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Published on: February 28, 2018
Environmental Enrichment Increases Radiation-induced Apoptosis Not Spontaneous Apoptosis in Mouse Intestinal Crypt
Shinya Yokomizo1,2, Mayumi Nishimura1, Takamitsu Morioka3
1Department of Radiation Effects Research, National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology (QST), Chiba, Japan.
Background/Aim:
An enriched environment (EE) modifies apoptotic cell death and promotes cell proliferation in the central nervous system (CNS) in mice. However, few studies have examined the effects of an EE on apoptosis in non-CNS organs in model orgamisms. In addition, the intestinal tract is one of organs at high-risk of carcinogenesis after radiation exposure. Herein we evaluated the effects of an EE on spontaneous and radiation-induced apoptosis in intestinal crypt cells of mice.
Materials And Methods:
Juvenile (3-week-old) and adult (11-week-old) male B6C3F1 mice were housed in a standard environment or EE for 8 weeks and then were whole-body irradiated with 2 Gy X-rays. Apoptosis in the small intestine and colon was analyzed with antibody against cleaved caspase 3.
Results:
The EE significantly reduced body weight; adipose tissue weight; and serum levels of total cholesterol, triglyceride, leptin, and insulin. Although EE did not change the spontaneous apoptotic index without irradiation, it significantly increased the index after irradiation in the colonic crypt. The apoptotic index in the small intestinal crypt showed similar patterns.
Conclusion:
An EE enhances radiation-induced apoptosis of stem/progenitor cells in the small intestine and colon without affecting spontaneous apoptosis. An EE may thus reduce the risk of cancer in the intestinal tract after radiation exposure such as radiotherapy.

