Histamine is a monoamine neurotransmitter that is involved with the immune system. It triggers responses due to inflammation or allergies.
It is responsible for dilating the blood vessels, lowering blood pressure, constricting the airways, production of gastric acid and for the sensation of itching.
Histamine is a monoamine; it has an amine group attached to an imidazole ring via an ethyl chain. This monoamine chain can be found in many neurotransmitters, including dopamine, serotonin and noradrenaline. It's also found in many drugs, examples being tryptamines and phenethylamines.
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