Powell L A, Nally S M, McMaster D, Catherwood M A, Trimble E R
Department of Clinical Biochemistry, The Royal Group of Hospitals, Belfast, UK.
Free Radic Biol Med. 2001 Nov 15;31(10):1149-55. doi: 10.1016/s0891-5849(01)00648-7.
Hyperglycemia-induced oxidative stress may play a key role in the pathogenesis of diabetic vascular disease. The purpose of this study was to determine the effects of glucose on levels of glutathione (a major intracellular antioxidant), the expression of gamma-glutamylcysteine synthetase (the rate-limiting enzyme in glutathione de novo synthesis), and DNA damage in human vascular smooth muscle cells in vitro. High glucose conditions and buthionine sulphoximine, an inhibitor of gamma-glutamylcysteine synthetase, reduced intracellular glutathione levels in vascular smooth muscle cells. This reduction was accompanied by a decrease in the mRNA expression of both subunits of gamma-glutamylcysteine synthetase as well as an increase in DNA damage. In high glucose conditions, incubation of the vascular smooth muscle cells with alpha-lipoic acid and L-cystine restored glutathione levels. We suggest that the decrease in GSH levels seen in high glucose conditions is mediated by the availability of cysteine (rate-limiting substrate in de novo glutathione synthesis) and the gene expression of the gamma-glutamylcysteine synthetase enzyme. Glutathione depletion is associated with an increase in DNA damage, which can be reduced when glutathione levels are restored.
高血糖诱导的氧化应激可能在糖尿病血管疾病的发病机制中起关键作用。本研究的目的是确定葡萄糖对谷胱甘肽（一种主要的细胞内抗氧化剂）水平、γ-谷氨酰半胱氨酸合成酶（谷胱甘肽从头合成中的限速酶）的表达以及体外培养的人血管平滑肌细胞中DNA损伤的影响。高糖条件以及γ-谷氨酰半胱氨酸合成酶抑制剂丁硫氨酸亚砜胺降低了血管平滑肌细胞内的谷胱甘肽水平。这种降低伴随着γ-谷氨酰半胱氨酸合成酶两个亚基的mRNA表达减少以及DNA损伤增加。在高糖条件下，用α-硫辛酸和L-胱氨酸孵育血管平滑肌细胞可恢复谷胱甘肽水平。我们认为，高糖条件下谷胱甘肽水平的降低是由半胱氨酸（谷胱甘肽从头合成中的限速底物）的可用性和γ-谷氨酰半胱氨酸合成酶的基因表达介导的。谷胱甘肽耗竭与DNA损伤增加有关，当谷胱甘肽水平恢复时，DNA损伤可减少。
