The putative <<silent>> 5-HT(1A) receptor antagonist, WAY 100635, has inverse agonist properties at cloned human 5-HT(1A) receptors

Cristina Cosi, Wouter Koek

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Agonist binding to G protein-coupled receptors induces the formation of a receptor-G protein complex and subsequent guanosine 5'-diphosphate/guanosine 5'-triphosphate (GDP/GTP) exchange. Some receptors, however, form receptor-G protein complexes and promote GDP/GTP exchange even when not occupied by agonists. Such receptors preferentially activate pertussis toxin-sensitive G proteins (i.e., G(i)/G(o)), and the interactions of receptors and G proteins are affected by monovalent cations (most notably Na+), both in the occupied and unoccupied state. We investigated the effects of Na+ on the intrinsic activity of 5-hydroxytryptamine(1A) (5-HT(1A)) receptor ligands, measured as maximal effect (E(MAX)), using guanosine 5'-0-(3-[35S]thio)-triphosphate ([35S]GTPγS) binding to membranes prepared from human epithelioid carcinoma (HeLa) cells, expressing 500 fmol/mg protein of cloned human 5-HT(1A) receptor (HA7 cells). A decrease of the NaCl concentration decreased the maximal effect of serotonin, increased basal [35S]GTPγS binding, and increased the negative intrinsic activity of spiperone and N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]-N-(2-pyridinyl)cyclohexanecarboxamide (WAY 100635). This ability of WAY 100635 to decrease basal [35S]GTPγS binding was antagonized by (s)-N-tert-butyl-3-(4-(2-methoxyphenyl)piperazine-1-yl)-2-phenylpropanamide ((s)-WAY 100135) (pA2=7.77). Further, WAY 100635 was able to antagonize carboxamidotryptamine (5-CT)-stimulated [35S]GTPγS binding with a pA2 of 9.9, in standard NaCl conditions, and of 9.7, in the absence of NaCl. Changes in membrane concentration did not affect the ability of WAY 100635 to decrease [35S]GTPγS binding. WAY 100635 did not affect basal [35S]GTPγS binding to membranes from untransfected HeLa cells. Pertussis toxin (200 ng/ml) prevented WAY 100635 and spiperone to decrease [35S]GTPγS binding, showing that their effects were mediated by G proteins of the G(i)/G(o) family. In conclusion, the constitutive and stimulated activity of human 5-HT(1A) receptors expressed in HA7 cells is sodium-dependent, which allowed to confirm the 5-HT(1A) inverse agonist properties of spiperone, and to show that WAY 100635 is an inverse agonist at 5-HT(1A) receptors that inhibits basal [35S]GTPγS binding to a lesser extent than spiperone. [35S]GTPγS binding to membranes from HA7 cells under low NaCl conditions appears to be especially suitable to evidence and pharmacologically analyze the inverse agonist properties of 5-HT(1A) receptor ligands. Copyright (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)9-15
Number of pages7
JournalEuropean Journal of Pharmacology
Issue number1
StatePublished - Jul 28 2000
Externally publishedYes


  • 5-HT(1A) receptor
  • Inverse agonist
  • WAY 100635
  • [S]GTPγS binding

ASJC Scopus subject areas

  • Pharmacology


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