Send to

Choose Destination
Neuropharmacology. 2014 Nov;86:378-88. doi: 10.1016/j.neuropharm.2014.08.008. Epub 2014 Aug 28.

The binding characteristics and orientation of a novel radioligand with distinct properties at 5-HT3A and 5-HT3AB receptors.

Author information

Department of Biochemistry, University of Cambridge, Cambridge, UK.
Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
VU University Medical Center, Dept Radiology & Nuclear Medicine, Amsterdam, The Netherlands.
Department of Biochemistry, University of Cambridge, Cambridge, UK. Electronic address:


VUF10166 (2-chloro-3-(4-methyl piperazin-1-yl)quinoxaline) is a ligand that binds with high affinity to 5-HT3 receptors. Here we synthesise [(3)H]VUF10166 and characterise its binding properties at 5-HT3A and 5-HT3AB receptors. At 5-HT3A receptors [(3)H]VUF10166 displayed saturable binding with a Kd of 0.18 nM. Kinetic measurements gave monophasic association (6.25 × 10(7) M(-1) min(-1)) and dissociation (0.01 min(-1)) rates that yielded a similar Kd value (0.16 nM). At 5-HT3AB receptors two association (6.15 × 10(-7), 7.23 M(-1) min(-1)) and dissociation (0.024, 0.162 min(-1)) rates were seen, yielding Kd values (0.38 nM and 22 nM) that were consistent with values obtained in saturation (Kd = 0.74 nM) and competition (Ki = 37 nM) binding experiments respectively. At both receptor types, specific binding was inhibited by classical 5-HT3 receptor-selective orthosteric ligands (5-HT, allosetron, d-tubocurarine, granisetron, mCPBG, MDL72222, quipazine), but not by non-competitive antagonists (bilobalide, ginkgolide B, picrotoxin) or competitive ligands of other Cys-loop receptors (ACh, bicuculline, glycine, gabazine). To explore VUF10166 ligand-receptor interactions we used in silico modelling and docking, and tested the predictions using site directed mutagenesis. The data suggest that VUF10166 adopts a similar orientation to 5-HT3 receptor agonists bound in AChBP (varenicline) and 5HTBP (5-HT) crystal structures.


5-HT(3); Agonist; Antagonist; Cys-loop; Ion channel; Radioligand

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center