Anxiolytic- and antidepressant-like profile of a new CRF1 receptor antagonist, R278995/CRA0450

1-[8-(2,4-dichlorophenyl)-2-methylquinolin-4-yl]-1,2,3,6-tetrahydropyridine-4-carboxamide benzenesulfonate (R278995/CRA0450) is a newly synthesized corticotropin-releasing factor subtype 1 (CRF1) receptor antagonist. In the present study, in vitro and in vivo pharmacological profiles of R278995/CRA0450 were investigated. R278995/CRA0450 showed high affinity for recombinant and native CRF1 receptors without having affinity for the CRF2 receptor. R278995/CRA0450 attenuated CRF-induced cyclic AMP formation in AtT-20 cells and CRF-induced forepaw treading in gerbils, indicating that R278995/CRA0450 is an antagonist of the CRF1 receptor. In addition to CRF1 receptor antagonism, R278995/CRA0450 showed high affinity for the sigma(1) receptor, and attenuated (+)-SKF 10,047-induced head-weaving behavior, suggesting sigma(1) receptor antagonism. R278995/CRA0450 showed dose-dependent in vivo occupancy when assessed by ex vivo receptor binding, indicating good brain penetration. R278995/CRA0450 did not alter spontaneous anxiety when tested in the rat elevated plus maze (up to 3 mg/kg, p.o.) or lick suppression test (up to 10 mg/kg, i.p.). However, potent anxiolytic-like properties were observed in rats subjected to swim stress prior to testing on the elevated plus-maze, indicating activity primarily in tests taxing stress-induced anxiety. R278995/CRA0450 was inactive in mouse tail suspension, rat forced swim and rat differential-reinforcement-of-low-rate 72-s (DRL72), while it showed dose-dependent antidepressant-like effects in the rat learned helplessness paradigm and the olfactory bulbectomy model, demonstrating activity in a subset of animal models of depression associated with subchronic stress exposure. No or only mild effects were seen in tests of locomotor activity, motor coordination and sedation. These results indicate that R278995/CRA0450 is an orally active CRF1 and sigma(1) receptor antagonist with potent anxiolytic-like and antidepressant-like activities. (C) 2003 Elsevier B.V. All rights reserved.