Nitric Oxide and gastric motility in female diabetics

女性糖尿病患者的一氧化氮和胃动力

• 批准号: 7384970
• 负责人: PANDU R GANGULA
• 金额: $ 1.26万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7384970
• 关键词: Abdominal Pain; Accounting; Affect; American; Anabolism; Attenuated; Biological; Biopterin; Body Weight decreased; Chronic; Clinic; Clinical; Complications of Diabetes Mellitus; Condition; Data; Diabetes Mellitus; Dimerization; Disease; Dyspepsia; Enzymes; Event; Experimental Models; Female; Functional disorder; Gastric Emptying; Gastric Tissue; Gastrointestinal Motility; Gastroparesis; Guanosine Triphosphate; Health; Hyperglycemia; Impairment; In Vitro; Insulin; Lead; Mechanics; Mediating; Messenger RNA; Molecular; Muscle Contraction; NOS1 protein, human; Nausea and Vomiting; Nervous system structure; Neurons; Neurotransmitters; Nitric Oxide; Nitric Oxide Synthase Type I; Non-Insulin-Dependent Diabetes Mellitus; Pathogenesis; Pathway interactions; Patients; Production; Progressive Disease; Range; Rate; Rattus; Recurrence; Regulation; Relaxation; Reporting; Retina; Role; Sex Bias; Sex Characteristics; Solid; Stomach; Streptozocin; Structure; Supplementation; Symptoms; Syndrome; Testing; Tissues; Type I Insulin; Vomiting; Woman; Work; base; cell motility; cofactor; design; diabetic; diabetic gastroparesis; diabetic rat; dimer; enzyme activity; gastrointestinal; in vivo; inhibitor/antagonist; kidney vascular structure; motility disorder; neuron loss; novel therapeutics; protein expression; research study; tetrahydrobiopterin; therapeutic target

DESCRIPTION (provided by applicant): Gastroparesis is a disabilitating disease affecting predominantly young women. The biological basis of this disorder and its associated gender bias remains poorly understood. Recent studies have implicated a role for dysregulation of neuronal nitric oxide synthase (nNOS) in myenteric neurons and we surmised that gender differences in nitrergic control of gastric motility may possibly account for observed vulnerability of females to diabetic gastroparesis. Our preliminary data suggests that a significant impairment of nitrergic relaxation and delayed gastric emptying for solids was demonstrated selectively in females after diabetes induction with streptozotocin (STZ). Most importantly, we have also shown that changes in nitrergic relaxation in both healthy and diabetic rats correlates well with the state of dimerization of nNOS1 but not with the expression of total nNOS (1, 2 and 3). Dimerization of nNOS is essential for activity of this enzyme but has not been previously studied in gastrointestinal tissue. In this proposal, we have focused on the role of tetrahydrobiopterin (BH4), an essential cofactor for nNOS activity that is required to maintain the homodimeric structure of nNOS. BH4 levels in tissue in turn depend on the activity of GTP cyclohydrolase1 (GTPCH1), the rate limiting enzyme in the de novo synthesis of BH4. In preliminary experiments we have demonstrated that GTPCH1 mRNA and protein expression are down regulated in the diabetic female gastric tissues along with significantly reduced BH4 content, suggesting reduced synthesis of biopterins leading to decreased nitrergic relaxation. In support of this, the GTPCH1 inhibitor, 2, 4 diamino-6-hydroxypyrimidine (DAHP), reduced nNOS1 dimerization, NO release and nitrergic relaxation of gastric tissue in normal female rats in vitro. Conversely, the exogenous addition of BH4 to female gastric tissues in vitro reverses a hyperglycemia-induced decrease in nitrergic relaxation. In addition, in vivo BH4 treatment attenuated reduced nNOS activity in diabetic gastric tissue. We therefore hypothesize that impaired biosynthesis of gastric BH4 accounts for the decrease in nNOS activity and nitrergic relaxation in female diabetic gastroparesis. To test this hypothesis we propose the following specific aims: Specific Aim 1: To determine whether diabetes results in impairment of the BH4 biosynthetic pathway, nNOS dimerization, nNOS activity and nitrergic relaxation in female rat gastric tissues. Specific Aim 2: To investigate whether BH4 supplementation restores delayed gastric emptying, impaired gastric nNOS dimerization, nNOS activity, NO synthesis and nitrergic relaxation in female diabetic rats. The data from these studies will provide important information as to the mechanisms of regulation of nNOS function in normal and diabetic female rat gastric tissues and thereby enhance our understanding of the pathophysiology of gastroparesis. Further, it may lead to the discovery of novel therapeutic targets for the management of this challenging clinical syndrome.Diabetes mellitus is a chronic progressive disease that affects 16 million Americans. Diabetes causes several complications that affect retina, kidney, vascular, gastrointestinal, and nervous system. The mechanism through which diabetic complications develop is unclear. Gastric dysmotility or gastropathy is one of the vigorous complications of diabetic mellitus in clinics and can cause disabling symptoms including nausea, vomiting and weight loss and often leads to delayed or accelerated gastric emptying. Reports indicate that 80% of patients are women suffering with this problem. Although the exact pathogenesis remains unknown, there is fairly convincing evidence in experimental models that diabetes results in the malfunctioning of specific neurons that produce the neurotransmitter nitric oxide (NO). This condition is due to loss of expression of the enzyme responsible for NO production (neuronal nitric oxide synthase: nNOS) and can be reversed with insulin replacement. The molecular events leading to loss of nNOS expression and altered (delay or accelerate) gastric emptying (mechanical due to loss of neuronal control of stomach muscle contractions and relaxations) in diabetic stomachs remain unknown. The data from these studies will provide important information as to the mechanisms of regulation of NO mediated gastric emptying and stomach contractions in diabetic female rat. Further, it may lead to the discovery of novel therapeutic targets for the management of this challenging clinical syndrome.

描述（由申请人提供）：胃轻瘫是一种影响年轻妇女的疾病。这种疾病及其相关性别偏见的生物学基础仍然知之甚少。最近的研究暗示了肌植物神经元中神经元一氧化物合酶（NNOS）失调的作用，我们推测，胃运动的硝化控制中性别差异可能可能解释女性与糖尿病性胃痛的脆弱性。我们的初步数据表明，在糖尿病诱导链霉菌素（STZ）后，在女性中有选择地证明了固体弛豫和胃排空的重大损害。最重要的是，我们还表明，健康和糖尿病大鼠的硝化弛豫的变化与NNOS1二聚化状态息息相关，但与总NNOS的表达无关（1、2和3）。 NNOS的二聚化对于该酶的活性至关重要，但以前尚未在胃肠道组织中进行研究。在此提案中，我们专注于四氢无菌蛋白酶（BH4）的作用，这是一种NNOS活性的必不可少的辅助因子，它是维持NNOS同型二聚体结构所需的。组织中的BH4水平反过来取决于GTP环氢酶1（GTPCH1）的活性，这是BH4从头合成中限制酶的速率限制酶。在初步实验中，我们已经证明GTPCH1 mRNA和蛋白表达在糖尿病女性胃组织中受到调节，同时BH4含量显着降低，这表明生物蛋白酶的合成降低，从而降低了硝化弛豫。为此，GTPCH1抑制剂，2，4二氨基-6-羟基苯胺（DAHP），NNOS1二聚化降低，无释放和硝化性释放和氮气在体外雌性大鼠的胃组织的松弛。相反，在体外向雌性胃组织外源性添加会逆转高血糖引起的硝化松弛降低。另外，体内BH4处理减少了糖尿病胃组织中的NNOS活性降低。因此，我们假设胃BH4的生物合成受损是女性糖尿病性胃轻瘫中NNOS活性和硝化弛豫的降低。为了检验该假设，我们提出以下特定目的：具体目的1：确定糖尿病是否导致BH4生物合成途径损害，NNOS二聚化，NNOS活性和女性大鼠胃组织中的硝化弛豫。具体目的2：研究补充BH4是否会恢复胃排空的延迟，胃NNOS二聚作用受损，NNOS活性，无合成和女性糖尿病大鼠的硝化弛豫。这些研究的数据将提供有关正常和糖尿病女性大鼠胃组织NNO功能调节机制的重要信息，从而增强了我们对胃肉食病理生理学的理解。此外，这可能导致发现了这种具有挑战性的临床综合征的新型治疗靶标。DiabetesMellitus是一种慢性进展疾病，影响了1600万美国人。糖尿病会引起几种并发症，影响视网膜，肾脏，血管，胃肠道和神经系统。糖尿病并发症发生的机制尚不清楚。胃不动或胃病是诊所中糖尿病性麦芽脂肪症的剧烈并发症之一，可能引起残疾症状，包括恶心，呕吐和体重减轻，并且通常导致延迟或加速胃排空。报告表明，有80％的患者是患有此问题的女性。尽管确切的发病机理尚不清楚，但在实验模型中有相当令人信服的证据表明糖尿病导致产生神经递质一氧化氮（NO）的特定神经元的故障。这种情况是由于酶的表达丧失，导致无生产的酶（神经元一氧化氮合酶：nNOS），并且可以通过胰岛素替代剂来逆转。糖尿病性胃中导致NNOS表达丧失并改变（由于对胃肌肉收缩和放松的神经元控制而导致的机械性）的分子事件仍然未知。这些研究的数据将提供有关糖尿病女性大鼠无介导的胃排空和胃收缩的调节机制的重要信息。此外，这可能导致发现了这种具有挑战性的临床综合征的新型治疗靶标。