EXPRESSION /REGULATION OF NEURONAL NOS IN ENTERIC NS

一氧化氮（NO）是神经元的信使分子，在多种生理和病理生理过程中发挥作用，包括谷氨酸神经毒性、神经变性和长期增强。神经元一氧化氮合酶（nNOS）基因的靶向破坏导致胃扩张和幽门括约肌肥大，一种类似于糖尿病性胃轻瘫的表型。nNOS-/-小鼠的大体解剖紊乱提示NO可能调节胃幽门功能。我们将采用酚红分光光度法和离体器官浴实验来确定NO神经传递在胃排空和胃幽门功能调节中的作用。我们还将确定nNOS在糖尿病小鼠胃幽门功能障碍中的作用。初步结果表明，糖尿病小鼠和nNOS-/-小鼠表现出相似的生理表型。提示NO功能异常可能是糖尿病动物紊乱的基础。我们将研究nNOS蛋白mRNA在组织制剂和培养肠神经元中的表达，为糖尿病患者肠道神经系统（ENS） nNOS下调奠定分子基础。初步结果表明，胰岛素存在时，nNOS蛋白表达增加。我们将以培养的肠神经元、原代皮层神经元和小脑颗粒细胞为模型，确定胰岛素、胰岛素生长因子（IGFs）及其受体在ENS和CNS中nNOS表达和调控中的作用。

Nitric oxide (NO) is a messenger molecule of neurons that plays a role in diverse physiological and pathophysiologic processes, including glutamate neurotoxicity, neurodegeneration and long-term potentiation. Targeted disruption of the neuronal nitric oxide synthase (nNOS) gene results in dilated stomachs and hypertrophied pyloric sphincter muscles, a phenotype that resembles diabetic gastroparesis. The gross anatomic disturbance in nNOS-/- mice suggests that NO may regulate gastropyloric function. We will use phenol red spectrophotometry and ex-vivo organ bath experiments to determine the role of NO neurotransmission in the regulation of gastric emptying and gastropyloric function. We will also ascertain the role of nNOS in gastropyloric dysfunction of diabetic mice. Preliminary results demonstrate that diabetic and nNOS-/- mice exhibit similar physiologic phenotypes. This suggests that abnormal NO function might underlie the disturbances in diabetic animals. We will study nNOS protein mRNA expression in tissue preparations and cultured enteric neurons to establish the molecular basis for enteric nervous system (ENS) nNOS down-regulation in diabetes. Initial results demonstrate that nNOS protein expression is increased in the presence of insulin. We will use cultured enteric neurons, primary cortical neurons and cerebellar granule cells as models to determine the role of insulin, insulin growth factors (IGFs) and their receptors in nNOS expression and regulation in the ENS and CNS.