Lee Hsin-Hsueh, Yang Ling-Ling, Wang Ching-Cheung, Hu Ssu-Yao, Chang Shwu-Fen, Lee Yi-Hsuan
Graduate Institute of Pharmaceutical Science, Taipei Medical University, Taipei, Taiwan
Brain Res. 2003 Oct 3;986(1-2):103-13. doi: 10.1016/s0006-8993(03)03197-4.
Neuronal injury in the central nervous system following ischemic insult is believed to result from glutamate toxicity and glucose deprivation. In this study, polyphenols isolated from Scutellaria baicalensis Georgi, including baicalin, baicalein, and wogonin, were investigated for their neuroprotective effects against glutamate/NMDA (Glu/NMDA) stimulation and glucose deprivation in primary cultured rat brain neurons. Cell death was accessed by lactate dehydrogenase (LDH) release assay for necrosis, and mitochondrial activity was accessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction activity assay. It was found that both baicalin and baicalein decreased LDH release of the cultured neurons after 24 h treatment, whereas wogonin profoundly increased LDH release after 2 h treatment and resulted in neuronal death after 24 h. Glu/NMDA treatment profoundly increased LDH release and moderately decreased MTT reduction activity in an NMDA receptor-dependent manner. Both baicalin and baicalein significantly reduced Glu/NMDA-increased LDH release, in which baicalein is much more potent than baicalin. Glu/NMDA-increased intracellular calcium was also significantly attenuated by baicalin and baicalein. Baicalin and baicalein did not affect glutamate receptor binding activity, but baicalein did moderately decrease Glu/NMDA-induced nitric oxide (NO) production. In the glucose deprivation (GD) study, baicalein but not baicalin showed significant protective effects on the GD-increased LDH release, without affecting the GD-induced NO production, in cultured rat brain neurons. These results suggest that baicalein is the most effective compound among three polyphenols tested in preventing neurotoxicity induced by both glutamate and GD, whereas baicalin was only effective in preventing glutamate toxicity. Wogonin might have a neurotoxic effect on the brain.
缺血性损伤后中枢神经系统中的神经元损伤被认为是由谷氨酸毒性和葡萄糖剥夺导致的。在本研究中，对从黄芩中分离出的多酚类物质（包括黄芩苷、黄芩素和汉黄芩素）针对原代培养的大鼠脑神经元中谷氨酸/N-甲基-D-天冬氨酸（Glu/NMDA）刺激和葡萄糖剥夺的神经保护作用进行了研究。通过乳酸脱氢酶（LDH）释放试验检测坏死来评估细胞死亡情况，通过3-(4,5-二甲基噻唑-2-基)-2,5-二苯基溴化四氮唑（MTT）还原活性试验评估线粒体活性。结果发现，黄芩苷和黄芩素在处理24小时后均降低了培养神经元的LDH释放，而汉黄芩素在处理2小时后显著增加了LDH释放，并在24小时后导致神经元死亡。Glu/NMDA处理以NMDA受体依赖性方式显著增加了LDH释放，并适度降低了MTT还原活性。黄芩苷和黄芩素均显著降低了Glu/NMDA增加的LDH释放，其中黄芩素比黄芩苷更有效。黄芩苷和黄芩素也显著减弱了Glu/NMDA增加的细胞内钙水平。黄芩苷和黄芩素不影响谷氨酸受体结合活性，但黄芩素适度降低了Glu/NMDA诱导的一氧化氮（NO）生成。在葡萄糖剥夺（GD）研究中，黄芩素而非黄芩苷对培养的大鼠脑神经元中GD增加的LDH释放显示出显著的保护作用，且不影响GD诱导的NO生成。这些结果表明，在测试的三种多酚类物质中，黄芩素是预防谷氨酸和GD诱导的神经毒性最有效的化合物，而黄芩苷仅在预防谷氨酸毒性方面有效。汉黄芩素可能对大脑具有神经毒性作用。
