Rat Histamine Receptor H1 (HRH1) Protein

Background

HRH1 is a G protein-coupled receptor activated by histamine, a biogenic amine involved in allergic responses, inflammation, and neurotransmission. HRH1 is widely expressed in smooth muscle cells, endothelial cells, and the central nervous system. Upon activation, HRH1 couples to Gq/11 proteins, leading to activation of phospholipase C (PLC), calcium mobilization, and protein kinase C (PKC) signaling. In peripheral tissues, HRH1 mediates allergic and inflammatory responses by inducing vasodilation, increased vascular permeability, and smooth muscle contraction, contributing to symptoms like itching, bronchoconstriction, and edema. In the central nervous system, HRH1 modulates wakefulness, appetite regulation, and cognition. Dysregulation of HRH1 is associated with allergic conditions, including rhinitis, urticaria, and asthma. HRH1 antagonists, such as antihistamines, are widely used to treat allergic reactions and inflammatory conditions. HRH1 also plays roles in neuroinflammation and psychiatric disorders like anxiety and schizophrenia, where altered histamine signaling disrupts neurological balance.