Biochemistry & Toxicology

Key goals for the 21st century are the prevention of disease and improvement of human health.

Current investigations include how to reduce the burden of human illness by understanding how environmental and social stressors affect various diseases, and the search for chemopreventative food phytochemicals.

Every day, we are exposed to various environmental and social stressors such as chemical pollutants, virus, bacteria, radiation, UV, noise, light, and psychosocial events. Recent epidemiological and animal experimental studies suggest the importance of environmental and social stressors in the occurrence and exacerbation of lifestyle-related diseases. Our research is aimed at reducing the burden of human illness by understanding how environmental and social stressors affect the development and progression of various diseases.

1. Biological responses to environmental and social stress
In modern highly stressed society, stress-related illnesses are now recognized as major public health issues. In particular, prolonged and chronic stress such as social, physiological, and physical stress have been recognized to play a key role in the etiology of stress-related illnesses. Therefore, we are investigating physiological changes following exposure to environmental and social stress using animal models.
(1) We are interested in the mechanism of the stress-stimulated development of breast cancer. The combined effect of estrogen metabolites and catecholamines on the development of breast cancer has been investigated.
(2) In group-housed mice, individual variability in the stress response was observed. Therefore, we established a method to distinguish individual mice in the group during the dark phase. Now, we are investigating behavioral phenotypes in socially stressed mice.
2. The effect of environmental and social stress on biorhythms
Most living organisms have a circadian rhythm and are under the influence of its cycle. Recently, differences in biological reactions related to circadian rhythms have been studied and applied to many fields, including clinical pharmacology, sitology, nutrition, and food science. In general, humans are exposed to many environmental chemicals in their active phase. However, dosing of chemicals in non-clinical safety studies using experimental animals such as mice are usually conducted in the light period, which is the inactive phase for the animals. We are investigating differences in the biological responses to chemicals in the light versus dark periods (inactive and active phases, respectively).
3. How can we prevent some environmental and social stress-related diseases?
We are investigating some foods/drugs that can protect humans from some diseases induced by environmental and social stressors. To that end, it is important to understand their beneficial or toxic effects by investigating the absorption, metabolism, and detoxification of endogenous and exogenous factors. In particular, we are investigating the preventive effect of flavonoids on stress-related breast cancer.


Kayoko ShimoPhD


Michiko YasudaPhD

Details are here





  1. Food Funct. , in press.
  2. Curr. Pharm. Des., in press.
  3. Exp. Physiol., 98(1), 290-303 (2013)
  4. Environmental Toxicology, 28(1), 21-30 (2013)
  5. Journal of Toxicological Science, 37(5), 1071-1076 (2012)
  6. Genes and Environment, 34, 129-135 (2012)
  7. Journal of Toxicological Sciences, 37(2), 427-430 (2012)
  8. Behavioral Brain Research, 220(2), 354-357 (2011)
  9. Bioorganic & Medicinal Chemistry, 18(17), 6310-6315 (2010)
  10. Experimental Animals, 59(5), 637-642 (2010)
  11. The Journal of Steroid Biochemistry and Molecular Biology, 118(1-2), 70-76 (2010)
  12. Physiological Genomics, 37(2), 79-87 (2009)