title: Effects of histamine and related compounds on regional cerebral blood flow in rats.
abstract: The effects of histamine and related compounds on regional cerebral blood flow (rCBF) in the hippocampus of conscious rats were studied. Intracerebroventricular injection of histamine caused a dose-dependent increase in rCBF in the hippocampus, and similar findings were observed with not only the H1 agonist, 2-thiazolylethylamine, but also the H2 agonist, dimaprit. Intraperitoneal injection of L-histidine also resulted in an increase in rCBF in the hippocampus, in parallel with elevation of histamine content in the brain. The increase in rCBF in the hippocampus induced by L-histidine was antagonized by both H1 and H2 antagonists (diphenhydramine, pyrilamine and zolantidine). In addition, when both antagonists were injected simultaneously, an additive effect was observed in antagonism of the L-histidine-induced increase in rCBF. L-Histidine caused no marked changes in blood pressure even at a dose of 1,500 mg/kg, which showed an increase in rCBF in the hippocampus. These results indicate that histamine elicited an increase in rCBF via both H1 and H2 receptors.
authors.affiliation: Department of Pharmacology, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
authors.forename: G
authors.initials: G
authors.lastname: Suzuki
authors.forename: Z
authors.initials: Z
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: Y
authors.initials: Y
authors.lastname: Fujii
authors.forename: C
authors.initials: C
authors.lastname: Kamei
mesh_terms: D000818:Animals; D052160:Benzothiazoles; D001794:Blood Pressure / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects*; D017259:Dimaprit / Q000494:pharmacology; D004155:Diphenhydramine / Q000494:pharmacology; D004347:Drug Interactions; D006624:Hippocampus / Q000098:blood supply*; D006632:Histamine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D017442:Histamine Agonists / Q000494:pharmacology*; D006633:Histamine Antagonists / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D006639:Histidine / Q000494:pharmacology; D008297:Male; D050198:Phenoxypropanolamines; D010880:Piperidines / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects*; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors
chemical_list: D052160:Benzothiazoles; D017442:Histamine Agonists; D006633:Histamine Antagonists; D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D050198:Phenoxypropanolamines; D010880:Piperidines; D013844:Thiazoles; C029345:2-(2-aminoethyl)thiazole; D006639:Histidine; D006632:Histamine; D004155:Diphenhydramine; D011738:Pyrilamine; C055302:zolantidine; D017259:Dimaprit