Oxidative Stress: A Recipe for Anxiety

描述（由申请人提供）：焦虑是一种正常的人类情绪，每个人在某些时候都会经历。在一种情况正常之前感到焦虑，通常在一个人离开造成这种情况的情况后不久就会结束。但对于数以百万计的人来说，这种焦虑并没有消失，而是随着时间的推移而恶化，导致心理或身体疾病。这些人有焦虑症。主要的治疗方法是苯二氮卓类药物和选择性血清素再摄取抑制剂（SSRIs）。虽然临床上有用，但长期使用苯二氮卓类药物会导致耐受性、依赖性和镇静。ssri类药物需要数周才能起作用，而且也不是没有副作用。现有的焦虑治疗需要更好的替代方案，但对焦虑的机制理解不足阻碍了新干预措施的发现。我们的项目解决了这一阻碍焦虑研究进展的关键障碍。我们最近发表的研究表明氧化应激在大鼠焦虑样行为中的因果作用。在单独的研究中，g蛋白信号蛋白(RGS)-2的调节剂和两种抗氧化酶，谷胱甘肽还原酶(Gsr)-1和乙草醛酶(Glo)-1被认为是焦虑的调节剂。我们的研究表明，氧化应激、Glo1、Gsr1和RGS2在焦虑中具有关键的趋同作用。在我们的初步研究中，通过l -丁硫氨酸-(S，R)-亚砜亚胺（BSO）处理诱导亚慢性氧化应激可降低大鼠蓝斑区（LC）、海马和杏仁核中的RGS2、Glo1和Gsr1水平，并增加焦虑样行为。另一方面，急性氧化应激增加了这些脑区的RGS2、Glo1和Gsr1水平，但没有产生大鼠的焦虑样行为。此外，慢病毒介导的RGS2在海马中的过表达挽救了亚慢性BSO治疗大鼠的焦虑表型。并且，Glo1和Gsr1蛋白的表达随着RGS2在海马内的过表达而增加。我们在神经细胞培养中的初步研究模拟了RGS2、Glo1和Gsr1的差异调节。急性氧化应激使RGS2、Glo1和Gsr1 mRNA和蛋白水平升高，而亚慢性氧化应激则使其水平降低。我们的假设是RGS2通过激活特定的信号级联在调节抗氧化酶Glo1和Gsr1中发挥核心作用，这对焦虑的病因至关重要。我们将通过追求两个具体目标来检验我们的假设。在目的1中，使用急性和亚慢性氧化应激的脑源性细胞培养模型，将研究PKC， p38和calpain途径以及转录因子（Nrf2, Sp-1）在RGS2依赖性的Glo1和Gsr1水平调节中的参与。在目的2中，利用我们已发表的急性和亚慢性氧化应激大鼠模型，将确定PKC、p38和calpain通路参与Glo1和Gsr1的RGS2依赖性调节以及对焦虑样行为的评估。从我们的建议中获得的机制见解将导致确定治疗焦虑症的药物设计的新靶点。

DESCRIPTION (provided by applicant): Anxiety is a normal human emotion that everyone experiences at some point. To feel anxious before a situation is normal and it usually ends soon after one is out of the situation that caused it. But for millions of people, the anxiety does not go away, and gets worse over time resulting in psychological or physical sickness. These people have anxiety disorders. The mainstays of treatment are benzodiazepines and selective serotonin reuptake inhibitors (SSRIs). Although clinically useful, chronic use of benzodiazepines leads to tolerance, dependence and sedation. SSRIs require weeks to work and are not without side effects either. Better alternatives over existing anxiety treatments are needed but poor mechanistic understanding of anxiety has impeded discovery of novel interventions. Our project addresses this critical barrier to progress in anxiety research. Our recently published work has suggested causal role of oxidative stress in anxiety-like behavior of rats. In separate studies Regulator of G-Protein Signaling protein (RGS)-2 and two antioxidant enzymes, glutathione reductase (Gsr)-1 and glyoxalase (Glo)-1 have been postulated as modulators of anxiety. Our work suggests a critical convergence of oxidative stress, Glo1, Gsr1 and RGS2 in anxiety. In our preliminary studies, induction of oxidative stress sub-chronically via L-Buthionine-(S,R)-sulfoximine (BSO) treatment reduced RGS2, Glo1 and Gsr1 levels in locus coeruleus (LC), hippocampus and amygdala and increased anxiety-like behavior of rats. On the other hand, acute oxidative stress increased RGS2, Glo1 and Gsr1 levels in these brain areas but did not produce anxiety-like behavior in rats. Furthermore, lentiviral-mediated overexpression of RGS2 in the hippocampus rescued the anxious phenotype of sub-chronically BSO treated rats. And, Glo1 and Gsr1 protein expression increased in response to RGS2 overepxression within the hippocampus. Our preliminary studies in neuronal cell cultures mimic animal studies with respect to differential regulation of RGS2, Glo1 and Gsr1. Acute oxidative stress increased RGS2, Glo1 and Gsr1 mRNA and proteins while sub- chronic treatment decreased their levels. Our hypothesis is that RGS2 via activation of specific signaling cascades plays a central role in modulating antioxidant enzymes, Glo1 and Gsr1, critical to the etiology of anxiety. We will test our hypothesis by pursuing two specific aims. In aim 1 using a brain-derived cell culture model of acute and sub-chronic oxidative stress, involvement of PKC, p38 and calpain pathways as well as involvement of transcription factors (Nrf2, Sp-1) in an RGS2 dependent regulation of Glo1 and Gsr1 levels will be studied. In aim 2 utilizing our published rat model of acute and sub-chronic oxidative stress, involvement of PKC, p38 and calpain pathways in an RGS2 dependent modulation of Glo1 and Gsr1 together with the assessment of anxiety-like behavior, would be determined. Mechanistic insights obtained from our proposal would lead to the identification of novel targets for drug design in the treatment of anxiety disorders. PUBLIC HEALTH RELEVANCE: Anxiety disorders affect an estimated 40 million people in the United States. Despite an enormous increase in anxiety disorder research, the mechanisms in the brain that regulate anxiety remain poorly understood. Emerging reports including ours, offer a strong argument for a causal role of oxidative stress in anxiety. This proposal seeks to determine those mechanisms representing a new line of investigation that would reveal unique avenues for treatment of anxiety.