Effects of Dietary Gizzerosine on Contents of Ash and Calcium in the Femur of Young and Ovariectomized Mice

Gizzerosine (2-amino-9-(4-imidazolyl)-7-azanonanoic acid) is a causative substance for the gizzard erosion in chicks. Small amount of dietary gizzerosine causes significant increase in the contents of ash and calcium (Ca) in the femur of chicks. If gizzerosine enhances the bone calcification in mammals as in chicks, it may be effective for prevention of the fragility in pigs and osteoporosis in postmenopausal women. In this study, in order to clarify the effect of dietary gizzerosine on the calcification of bone in growing and ovariectomized mice, as model animals of ospeoporosis, two experiments were conducted. In experiment 1, the young mice were fed the diets containing gizzerosine at 0, 2 and 10ppm ad libitum. In the mice fed 10ppm gizzerosine diet, though body weight and femur weight were not affected, the contents of ash and Ca in the femur increased significantly. In experiment 2, ovariectomized mice were fed diets containing gizzerosine at 0, 10, 30 and 100ppm ad libitum and non-ovariectomized mice were fed a diet without gizzerosine. Though the body weights of ovariectomized mice fed the diet without gizzerosine were significantly heavier, the contents of ash and Ca in the femur of ovariectomized were lower than those of non-ovariectomized mice. The body weights and contents of ash and Ca in the femur of ovariectomized mice increased with increasing dietary gizzerosine levels, reached to maximum and then decreased slightly. Dietary gizzerosine levels did not affect concentrations of plasma Ca and pH of the digesta in the duodenum of ovariectomized mice. These results suggested that gizzerosine was effective for acceleration of bone calcification in ovariectomized mice as in chicks. In the case of chicks, gizzerosine decreased pH of digesta in the gizzard, the low pH increased the solubility and absorption of Ca and resulted in enhancement of bone calcification. However, pH of the digesta in the duodenum of mice was not affected by gizzerosine. This showed that the enhancement of bone calcification in mice was affected by different mechanism in chicks.