ATC0175: an orally active melanin-concentrating hormone receptor 1 antagonist for the potential treatment of depression and anxiety.

Melanin-concentrating hormone (MCH) has been implicated in a variety of physiological events. Recent studies clearly suggest that MCH plays an important role in the regulation of stress and emotion. To date, two receptor subtypes of MCH (MCH1R and MCH2R) have been identified. MCH1R has been suggested to mediate most of the physiological functions of MCH. Recently, we synthesized an orally active, nonpeptidic antagonist of MCH1R, N-(cis-4-{[4-(dimethylamino)quinazolin-2-yl]amino}cyclohexyl)-3,4-difluorobenzamide hydrochloride (ATC0175). This compound is a potent antagonist with a high affinity for MCH1R and additional affinities for 5-HT1A and 5-HT2B receptors. The receptor binding and the functional assay (MCH-induced increase in [Ca2+]i) indicated that ATC0175 is a noncompetitive antagonist at MCH1Rs. ATC0175 exhibited anxiolytic effects in numerous animal models of anxiety including the elevated plus-maze test, social interaction test, stress-induced hyperthermia and maternal separation-induced vocalization. Like with other stress-related peptide receptor antagonists, such as antagonists of corticotropin-releasing factor or vasopressin V1b receptor antagonists, anxiolytic effects of ATC0175 were more pronounced in models containing a stress component. ATC0175 also exhibited antidepressant effects in the forced swimming test. ATC0175 increased swimming performance without altering climbing behavior, as observed with selective serotonin reuptake inhibitors. ATC0175 has adequate ADME profile (reasonable oral bioavailability and brain penetration) and potent oral activity in animal models. In contrast, ATC0175 did not affect spontaneous locomotor activity, hexobarbital-induced sleeping time and did not impair rotarod performance. Thus, ATC0175 may be devoid of unwanted central nervous system side effects, which are sometimes observed with current medications. In addition, ATC0175 was well tolerated in rat repeated toxicity study, and had no genotoxic liability. Therefore, ATC0175 has the potential to be effective in the treatment of patients with depression and/or anxiety disorders.