VITAMIN D AND CALCIUM IN LACTATING AND SUCKLING RATS

拟议研究的长期目标是：（1）确定 肠钙调节的相关因素及相互关系 吸收和分泌甲状旁腺激素和2）， 确定维生素D和断奶对骨基质和血浆的影响 哺乳期和刚断奶的后代中的磷酸盐水平。 具体目标 与哺乳期大鼠相关的方法包括确定a） 摄食、肠道肥大-增生、胃泌素分泌和 甲状旁腺激素（PTH）分泌; B）皮质酮的作用， 促胰液素等胃肠激素对体内甲状旁腺激素分泌的影响 c）肠促排效率与肠促排效率之间的关系 钙吸收与泌乳强度、高泌乳素血症净 维生素B12的骨吸收和血浆离子钙浓度 D-缺乏和D-充足的哺乳大鼠;和d）D-缺乏和D-充足的哺乳大鼠之间的相互作用。 碳水化合物和维生素D。 与哺乳有关的具体目标， 断奶的幼鼠包括确定维生素D和断奶对 血磷、骨矿含量、骨胶原 交联模式。 拟议的研究将利用以前开发的 生产维生素D缺乏的哺乳期大鼠的饮食方法， 哺乳幼犬甲状旁腺放射免疫测定的标准方法 激素、皮质酮和胃泌素体内和体外测定 骨矿物质含量，钙吸收测定净吸收， 体内和具有不同肠段的原位环的方法 用于测定胶原交联的相对量和分布， 未矿化和矿化骨基质。 这些研究的结果 应该增加我们对维生素D生理学和药理学的了解 以及与钙代谢适应有关的因素和机制 在哺乳期，以及机制参与成熟的骨和 断奶时的矿物质代谢。

The long-term objectives of the proposed research are 1) to identify factors and relationships involved in regulation of intestinal calcium absorption and parathyroid hormone secretion during lactation and 2) to determine the effect of vitamin D and weaning on bone matrix and plasma phosphate level in the suckling and newly weaned offspring. Specific aims related to lactating rats include determining a) the relationships between feeding, intestinal hypertrophy-hyperplasia, gastrin secretion and parathyroid hormone (PTH) secretion; b) the effects of corticosterone, secretin and other gastrointestinal hormones on secretion of PTH in vivo and in vitro; c) the relationship between efficiency of intestinal absorption of calcium and lactational intensity, hyperprolactinemia net bone resorption and ionized plasma calcium concentrations in vitamin D-deficient and D-replete lactating rats; and d) the interaction between dietary carbohydrate and vitamin D. Specific aims related to suckling and weaned rat pups include determining the effects of vitamin D and weaning on the plasma phosphate level, bone mineral content and bone collagen crosslink pattern. The proposed studies will utilize previously developed dietary procedures for producing vitamin D-deficient lactating rats and suckling pups, standard methods for radio-immunoassay of parathyroid hormone, corticosterone and gastrin, in vivo and in vitro determination of bone mineral content, calcium absorption determination by net absorption in vivo and with in-situ loops of different intestinal segments, and methods for determining relative amounts and distribution of collagen crosslinks in unmineralized and mineralized bone matrix. The results of these studies should increase our knowledge of physiology and pharmacology of vitamin D and of factors and mechanisms involved in adaptation of calcium metabolism during lactation, as well as mechanisms involved in maturation of bone and mineral metabolism at time of weaning.