BU 224 hydrochloride is a potent and selective ligand for the imidazoline I₂ receptor, acting primarily as an antagonist at this site. It is used in scientific research to investigate the role of I₂ receptors in modulating monoamine oxidase activity, neurotransmitter regulation, neuroprotection, and related physiological processes. Commonly applied in neuropharmacology studies on mood disorders, anxiety, depression, addiction, and pain modulation. Its high selectivity distinguishes I₂ receptor functions from those of I₁ imidazoline or α₂-adrenergic receptors, enabling precise experimental control. Typically employed in in vitro assays, cell-based models, and in vivo rodent studies to explore I₂ receptor involvement in behavioral and neurological responses.