Histamine is an organic nitrate compound (Formed from amino acid histidine), which is involved in:
Immune response (allergic and immune response)
Resulting physiological function
Acting as a neurotransmitter
It is a naturally occurring imidazole derivatives.
It is produced by endogenously by decarboxylation of amino acid histidine in the presence of enzyme histidine decarboxylase.
Histidine is stored in the granules of mast cells, basophils and histaminergic neuron of CNS.
The highest concentration of histamine is present in lungs, skin, mucosal layer of GIT and intestine, liver and placenta. Histamine is also present in blood, most body secretions, venoms and pathological fluids.
Synthesis of Histamine
It is synthesized locally from the amino acid histidine by the enzyme histidine decarboxylase. It is degraded by oxidation and methylation.
Release of histamine
Allergies and anaphylaxis trigger significant release of histamine
When allergies enter into the body that results trigger immune cells to produce large IgE.
Some IgE attaches to the surface of mast cell (sensitized). On any subsequent exposer to the same allergen, the allergen interact with the specific IgE on the surface of the mast cells.
In response, the activated mast cell rapidly release histamine.
Stimulate and release of Adr, which can cause rise in BP.
Intracerebroventricular administration produce rise in BP, cardiac stimulation, behavioral arousal, hypothermia, vomiting and anti-diuretic hormone (ADH) release.
There is no effect on administration i.v.
Histamine does not penetrate BBB.
Histamine stimulate HCL secretion in the stomach.
Histamine is released locally under the influence of all stimuli that evoke gastric secretion and activate the proton pump (H+K+ ATPase). (Stimuli: Cholinergic drugs, Gastrin, vagal secretion, prostaglandin).
H2 blocker diminish the acid secretion and also suppress the action of Ach and gastrin.
Release of histamine from mast cell causes AG-AB reaction on their surface and immediate types of hypersensitivity reaction like urticarial, angioedema, bronchoconstriction and anaphylactic shock produce.
H1 receptor inhibit the action of hypersensitivity.
Histamine is the afferent transmitter which initiate the secretion of itch and pain at sensory nerve ending.
Histamine produce vasodilatation effect during inflammation.
Tissue growth and repair
Histamine is present in high concentration at growing and regenerating tissue, hence it play an important role of growth and repair.
Vascular headache but no convulsion occur.
Uses of histamine:
the uses of histamine is not used recently, but some oldest techniques are used as below:
Test for acid secrete at stomach.
Histamine has less or no clinical effect, but agents that inhibit the action of action of histamine or blocks the histamine receptor called anti-histamine.
Hello! My name is Smrutiranjan Dash, a pharmacy professional. belonging from, Bargarh, Odisha. I have acquired Master degree in Pharmacy (Pharmacology) form B.P.U.T, Rourkela, Odisha. Currently I am working as an Assistant Professor at The pharmaceutical college, Barpali.