The effects of histamine on the concentrations of immunoreactive thyrotropin-releasing hormone in the stomach and hypothalamus in rats.
The effects of histamine and its related compounds on the concentrations of immunoreactive thyrotropin-releasing hormone (ir-TRH) in the stomach, gastric juice and hypothalamus in rats were studied. Histamine, ranitidine or ethanolamine was injected intraperitoneally, and the rats were decapitated at various times after the injection. Ir-TRH concentrations in the stomach, gastric juice and hypothalamus were measured by a radioimmunoassay. Ir-TRH concentrations in the stomach decreased significantly after histamine injection and increased significantly after ranitidine injection in a dose-dependent manner, but did not change with ethanolamine. Ir-TRH concentrations in the gastric juice increased in a dose-dependent manner, peaking at 30 min after histamine injection, and its effect was blocked with ranitidine. Ir-TRH concentrations in the hypothalamus elevated significantly after histamine injection and reduced significantly after ranitidine injection, but did not change with ethanolamine. The effects of histamine on ir-TRH concentrations in the stomach and hypothalamus were significantly blocked with ranitidine, but not with ethanolamine. These findings suggest that histamine stimulates ir-TRH release from the stomach and inhibits ir-TRH release from the hypothalamus, and that these effects of histamine on ir-TRH release are mediated via an H2-receptor.
Nakada
K
K
Fourth Department of Internal Medicine, Aichi Medical University, Japan.
Mitsuma
T
T
Furusawa
A
A
Maeda
Y
Y
Morise
K
K
D000818:Animals; D019856:Ethanolamine; D004983:Ethanolamines; D005750:Gastric Juice / Q000737:chemistry; D006632:Histamine / Q000494:pharmacology*; D007031:Hypothalamus / Q000737:chemistry*; D008297:Male; D011863:Radioimmunoassay; D011899:Ranitidine; D051381:Rats; D011919:Rats, Inbred Strains; D013270:Stomach / Q000737:chemistry*; D013973:Thyrotropin-Releasing Hormone / Q000187:drug effects* / Q000378:metabolism
D004983:Ethanolamines; D019856:Ethanolamine; D013973:Thyrotropin-Releasing Hormone; D006632:Histamine; D011899:Ranitidine