Baitharu Iswar, Jain Vishal, Deep Satya Narayan, Shroff Sabita, Sahu Jayanta Kumar, Naik Pradeep Kumar, Ilavazhagan Govindasamy
Department of Zoology, Guru Ghasidas Central University, Bilaspur, Chattishgarh, India; Department of Neurobiology, Defence Institute of Physiology and Allied Sciences, Defense Research Development Organisation, Timarpur, Delhi, India.
Department of Neurobiology, Defence Institute of Physiology and Allied Sciences, Defense Research Development Organisation, Timarpur, Delhi, India.
PLoS One. 2014 Oct 13;9(10):e105311. doi: 10.1371/journal.pone.0105311. eCollection 2014.
Withania somnifera root extract has been used traditionally in ayurvedic system of medicine as a memory enhancer. Present study explores the ameliorative effect of withanolide A, a major component of withania root extract and its molecular mechanism against hypoxia induced memory impairment. Withanolide A was administered to male Sprague Dawley rats before a period of 21 days pre-exposure and during 07 days of exposure to a simulated altitude of 25,000 ft. Glutathione level and glutathione dependent free radicals scavenging enzyme system, ATP, NADPH level, γ-glutamylcysteinyl ligase (GCLC) activity and oxidative stress markers were assessed in the hippocampus. Expression of apoptotic marker caspase 3 in hippocampus was investigated by immunohistochemistry. Transcriptional alteration and expression of GCLC and Nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2) were investigated by real time PCR and immunoblotting respectively. Exposure to hypobaric hypoxia decreased reduced glutathione (GSH) level and impaired reduced gluatathione dependent free radical scavenging system in hippocampus resulting in elevated oxidative stress. Supplementation of withanolide A during hypoxic exposure increased GSH level, augmented GSH dependent free radicals scavenging system and decreased the number of caspase and hoescht positive cells in hippocampus. While withanolide A reversed hypoxia mediated neurodegeneration, administration of buthionine sulfoximine along with withanolide A blunted its neuroprotective effects. Exogenous administration of corticosterone suppressed Nrf2 and GCLC expression whereas inhibition of corticosterone synthesis upregulated Nrf2 as well as GCLC. Thus present study infers that withanolide A reduces neurodegeneration by restoring hypoxia induced glutathione depletion in hippocampus. Further, Withanolide A increases glutathione biosynthesis in neuronal cells by upregulating GCLC level through Nrf2 pathway in a corticosterone dependenet manner.
印度人参根提取物在阿育吠陀医学体系中传统上被用作记忆增强剂。本研究探讨了印度人参根提取物的主要成分睡茄内酯A对缺氧诱导的记忆损伤的改善作用及其分子机制。在暴露于25000英尺模拟海拔的21天预暴露期之前和暴露的7天期间，给雄性Sprague Dawley大鼠施用睡茄内酯A。评估海马中的谷胱甘肽水平、谷胱甘肽依赖性自由基清除酶系统、ATP、NADPH水平、γ-谷氨酰半胱氨酸连接酶（GCLC）活性和氧化应激标志物。通过免疫组织化学研究海马中凋亡标志物半胱天冬酶3的表达。分别通过实时PCR和免疫印迹研究GCLC和核因子（红细胞衍生2）相关因子2（Nrf2）的转录改变和表达。暴露于低压缺氧会降低海马中还原型谷胱甘肽（GSH）水平，并损害还原型谷胱甘肽依赖性自由基清除系统，从而导致氧化应激升高。在缺氧暴露期间补充睡茄内酯A可提高GSH水平，增强GSH依赖性自由基清除系统，并减少海马中半胱天冬酶和Hoechst阳性细胞的数量。虽然睡茄内酯A可逆转缺氧介导的神经退行性变，但与睡茄内酯A一起施用丁硫氨酸亚砜胺会削弱其神经保护作用。外源性施用皮质酮会抑制Nrf2和GCLC表达，而抑制皮质酮合成会上调Nrf2以及GCLC。因此，本研究推断睡茄内酯A通过恢复缺氧诱导的海马谷胱甘肽耗竭来减少神经退行性变。此外，睡茄内酯A通过以皮质酮依赖性方式通过Nrf2途径上调GCLC水平来增加神经元细胞中的谷胱甘肽生物合成。
