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H1 Receptor (h1 + receptor)

Distribution by Scientific Domains

Medical Sciences	81%

Kinds of H1 Receptor

histamine h1 receptor

Terms modified by H1 Receptor

h1 receptor antagonist

Selected Abstracts

Development of Amygdaloid Kindling in Histidine Decarboxylase,deficient and Histamine H1 Receptor,deficient Mice

EPILEPSIA, Issue 4 2004
Tadashi Hirai
Summary: Purpose: This study attempted to clarify the role of histamine or histamine H1 receptors in the development of amygdaloid kindling by using histidine decarboxylase (HDC)-deficient and histamine H1 receptor (H1R)-deficient mice. Methods: Under pentobarbital anesthesia, mice were fixed to a stereotaxic apparatus, and bipolar electrodes were implanted into the right amygdala. Electrodes were connected to a miniature receptacle, which was embedded in the skull with dental cement. A bipolar electroencephalogram was recorded; bipolar stimulation of the amygdala was applied every day with a constant-current stimulator and continued until a generalized convulsion was obtained. Results: The development of amygdaloid kindling in HDC-deficient and H1R-deficient mice was significantly accelerated compared with that in their respective wild-type mice. In addition, the afterdischarge (AD) duration and generalized seizure duration in HDC-deficient and H1R-deficient mice were prolonged. Intraperitoneal injection of histidine resulted in an inhibition of amygdaloid kindled seizures in wild-type mice at doses that caused an increase in the histamine contents of the brain. However, no significant effect was observed with histidine in H1R-deficient mice at the same dose. Conclusions: These findings suggest that histaminergic mechanisms through H1 receptors play a crucial role not only in amygdaloid kindled seizures but also in the development of amygdaloid kindling. [source]

Histamine induces neural stem cell proliferation and neuronal differentiation by activation of distinct histamine receptors

JOURNAL OF NEUROCHEMISTRY, Issue 2 2008
Anayansi Molina-Hernández
Abstract Histamine has neurotransmitter/neuromodulator functions in the adult brain, but its role during CNS development has been elusive. We studied histamine effects on proliferation, cell death and differentiation of neuroepithelial stem cells from rat cerebral cortex in vitro. RT-PCR and Western blot experiments showed that proliferating and differentiated cells express histamine H1, H2 and H3 receptors. Treatments with histamine concentrations (100 nM,1 mM) caused significant increases in cell numbers without affecting Nestin expression. Cell proliferation was evaluated by BrdU incorporation; histamine caused a significant increase dependent on H2 receptor activation. Apoptotic cell death during proliferation was significantly decreased at all histamine concentrations, and cell death was promoted in a concentration-dependent manner by histamine in differentiated cells. Immunocytochemistry studies showed that histamine increased 3-fold the number of neurons after differentiation, mainly by activation of H1 receptor, and also significantly decreased the glial (astrocytic) cell proportion, when compared to control conditions. In summary, histamine increases cell number during proliferative conditions, and has a neuronal-differentiating action on neural stem cells, suggesting that the elevated histamine concentration reported during development might play a role in cerebrocortical neurogenesis, by activation of H2 receptors to promote proliferation of neural precursors, and favoring neuronal fate by H1 -mediated stimulation. [source]

Histamine H1 receptor blockade predominantly impairs sensory processes in human sensorimotor performance

BRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2009
P Van Ruitenbeek
Background and purpose:, Centrally active antihistamines impair cognitive performance, particularly sensorimotor performance. The aim of the present study was to further elucidate the scarcely studied subprocesses involved in sensorimotor performance, which may be affected by H1 receptor blockade. Better knowledge about the cognitive deficits associated with histamine dysfunction can contribute to better treatment of clinical disorders in which histamine hypofunction may be a contributing factor, such as in schizophrenia. Experimental approach:, Interactions of dexchlorpheniramine with specific task manipulations in a choice reaction time task were studied. Task demands were increased at the level of sensory subprocesses by decreasing stimulus quality, and at the level of motor subprocesses by increasing response complexity. A total of 18 healthy volunteers (9 female) aged between 18 and 45 years participated in a three-way, double-blind, crossover design. Treatments were single oral doses of 4 mg dexchlorpheniramine, 1 mg lorazepam and placebo. Behavioural effects were assessed by measuring reaction times and effects on brain activity by event-related potentials. Key results:, Dexchlorpheniramine significantly slowed reaction times, but did not significantly interact with task manipulations. However, it did significantly interact with stimulus quality, as measured by event-related potentials. Lorazepam slowed reaction times and interacted with perceptual manipulations, as shown by effects on reaction times. Conclusions and implications:, The results confirm that the histamine system is involved in sensory information processing and show that H1 blockade does not affect motoric information processing. Histamine hypofunction in clinical disorders may cause impaired sensory processing, which may be a drug target. [source]

Desloratadine partially inhibits the augmented bacterial responses in the sinuses of allergic and infected mice

CLINICAL & EXPERIMENTAL ALLERGY, Issue 10 2004
V. Kirtsreesakul
Summary Background Allergic rhinitis (AR) is considered a major predisposing factor for the development of acute bacterial rhinosinusitis. How AR augments a bacterial infection is unknown. Objective Our purpose in this study was to test whether an H1 receptor antagonist, desloratadine, could reduce the augmented effect of an ongoing allergic reaction on acute bacterial rhinosinusitis. Methods Three groups of infected and ovalbumin (OVA)-sensitized mice were studied: (1) infected and allergic mice treated with desloratadine, (2) infected and allergic mice treated with placebo, and (3) infected mice. A fourth group of uninfected, non-sensitized mice served as a control for the cellular changes. BALB/c mice were sensitized by two intraperitoneal injections of OVA given 8 days apart. One day after the second injection, the mice were nasally exposed daily to 6% OVA (the groups treated with desloratadine or placebo) or phosphate-buffered saline (PBS) (the infection-only group) for 5 days. After the second OVA exposure, the mice were intranasally inoculated with Streptococcus pneumoniae. Desloratadine or placebo was given daily throughout the OVA exposure period. Nasal allergic symptoms were observed by counting of nasal rubbing and sneezing for 10 min after OVA or PBS nasal challenge. On day 5 post-infection, nasal lavage culture was done, and the inflammatory cells in the sinuses were evaluated by flow cytometry. Results Mice that were made allergic, infected, and treated with placebo showed more organisms and phagocytes than did only infect mice. They also manifested allergic nasal symptoms and eosinophil influx into the sinuses. Desloratadine treatment during allergen exposure reduced allergic symptoms and reduced sinonasal infection (P<0.05). There tended to be less myeloid cell and neutrophil influx (P=0.09 both), but not eosinophil influx (P=0.85) compared with that in the placebo-treated group. Conclusion Desloratadine treatment during nasal challenge inhibited allergic symptoms and reduced sinonasal infection, suggesting that histamine via an H1 receptor plays a role in the augmented infection in mice with an ongoing allergic reaction. [source]

Effect of H1 -receptor antagonists on proliferative response, cytokine production, and cellular migration of human T cells and macrophages

CLINICAL & EXPERIMENTAL ALLERGY REVIEWS, Issue 2 2008
S. Iwata
Summary Cytokine imbalance and cellular migration to inflammatory sites are critical components of allergic diseases. Redirecting cytokine imbalance and inhibiting cell migration therefore represent important therapeutic strategies for the treatment of these disorders. We studied the in vitro effect of the non-sedating H1 -receptor antagonists ebastine, carebastine, epinastine, cetirizine, and ketotifen on cytokine secretion by human T cells under various co-stimulatory conditions and the migratory activity of activated T cells as well as production of pro-inflammatory cytokines by macrophages. Ebastine and carebastine inhibited T cell proliferation and production of IL-4, IL-5, IL-6, and TNF-, by T cells under co-stimulation with CD28 plus CD3, CD26 plus CD3, and CD3 plus phorbol myristate acetate, whereas these drugs had no effect on the production of IL-2 and IFN-,. Ebastine and carebastine also inhibited T cell migration and production of TNF-, and IL-6 by macrophages. Epinastine inhibited T cell proliferation and production of IL-2, IFN-,, IL-4, and IL-5, whereas it elicited no effect on the production of IL-6 and TNF-, by T cells and macrophages as well as T cell migration. Cetirizine and ketotifen had no effects on cytokine production and T cell migration. Our results suggest that certain H1 -receptor antagonists, most notably ebastine and carebastine, can influence T cell migration and cytokine production in addition to antagonizing the H1 receptor. These drugs therefore might be useful against T cell-mediated allergic inflammatory disorders such as asthma, atopic dermatitis, and psoriasis. [source]

Development of Amygdaloid Kindling in Histidine Decarboxylase,deficient and Histamine H1 Receptor,deficient Mice

Novel Fused Pyrrole Heterocyclic Ring Systems as Structure Analogs of LE 300: Synthesis and Pharmacological Evaluation as Serotonin 5-HT2A, Dopamine and Histamine H1 Receptor Ligands

ARCHIV DER PHARMAZIE, Issue 2 2010
Sherif A. F. Rostom
Abstract LE 300 represents a structurally novel type of antagonists acting preferentially at the dopamine D1/D5 receptors and the serotonin 5-HT2A receptor. This compound consists of a ten-membered central azecine ring fused to an indole ring on one side and a benzene moiety on the other side. To estimate the importance of the indole and / or phenyl moieties in this highly active benz-indolo-azecine, both rings were removed and replaced with a 1H -pyrrole counterpart. Accordingly, some new analogs of LE 300 namely, pyrrolo[2,3- g]indolizine, pyrrolo[3,2- a]quinolizine rings and their corresponding dimethylpyrrolo[2,3- d]azonine, and dimethylpyrrolo[2,3- d]azecine were synthesized to be evaluated for their activity at the 5-HT2A and dopamine D1, D2L, D4, D5 receptors in relation to LE 300. In addition, their activity at the H1 -histamine receptors was also determined. The results suggested that the rigid pyrrolo[2,3- g]indolizine 7 and pyrrolo[3,2- a]quinolizine 8 analogs lacked biological activity in the adopted three bioassays. However, their corresponding flexible pyrrolo[2,3- d]azonine 11 and pyrrolo[2,3- d]azecine 12 derivatives revealed weak partial agonistic activity and weak antagonistic potency at the serotonin 5-HT2A and histamine H1 receptors, respectively. Meanwhile, they showed no affinity to any of the four utilized dopamine receptors. Variation in ring size did not contribute to a significant influence on the three tested bioactivities. Removal of the hydrophobic moiety (phenyl ring) and replacement of the indole moiety with a 1H -pyrrole counterpart led to a dramatic alteration in the profile of activity of such azecine-type compounds. [source]

Pharmacological profile of the new antihistamines

CLINICAL & EXPERIMENTAL ALLERGY REVIEWS, Issue 1 2005
J.-P. Tillement
Summary The second-generation H1 antihistamines are a highly efficacious drug class in the treatment of allergic rhinitis (AR) and dermatitis, and distinct from the first-generation H1 antihistamines, predominantly because of their non-sedating nature at recommended dosages. Despite a marked chemical heterogeneity, the non-sedating H1 antihistamines have many similarities, in particular, high affinity for H1 receptors, high efficacy, anti-inflammatory effects, which may be independent of direct H1 -receptor function, and lack of central nervous system side-effects. Some studies have suggested that differences in the chemical structures of these compounds generally lead to differences in the pharmacokinetic properties, which determine their overall clinical usefulness. In particular, it has been demonstrated that there are differences in selectivity for H1 receptors, the apparent volume of distribution, metabolism and elimination and interaction with other drugs. A comparison of levocetirizine, fexofenadine, desloratadine and mizolastine (some of the most commonly prescribed drugs in the treatment of AR and dermatitis) has demonstrated that, unlike levocetirizine and fexofenadine, desloratadine and mizolastine can bind to muscarinic receptors and cardiac K+ channels, and therefore have both lower selectivity and the potential to induce muscarinic and serious cardiac side-effects. However, this is noted at higher than recommended doses. Similarly, desloratadine and mizolastine undergo extensive metabolism and, together with fexofenadine, have the potential to interact with other drugs, in turn increasing the potential for severe toxic effects. In contrast, levocetirizine is not metabolized, is eliminated rapidly from the body, does not demonstrate any significant drug interactions and has the lowest volume of distribution. These findings suggest that levocetirizine is likely to be a safer drug than fexofenadine, desloratadine and mizolastine. [source]