title: Rodent antinociception following acute treatment with different histamine receptor agonists and antagonists.
abstract: The effects of different histamine receptor agonists and antagonists on the nociceptive threshold were investigated in mice by two different kinds of noxious stimuli: thermal (hot plate) and chemical (acetic acid-induced abdominal writhing). Intracerebroventricular (icv) injection of the histamine H(1) receptor agonist, HTMT (6-[2-(4-imidazolyl)ethylamino]-N-(4-trifluoromethylphenyl) heptanecarboxamide) (50 microg/mouse), produced a hypernociception in the hot plate and writhing tests. Conversely, intraperitoneal (ip) injection of dexchlorpheniramine (30 and 40 mg/kg) and diphenhydramine (20 and 40 mg/kg) increased the pain threshold in both tests. The histamine H(2) receptor agonist, dimaprit (50 and 100 microg/mouse icv), or antagonist, ranitidine (50 and 100 microg/mouse icv), raised the pain threshold in both hot plate and writhing tests. In the mouse hot plate test, the histamine H(3) receptor agonist, imetit (50 mg/kg ip), reduced the pain threshold, while the histamine H(3) receptor antagonist, thioperamide (10 and 20 mg/kg ip), produced an antinociception. The hypernociceptive effects of HTMT and imetit were antagonized by dexchlorpheniramine (20 mg/kg ip) and thioperamide (5 mg/kg ip), respectively. The results suggest that histaminergic mechanisms may be involved in the modulation of nociceptive stimuli.
authors.affiliation: Department of Pharmacology, School of Medicine, Mazandaran University of Medical Sciences, Sari 48168, Iran. davoodfarzin@yahoo.com
authors.forename: Davood
authors.initials: D
authors.lastname: Farzin
authors.forename: Ladan
authors.initials: L
authors.lastname: Asghari
authors.forename: Mahvash
authors.initials: M
authors.lastname: Nowrouzi
mesh_terms: D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D017442:Histamine Agonists / Q000494:pharmacology*; D006633:Histamine Antagonists / Q000494:pharmacology*; D008297:Male; D051379:Mice; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects* / Q000502:physiology; D011968:Receptors, Histamine / Q000502:physiology*
chemical_list: D000700:Analgesics; D017442:Histamine Agonists; D006633:Histamine Antagonists; D011968:Receptors, Histamine