Early Dysfunction of Islet Nerves in Type 1 Diabetes

描述(申请人提供)：我们对非糖尿病动物进行了为期十年的研究 而人类表明，胰升糖素对胰岛素诱导的低血糖的反应 (IIH)是自主调节的。由于这种特定的胰高血糖素反应丢失 在1型糖尿病早期，可能与早期自主神经缺陷有关。我们的 最近的初步数据显示，早期、明显和选择性的损害 BB糖尿病大鼠胰岛交感神经末梢。因此，我们的第一个 具体目的是将该神经末梢的时间进程和大小联系起来 对BB糖尿病大鼠胰升糖素反应受损的损害。胰岛交感神经 神经末梢将通过水泡的双重免疫组织化学进行可视化 单胺转运体2(VMAT2)和胰升糖素。我们的第二个具体目标是 通过防止神经末梢减少对IIH的胰升糖素反应 发病前应用神经生长因子(NOF)治疗BB大鼠损伤 他们的糖尿病。我们的第三个具体目标是复制失去的胰高血糖素 糖尿病抵抗的BB大鼠对IIH的神经组合反应 6-羟基多巴胺(6-OHDA)致终末损伤与胰岛B细胞丢失 链脲佐菌素(STZ)诱导。 由于神经末梢损伤会削弱神经元胞体的反应性 对于激活，我们的第四个具体目标是确定这个 BB糖尿病大鼠的反应性受损及其在失血中的作用 高血糖素对IIH的反应。这些神经元的反应将通过以下方式进行评估 计算那些表达核Fos的基因。因此，腹腔神经节(CG)Fos 将在手术前和手术期间对夹闭的IIH的表达进行评估 BB糖尿病的第一周以及糖尿病大鼠接受任何一种全身性治疗 病毒转染法诱导的NGF或神经节细胞NGF。 最终的具体目标是确定神经末梢的贡献。 损伤、胰岛B细胞丢失和神经节细胞NGF对此受损的影响 响应性。因此，抵抗糖尿病的BB大鼠将获得 将测量6-OHDA和STZ以及CG Fos对夹闭的IIH的响应。 最后，将用酶联免疫吸附试验测定神经节细胞中神经生长因子水平。 之前的实验表明，它们与反应能力受损有直接关系。 这些实验将共同决定时间、震级和位置 BB的胰岛交感神经功能障碍(神经末梢或胞体) 糖尿病大鼠及其在IIH后高血糖素反应丧失中的作用。

DESCRIPTION (provided by applicant): Our ten-year study of nondiabetic animals and humans shows that the glucagon response to insulin-induced hypoglycemia (IIH) is autonomically mediated. Since this specific glucagon response is lost early in type 1 diabetes, an early autonomic defect may be responsible. Our recent preliminary data demonstrate an early, marked and selective damage to islet sympathetic nerve terminals in BB diabetic rats. Therefore, our first specific aim is to relate the time course and magnitude of this nerve terminal damage to impaired glucagon responses in BB diabetic rats. Islet sympathetic nerve terminals will be visualized by dual immunohistochemistry for vesicular monoamine transporter 2 (VMAT2) and glucagon. Our second specific aim is to prevent the loss of the glucagon response to IIH by preventing nerve terminal damage using nerve growth factor (NOF) to treat BB rats before the onset of their diabetes. Our third specific aim is to reproduce the loss of the glucagon response to IIH in diabetes resistant BB rats by a combination of nerve terminal damage induced by 6-hydroxydopamine (6-OHDA) and islet B-cell loss induced by streptozotocin(STZ). Since nerve terminal damage impairs the responsiveness of neuronal cell bodies to activation, our fourth specific aim is to determine the magnitude of this impaired responsiveness in BB diabetic rats and its contribution to the loss of the glucagon response to IIH. The response of these neurons will be assessed by counting those that express nuclear Fos. Thus, celiac ganglia (CG) Fos expression will be assessed in response to clamped IIH before and during the first week of BB diabetes and in diabetic rats pretreated with either systemic NGF or ganglionic NGF induced by viral transfection. The final specific aim is to determine the contributions of nerve terminal damage, islet B-cell loss and loss of ganglionic NGF to this impaired responsiveness. Thus, diabetes resistant BB rats will receive a combination of 6-OHDA and STZ and the CG Fos responses to clamped IIH will be measured. Finally, ganglionic levels of NGF will be measured by ELISA in this and previous experiments to directly relate them to the impaired responsiveness. Together these experiments will determine the timing, magnitude and location (nerve terminals or cell bodies) of islet sympathetic dysfunction in BB diabetic rats and its contribution to the loss of the glucagon response to IIH.