Kuruvilla R, Eichberg J
Department of Biochemical and Biophysical Sciences, University of Houston, Texas 77204-5934, USA.
J Neurochem. 1998 Aug;71(2):775-83. doi: 10.1046/j.1471-4159.1998.71020775.x.
In experimental diabetic neuropathy, defective arachidonic acid metabolism characterized by a decrease in the proportion of glycerophospholipid arachidonoyl-containing molecular species (ACMS) occurs and has been implicated in the pathogenesis of the disorder. In this study, we evaluated the suitability of a tumor-derived human Schwann cell line (NF1T) as a model to investigate the mechanism underlying the loss of ACMS. NF1T cells grown in 30 versus 5.5 mM glucose undergo a marked reduction in ACMS in phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol, in a manner resembling that of diabetic nerve. The depletion of ACMS can be reversed on transferring the cells from 30 mM glucose to medium containing physiological levels of glucose. Cells maintained in 5.5 mM glucose plus 25 mM mannitol or sorbitol did not exhibit decreased ACMS levels, indicating that osmotic effects were not responsible for ACMS depletion. However, growth in 25 mM fructose elicited a reduction of ACMS similar to that produced by 30 mM glucose. Excessive glucose flux through the polyol pathway has been implicated in the neural and vascular abnormalities associated with diabetes. Therefore, we examined the effects of polyol pathway inhibitors, including two aldose reductase inhibitors, zopolrestat and sorbinil, and a sorbitol dehydrogenase inhibitor (SDI), CP166,572, on ACMS levels in NF1T cells cultured in elevated glucose concentrations. At 200 microM, zopolrestat fully and sorbinil partially corrected ACMS depletion. The SDI at concentrations up to 100 microM failed to affect diminished ACMS levels. Neither zopolrestat nor the SDI restored ACMS levels reduced in the presence of elevated fructose concentrations. These findings suggest that enhanced flux through the polyol pathway and, in particular, elevated aldose reductase activity may play a significant role in the reduction of ACMS levels in the cells brought about by elevated glucose levels.
在实验性糖尿病神经病变中，会出现以含花生四烯酰基甘油磷脂分子种类（ACMS）比例降低为特征的花生四烯酸代谢缺陷，且这一缺陷与该疾病的发病机制有关。在本研究中，我们评估了一种肿瘤来源的人雪旺细胞系（NF1T）作为研究ACMS缺失潜在机制模型的适用性。在30 mM葡萄糖与5.5 mM葡萄糖中培养的NF1T细胞，其磷脂酰胆碱、磷脂酰乙醇胺和磷脂酰肌醇中的ACMS显著降低，其方式类似于糖尿病神经。将细胞从30 mM葡萄糖转移至含生理水平葡萄糖的培养基中后，ACMS的减少可得到逆转。维持在5.5 mM葡萄糖加25 mM甘露醇或山梨醇中的细胞未表现出ACMS水平降低，表明渗透效应并非ACMS减少的原因。然而，在25 mM果糖中生长会引发与30 mM葡萄糖产生的ACMS减少相似的情况。通过多元醇途径的过量葡萄糖通量与糖尿病相关的神经和血管异常有关。因此，我们研究了多元醇途径抑制剂对在高葡萄糖浓度下培养的NF1T细胞中ACMS水平的影响，这些抑制剂包括两种醛糖还原酶抑制剂唑泊司他和索比尼尔，以及一种山梨醇脱氢酶抑制剂（SDI）CP166,572。在200 μM时，唑泊司他完全纠正且索比尼尔部分纠正了ACMS的减少。浓度高达100 μM的SDI未能影响降低的ACMS水平。在存在高果糖浓度的情况下，唑泊司他和SDI均未恢复降低的ACMS水平。这些发现表明，通过多元醇途径的通量增加，尤其是醛糖还原酶活性升高，可能在高葡萄糖水平导致的细胞ACMS水平降低中起重要作用。
