Madesh M, Benard O, Balasubramanian K A
Department of Gastrointestinal Sciences, Christian Medical College & Hospital, Vellore, India.
Free Radic Biol Med. 1999 Feb;26(3-4):431-8. doi: 10.1016/s0891-5849(98)00218-4.
Recent findings suggest that intracellular oxidants are involved in the induction of apoptosis and this type of cell death can be inhibited by various antioxidants. In our accompanying paper, we have shown apoptosis in the villus tip cells of the monkey small intestinal epithelium. The aim of the present study was to evaluate the possible relationship between oxidative stress, antioxidant levels and the apoptotic process in the monkey small intestinal epithelium. Monkey small intestinal epithelial cells were isolated into different fractions consisting of villus, middle and crypt cells. Mitochondrial function was assessed by the reduction of the tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), with and without succinate. The extent of lipid peroxidation was assessed by measuring the formation of conjugated diene, depletion of polyunsaturated fatty acids and alpha-tocopherol. Level of antioxidant enzymes like, superoxide dismutase (SOD), catalase, glutathione S-transferase (GST), glutathione peroxidase (GPx) and glutathione reductase were also quantitated in various cell fractions. MTT reduction was significantly decreased in villus cells as compared to the cells from other fractions and this was evident even in presence of the respiratory substrate, succinate. Increased formation of conjugated diene and depletion of polyunsaturated fatty acids were seen in villus and crypt cells as compared to middle fraction cells. The alpha-tocopherol level was decreased in both villus and crypt cells as compared to cells from middle region. Significant decrease of SOD activity was seen in the villus tip cells and a slight decrease was seen in the crypt fractions. Glutathione dependent enzymes like GST, GPx and GSH reductase showed higher activity in the villus fractions. A similar observation was also seen in the catalase activity. This study has shown that although oxidative stress is seen in both villus and crypt cells, decreased mitochondrial function was seen in villus tip cells which may be responsible for apoptotic process in the intestinal epithelium.
最近的研究结果表明，细胞内氧化剂参与细胞凋亡的诱导，并且这种类型的细胞死亡可被各种抗氧化剂抑制。在我们的附随论文中，我们已经展示了猴小肠上皮绒毛顶端细胞中的细胞凋亡。本研究的目的是评估猴小肠上皮中氧化应激、抗氧化剂水平与凋亡过程之间的可能关系。猴小肠上皮细胞被分离成由绒毛、中段和隐窝细胞组成的不同部分。通过在有和没有琥珀酸的情况下还原四氮唑染料3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）来评估线粒体功能。通过测量共轭二烯的形成、多不饱和脂肪酸的消耗和α-生育酚来评估脂质过氧化程度。还对各种细胞部分中的超氧化物歧化酶（SOD）、过氧化氢酶、谷胱甘肽S-转移酶（GST）、谷胱甘肽过氧化物酶（GPx）和谷胱甘肽还原酶等抗氧化酶水平进行了定量。与其他部分的细胞相比，绒毛细胞中的MTT还原显著降低，即使在存在呼吸底物琥珀酸的情况下也是如此。与中段部分细胞相比，绒毛和隐窝细胞中可见共轭二烯形成增加和多不饱和脂肪酸消耗。与中部区域的细胞相比，绒毛和隐窝细胞中的α-生育酚水平均降低。绒毛顶端细胞中SOD活性显著降低，隐窝部分略有降低。谷胱甘肽依赖性酶如GST、GPx和谷胱甘肽还原酶在绒毛部分显示出较高活性。过氧化氢酶活性也有类似观察结果。这项研究表明，虽然绒毛和隐窝细胞中都存在氧化应激，但绒毛顶端细胞中线粒体功能下降，这可能是肠道上皮细胞凋亡过程的原因。
