title: Centrally injected histamine increases posterior hypothalamic acetylcholine release in hemorrhage-hypotensive rats.
abstract: Histamine, acting centrally as a neurotransmitter, evokes a reversal of hemorrhagic hypotension in rats due to the activation of the sympathetic and the renin-angiotensin systems as well as the release of arginine vasopressin and proopiomelanocortin-derived peptides. We demonstrated previously that central nicotinic cholinergic receptors are involved in the pressor effect of histamine. The aim of the present study was to examine influences of centrally administrated histamine on acetylcholine (ACh) release at the posterior hypothalamus-a region characterized by location of histaminergic and cholinergic neurons involved in the regulation of the sympathetic activity in the cardiovascular system-in hemorrhage-hypotensive anesthetized rats. Hemodynamic and microdialysis studies were carried out in Sprague-Dawley rats. Hemorrhagic hypotension was induced by withdrawal of a volume of 1.5 ml blood/100 g body weight over a period of 10 min. Acute hemorrhage led to a severe and long-lasting decrease in mean arterial pressure (MAP), heart rate (HR), and an increase in extracellular posterior hypothalamic ACh and choline (Ch) levels by 56% and 59%, respectively. Intracerebroventricularly (i.c.v.) administered histamine (50, 100, and 200 nmol) dose- and time-dependently increased MAP and HR and caused an additional rise in extracellular posterior hypothalamic ACh and Ch levels at the most by 102%, as compared to the control saline-treated group. Histamine H1 receptor antagonist chlorpheniramine (50 nmol; i.c.v.) completely blocked histamine-evoked hemodynamic and extracellular posterior hypothalamic ACh and Ch changes, whereas H2 and H3/H4 receptor blockers ranitidine (50 nmol; i.c.v.) and thioperamide (50 nmol; i.c.v.) had no effect. In conclusion, centrally administered histamine, acting via H1 receptors, increases ACh release at the posterior hypothalamus and causes a pressor and tachycardic response in hemorrhage-hypotensive anesthetized rats.
authors.affiliation: Department of Physiology, Faculty of Veterinary Medicine, Uludag University, Bursa 16059, Turkey.
authors.forename: Burcin
authors.initials: B
authors.lastname: Altinbas
authors.affiliation: Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Uludag University, Bursa, 16059, Turkey.
authors.forename: Mustafa S
authors.initials: MS
authors.lastname: Yilmaz
authors.affiliation: Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Uludag University, Bursa, 16059, Turkey.
authors.forename: Vahide
authors.initials: V
authors.lastname: Savci
authors.affiliation: Department of Basic Medical Sciences, School of Public Health, Medical University of Silesia, Bytom 41-902, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Jochem
authors.affiliation: Department of Physiology, Faculty of Veterinary Medicine, Uludag University, Bursa 16059, Turkey. Electronic address: muraty@uludag.edu.tr.
authors.forename: Murat
authors.initials: M
authors.lastname: Yalcin
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002744:Chlorpheniramine / Q000494:pharmacology; D002794:Choline / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006470:Hemorrhage / Q000188:drug therapy / Q000209:etiology / Q000473:pathology; D006632:Histamine / Q000627:therapeutic use*; D017442:Histamine Agonists / Q000627:therapeutic use*; D006633:Histamine Antagonists / Q000494:pharmacology; D007022:Hypotension / Q000150:complications*; D007034:Hypothalamus, Posterior / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D017442:Histamine Agonists; D006633:Histamine Antagonists; D010880:Piperidines; D002744:Chlorpheniramine; D006632:Histamine; C052075:thioperamide; D002794:Choline; D000109:Acetylcholine
keywords: Acetylcholine; Brain histamine; Choline; Heart rate; Hemorrhagic shock; Intracerebroventricular; Mean arterial pressure; Microdialysis; Posterior hypothalamus