Using specific histamine H1 and H2 receptor antagonists, evidence is presented for the existence of both H1 and H2 receptors on human articular chondrocytes in vitro. Stimulation of the H1 receptor by histamine (range 0.18 to 17.8 mumol/l) significantly increased prostaglandin E (PGE) production, while activation of the histamine H2 receptor increased intracellular cyclic adenosine-5'-monophosp...

the aim of the present study was to investigate whether and by which mechanism; histamine can induce state-dependent retrieval of passive avoidance task. the pre-training or pre-test intracerebroventricular (i.c.v.) injection of histamine (20µg/mouse) impaired retrieval, when it was tested 24 h later. in the animals, which retrieval was impaired due to histamine pre-training administration, pre...

The preoptic area/anterior hypothalamus, a region that contains neurons that control thermoregulation, is the main locus at which histamine affects body temperature. Here we report that histamine reduced the spontaneous firing rate of GABAergic preoptic neurons by activating H3 subtype histamine receptors. This effect involved a decrease in the level of phosphorylation of the extracellular sign...

In the present study, the effects of intracerebroventricular (ICV) administration of normal saline (control), histamine, mepyramine (a histamine H1-receptor antagonist) and ranitidine (a histamine H2-receptor antagonist) were investigated on the formalin-induced pain in rabbits. Subcutaneous (SC) injection of a formalin (100 μl, 5%) solution into the ventral surface of the right hind paw was pe...

Histamine is present in high concentrations in the intestine and we investigated the possibility that it might have a role here in intestinal transport. When added to the basal side of rabbit ileal mucosa in vitro histamine (10(-4)M) induced a short-lived increase in electrical potential difference and short circuit current. It inhibited net chloride absorption but did not influence sodium tran...

Histamine H1 receptors mediate activation of phospholipase C, with subsequent increases in cytosolic Ca2+ concentration ([Ca2+]i), and H2 receptors mediate accumulation of cAMP. HL-60 promyelocytes possess H2 receptors, but it is not known whether these cells also possess H1 receptors. We studied the effects of histamine on [Ca2+]i and the functional importance of histamine receptors in HL-60 p...

objective: the nucleus accumbens (nac) receive histaminergic neurons from tuberomammillary nuclei. there are reports indicating that central histamine systems are involved in many physiological behavioral processes, including anxiety. the aim of the present study was to assess whether the histaminergic system of the nac is involved in anxiety-related behaviors. methods:   rats   were   anesthet...

  Objective(s): The present study investigated the effects of microinjection of histamine and histamine H1, H2, and H3 receptor antagonists, chlorpheniramine, ranitidine and thioperamide, respectively into the primary somatosensory cortex (PSC) on inflammatory pain.   Material and Methods: Two stainless steel guide canulas were bilaterally implanted into the PSC of anaesthetized rats. Inf...

We evaluated changes in the binding properties of sedative and non-sedative histamine H1-receptor antagonists induced by internalization of H1 receptors in intact human U373 MG astrocytoma cells. Internalization of H1 receptors was induced without their degradation by treatment with 0.1 mM histamine for 30 min at 37 degrees C, and then the intact cell binding assay was performed at 4 degrees C....

BACKGROUND Histamine drives pruritus in allergic skin diseases which clinically constitutes a most disruptive symptom. Skin pathology in allergic skin diseases is crucially influenced by different T-helper subsets. However, the contribution of different histamine-receptors to T-helper cell dependent skin pathology has not been definitively answered. Models which can specifically address the fun...