5-HT(1F) receptor.
Wainscott
David B
DB
Neuroscience Research, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, USA. dbwainscott@lilly.com
Krushinski
Joseph H
JH
Audia
James E
JE
Schaus
John M
JM
Zgombick
John M
JM
Lucaites
Virginia L
VL
Nelson
David L
DL
D000818:Animals; D001549:Benzamides / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology*; D008024:Ligands; D011869:Radioligand Assay; D051381:Rats; D011985:Receptors, Serotonin / Q000032:analysis* / Q000187:drug effects / Q000235:genetics; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D014162:Transfection; D014316:Tritium; D000096642:Receptor, Serotonin, 5-HT1F
D001549:Benzamides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D007211:Indoles; D008024:Ligands; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D014316:Tritium; D000096642:Receptor, Serotonin, 5-HT1F; C108218:4-fluoro-N-(3-(1-methyl-4-piperidinyl)-1H-indol-5-yl)benzamide