Mood-Stabilizing Medications and the Inositol Signaling System

描述（由申请人提供）： 项目摘要/摘要双相情感障碍（BD）是一种影响许多退伍军人的毁灭性疾病。锂和丙戊酸盐是治疗BD躁狂期的首选药物。虽然治疗有效，但其作用机制尚未完全了解，并且不良副作用很常见。锂抑制脑肌醇单磷酸酶（IMPase），从而耗尽游离肌醇的可用池，并导致BD躁狂期的纠正。肌醇合酶（IPS）是通过产生前体肌醇磷酸（IP）来调节肌醇水平的关键酶。我们的初步数据表明，大鼠脑IPS是上调慢性锂治疗，这将有相同的净效应肌醇消耗相对于磷酸肌醇。我们假设锂和其他情绪稳定剂通过上调IPS表达，增加可用的磷酸肌醇库来发挥其治疗作用。这意味着BD的病理生理机制是维持游离肌醇与磷酸肌醇池比例适当平衡的障碍。我们的长期目标是确定情绪稳定剂是如何工作的，并在BD的病理生理学中找到共同的治疗靶点，以便设计新的药物。我们的具体目标是：1）确定慢性锂和丙戊酸盐给药后脑区新鉴定的IPS亚型的丰度和活性变化; 2）确定锂和丙戊酸盐对IPS与网格蛋白结合和受体介导的内吞作用的影响; 3）建立IPS缺陷小鼠中肌醇代谢和行为之间的联系;和4）确定锂、丙戊酸盐和拉莫替嗪反应基因的药物靶向会聚途径。为了实现目标1，将通过酶活性测定、蛋白质印迹和Q-PCR方法在药物处理的大鼠脑区域中定量IPS及其亚型。为了实现目标2，将通过Western和质谱分析来分析脑IPS及其复合物。将通过以下转铁蛋白受体运输和荧光共振能量转移（FRET）分析监测对受体介导的内吞作用的影响。对于目标3，将对锂和丙戊酸盐处理和未处理的IPS敲除小鼠进行标准化行为测试，并测定其大脑中肌醇代谢中的关键酶。目标4将通过微阵列和"途径"分析来解决，以绘制和比较人类神经元细胞系和大鼠原代皮层神经元细胞培养物中的慢性锂、丙戊酸盐和拉莫三嗪转录组。从IPS功能的角度定义锂对脑中肌醇代谢的作用机制可能会在肌醇调节和行为之间建立直接联系。从而推进我们对BD的病理生理学的理解，并揭示治疗BD的新的治疗靶点。 公共卫生相关性： 双相情感障碍（BD）是退伍军人的一个主要临床问题，有许多伊拉克战争退伍军人接受VA精神病学服务的锂抗性BD。为了更好地管理这些患者，我们必须能够确定情绪稳定剂的共同目标，以便将来可以设计出具有更大疗效和更少副作用的药物。锂纠正BD的一种方法是调节脑肌醇信号通路。大脑通过三种途径维持肌醇（一种糖）的体内平衡。肌醇磷酸合酶（IPS）是唯一的从葡萄糖合成肌醇的生物合成手段。IPS是与BD发生相关的新靶点。脑IPS酶的刺激剂，其随后将引起人脑内肌醇的产生，可以被认为是一类重要的新的情绪稳定药物。这些研究的结果将对BD退伍军人的健康产生非常积极的影响。

DESCRIPTION (provided by applicant): Project Summary/Abstract Bipolar disorder (BD) is a devastating condition affecting many Veterans. Lithium and valproate are the drugs of choice for the manic phase of BD. While therapeutically effective, their mechanisms of action are not fully understood, and undesirable side effects are common. Lithium inhibits brain inositol monophosphatase (IMPase), thereby depleting the available pool of free inositol, and resulting in the correction of the manic phase of BD. Inositol synthase (IPS) is a key enzyme that regulates inositol levels by generating the precursor, inositol phosphate (IP). Our preliminary data demonstrate that rat brain IPS is up-regulated by chronic lithium treatment, which would have the same net effect as inositol depletion relative to inositol phosphate. We hypothesize that lithium and other mood stabilizers exert their therapeutic effects by up-regulating IPS expression, increasing the available inositol phosphate pool. This implies that the pathophysiological mechanism underlying BD is a disturbance in maintaining a proper balance in the ratio of free inositol to inositol phosphate pools. Our long-term objective is to define how mood stabilizers work, and to find common therapeutic targets in the pathophysiology of BD so new medications can be designed. Our specific aims are: 1) Determine the changes in abundance and activity of the newly-identified isoforms of IPS in brain regions after chronic lithium and valproate; 2) Determine the effects of lithium and valproate on IPS binding to clathrin and receptor-mediated endocytosis; 3) Establish the link between inositol metabolism and behavior in IPS-deficient mice; and 4) Identify drug-targetable convergent pathways for lithium, valproate and lamotirgine responsive genes. To accomplish Aim 1, IPS and its isoforms will be quantified in drug-treated rat brain regions by enzyme activity assay, Western blot, and Q-PCR methods. To accomplish Aim 2, brain IPS and its complexes will be analyzed by Western and mass spectral analyses. Effects on receptor-mediated endocytosis will be monitored by following transferrin receptor trafficking and fluorescence resonance energy transfer (FRET) analysis. For Aim 3, lithium and valproate treated and untreated IPS knock-out mice will be subjected to standardized behavioral tests and their brains assayed for key enzymes in inositol metabolism. Aim 4 will be addressed by microarray and "pathway" analyses to map and compare the chronic lithium, valproate and lamotrigine transcriptomes in human neuronal cell lines and in rat primary cortical neuronal cell cultures. Defining the mechanisms of lithium action on inositol metabolism in the brain from the perspective of IPS function may establish a direct connection between inositol regulation and behavior. Thus advancing our understanding of the pathophysiology of BD and disclosing new therapeutic targets for treating BD. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE (Potential Relevance to Veterans' Health) Bipolar Disorder (BD) is a major clinical problem for Veterans, and there are many Iraq War Veterans treated by VA Psychiatry Service for lithium-resistant BD. To better manage these patients we must be able to identify common targets of mood-stabilizers so that future medications can be designed that have greater efficacy and fewer side effects. One way lithium can correct BD is by modulating brain inositol signal pathways. The brain maintains inositol (a sugar) homeostasis through three routes. Inositol phosphate synthase (IPS) is the only biosynthetic means of generating inositol from glucose. IPS is a new target linked to the genesis of BD. Stimulators of brain IPS enzyme which will then cause the generation of inositol inside the human brain, can be considered as an important new class of mood stabilizing medications. The results from these studies will provide a highly positive impact on the health of Veterans with BD.