Central histaminergic mechanisms mediate the vasopressin-induced pituitary adrenocortical stimulation.
Involvement of histamine receptors and hypothalamic and hippocampal histamine in stimulation of the hypothalamic-pituitary-adrenal (HPA) axis by vasopressin (AVP) was investigated in conscious rats. The HPA activity was assessed by measuring serum corticosterone levels. One hour after administration AVP, (5 micrograms/kg) given i.p. significantly raised the serum corticosterone and hippocampal histamine levels, while the hypothalamic histamine content was not affected. Pretreatment with the inhibitor of the brain histamine synthesis alpha-fluoromethylhistidine (alpha-FMH) (50 mg/kg i.p.) considerably reduced both the AVP-elicited serum corticosterone response and the hypothalamic and hippocampal histamine levels. The histamine H1- and H2-receptor-antagonists mepyramine (0.01 mg/kg) and ranitidine (0.1 mg/kg), given ip 15 min prior to AVP, significantly impaired the AVP-induced rise in the serum corticosterone level and totally abolished the AVP-elicited increase in the histamine content in the hippocampus; moreover mepyramine significantly lowered this content in hypothalamus. Pretreatment with the histamine H3-receptor antagonist thioperamide (5 mg/kg i.p.) also significantly decreased the AVP-elicited corticosterone response, but did not alter the histamine content in either brain structure examined. These results indicate that central histamine H1-, H20 and H3-receptors significantly mediate the stimulatory action of AVP on the pituitary-adrenocortical axis. Hippocampal histamine may be involved in mediation of the AVP-induced effect via H1- and H2-receptors. The inhibitory effect of thioperamide seems to be located directly at non H3-intracellular sites of the pituitary-adrenocortical axis.
Bugajski
J
J
Department of Physiology, Polish Academy of Sciences, Cracow, Poland.
Gadek-Michalska
A
A
Ołowska
A
A
Borycz
J
J
Głód
R
R
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D003345:Corticosterone / Q000097:blood; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006632:Histamine / Q000378:metabolism; D006633:Histamine Antagonists / Q000494:pharmacology; D006640:Histidine Decarboxylase / Q000037:antagonists & inhibitors; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008762:Methylhistidines / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011968:Receptors, Histamine / Q000187:drug effects / Q000502:physiology*
D004791:Enzyme Inhibitors; D006633:Histamine Antagonists; D008762:Methylhistidines; D010880:Piperidines; D011968:Receptors, Histamine; D001127:Arginine Vasopressin; C028309:alpha-fluoromethylhistidine; D006632:Histamine; D000324:Adrenocorticotropic Hormone; D006640:Histidine Decarboxylase; C052075:thioperamide; D003345:Corticosterone