Neuropharmacology of a new potential anxiolytic compound, F 2692, 1-(3'-trifluoromethyl phenyl) 1,4-dihydro 3-amino 4-oxo 6-methyl pyridazine. 1. Acute and in vitro effects

F 2692 [1-(3'-trifluoromethyl phenyl) 1,4-dihydro 3-amino 4-oxo 6-methyl pyridazine] exhibited dose-dependent "anxiolytic" properties in the elevated plus-maze and the punished drinking tests in rats. It was also active in the two-compartment test in mice. The "anxiolytic" effects were antagonised by the benzodiazepine antagonists, flumazenil and ZK 93426. The compound exhibited anticonvulsant, sedative, myorelaxant and amnesic effects at doses 3-30 times higher than those required for "anxiolytic" activity. F 2692 has a very low affinity for benzodiazepine binding sites in vitro and in vivo (about 1000 and 160 fold lower than diazepam respectively). In addition it displayed no affinity for GABAA, alpha 2-adrenergic, 5-HT1A or 5-HT2 receptors. These data suggest that F 2692 may be a potential anxiolytic compound with an unusual mechanism of action.