Mechanism of Impaired Nerve Regeneration in Experimental Diabetic Rats

实验性糖尿病大鼠神经再生受损的机制

基本信息

批准号：
08670703
负责人：
TERADA Masahiko
金额：
$ 0.9万
依托单位：
Shiga University of Medical Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

To clarify the ability of diabetic nerves to regenerate in diabetic neuropathy, we evaluated nerve regeneration after nerve crush and degeneration after nerve transection in diabetic (DM) and age-matched control rats. In nerve crush model, electrophysical examination indicated that the elongation rate of regenerative nerves and their velocity was slower in DM.Morphologically, the number of regenerative nerve was significantly decreased and its diameter was smaller in DM.In nerve transection model, morphometric analysis indicated that WD was delayed in DM.Immunoblot analysis showed a delay in the degradation of neurofilaments (NFs) in DM during WD.Moreover, phosphorylated NFs detected by SMI31 were more recognized in intact diabetic nerves in comparison with control, while the opposite was true for unphosphorylated NFs detected by SMI32.These results suggest that nerve regeneration is impaired in DM.This impairment, in part, might be due to delay of WD, because WD is prerequisite for nerve regeneration. Since it is known that the sensitivity of NF to calpain-mediated proteolysis is modulated by its carboxyl-terminal phosphorylation state and phosphorylated NFs are resistant to calpains, we concluded that abnormal NF phosphorylation state in diabetes could be one of the mechanisms by which axonal degeneration was delayed.The excessive NF phosphorylation in STZ-diabetic rats could be due to an increase in kinase activity. Proline-directed protein kinases, such as Cdk5/p35, GSK3 beta JNK, ERK, and p38, are potential candidates for NF kinases. We confirmed the existence of Cdk5/p35, JNK, and ERK using immunoblot and immunohistochemistry. Moreover, both JNK and ERK were activated in DRG and sciatic nerve of 12 weeks STZ-diabetic rats. These results suggest that JNK and ERK make an important role in hyperphosphorylation of NF in diabetic rats.

为了阐明糖尿病神经病变中糖尿病神经再生的能力，我们评估了糖尿病（DM）和年龄匹配的对照大鼠神经挤压后的神经再生和神经横断后的退化。在神经挤压模型中，电物理检查显示DM中再生神经的伸长率和速度较慢。形态上，DM中再生神经的数量明显减少，其直径更小。在神经横断模型中，形态测量分析表明： DM 的 WD 延迟。免疫印迹分析显示 WD 期间 DM 的神经丝 (NF) 降解延迟。此外，SMI31 检测到的磷酸化 NF与对照相比，在完整的糖尿病神经中更容易识别，而对于 SMI32 检测到的非磷酸化 NF 则相反。这些结果表明 DM 中的神经再生受损。这种损害部分可能是由于 WD 的延迟，因为 WD是神经再生的先决条件。由于已知 NF 对钙蛋白酶介导的蛋白水解的敏感性是由其羧基末端磷酸化状态调节的，并且磷酸化的 NF 对钙蛋白酶具有抵抗力，因此我们得出结论，糖尿病中异常的 NF 磷酸化状态可能是轴突变性的机制之一STZ 糖尿病大鼠中 NF 过度磷酸化可能是由于激酶活性增加所致。脯氨酸定向蛋白激酶，例如 Cdk5/p35、GSK3 beta JNK、ERK 和 p38，是 NF 激酶的潜在候选者。我们使用免疫印迹和免疫组织化学证实了 Cdk5/p35、JNK 和 ERK 的存在。此外，12周STZ糖尿病大鼠的DRG和坐骨神经中JNK和ERK均被激活。这些结果表明 JNK 和 ERK 在糖尿病大鼠 NF 过度磷酸化中发挥重要作用。