Serotonin [5-hydroxytryptamine (5-HT)] is released from enterochromaffin cells in the mucosa of the small intestine. We tested a hypothesis that elevation of 5-HT in the environment of enteric mast cells might degranulate the mast cells and release mediators that become paracrine signals to the enteric nervous system, spinal afferents, and secretory glands. Western blotting, immunofluorescence,...

Ciproxifan, i.e., cyclopropyl-(4-(3-1H-imidazol-4-yl)propyloxy) phenyl) ketone, belongs to a novel chemical series of histamine H3-receptor antagonists. In vitro, it behaved as a competitive antagonist at the H3 autoreceptor controlling [3H]histamine release from synaptosomes and displayed similar Ki values (0.5-1.9 nM) at the H3 receptor controlling the electrically-induced contraction of guin...

The histamine H4 receptor (H4R) was first noted as a sequence in genomic databases that had features of a class A G-protein coupled receptor. This putative receptor was found to bind histamine consistent with its homology to other histamine receptors and thus became the fourth member of the histamine receptor family. Due to the previous success of drugs that target the H1 and H2 receptors, an e...

One mechanism of histamine-mediated inhibition of the immune response in man is to activate T suppressor cells that bear the Leu 2 (OKT8) marker. The current study was undertaken to characterize the histamine-induced suppressor cell using a monoclonal antibody (9.3) shown previously to distinguish cytotoxic T cells from antigen-specific suppressor T cells. Leu 2+ cells isolated from peripheral ...

The effects of ranitidine, a new H2-receptor antagonist which does not contain an imidazole ring, and cimetidine have been determined on histamine, meal-induced gastric acid secretion, and serum gastrin levels in duodenal ulcer patients. Compared with cimetidine, ranitidine was found to be about eight times more potent an inhibitor of histamine-induced secretion and four to five times more pote...

Histaminergic neurons play an important role in the regulation of sleep-wake behavior through histamine H(1) receptors (H(1)R). Blockade of the histamine H(3) receptor (H(3)R) is proposed to induce wakefulness by regulating the release of various wake-related transmitters, not only histamine. In the present study, we characterized sleep-wake cycles of H(1)R knockout (KO) mice and their arousal ...

Histamine affects pancreatic secretion, but its direct action on ion transport by pancreatic duct epithelial cells (PDEC) has not been defined. We now characterize the secretory effects of histamine on cultured, well-differentiated, and nontransformed dog PDEC. Histamine stimulated, in a concentration-dependent manner (1-100 μM), a cellular125I-efflux that was inhibited by 500 μM 5-nitro-2-(3-p...

The medical mechanism against type I allergies is to block the release or production of chemical mediators from mast cells or to block the H(1)-receptor signaling. We previously reported that the anti-allergic action of the dry powder from Bidens pilosa L. var. radiata SCHERFF treated with the enzyme cellulosine (eMMBP) was dependent on the inhibition of histamine release from mast cells. Here,...

Histamine receptors are present on the surface of various normal and tumor-derived cell types, where their biological function is incompletely understood. Here we report that histamine not only stimulates cell proliferation under serum-free conditions, but also is chemotactic for human carcinoma (Hela and A431) and melanoma (A875) cells expressing H1 type receptors. Histamine was found to be a ...

introduction: anxiety is among the most common and treatable mental disorders. adrenergic and cannabinoid systems have an important role in the neurobiology of anxiety. the elevated plus-maze (epm) has broadly been used to investigate anxiolytic and anxiogenic compounds. the present study investigated the effects of intraperitoneal (ip) injection of cannabinoid cb1 receptor antagonist (am251) i...