title: Activation of histamine H3 receptors in human nasal mucosa inhibits sympathetic vasoconstriction.
abstract: The peripheral histamine H3 receptor is a presynaptic heterologous receptor located on postganglionic sympathetic nerve fibers innervating sympathetic effector systems such as blood vessels and the heart. An extensive body of evidence shows that activation of the histamine H3 receptor attenuates sympathetic tone by presynaptic inhibition of noradrenaline release. It is proposed that this sympathoinhibitory action, in vivo, leads to reduced vasoconstriction, thereby eliciting a vasodilatory effect. In humans, the peripheral histamine H3 receptor has also been shown to exert a sympathoinhibitory function on specific peripheral autonomic effector systems. For example, human saphenous vein and heart possess functional presynaptic histamine H3 receptors on the sympathetic nerve terminals that upon activation decrease the sympathetic tone to these respective organs. The present studies were conducted to define the role of histamine H3 receptors on neurogenic sympathetic vasoconstrictor responses in human nasal turbinate mucosa. Contractility studies were conducted to evaluate the effect of histamine H3 receptor activation on sympathetic vasoconstriction in surgically isolated human nasal turbinate mucosa. We found that the histamine H3 receptor agonist, (R)-alpha-methylhistamine (30 and 300 nM), inhibited electrical field stimulation-induced (neurogenic) sympathetic vasoconstriction in a concentration-dependent fashion. Pretreatment with the selective histamine H3 receptor antagonist, clobenpropit (100 nM), blocked the sympathoinhibitory effect of (R)-alpha-methylhistamine on the neurogenic sympathetic vasoconstriction. In addition, analysis of Taqman mRNA expression studies showed a specific, high level of distribution of the histamine H3 receptor localized in the human nasal mucosa. Taken together, these studies indicate that histamine H3 receptors modulate vascular contractile responses in human nasal mucosa most likely by inhibiting noradrenaline release from sympathetic nerve terminals in nasal mucosa. It is further suggested that histamine H3 receptors may play a role in the regulation of vascular tone and nasal patency in histamine-dependent allergic nasal congestive disease.
authors.affiliation: Allergy, Schering Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033-1300, USA. lori.varty@spcorp.com
authors.forename: LoriAnn M
authors.initials: LM
authors.lastname: Varty
authors.forename: Eric
authors.initials: E
authors.lastname: Gustafson
authors.forename: Maureen
authors.initials: M
authors.lastname: Laverty
authors.forename: John A
authors.initials: JA
authors.lastname: Hey
mesh_terms: D000293:Adolescent; D000320:Adrenergic Fibers / Q000187:drug effects / Q000378:metabolism*; D000328:Adult; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006633:Histamine Antagonists / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009297:Nasal Mucosa / Q000187:drug effects / Q000378:metabolism*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D018100:Receptors, Histamine H3 / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
chemical_list: D006633:Histamine Antagonists; D018100:Receptors, Histamine H3