Agmatine--a novel endogenous ligand of imidazoline receptors.

Agmatine (AGM) is decarboxylated arginine found in bovine brain which binds to imidazoline receptors. It differs substantially from earlier discovered clonidine displacing substance (CDS) and ir-CDS. AGM is synthetized in brain from arginine decarboxylase, and metabolized by diamine oxidase. It is widely and unequally distributed in peripheral tissues and in the brain. AGM interacts with both I-1 and I-2 imidazoline receptors as well as with alpha 2-adrenoreceptors. AGM can regulate cardiovascular functions and can modulate some processes in the central nervous system.