Yoshihisa Urita1, Toshiyasu Watanabe1, Tsunehiko Imai2, Yasuyuki Miura3, Naohiro Washizawa3, Masaki Sanaka1, Hitoshi Nakajima1, Motonobu Sugimoto1

Departments of General Medicine and Emergency Care1, Environmental and Occupational Health2, and Surgery3
Toho University School of Medicine, Tokyo, Japan.

Background: Despite a close association between gastrointestinal motility and sex hormones, it has been unknown whether ovarian hormones affect absorption and metabolism of nutrients. The aim of this study is, therefore, to evaluate metabolism of acetate in rats with age and the influence of ovariectomy on its change. Methods: Fourteen female rats of the F344 strain were used, and 13C-acetate breath test was performed at 2, 7 and 13 months of age. Seven rats were ovariectomized at three weeks of age (ovariectomy group) and the remaining seven rats were studied as control group. After 24-hr fasting, rats are orally administrated 1ml of water containing sodium 13C-acetate (100mg/kg) and housed in an animal chamber. The expired air in the chamber is collected in a breath-sampling bag using a aspiration pump. The 13CO2 concentration is measured using an infrared spectrometer for 120 min and expressed as delta per mil. Results: The breath 13CO2 excretion increased with time and peaked 30 min in control rats. In ovariectomized rats, thee peak time of 13CO2 excretion was prolonged to 40 min at 7 and 13 months of age. Cmax was significantly higher at 2 months of age but lower at 4 months of age in ovariectomized rats than in control rats. Those of two groups became equal at 7 months of age. Conclusions: From the viewpoint of acetate metabolism, removal of ovarian hormones might make rats to be precocious ones and accelerate ageing. (Urita Y, Watanabe T, Imai T, Yasuyuki Miura Y, Washizawa N, Masaki Sanaka M, Nakajima H, Sugimoto M. Removal of ovarian hormones affects the ageing process of acetate metabolism. North Am J Med Sci 2009; 1: 58-62).

Key words Acetate oxidation, 13C-acetate breath test, ovariectomy, aging.

Corresponding to: DR. Yoshihisa Urita, MD, PhD, FACG. 1Department of General Medicine, Toho University School of Medicine, 6-11-1, Omori-Nishi, Ota-Ku, Tokyo 143-8541, Japan. Tel 81-3-762-4151, Fax 81-3-3765-6518. Email: foo@eb.mbn.or.jp