Dose Response Effects of Alcohol on Bone Metabolism

描述（由申请人提供）：慢性酒精滥用是最 骨质疏松症的重要“生活方式”危险因素。的长期目标 拟议的研究是了解细胞和分子机制， 负责调节酒精对骨骼的有害作用， 在此基础上，制定有效的对策。 在当前供资期间进行的研究提供了强有力的证据 酒精导致的骨质流失是由于骨骼重塑受到干扰 周期具体地说，骨形成与骨形成之间的耦合不平衡， 普遍的骨吸收率产生的新骨不足以补偿 导致净骨丢失。在分子水平上，我们 已经建立了骨形成与骨形成之间的明确正相关， 骨组织中胰岛素样生长因子-I（IGF-1）基因表达。 此外，在胚胎发育过程中， 与垂体切除术后的结果惊人地相似 （HYPOX），这表明骨骼反应的潜在机制， 酒精滥用和生长激素（GH）缺乏症是相似的。因为大部分 GH对骨细胞的作用是由局部产生的IGF-1介导的， 酒精滥用和生长激素缺乏对骨骼的不利影响可能会分享 干扰IGF-1信号作为一个共同的途径。的拮抗作用 甲状旁腺激素（PTH）可以逆转HYPOX对骨形成的影响， 通过骨细胞上调IGF-1的表达。根据这些发现，我们 工作假设是酒精引起的骨质疏松症主要是由于 成骨细胞的IGF-1表达减少，并且可以通过以下方法预防或逆转： 治疗PTH。我们建议在成人和青少年中测试这些假设 雌性大鼠慢性酒精滥用模型，通过测定骨和 矿物质代谢：（1）HYPOX和正常大鼠喂食酒精;（2）HYPOX和 健康大鼠灌胃酒精和GH治疗;（3）HYPOX和健康大鼠灌胃 酒精和IGF-1处理;（4）HYPOX和完整大鼠同时 喂食酒精并用PTH处理;和（5）喂食酒精以诱导 骨质流失然后用PTH治疗一套补充技术将 在这些实验中用于评估骨骼变化，包括 动态和静态骨组织形态计量学、骨密度计量学、显微CT、 生化标志物，机械测试，免疫组织化学，放射自显影 通过北方印迹和RNA酶保护测定进行RNA分析。

DESCRIPTION (provided by applicant): Chronic alcohol abuse is the most important "life style" risk factor for osteoporosis. The long-term goal of the proposed research is to understand the cellular and molecular mechanisms responsible for mediating alcohol's detrimental actions on the skeleton and, with this improved understanding, to develop effective countermeasures. Research performed during the current funding interval provides strong evidence that alcohol-induced bone loss is due to a disturbance in the bone remodeling cycle. Specifically, an imbalance in the coupling of bone formation to the prevailing rate of bone resorption creates inadequate new bone to compensate for bone resorption, resulting in net bone loss. At the molecular level, we have established a clear positive association between bone formation and insulin-like growth factor-I (IGF-1) gene expression in bone tissue. Furthermore, the architectural, cellular and gene expression changes in tibiae of rats fed alcohol are strikingly similar to those that follow hypophysectomy (HYPOX), suggesting that the underlying mechanisms for the skeletal response to alcohol abuse and growth hormone (GH) deficiency are similar. Because most of the effects of GH on bone cells are mediated by locally produced IGF-1, the detrimental skeletal effects of alcohol abuse and GH deficiency may share disturbed IGF-1 signaling as a common pathway. The antagonistic effects of HYPOX on bone formation can be reversed with parathyroid hormone (PTH), which up-regulates IGF-1 expression by bone cells. Based on these findings, our working hypotheses are that alcohol-induced osteoporosis is largely due to decreased IGF-1 expression by osteoblasts, and can be prevented or reversed by treatment with PTH. We propose to test these hypotheses in adult and adolescent female rat models for chronic alcohol abuse by determining changes in bone and mineral metabolism in: (1) HYPOX and intact rats fed alcohol; (2) HYPOX and intact rats fed alcohol and treated with GH; (3) HYPOX and intact rats fed alcohol and treated with IGF-1; and (4) HYPOX and intact rats simultaneously fed alcohol and treated with PTH; and (5) intact rats fed alcohol to induce bone loss and then treated with PTH. A suite of complementary techniques will be employed in these experiments to evaluate the skeletal changes, including dynamic and static bone histomorphometry, bone densitometry, micro-CT, biochemical markers, mechanical testing, immunohistochemistry, radioautography and RNA analysis by Northern blots and RNase protection assays.