Receptor affinity and drug delivery to the receptor sites could be determinant factors for the increased bronchial responsiveness seen in asthma. Competitive antagonism blockade which is measured as dose ratio-l (DR-I) depends only on these two factors. Therefore, in this study we have examined histamine HI blockade by chlorpheniramine on isolated tracheal chains of asthmatic compared to co...

In the present study, the effects of intracerebroventricular (ICV) injections of histamine, chlorpheniramine (H1-receptor antagonist) and ranitidine (H2-receptor antagonist) were investigated on visceral nociception induced by an intraperitoneal (IP) injection of acetic acid in rats. The latency time to the beginning of the first abdominal wall contraction (the first writhe) was recorded and th...

in the present study, the effects of intracerebroventricular (icv) injections of histamine, chlorpheniramine (h1-receptor antagonist) and ranitidine (h2-receptor antagonist) were investigated on visceral nociception induced by an intraperitoneal (ip) injection of acetic acid in rats. the latency time to the beginning of the first abdominal wall contraction (the first writhe) was recorded and th...

conclusions cyclosom and histamine synergistically exert catalepsy in old rats. in light of these data, the combination of the decreased brain level of somatostatin and increased brain level of histamine may be of pathogenic relevance for extrapyramidal signs in pd. results cyclosom (0.2, 1.0, and 5.0 µg) and histamine (1.0 and 10.0 µg) alone were ineffective in both young and old animals. in c...

the effects of some histaminergic agents were evaluated on stress- induced immunosuppression in immunized nale rats. in rat immunized with sheep red blood cells ( srbcs). restraint stress (rs) prevented the booster-induced rise in anti-srbc antibody titre and cell immunity response. intracerebroventicular (i.c>v) injection of histamine (150 µg/rat) induced a similar effect with rs. pretreatment...

  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...

Restraint-induced stress (RS) increases histamine concentration in the brain. There is no previous report regarding the role of histamine receptors in immunomodulatory effect of RS. In the present study the role of brain histamine receptors on reduction of humoral and cellular immune function induced by RS was evaluated. For this purpose male Wistar rats (200-250 g) were immunized with sheep re...

The histamine H4 receptor is a novel G-protein-coupled receptor with a unique pharmacological profile. The distribution of H4 mRNA suggests that it may play a role in the regulation of immune function, particularly with respect to allergy and asthma. To define the histamine-binding site of this receptor, molecular modeling and site-directed mutagenesis were used to predict and alter amino acids...