Suryanarayana P, Patil Madhoosudan A, Reddy G Bhanuprakash
Biochemistry Division, National Institute of Nutrition, Hyderabad 500 604, India.
Indian J Exp Biol. 2011 Oct;49(10):749-55.
Cataract, the leading cause of blindness worldwide, is associated with many risk factors including diabetes. Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) states are associated with pre-diabetes and insulin resistance. This condition subsequently leads to the development of type-2 diabetes. Epidemiological studies indicated that not only diabetes but IGT/IFG will also lead to the development of microvascular disorders and cataract. However, there are no studies on the mechanism of insulin resistance induced changes in the eye lens. In the present study, IGT/IFG-induced changes in lens using neonatal-streptozotocin (nSTZ) rat model have been investigated. Though, nSTZ rats showed the signs of IGT and insulin resistance starting from two months old, they did not develop cataract even at the age of 8-months. However, biochemical analysis indicates a three-fold increase in sorbitol levels in nSTZ lens upon prolonged (6-months) IGT and insulin resistance. Also there was an increase in lipid peroxidation and alterations in antioxidant enzymes. Results of this study showed that activation of polyol pathway and increased oxidative stress, commonly associated with long-term complications of diabetes, have been observed in eye lens due to prolonged IGT and insulin resistance which may lead to cataract.
白内障是全球失明的主要原因，与包括糖尿病在内的许多风险因素相关。糖耐量受损（IGT）和空腹血糖受损（IFG）状态与糖尿病前期和胰岛素抵抗有关。这种情况随后会导致2型糖尿病的发展。流行病学研究表明，不仅糖尿病，IGT/IFG也会导致微血管疾病和白内障的发展。然而，目前尚无关于胰岛素抵抗引起晶状体变化机制的研究。在本研究中，使用新生链脲佐菌素（nSTZ）大鼠模型研究了IGT/IFG诱导的晶状体变化。虽然nSTZ大鼠从两个月大开始就表现出IGT和胰岛素抵抗的迹象，但它们即使在8个月大时也没有发展为白内障。然而，生化分析表明，在长期（6个月）的IGT和胰岛素抵抗后，nSTZ晶状体中的山梨醇水平增加了三倍。脂质过氧化也增加，抗氧化酶发生改变。本研究结果表明，由于长期的IGT和胰岛素抵抗，在晶状体中观察到了多元醇途径的激活和氧化应激增加，这通常与糖尿病的长期并发症相关，可能导致白内障。
