OSTEOPOROSIS/DIHYDROXYVITAMIN REGULATED GENE EXPRESSION

我们建议在雄性和雌性大鼠中研究衰老的变化， 两个基因的表达参与肠钙吸收， 在维生素D调节肾脏处理钙;钙结合蛋白（维生素D- 依赖性钙结合蛋白）和维生素D受体（VDR）。 我们 一种假说认为，衰老导致维生素D的改变， 内分泌系统和1，25二羟维生素D（1，25（OH）3D 3）调节 基因表达，导致正常的适应性退化， 对钙摄入不足或钙需求的反应。 有效 1，25（OH）2D 3调节基因缺陷导致的钙缺乏 表达成为一个潜在的越来越重要的问题， 随着年龄的增长，导致与年龄相关的骨质流失， 缺陷 第一个具体目标是确定年龄的影响， 性别对肠道维生素D3受体和钙结合蛋白基因表达的影响 确定这与骨矿化的关系。蛋白和mRNA水平 (by受体钙结合蛋白的北方和狭缝印迹分析）。 在3、6、12和24月龄雄性和雌性大鼠中测量。 血清钙 还将评估骨矿化。第二个具体目标是 确定年龄和性别对肠道和肾脏的影响， 对1，25（OH）2D 3或维生素D3的反应性以及对 膳食钙 3、6、12和24个月大的雄性和雌性大鼠将 喂食锶饮食（0.8%）6天以诱导功能性 1，25（OH）2D 3缺乏症。 动物将在之后的不同时间处死 单次腹膜内剂量的1，25（OH）2D 3。 肠钙结合蛋白和 将分析1，25（OH）2D 3受体蛋白和mRNA。 为了 确定年龄和性别对适应膳食钙的影响，男性 3、6、12和24个月的雌性大鼠也将被喂食低和高 钙饲料10-30天。 肠和肾钙结合蛋白的变化 蛋白质和mRNA以及骨矿化的作用。 没有 关于雌性大鼠的变化， 肠钙结合蛋白和1，25（OH）2D 3受体基因表达的变化。 确实有可能存在某种程度的与年龄相关的抵抗力 肠粘膜和肾脏对1，25（OH）_2D_3作用的影响 老化过程 现在是确定维生素D变化的时候了 调节衰老。 更好地了解维生素D依赖 老年雌性和雄性动物的适应将使我们能够获得 关于成熟和衰老的各个阶段如何影响骨骼的信息 密度和维生素D依赖性基因表达。 这些研究可能会导致 未来的研究涉及钙的基因操纵 在衰老过程中的反应。

We propose to examine changes with aging in both male and female rats in the expression of two genes involved in intestinal calcium absorption and in vitamin D regulated renal handling of calcium; calbindin (the vitamin D- dependent calcium binding protein) and the vitamin D receptor (VDR). Our hypothesis is that aging results in an alteration in the vitamin D endocrine system and in 1,25 dihydroxyvitamin D (1,25(OH)3D3) regulated gene expression which results in a deterioration in the normal adaptive response to inadequate calcium intake or to calcium need. Effective calcium deficiency as a result of defective l,25(OH)2D3 regulated gene expression becomes a potentially more and more important problem with advancing age, resulting in age related bone loss aggravated by calcium deficiency. The first specific aim is to determine the effect of age and sex on intestinal vitamin D3 receptor and calbindin gene expression and to determine how this relates to bone mineralization. Protein and mRNA levels (by Northern and slot blot analysis) for receptor calbindin will be measured in 3, 6, 12 and 24 month old male and female rats. Serum calcium and bone mineralization will also be evaluated. The second specific aim is to determine the effect of age and sex on intestinal and renal responsiveness to l,25(OH)2D3 or vitamin D3 and on adaptation to changes in dietary calcium. Three, 6, 12 and 24 month old male and female rats will be fed a strontium diet (0.8%) for 6 days to induce a functional l,25(OH)2D3 deficiency. Animals will be sacrificed at various times after a single intraperitoneal dose of l,25(OH)2D3. Intestinal calbindin and 1,25(OH)2D3 receptor protein and mRNA will be analyzed. In order to determine the effect of age and sex on adaptation to dietary calcium, male and female rats at 3, 6, 12 and 24 months will also be fed low and high calcium diets for 10-30 days. Changes in intestinal and renal calbindin protein and mRNA and in bone mineralization will be evaluated. No manuscripts have been published concerning changes in female rats in intestinal calbindin and 1,25(OH)2D3 receptor gene expression during aging. It is indeed probable that there is some degree of age related resistance of the intestinal mucosa and kidney to the action of 1,25(OH)2D3 during the aging process. It is now timely to determine changes in vitamin D regulation with aging. A greater understanding of vitamin D-dependent adaptation in older female as well as male animals will enable us to obtain information on how various stages of maturation and aging can affect bone density and vitamin D-dependent gene expression. These studies could lead to future investigations concerning genetic manipulation of calcium responsiveness during aging.