Clobenpropit, a histamine H3 receptor antagonist/inverse agonist, inhibits [3H]-dopamine uptake by human neuroblastoma SH-SY5Y cells and rat brain synaptosomes

Pharmacol Rep. 2018 Feb;70(1):146-155. doi: 10.1016/j.pharep.2017.08.007. Epub 2017 Aug 30.


Background: Clobenpropit, a potent antagonist/inverse agonist at the histamine H3 receptor (H3R), reduced the cytotoxic action of 6-hydroxydopamine (6-OHDA) in neuroblastoma SH-SY5Y cells transfected with the human H3R. We therefore set out to study whether this effect involved a receptor-independent action on dopamine transport.

Methods: The uptake of [3H]-dopamine was assayed in SH-SY5Y cells and rat striatal or cerebro-cortical isolated nerve terminals (synaptosomes). Clobenpropit binding to the human norepinephrine (NET) and dopamine (DAT) transporters was analyzed by molecular modeling.

Results: In SH-SY5Y cells, [3H]-dopamine uptake was inhibited by desipramine (selective NET inhibitor), GBR-12909 (selective DAT inhibitor), and fluoxetine (selective inhibitor of the serotonin transporter, SERT) with IC50 values 37, 537, and 2800nM, respectively. The potency rank order indicates that [3H]-dopamine uptake is primarily performed by NET. Clobenpropit inhibited [3H]-dopamine uptake (maximum inhibition 82.7±2.8%, IC50 490nM), and the effect was reproduced by the H3R antagonist/inverse agonist iodophenpropit, but not by the agonists R-α-methylhistamine and immepip or the antagonists/inverse agonists ciproxifan and A-331440. Clobenpropit also inhibited [3H]-dopamine uptake by rat striatal and cerebro-cortical synaptosomes (-54.6±11.3% and -46.3±9.6%, respectively, at 10μM). Modeling of the human NET and DAT obtained by homology from the crystal of Drosophila melanogaster DAT showed that clobenpropit can bind to a site also recognized in both transporters by nisoxetine, a potent NET inhibitor.

Conclusion: These data indicate a direct inhibitory effect of clobenpropit on catecholamine transport.

Keywords: Clobenpropit; Dopamine transporter; Histamine H(3) receptor; Norepinephrine transporter; SH-SY5Y cells.

MeSH terms

  • Animals
  • Binding Sites
  • Brain / drug effects*
  • Brain / metabolism
  • Cell Line, Tumor
  • Dopamine / metabolism*
  • Dopamine Plasma Membrane Transport Proteins / antagonists & inhibitors*
  • Dopamine Plasma Membrane Transport Proteins / chemistry
  • Dopamine Plasma Membrane Transport Proteins / metabolism
  • Dopamine Uptake Inhibitors / chemistry
  • Dopamine Uptake Inhibitors / metabolism
  • Dopamine Uptake Inhibitors / pharmacology*
  • Dose-Response Relationship, Drug
  • Drosophila Proteins / antagonists & inhibitors
  • Drosophila Proteins / metabolism
  • Drug Inverse Agonism
  • Histamine H3 Antagonists / chemistry
  • Histamine H3 Antagonists / metabolism
  • Histamine H3 Antagonists / pharmacology*
  • Humans
  • Imidazoles / chemistry
  • Imidazoles / metabolism
  • Imidazoles / pharmacology*
  • Molecular Docking Simulation
  • Norepinephrine Plasma Membrane Transport Proteins / antagonists & inhibitors
  • Norepinephrine Plasma Membrane Transport Proteins / metabolism
  • Protein Binding
  • Protein Conformation
  • Rats
  • Receptors, Histamine H3 / drug effects*
  • Receptors, Histamine H3 / metabolism
  • Synaptosomes / drug effects*
  • Synaptosomes / metabolism
  • Thiourea / analogs & derivatives*
  • Thiourea / chemistry
  • Thiourea / metabolism
  • Thiourea / pharmacology


  • DAT protein, Drosophila
  • Dopamine Plasma Membrane Transport Proteins
  • Dopamine Uptake Inhibitors
  • Drosophila Proteins
  • Histamine H3 Antagonists
  • Imidazoles
  • Norepinephrine Plasma Membrane Transport Proteins
  • Receptors, Histamine H3
  • SLC6A2 protein, human
  • Thiourea
  • clobenpropit
  • Dopamine