维生素K对幼鼠骨代谢的影响

Effect of Various Levels of Vitamin K Intake on Bone Metabolism of Rat

目的探讨不同剂量的维生素Ｋ对幼鼠骨代谢的影响。方法选用４０只雄性断乳大鼠，分为４组：１组饲料中维生素Ｋ水平为５０μｇ／ｋｇ，并添加１％磺胺药阻断肠道菌群合成维生素Ｋ，其余３组饲料维生素Ｋ水平分别为５０、３００、２５５０μｇ／ｋｇ。实验进行３个月，通过钙代谢实验、骨代谢生化指标及骨密度的改变，综合评价维生素Ｋ对幼鼠骨代谢的影响。结果不同剂量水平的维生素Ｋ对大鼠胃肠道钙吸收无显著影响；维生素Ｋ缺乏组动物尿钙、尿羟脯氨酸排出增高，提示维生素Ｋ缺乏导致骨分解代谢增强；血清骨钙素及股骨骨密度随膳食维生素Ｋ摄入水平增加而提高，高剂量组显著高于维生素Ｋ缺乏组，而凝血酶原时间各组间差异无显著性。结论目前根据凝血功能制定的大鼠饲料维生素Ｋ的供给量不能满足幼鼠骨生长发育要求，幼鼠骨发育对维生素Ｋ的需求很可能高于５０μｇ／ｋｇ饲料。

Objective To explore the effect of various levels of vitamin K intake on bone development. Methods Forty weanling Wistar male rats were divided into four groups. In one group, 1% sulfadiazine was added to regular diet (vitamin K 50 μg/kg) to induce vitamin K deficiency. In the other three groups, the vitamin K levels in diets were 50 μg/kg, 300 μg/kg, 2 550 μg/kg respectively. Twelve weeks later, the rats were killed and the effects of the different levels of vitamin K intake on bone development were evaluated by the parameters of calcium metabolism, bone metabolic biochemistry, and bone mineral density (BMD). Results Vitamin K did not affect the intestinal absorption of calcium. Vitamin K deficiency led to the high levels of urinary calcium and hydroxyapatite excretion, suggesting an increase of bone absorption. Different levels of dietary vitamin K significantly affect circulating osteocalcin and OC bound content. The level of serum 2 osteocalcin , OC bound and BMD elevated with the increase of dietary VK levels, whereas the parameters of PTH (thrombo plastin time) were not different between all groups. Conclusion Vitamin K can enhance the bone development of rat. The rat vitamin K requirement may be higher than that of the current recommendation (50 μg/kg).