Clozapine and olanzapine behave as weak H3-receptor antagonists in vitro with Ki values around 1 and 50 microM, respectively. Despite these modest apparent affinities, both compounds given orally to mice, nearly doubled steady-state tele-methylhistamine levels in brain, with ED50 values as low as 1 and 3 mg/kg, respectively, an effect comparable to those of potent H3-receptor antagonists. This ...

Histamine Hi and H2 receptors are present in the canine renal circulation. We have examined the effects of H, and H2 receptor antagonists on autoregulation of renal blood flow in the dog. Renal arterial pressure was reduced in a step-wise fashion to 80 mm Hg by means of an adjustable aortic clamp positioned above the left renal artery. Infusion of H2 antagonists, cimetidine or ranitidine, into ...

The present study suggests that newly synthesized histamine is involved in the development of some animal tumors (e.g., Lewis lung carcinoma in mice and Morris hepatoma in rats). A marked induction of histidine decarboxylase (HOC) and an in crease in the histamine concentration were observed in the tumors approximately 1 week after inoculation, and there were parallel increases in ornithine dec...

Previous studies have shown that histamine is able to modulate the function of dendritic cells (DCs). Histamine seems to be required for the normal differentiation of DCs. Moreover, it is capable of stimulating the chemotaxis of immature DCs and of promoting the differentiation of T CD4+ cells into a Th2 profile. In this study, we analyzed whether histamine was able to modulate endocytosis and ...

Histamine and tumor necrosis factor alpha (TNF-alpha) can each contribute to the pathogenesis of allergic reactions and chronic inflammatory diseases. We now report the effect of histamine on gene expression and total cellular synthesis of TNF-alpha. Lipopolysaccharide (LPS)-induced synthesis of TNF-alpha in peripheral blood mononuclear cells (PBMC) from 18 healthy donors was suppressed by hist...

A role of IL-18 in the induction of gastric lesions by water immersion and restraint stress (WRS) was investigated. When wild-type BALB/c mice were exposed to WRS, levels of IL-18 in the serum and stomach increased rapidly with the development of acute gastric lesions. In IL-18-deficient mice [IL-18 knockout (KO) mice] similarly exposed to WRS, no gastric lesions were observed, but the administ...

Toreforant is a potent and selective histamine H4 receptor (H4R) antagonist with a Ki at the human receptor of 8.4 ± 2.2 nM and excellent selectivity over other receptors including the other histamine receptors. The compound acts as an antagonist in all species tested and inhibits histamine-induced eosinophil shape change in vitro. Toreforant was anti-inflammatory in mouse models of asthma and ...

Cl(-) efflux induces depolarization and contraction of smooth muscle cells. This study was undertaken to explore the role of Cl(-) flux in histamine-induced contraction in the rabbit basilar artery. Male New Zealand White rabbits (n = 16) weighing 1.8-2.5 kg were euthanized by an overdose of pentobarbital sodium. The basilar arteries were removed for isometric tension recording. Histamine produ...

background and objective: host genetic factors such as cytokine gene polymorphisms as well as helicobacter pylori (h. pylori) infection have been found to be associated with gastric cancer risk . interleukin 1 is a pro-inflammatory cytokine involved in h. pylori-induced gastric inflammation. therefore, we analyzed the association between il-1β and il-1-rn polymorphisms and gastric cancer in per...

The effects of both an H1 receptor antagonist and an H2 receptor antagonist on changes in monovalent ion flux induced by topical sodium taurocholate were studied in antrectomised dogs fashioned with a denervated fundic pouch. The magnitude of taurocholateinduced ion flux was unaffected by topical administration of H1 or H2 receptor antagonists. Parenteral administration of H1 or H2 receptor ant...