Imidazoline Receptors

Imidazoline receptors are the primary receptors on which clonidine and other imidazolines act. There are three classes of imidazoline receptors: I1 receptor – mediates the sympatho-inhibitory actions of imidazolines to lower blood pressure, (NISCH or IRAS, imidazoline receptor antisera selected), I2 receptor - an allosteric binding site of monoamine oxidase and is involved in pain modulation and neuroprotection, I3 receptor - regulates insulin secretion from pancreatic beta cells. Activated I1-imidazoline receptors trigger the hydrolysis of phosphatidylcholine into DAG. Elevated DAG levels in turn trigger the synthesis of second messengers arachidonic acid and downstreameicosanoids. In addition, the sodium-hydrogen antiporter is inhibited, and enzymes of catecholamine synthesis are induced. The I1-imidazoline receptor may belong to the neurocytokine receptorfamily, since its signaling pathways are similar to those of interleukins.