Involvement of central H1 and H2 receptors in water intake induced by hyperosmolarity, hypovolemia and central cholinergic stimulation.
In the present study we investigated the participation of central H1 and H2 histaminergic receptors in water intake induced by hyperosmolarity (evoked by intragastric salt load), by hypovolemia (promoted by the subcutaneous administration of polyethyleneglycol) and by the pharmacological stimulation of central cholinergic pathways by the muscarinic agonist carbachol in male Wistar rats. The data presented here show that the pharmacological blockade of central H1 histaminergic receptors by third ventricle injections of mepyramine significantly decreased water intake induced by hyperosmolarity, hypovolemia and by the intracerebroventricular injections of carbachol. On the other hand, the pharmacological blockade of central H2 histaminergic receptors by third ventricle injections of cimetidine significantly reduced water intake in hypovolemic and hyperosmotic animals, but failed to alter water intake induced by central cholinergic stimulation by carbachol. We conclude that H1 and H2 brain histaminergic receptors are involved in inducing thirst during hyperosmolarity and hypovolemia and that H1 histaminergic receptors located post-synaptically in relation to cholinergic pathways seem to be important in triggering drinking following central pharmacological cholinergic stimulation.
Magrani
Janeide
J
Department of Physiology, Health Sciences Institute, Federal University of Bahia, 40110-100 Salvador-Bahia, Brazil.
de Castro E Silva
Emilio
E
Athanazio
Rodrigo
R
Improta
Lilia
L
Fregoneze
Josmara B
JB
D000818:Animals; D001810:Blood Volume / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D002799:Cholinergic Fibers / Q000187:drug effects / Q000502:physiology*; D004326:Drinking / Q000502:physiology*; D020896:Hypovolemia / Q000503:physiopathology; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D011969:Receptors, Histamine H1 / Q000502:physiology*; D011970:Receptors, Histamine H2 / Q000502:physiology*; D013894:Thirst / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000502:physiology*
D018679:Cholinergic Agonists; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D002217:Carbachol