Psychotropic effects of Japanese valerian root extract

The psychotropic effects of "Hokkai-Kisso", i.e. roots of Japanese valerian, were compared with those of diazepam and imipramine. Both 30% EtOH extract of valerian root (11.2 g/kg) and diazepam (3 mg/kg) significantly prolonged hexobarbital-induced sleep in mice. Spontaneous ambulation and rearing during an open field test were significantly decreased by valerian extract (11.2 g/kg), but kessyl glycol diacetate (KGD, 400 mg/kg) and diazepam (3 mg/kg) significantly increased ambulation. Diazepam (10 mg/kg) significantly decreased approach-avoidance conflict in mice in a water-lick conflict test, but valerian extract and KGD did not. By contrast, valerian extract (4.1 g/kg) and imipramine (20 mg/kg) significantly inhibited immobility induced by a forced swimming test in rats, but did not increase spontaneous motor activity during an open field test just before the forced swimming test. In addition, valerian extract and imipramine significantly reversed reserpine-induced hypothermia in mice. These results indicate that valerian extract acts on the central nervous system and may be an antidepressant.