Intake of Fermented Soybean (Natto) Increased Locomotor Activity in Mice(Communications to the Editor)

We fed mice food granules containing fermented soybean (natto in Japanese) powder (hereafter "natto granules") for 14 d to investigate whether natto granules had any effects on mouse behavior. We noted an enhancement of locomotor activity in natto-granule-fed mice compared to control and soybean-pelletfed mice. This enhanced locomotor activity was blocked by a low dose of haloperidol (1μg/kg i.p.), a dopamine receptor antagonist, but not by methysergide, a serotonin 5-HT_<1/2> receptor antagonist. The results suggest that the enhanced locomotor activity induced by continuous intake of natto granules in mice is sensitive to haloperidol.