Search results
Results From The WOW.Com Content Network
The role of histamine in health and disease is an area of ongoing research. For example, histamine is researched in its potential link with migraine episodes, when there is a noted elevation in the plasma concentrations of both histamine and calcitonin gene-related peptide (CGRP).
Histamine release in the brain triggers secondary release of excitatory neurotransmitters such as glutamate and acetylcholine via stimulation of H 1 receptors in the cerebral cortex. Consequently, unlike the H 1 -antihistamines which are sedating, H 3 -antihistamines have stimulant and cognition-modulating effects.
H 1 antagonists, also called H 1 blockers, are a class of medications that block the action of histamine at the H 1 receptor, helping to relieve allergic reactions.Agents where the main therapeutic effect is mediated by negative modulation of histamine receptors are termed antihistamines; other agents may have antihistaminergic action but are not true antihistamines.
Histamine is a weak base (a compound able to react with a hydrogen ion to form an acid) that can link with acid groups within the granules of the mast cells. [8] The mechanism of the displacement theory. The crux of this theory lies in the assumption that histamine liberators release histamine by displacing it from cells.
A histamine agonist is a drug which causes increased activity at one or more of the four histamine receptor subtypes. H 1 agonists promote wakefulness. [1] H 2: Betazole and Impromidine are examples of agonists used in diagnostics to increase histamine. H 3: Betahistine is a weak Histamine 1 agonist and a very strong antagonist of the Histamine ...
Type I hypersensitivity can be further classified into immediate and late-phase reactions. Within minutes of exposure to an antigen, the immediate hypersensitivity occurs, releasing histamines and lipid mediators which are responsible for the initial allergic reaction response.
Histamine is a ubiquitous messenger molecule released from mast cells, enterochromaffin-like cells, and neurons. [5] Its various actions are mediated by histamine receptors H 1, H 2, H 3 and H 4. The histamine receptor H 2 belongs to the rhodopsin-like family of G protein-coupled receptors.
Histaminergic means "working on the histamine system", and histaminic means "related to histamine". [1] A histaminergic agent (or drug) is a chemical which functions to directly modulate the histamine system in the body or brain. Examples include histamine receptor agonists and histamine receptor antagonists (or antihistamines).