不同钙营养条件下氟中毒大鼠血清甲状旁腺激素的变化

Changes of parathyroid hormone in the serum of fluorosis rats taking different levels of calcium

目的动态观察不同钙营养条件下过量氟对大鼠血清甲状旁腺激素(PTH)的影响。方法以SD雄性大鼠为实验对象,采用3×2×3析因设计,按体质量随机分为6组:高钙对照组、高钙氟化钠组、常钙对照组、常钙氟化钠组、低钙对照组、低钙氟化钠组。分别饲以含钙量不同的合成饲料,各对照组饮用去离子水,各氟化钠组饮用含氟100 mg／L的去离子水。每8周处死一批大鼠,观察氟斑牙发生情况,用氟离子选择电极法测定血清氟、骨氟,用比色法测定血清钙,用放射免疫方法检测血清PTH水平。结果不同钙营养条件下加氟组大鼠均出现氟中毒;随染氟时间延长,不同钙营养条件下氟中毒大鼠的血清PTH活性升高,尤其高钙和低钙氟中毒大鼠血清PTH活性比常钙对照组显著升高(P<0．05或0．01);在实验初期常钙和高钙氟中毒大鼠血清钙低于其对照组(P<0．01),后期高钙氟中毒大鼠血清钙明显低于其对照组(P<0．05)。结论长期摄入过量氟可使机体血清PTH水平代偿性增高以维持血钙保持在正常范围内;长期摄入过量钙可减少氟在体内的蓄积。

Objective To dynamically investigate the effect of fluoride on the parathyroid hormone in the serum of rats with different calcium intake. Methods 3 × 2× 3 factorial design were used and SD rats were taken as the experimental objects. Rats with different weights were randomly allocated into 6 groups： low calcium control group, low calcium and excessive fluoride group, normal calcium control group, normal calcium and excessive fluoride group, high calcium control group and high calcium and excessive fluoride group. One third of rats were killed ever eight weeks, dental fluorosis of rats were examined, fluorine in the serum and bones of rats, and the levels of calcium and parathyroid hormone in the serum of rats were determined. Results Rats taking excessive fluoride with different calcium intake were all suffered fluorosis. Constantly taking excessive fluoride, fluorosis rats had an increasing tendency of the level of parathyroid hormone in their serum, but only those taking low or high calcium and excessive fluoride had significant difference compared with those taking normal calcium （P 〈 0.01 or 0.05）. At the early phase of the experiment, the levels of serum calcium decreased in the fluorosis rats with normal and high calcium intake（P 〈 0.01 ）, later only in the fluorosis rats with high calcium intake（P 〈 0.05）. Conclusions Taking excessive fluoride for a long time leads to a compensative increase level of parathyroid hormone in the serum of rats, to maintain the serum calcium concentration in a normal range, which is important for living things to survive. High calcium intake can decrease the accumulation of fluorine in the fluorosis body.