孕期及哺乳期钙及维生素D_3干预对铅暴露小鼠骨骼铅动员影响的析因设计研究

Effect of Protection of Calcium and VD3 on Lead Mobilization from Maternal Skeleton in Gestation and Lactation

目的研究母体孕期及哺乳期骨骼铅动员的规律,并评价大剂量补充钙及VD3的干预效果。方法根据2×6析因设计原理,以补钙与否、孕期及哺乳期6个阶段分组,每组6只,将72只清洁级雌性昆明小鼠通过饮水暴露于乙酸铅(以铅计,50 mg/L),4周后与雄鼠同笼并受孕;铅暴露+钙及维生素D(3VD3)补充组母鼠在孕期及哺乳期内通过饮水补充碳酸钙(50 mg/L)及VD(30.42μg/L),单纯铅暴露组母鼠饮用蒸馏水,连续染毒42 d。分别在孕期的第1、7和14天,哺乳期的第1、10和21天取全血、股骨,采用石墨炉原子吸收法、火焰原子吸收法测定铅、钙含量。结果孕期及哺乳期不同阶段、补充钙及VD3与否均对母鼠血液、骨骼的铅、钙含量有影响(P=0.000),且两个因素之间存在着协同作用(P=0.000)。在整个观察期内,单纯铅暴露组母鼠的血钙、骨钙及骨铅水平持续下降(P<0.05),血铅水平持续上升(P<0.05);铅暴露+钙及VD3补充组母鼠的血钙、骨钙及骨铅水平相对稳定(P>0.05),血铅水平有所下降(P<0.05)。两组母鼠的血铅水平与血钙水平之间呈现负相关关系(r=-0.702,P<0.01),血铅水平与骨铅水平之间呈现负相关关系(r=-0.904,P<0.01)。结论铅染毒小鼠孕期及哺乳期存在着骨骼铅动员现象,并可被大剂量补充钙及VD3部分抑制。

Objective To know the fact of mobilization of lead from maternal skeleton during gestation and lactation and to evaluate the protective effect of high level calcium and vitamin D3 supplements. Methods Factorial design was adopted according to different period of gestation and lactation,calcium and vitamin D3 supplements or not. Seventy-two Kunming female mice were provided with lead acetate via drinking water （50 mg/L） for 4 consecutive weeks before pregnancy,then calcium and VD3 supplemented drinking water （50 mg/L calcium element, 0.42 μg/L VD3） for females in lead exposed, calcium and vitamin D3 supplemented groups,or distilled water for females in merely lead exposed group during gestation and lactation. The levels of calcium and lead in blood and femur were measured on the lst,7th and 14th day of gestation,on the 1st, 10th and 21st day of lactation by atomic absorption spectrophotometry using a heated graphite atomizer or by flame atomic absorption spectrophotometry. Results Both different period and calcium and vitamin D3 supplements could change the levels of lead and calcium in blood or bone （P=0.000）, and there was interaction between them （P=0.000）. In single lead exposed group, the levels of calcium in blood and bone,the levels of lead in bone gradually decreased （P〈0.05）,the levels of lead in blood gradually increased （P〈0.05）.In lead exposure, calcium and vitamin D3 supplemented groups, the levels of calcium in blood and bone,the levels of lead in bone did not obviously changed（P〉0.05）,the levels of lead in blood gradually decreased（P〈0.05）. There was a negative correlation between the levels of lead in blood and the levels of calcium in blood （r=-0.702,P〈0.01）,and a negative correlation between the levels of lead in blood and levels of lead in bone. Conclusion Lead will be mobilized from maternal bone during gestation and lactation, and the mobilization will be restricted by supplements of high level calcium and VD3.