Biol. Pharm. Bull. 29(7) 1498—1500 (2006)

the Japanese have eaten since ancient times. It contains several biologically active components that may contribute individually or synergistically to the health benefit. As consumers in the world are becoming increasingly aware of the health benefits of soybean, attention has turned to the way to take soybeans that provide improved taste, functional characteristics, and health benefits. Many studies in the biological field have demonstrated the effect of soy isoflavones on signaling pathways, including but not limited to, cell proliferation and differentiation, cell cycle regulation, apoptosis, angiogenesis, cell adhesion and migration, metastasis, and activity of different enzymes in vitro. Experimental and epidemiological evidence in the life science suggest that soybean-derived products can prevent some diseases such as cancer, cardiovascular disease and osteoporosis. Soybean also contains soy protein, isoflavones, fiber and saponins, and recent works revealed that isoflavones have significant effects on some diseases of animal models. It is not well known the usefulness of soybean itself as a food on the brain function, whereas it has been clarified that soy-extracted phytoestrogens (isoflavones) may regulate the learning and memory in rats. In human, high soybean diet for 10 weeks has been reported to improve the episodic memory. Furthermore, there are some reports that such isoflavones are implicated with anxious behavior, but those effects of extracted and purified components might depend on the span of treatment. Thus, in this study we examined the effects of soybean itself on anxiety-related behavior after the intake of the pellets containing soybean powder in mice.