Ponce Jovita, de la Ossa Natalia Pérez, Hurtado Olivia, Millan Mónica, Arenillas Juan F, Dávalos Antonio, Gasull Teresa
Neuroscience Basic Research Lab, Fundació Institut d'Investigació en Ciències de Salut Germans Trias i Pujol, Badalona, Spain.
Stroke. 2008 Apr;39(4):1269-75. doi: 10.1161/STROKEAHA.107.498923. Epub 2008 Mar 6.
Excess brain extracellular glutamate induced by cerebral ischemia leads to neuronal death, mainly through overactivation of N-methyl-D-aspartate (NMDA) receptors. The cholesterol-lowering drugs statins have been reported to protect from NMDA-induced neuronal death but, so far, the mechanism underlying this protection remains unclear. Because NMDA receptors have been reported to be associated with the cholesterol-rich membrane domains known as lipid rafts, we have investigated the effect of treatments that deplete cholesterol levels on excitotoxicity and on association of NMDA receptors to lipid rafts.
Primary neuronal cultures were pretreated with inhibitors of cholesterol synthesis and cholesterol, and NMDA-induced cell death was determined by measuring release of lactate dehydrogenase. Lipid raft fractions were isolated and Western blots were performed.
Treatment with the inhibitors of cholesterol synthesis simvastatin, which inhibits the first step of cholesterol synthesis, or AY9944, which inhibits the last step of cholesterol synthesis, protected neurons from NMDA-induced neuronal death by 70% and 54%, respectively. Treatment with these compounds reduced neuronal cholesterol levels by 35% and 13%, respectively. Simvastatin and AY9944 reduced the association of the subunit 1 of NMDA receptors (NMDAR1) to lipid rafts by 42% and 21%, respectively, and did not change total expression of NMDAR1. Addition of cholesterol reduced neuroprotection by statins and AY9944, and partially reverted the effect of simvastatin on the association of NMDAR1 to lipid rafts.
These data demonstrate that reduction of cholesterol levels protects from NMDA-induced neuronal damage probably by reducing the association of NMDA receptors to lipid rafts.
脑缺血诱导产生的过量脑细胞外谷氨酸主要通过N-甲基-D-天冬氨酸（NMDA）受体的过度激活导致神经元死亡。据报道，降胆固醇药物他汀类可保护神经元免受NMDA诱导的死亡，但迄今为止，这种保护作用的潜在机制仍不清楚。由于据报道NMDA受体与称为脂筏的富含胆固醇的膜结构域相关联，因此我们研究了降低胆固醇水平的处理对兴奋性毒性以及NMDA受体与脂筏关联的影响。
用胆固醇合成抑制剂和胆固醇对原代神经元培养物进行预处理，通过测量乳酸脱氢酶的释放来确定NMDA诱导的细胞死亡。分离脂筏组分并进行蛋白质免疫印迹分析。
用胆固醇合成抑制剂辛伐他汀（抑制胆固醇合成的第一步）或AY9944（抑制胆固醇合成的最后一步）处理分别使神经元免受NMDA诱导的神经元死亡的保护率达到70%和54%。用这些化合物处理分别使神经元胆固醇水平降低了35%和13%。辛伐他汀和AY9944分别使NMDA受体亚基1（NMDAR1）与脂筏的关联减少了42%和21%，并且没有改变NMDAR1的总表达。添加胆固醇降低了他汀类药物和AY9944的神经保护作用，并部分逆转了辛伐他汀对NMDAR1与脂筏关联的影响。
这些数据表明，降低胆固醇水平可能通过减少NMDA受体与脂筏的关联来保护神经元免受NMDA诱导的损伤。
