Oxidative Stress and Free Radical Biology Laboratory, Department of Physiology, University of Calcutta, 92, APC Road, Kolkata 700009, India.
Oxidative Stress and Free Radical Biology Laboratory, Department of Physiology, University of Calcutta, 92, APC Road, Kolkata 700009, India; Department of Physiology, Vidyasagar College, 39, Sankar Ghosh Lane, Kolkata 700006, India.
Life Sci. 2020 Jun 1;250:117596. doi: 10.1016/j.lfs.2020.117596. Epub 2020 Mar 30.
β-Estradiol (β-E), one of the chemical forms of female gonad hormone exhibited antioxidant efficacy in biochemical system, in vitro. The aim of the study was to investigate whether any other mechanism of protection by β-E to hepatic mitochondria in presence of stressor agent i.e.,a combination of Cu and ascorbic acid is involved.
Freshly prepared goat liver mitochondria was incubated with stressors and 1 μM β-E and post incubated with the same concentration at 37 °C at pH 7.4. Mitochondrial viability, biomarkers of oxidative stress, activities of Krebs cycle enzymes, mitochondrial membrane potential, Ca permeability were measured. Mitochondrial morphology and binding pattern of β-E with stressors were also studied.
Upon incubation of mitochondria with Cu, ascorbic acid and their combination there is a significant decline in activities of four of Krebs cycle enzymes in an uncompetitive manner with a concomitant increase in Ca permeability and membrane potential of inner mitochondrial membrane, which is withdrawn during co-incubation with β-E, but was not reversed during post incubation with the β-E. The final studies on mitochondrial membrane morphology using scanning electron microscope also exhibited damage. Isothermal titration calorimetry data also showed the negative heat change in the mixture of β-E with ascorbic acid and also its combination with Cu.
Our results for the first time demonstrated that β-E protects againstCu-ascorbate induced oxidative stress by binding with ascorbic acid. The new mechanism of binding of β-E with stress agents may have a future therapeutic relevance.
β-雌二醇（β-E）是女性性腺激素的化学形式之一，具有抗氧化功效，已在生化系统中得到证实。本研究旨在探讨β-E 对肝线粒体的保护作用是否涉及应激剂（即铜和抗坏血酸的组合）以外的其他机制。
新鲜制备的山羊肝线粒体与应激剂和 1 μM β-E 孵育，然后在 37°C 下 pH 7.4 下用相同浓度的β-E 再孵育。测量线粒体活力、氧化应激生物标志物、三羧酸循环酶活性、线粒体膜电位、Ca 通透性。还研究了线粒体形态和β-E 与应激剂的结合模式。
在与铜、抗坏血酸及其组合孵育线粒体时，四种三羧酸循环酶的活性呈非竞争性显著下降，同时伴随着 Ca 通透性和内膜线粒体膜电位的增加，β-E 共孵育时这种情况得到逆转，但β-E 后孵育时并未逆转。使用扫描电子显微镜对线粒体膜形态的最终研究也显示出损伤。等温滴定量热法数据还显示β-E 与抗坏血酸混合物以及与铜的混合物的负热变化。
我们的研究结果首次表明，β-E 通过与抗坏血酸结合来保护肝线粒体免受 Cu-抗坏血酸诱导的氧化应激。β-E 与应激剂结合的新机制可能具有未来的治疗相关性。
