Study was made of the developmental mechanism of histamine induced ulcers and inhibitory effects of receptor antagonists from the view point of gastric acidity and microvasculature of the gastric mucosa, and the following results were obtained. 1. In histamine induced ulcers, hypersecretion of gastric acid caused by histamine is not the primary developmental mechanism of the lesion. The main ca...

A novel histamine receptor subtype, histamine H(3) receptor, mediates inhibition of peripheral autonomic neurotransmission. The present study was designed to examine vascular effects of histamine H(3) receptor by using a selective histamine H(3) receptor agonist, R-(-)-alpha methylhistamine (alpha-methylhistamine), in rat mesenteric resistance arteries. The isolated mesenteric vascular beds wer...

Atypical antipsychotics such as clozapine and olanzapine have been shown to enhance histamine turnover and this effect has been hypothesized to contribute to their improved therapeutic profile compared to typical antipsychotics. In the present study, we examined the effects of antipsychotic drugs on histamine (HA) efflux in the mPFC of the rat by means of in vivo microdialysis and sought to dif...

The precise mechanism(s) underlying the thermal hyperemic response to local heating of human skin are not fully understood. The purpose of this study was to investigate a potential role for H1 and H2 histamine-receptor activation in this response. Two groups of six subjects participated in two separate protocols and were instrumented with three microdialysis fibers on the ventral forearm. In bo...

Leukotriene B(4) (LTB(4)) is a potent leukocyte chemoattractant recently implicated in the pathogenesis of atherosclerosis. The aim of this study was to assess the effects of LTB(4) on isolated aortic preparations. Rings of guinea pig aorta were challenged with LTB(4) for recording mechanical responses and measurements of mediator release, and LTB(4) receptor (BLT(1)) expression was assessed by...

The possible role of histamine sensitive sites in hippocampus and the nucleus accumbens on memory and exploratory motivation was studied. As a model of memory, the learning of an active avoidance response to an ultrasonic tone anticipating an electric shock was used. As a model of motivation, an elevated asymmetric plus-maze with arms differing in the presence or absence of walls (APM) was used...

The role of histamine in the regulation of food and water intake in mammals and birds of the review, this study evaluated the effects of intraperitoneal administration of famotidine as histamine H2 -receptor antagonist, in broiler chicks on feed intake and satiety in water and was hungry. 32 male Ross broiler chicks reared in groups of four weeks, 16 samples (control and test ) were then inject...

PURPOSE Based on the close relationship between histamine and interleukin 6 (IL-6), we hypothesized that histamine may regulate the production of cytokines, such as IL-6, during allergic inflammation. Here, we examined the role of histamine in IL-6 production and histamine receptor activity in nasal fibroblasts, along with the mechanisms underlying these effects. METHODS Experiments were perf...

To evaluate the ability of histamine to induce ventricular arrhythmias, we studied the effects of histamine on ventricular rhythmicity in the isolated guinea pig heart with complete atrioventricular conduction block. As a function of dose (0.1-30 microgram), histamine enhanced the idioventricular rate by increasing the rate of firing of the original pacemaker and also by causing the sudden appe...

Antihistamines, more formally termed H1 receptor antagonists, are well known to exert sedative effects in humans, yet their locus and mechanism of action in the human brain remains unknown. To better understand this phenomenon, the effects of histamine upon human cortical neurons were studied using intracellular recordings in brain slices maintained in vitro. Bath application of 50 microM hista...