The role of central histamine H1- and H2-receptors in hypothermia induced by histamine in the rat.
Histamine administered intraventricularly or into the anterior hypothalamic preoptic region induced dose-dependent hypothermia in rats with chronic i.c.v. cannula. This hypothermia was almost totally abolished by both the histamine H1- and H2-receptor antagonists, mepyramine or chloropyramine and metiamide or cimetidine, respectively, give i.c.v. prior to histamine. In behavioural thermoregulation studies histamine considerably diminished the mean duration of dwelling of the rat under the heat lamp. This effect was abolished by histamine H1- but not by H2-receptor antagonists. It is concluded that histamine induces hypothermia by lowering the set point of the hypothalamic thermostat by means of H1-receptors. Histamine H2-receptor blockers antagonized the increase in tail skin temperature after histamine administration, suggesting that h2-receptors are involved in a heat loss mechanism.
D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D001833:Body Temperature Regulation / Q000187:drug effects; D001921:Brain / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011968:Receptors, Histamine / Q000502:physiology*; D011969:Receptors, Histamine H1 / Q000502:physiology*; D011970:Receptors, Histamine H2 / Q000502:physiology*; D012879:Skin Physiological Phenomena
D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D006632:Histamine