Luciferase Reporter Gene Assay on Human, Murine and Rat Histamine H4 Receptor Orthologs: Correlations and Discrepancies between Distal and Proximal Readouts
Figure 5
Effect of selected standard ligands on H4R orthologs.
(A) Potencies and efficacies of histamine (HA), thioperamide (THIO), UR-PI294 and JNJ 7777120 at the hH4R, (B) the mH4R and (C) the rH4R (agonist mode). (D) Reversal of the HA (100–150 nM) mediated inhibition of the forskolin-stimulated luciferase activity by JNJ 7777120 at the hH4R and the mH4R (antagonist mode), in the luciferase reporter gene assay in HEK293T cells. Reaction mixtures contained ligands at the concentrations indicated on the abscissa to achieve saturated concentration response curves. Data points shown are the mean ± SEM of at least three independent experiments performed in triplicate. Data points connected by dashed lines reflect H4R-independent increase in luciferase activity at high ligand concentrations. The corresponding values were therefore excluded from non-linear correlations (D).