title: Evaluation of histamine H1-, H2-, and H3-receptor ligands at the human histamine H4 receptor: identification of 4-methylhistamine as the first potent and selective H4 receptor agonist.
abstract: The histamine H(4) receptor (H(4)R) is involved in the chemotaxis of leukocytes and mast cells to sites of inflammation and is suggested to be a potential drug target for asthma and allergy. So far, selective H(4)R agonists have not been identified. In the present study, we therefore evaluated the human H(4)R (hH(4)R) for its interaction with various known histaminergic ligands. Almost all of the tested H(1)R and H(2)R antagonists, including several important therapeutics, displaced less than 30% of specific [(3)H]histamine binding to the hH(4)R at concentrations up to 10 microM. Most of the tested H(2)R agonists and imidazole-based H(3)R ligands show micromolar-to-nanomolar range hH(4)R affinity, and these ligands exert different intrinsic hH(4)R activities, ranging from full agonists to inverse agonists. Interestingly, we identified 4-methylhistamine as a high-affinity H(4)R ligand (K(i) = 50 nM) that has a >100-fold selectivity for the hH(4)R over the other histamine receptor subtypes. Moreover, 4-methylhistamine potently activated the hH(4)R (pEC(50) = 7.4 +/- 0.1; alpha = 1), and this response was competitively antagonized by the selective H(4)R antagonist JNJ 7777120 [1-[(5-chloro-1H-indol-2-yl)-carbonyl]-4-methylpiperazine] (pA(2) = 7.8). The identification of 4-methylhistamine as a potent H(4)R agonist is of major importance for future studies to unravel the physiological roles of the H(4)R.
authors.affiliation: Leiden/Amsterdam Center for Drug Research, Department of Medicinal Chemistry, Vrije Universiteit Amsterdam, The Netherlands.
authors.forename: Herman D
authors.initials: HD
authors.lastname: Lim
authors.forename: Richard M
authors.initials: RM
authors.lastname: van Rijn
authors.forename: Ping
authors.initials: P
authors.lastname: Ling
authors.forename: Remko A
authors.initials: RA
authors.lastname: Bakker
authors.forename: Robin L
authors.initials: RL
authors.lastname: Thurmond
authors.forename: Rob
authors.initials: R
authors.lastname: Leurs
mesh_terms: D002460:Cell Line; D017442:Histamine Agonists / Q000494:pharmacology*; D006801:Humans; D007093:Imidazoles / Q000378:metabolism; D007211:Indoles / Q000378:metabolism; D007550:Isothiuronium / Q000031:analogs & derivatives / Q000378:metabolism; D008024:Ligands; D008761:Methylhistamines / Q000494:pharmacology*; D010879:Piperazines / Q000378:metabolism; D011869:Radioligand Assay; D043562:Receptors, G-Protein-Coupled / Q000819:agonists* / Q000378:metabolism; D011968:Receptors, Histamine / Q000378:metabolism; D011969:Receptors, Histamine H1 / Q000378:metabolism*; D011970:Receptors, Histamine H2 / Q000378:metabolism*; D018100:Receptors, Histamine H3 / Q000378:metabolism*; D000074040:Receptors, Histamine H4
chemical_list: C418607:HRH4 protein, human; D017442:Histamine Agonists; D007093:Imidazoles; D007211:Indoles; D008024:Ligands; D008761:Methylhistamines; D010879:Piperazines; D043562:Receptors, G-Protein-Coupled; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D018100:Receptors, Histamine H3; D000074040:Receptors, Histamine H4; D007550:Isothiuronium; C077791:iodophenpropit; C484309:1-((5-chloro-1H-indol-2-yl)carbonyl)-4-methylpiperazine; C025566:4-methylhistamine