Group - Histamine H1 receptor

The H1 receptor is a histamine receptor, and thus an important target for clinically important drugs, and is likely one of the most important receptors for modulating mammalian circadian cycles. Histamine H1 receptor are metabotropic G-protein-coupled receptors expressed throughout the body, specifically in smooth muscles, on vascular endothelial cells, in the heart, and in the central nervous system. The H1 receptor is linked to an intracellular G-protein (Gq) that activates phospholipase C and the phosphatidylinositol (PIP2) signaling pathway. The production of prostaglandin E2 synthase induces the release of histamine from neurons, causing systemic vasodilation, along with increased cell permeability due to its action on H1 receptors.