Pharmacological studies on a new thymoleptic antidepressant, 1-[3-(dimethylamino)propyl]-5-methyl-3-phenyl-1H-indazole (FS-32).

Some pharmacological actions of 1-[3-(dimethylamino)propyl]-5-methyl-3-phenyl-1H-indazole (FS-32), a newly synthesized indazole derivative, were investigated in comparison with imipramine. FS-32 showed anti-reserpine activity in a dose-dependent manner, whereas imipramine exhibited a bell-shaped dose-response pattern. Catecholaminergic potentiation was demonstrated with FS-32. The results obtained from a norepinephrine potentiation test in vitro suggest that FS-32 may act in a manner qualitatively different from the tricyclic antidepressant. FS-32 produced a definite suppressive effect on isolation-induced fighting without affecting coordinated motor activity and on the duration of afterdischarge elicited by electrical stimulation to the amygdala or the hippocampus without producing a slow wave pattern in the EEG. Similar effects on fighting behavior and the afterdischarge were shown under imipramine with a slight motor incoordination and with a slow wave pattern, respectively. FS-32 produced practically no peripheral anti-cholinergic action, while it antagonized central cholinergic activity. FS-32 tended to produce an increase in chatecholamine content in the brain without MAO or COMT inhibitory activity. Norepinephrine uptake was inhibited by FS-32, but less than by imipramine. These pharmacological properties suggest a potential clinical utility of FS-32 as an antidepressant possessing thymoleptic activities.