ROLE OF NRF2 IN NITRERGIC MEDIAITED STOMACH MOTILITY

胃轻瘫是糖尿病的常见并发症，可能涉及致病性氧化应激。在啮齿动物模型中，由于神经元型一氧化氮合酶（nNOS）解偶联和活性氧（ROS）增加而导致的一氧化氮（NO）生物利用度降低已被证明在胃排空延迟中起作用。转录因子核因子（红细胞衍生2）样2（NRF 2）调节II期抗氧化和解毒基因的表达。在啮齿动物糖尿病模型中的初步研究表明，NRF 2及其靶基因Gclc和Gclm的表达受到抑制，而氧化应激升高。我们已经证明，与年龄匹配的野生型小鼠相比，NRF 2（Nfe 2/2-/-）的缺失导致四氢生物蝶呤（BH 4，nNOS二聚化和酶活性的关键辅因子）水平降低，这导致氧化应激，nNOS解偶联，NO水平降低，胃氮能神经元功能障碍和胃排空延迟。这些数据支持这样的观点，即糖尿病中NRF 2表达的缺失损害了抗氧化剂基因的表达，从而使NO合成失调，从而促进胃轻瘫的发展。我们提供的证据表明，性激素，雌二醇-17 β（E2）介导的NRF 2/nNOS的表达和功能在糖尿病的发病受损。此外，我们已经表明，糖原合成酶激酶3 β（GSK-3β）或E2调节雌性胃中NO的合成。该数据表明，高血糖期间NRF 2表达的丧失是GSK-3β/CUL 1/SCF/TrCP/RBX 1轴激活的结果。我们的中心假设是，氮能介导的胃动力是由NRF 2调节。具体目标1：将检验高血糖期间NRF 2表达的丧失是GSK-3β/CUL 1/SCF/TrCP/RBX 1轴活化的结果的假设;具体目标2：将检验糖尿病中NRF 2和NRF 2调节的抗氧化酶表达的恢复将导致正常胃运动和胃排空的假设;以及具体目标3：将检验NRF 2和nNOS介导的胃运动受雌性性激素调节的假设;在糖尿病动物中，17-雌二醇（E2）、孕酮和/或它们的胃受体。具体目的4：研究牙周病原体是否抑制肥胖/糖尿病雌性小鼠的胃肠（GI）运动。这些研究的数据将提供重要的信息，NRF 2介导的nNOS功能的调节机制，从而提高我们对胃轻瘫的病理生理学的理解。这些目标中概述的研究具有转化相关性，因为它有可能为糖尿病引起的胃轻瘫确定新的治疗选择。

Gastroparesis is a common complication of diabetes and can involve pathogenic oxidative stress. In rodent models, reduced nitric oxide (NO) bioavailability as a result of neuronal nitric oxide synthase (nNOS) uncoupling and increased reactive oxygen species (ROS) has been shown to play a role in delayed gastric emptying. The transcription factor nuclear factor (erythroid-derived-2)-like 2 (NRF2) regulates the expression of Phase II antioxidant and detoxification genes. Preliminary studies in rodent model of diabetes showed that the expression of NRF2 and its target genes, Gclc and Gclm, is suppressed while oxidative stress is elevated. We have demonstrated that loss of NRF2 (Nfe2/2-/-) resulted in decreased levels of tetrahydrobiopterin (BH4, a critical cofactor for nNOS dimerization and enzyme activity) and that this led to oxidative stress, uncoupling of nNOS, reduced NO levels, gastric nitrergic neuron dysfunction, and delayed gastric emptying compared to age-matched wild-type mice. These data support the notion that loss of NRF2 expression in diabetes impairs antioxidant gene expression, which deregulates NO synthesis, thereby contributing to the development of gastroparesis. We provide evidence that sex hormone, estradiol-17β (E2) mediated NRF2/nNOS expression and function is impaired in the onset of diabetes. In addition, we have shown that glycogen synthase kinase 3beta (GSK-3β) or E2 regulate the synthesis of NO in female stomachs. This data suggest that loss of NRF2 expression during hyperglycemia is a consequence of activation of a GSK-3β/CUL1/SCF/TrCP/RBX1 axis. Our central hypothesis is that nitrergic mediated gastric motility is regulated by NRF2. Specific Aim 1: will test the hypothesis that loss of NRF2 expression during hyperglycemia is a consequence of activation of a GSK-3β/CUL1/SCF/TrCP/RBX1 axis; Specific Aim 2: will test the hypothesis that restoration of NRF2 and NRF2-regulated antioxidant enzyme expression in diabetes will result in normal gastric motility and gastric emptying; and Specific Aim 3: will test the hypothesis that NRF2 and nNOS mediated gastric motility are regulated by female sex hormones; 17-estradiol (E2), progesterone and/or their gastric receptors in diabetic animals. Specific Aim 4: Investigate whether periodontal pathogens inhibit gastrointestinal (GI) motility in obese/diabetic female mice. The data from these studies will provide important information as to the mechanisms of regulation of NRF2-mediated nNOS function and thereby enhance our understanding of the pathophysiology of gastroparesis. The research outlined in these aims has translational relevance as it has the potential to identify novel treatment options for diabetes-induced gastroparesis.