Wankhar Wankupar, Srinivasan Sakthivel, Rajan Ravindran, Sheeladevi Rathinasamy
Department of Physiology, Dr. ALM PG Institute of Basic Medical Sciences,University of Madras, Taramani Campus, Chennai 600 113, India.
J Biomed Res. 2017 Jan 19;31(2):143-153. doi: 10.7555/JBR.31.20150063.
Noise has been regarded as an environmental/occupational stressor that causes damages to both auditory and non-auditory organs. Prolonged exposure to these mediators of stress has often resulted in detrimental effect, where oxidative/nitrosative stress plays a major role. Hence, it would be appropriate to examine the possible role of free radicals in brain discrete regions and the "antioxidants" mediated response of S. dulcis. Animals were subjected to noise stress for 15 days (100 dB/4 hours/day) and estimation of endogenous free radical and antioxidant activity were carried out on brain discrete regions (the cerebral cortex, cerebellum, brainstem, striatum, hippocampus and hypothalamus). The result showed that exposure to noise could alleviate endogenous free radical generation and altered antioxidant status in brain discrete regions when compared to that of the control groups. This alleviated free radical generation (HO and NO) is well supported by an upregulated protein expression on immunohistochemistry of both iNOS and nNOS in the cerebral cortex on exposure to noise stress. These findings suggest that increased free radical generation and altered anti-oxidative status can cause redox imbalance in the brain discrete regions. However, free radical scavenging activity of the plant was evident as the noise exposed group treated with S. dulcis[200 mg/(kg·b·w)] displayed a therapeutic effect by decreasing the free radical level and regulate the anti-oxidative status to that of control animals. Hence, it can be concluded that the efficacy of S. dulcis could be attributed to its free radical scavenging activity and anti-oxidative property.
噪声被视为一种环境/职业应激源，会对听觉和非听觉器官造成损害。长期暴露于这些应激介质通常会产生有害影响，其中氧化/亚硝化应激起主要作用。因此，研究自由基在脑不同区域可能发挥的作用以及甜菊的“抗氧化剂”介导的反应是合适的。将动物置于噪声应激下15天（100分贝/每天4小时），并对脑不同区域（大脑皮层、小脑、脑干、纹状体、海马体和下丘脑）进行内源性自由基和抗氧化活性的评估。结果表明，与对照组相比，暴露于噪声可减轻脑不同区域内源性自由基的产生并改变抗氧化状态。暴露于噪声应激时，大脑皮层中诱导型一氧化氮合酶（iNOS）和神经元型一氧化氮合酶（nNOS）免疫组化的蛋白质表达上调，很好地支持了这种自由基产生的减轻（羟基自由基和一氧化氮）。这些发现表明，自由基产生增加和抗氧化状态改变可导致脑不同区域的氧化还原失衡。然而，植物的自由基清除活性很明显，因为用甜菊[200毫克/（千克·体重）]处理的噪声暴露组通过降低自由基水平并将抗氧化状态调节至对照动物水平而显示出治疗效果。因此，可以得出结论，甜菊的功效可归因于其自由基清除活性和抗氧化特性。
