Characterisation of a cloned human 5-HT1A receptor cell line using [35S]GTP gamma S binding

Eur J Pharmacol. 1997 Feb 12;320(2-3):267-75. doi: 10.1016/s0014-2999(96)00914-4.


Compound potencies and efficacies depend upon receptor reserve and hence estimating this parameter in assay systems allows for a more meaningful interpretation of the data generated. This study describes a method whereby the degree of receptor reserve, with respect to 5-hydroxytryptamine (5-HT), was determined for a HeLa cell line expressing the human 5-HT1A receptor using the agonist-induced [35S]guanosine 5'[gamma-thio]triphosphate ([35S]GTP gamma S) binding assay, followed by a comparison of the potencies and relative efficacies of several compounds. Following irreversible antagonism with benextramine 5-HT yielded a pKA of 7.3, compared with a pKobs of 8.4 from saturation analysis, indicating the presence of high and low affinity state receptors. A 20% receptor occupancy elicited a half-maximal functional response consistent with the presence of receptor reserve. 5-HT, 5-carboxamidotryptamine (5-CT), 8-hydoxy-dipropylamino-tetralin (8-OH-DPAT), 5-methoxy-3-(1,2,3,6-tetrahydropyridin-4-yl)-1 H-indole (RU24969), buspirone, gepirone, mesulergine and sumatriptan were equally efficacious. 1-(2-Methoxyphenyl)-4-[4-(2-phthalimido)butyl]piperazine (NAN 190) displayed reduced relative efficacy and methiothepin inverse agonism.

MeSH terms

  • 8-Hydroxy-2-(di-n-propylamino)tetralin / metabolism
  • 8-Hydroxy-2-(di-n-propylamino)tetralin / pharmacology
  • Adrenergic alpha-Antagonists / metabolism
  • Adrenergic alpha-Antagonists / pharmacology
  • Cell Line
  • Clone Cells
  • Cystamine / analogs & derivatives
  • Cystamine / metabolism
  • Cystamine / pharmacology
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism*
  • HeLa Cells
  • Humans
  • Radioligand Assay
  • Receptors, Serotonin / metabolism*
  • Receptors, Serotonin, 5-HT1
  • Serotonin / metabolism
  • Serotonin / pharmacology
  • Serotonin Receptor Agonists / metabolism
  • Serotonin Receptor Agonists / pharmacology
  • Sulfur Radioisotopes
  • Tritium


  • Adrenergic alpha-Antagonists
  • Receptors, Serotonin
  • Receptors, Serotonin, 5-HT1
  • Serotonin Receptor Agonists
  • Sulfur Radioisotopes
  • Tritium
  • Serotonin
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • benextramine
  • 8-Hydroxy-2-(di-n-propylamino)tetralin
  • Cystamine