Histamine H1 receptor

Histamine H1 receptor is a subtype of the histamine receptor, a G protein-coupled receptor (GPCR) that responds to histamine to mediate physiological responses such as inflammation, gastric acid secretion, and neurotransmission. The H1 receptor is found in various tissues, including the central nervous system, smooth muscle tissue, and endothelial cells.

Structure

The H1 receptor is a transmembrane protein that spans the cell membrane seven times. It is coupled to a G protein, which activates an intracellular second-messenger system when the receptor is bound by histamine. The structure of the H1 receptor is similar to that of other GPCRs, with seven transmembrane helices, an extracellular N-terminus, and an intracellular C-terminus.

Function

The primary function of the H1 receptor is to mediate the effects of histamine. When histamine binds to the H1 receptor, it causes a conformational change in the receptor that activates the associated G protein. This in turn triggers a cascade of intracellular events, leading to responses such as vasodilation, increased vascular permeability, and contraction of smooth muscle.

In the central nervous system, H1 receptors are involved in the regulation of sleep-wake cycle, appetite, and body temperature. They also play a role in the mediation of allergic responses, including the symptoms of hay fever and asthma.

Pharmacology

Several drugs target the H1 receptor to treat conditions such as allergies and insomnia. Antihistamines are drugs that block the H1 receptor, preventing histamine from binding and triggering a response. These drugs are commonly used to treat allergic reactions and to induce sleep.

See also

• Histamine H2 receptor
• Histamine H3 receptor
• Histamine H4 receptor

References

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