RESEACH FOR THE PATHOGENIC MECHANISM OF DIABETIC NEUROPATHY

目的：多元醇通路过度活跃和PKC活性改变被认为是糖尿病神经病变的发病机制。然而，多元醇途径与PKC活性之间的关系尚未得到精确的研究。本研究旨在探讨高糖多元醇途径对PKC-MAPK级联和细胞生长的影响。培养大鼠神经鞘瘤细胞（JS-1细胞）。方法：用依帕司他（Ep; 1μM）或不加依帕司他（Ep; 1μM）在5.5或20 mM葡萄糖（HG）中培养JS-1细胞14天，或用反义抗PKC-α (AS)或p38 MAPK特异性抑制剂SB-203580 （SB）处理。通过[^3H]-胸腺苷摄取（占对照组的%）测定细胞增殖活性，通过膜组分中PKCα蛋白表达测定细胞活性，通过磷酸化p38蛋白与总p38蛋白表达的比值测定细胞活性。结果：1)HG组PKC-a和p38活性降低，Ep组改善了HG组PKC-a和p38活性。2)AS组PKC-α蛋白表达和p3S活性呈时间和剂量依赖性降低。3) AS和SB均使细胞增殖活性降低，且呈剂量依赖性。结论：高糖可使PKC-α和p38 MAPK活性通过接近还原酶敏感的方式降低。PKC-α-p38级联可能在神经细胞增殖过程中发挥重要作用，提示葡萄糖诱导的多元醇。通路过度活跃会使proI恶化。通过降低PKC-α和p38 MAPK的活性来干扰Sdiwmm细胞，导致糖尿病性神经病变。

Aims : Polyol pathway hyperactivity and altered PKC activity have been proposed as the pathogenic mechanism of diabetic neuropathy. However, the relationship between polyol pathway and PKC activity has not been precisely investigated. The present study was conducted to investigate the effects of high glucose and polyol pathway on the PKC-MAPK cascade and cell growth using.cultured rat Schwannoma cells (JS-1 cells).Methods : JS-1 cells were cultured in 5.5 or 20 mM glucose (HG) with or without epalrestat (Ep ; 1μM) for 14 days, or treated with an antisense against PKC-α (AS) or a p38 MAPK specific inhibitor, SB-203580 (SB). The proliferation activity by assay of [^3H]-thyraidine uptake (% of control), PKCα activity by its protein expression in membrane fraction, and p38 activity by the ratio of phosphorylated to total p38 protein expression were measured.Results : 1) PKC-a and p38 activityies were decreased under the HG condition, which were ameliorated by Ep. 2) With AS treatment, the protein expression of PKC-α and p3S activity were decreased in a time- and dose-dependent fashion. 3) Proliferation activity was decreased by both AS and SB in a dose-dependent fashion. Conclusions: These results suggest that PKC-α and p38 MAPK activities are decreased by high glucose through the alclose reductase-sensit.ive pathway, and that PKC-α-p38 cascade would play an important- role in proliferation of neural cells, indicating,that glucose-induced polyol. Pathway hyperactivity would deteriorate the proI.ifernIion of Sdiwmm cells through' the decreased activities of PKC-α and p38 MAPK, leading t.o diabetic neuropathy.