去氢表雄酮对抗NMDA神经毒性与抑制细胞内Ca^(2+)升高有关(英文)

Dehydroepiandrosterone (DHEA) Prevents N-methyl-D-aspartic acid (NMDA)-induced Death of Cortical Neurons by Inhibiting of The Intracellular Ca^(2+) Elevation

去氢表雄酮(Dehydroepiandrosterone,DHEA)是一种神经甾体物质,虽然已经发现对中枢神经系统有保护作用,但其分子机制尚未阐明.从胚胎小鼠(E15～16)大脑皮层分离神经元,离体培养10d,用MTT法检测DHEA对抗NMDA神经毒性的作用.用荧光染料Fluo＿3处理后,激光共聚焦显微镜分析胞内Ca2+浓度的变化,研究了DHEA神经保护作用与胞内Ca2+浓度的相关性.结果发现:(1)NMDA的剂量、时间依赖方式降低神经元的活性,(2)DHEA预处理可以明显改善NMDA诱导的形态学变化,且剂量依赖性预防NMDA的毒性,(3)1mmoL/LNMDA诱导细胞内游离Ca2+荧光浓度的迅速升高,而DHEA可以阻断这种变化.以上数据表明,DHEA可以保护神经元,对抗NMDA的神经毒性作用,其机制可能与抑制胞内Ca2+升高有关.

Dehydroepiandrosterone(DHEA) is a neurosteroid which has played a neuroprotective role on the central nervous system, especially protecting hippocampus targeted by toxic insults. However, the molecular mechanisms underlying the neuroprotective effects of DHEA are not demonstrated. To explore whether neuroprotection of DHEA is related with intracellular Ca^(2+) concentration, primary cortical neuorns were isolated from embryonic rats (E15～16d) and cultured for 10 days; then the effects of DHEA on NMDA_induced toxicity were determined with MTT assay. The alterations of intracellular Ca^(2+) concentration were measured by using confocal microscope with the fluorescent Ca^(2+) _indicator fluo_3. It was found that NMDA decreased cortical neuron survival in dose_ and time_dependent fashions. After pretreatment of DHEA prior to NMDA challenge, neuronal morphology were clearly improved, and NMDA_induced neurotoxicity were prevented. The treatment with NMDA(1 mmoL/L) caused a rapid enhancement in intracellular Ca^(2+) fluorescence intensity, which could be blocked by the pretreatment of DHEA (50 and 100 nmoL/L) in a dose_dependent manner. These data suggest that the neuroprotective role of DHEA on NMDA_induced neurotoxicity may be related to the inhibition of intracellular Ca^(2+) elevation. The final objective is to provide additional therapeutic potentials of neurosteroids in normal and /or pathological conditions.