抗糖尿病新药(D-Ser2)Oxm拮抗淀粉样β蛋白细胞毒性的神经保护效应观察

Neuroprotective effects of a novel antidiabetic drug (D-Ser2)Oxm on amyloid β protein-induced cytotoxicity

淀粉样β蛋白(amyloidβ-protein,Aβ)在脑内的沉积及其神经毒性是阿尔茨海默病(Alzheimer’s disease,AD)的主要原因之一,目前仍缺乏拮抗Aβ的有效药物。最新报道表明,一种新的抗糖尿病药物(D-Ser2)Oxm不仅可以改善2型糖尿病(T2DM)大鼠的血糖和胰岛素水平,也具有促进皮层和海马神经元及其突触发生的效应。然而,(D-Ser2)Oxm是否能拮抗AD时Aβ所致的细胞损伤仍缺乏实验依据。本研究在培养原代大鼠海马神经细胞基础上,通过细胞活性和早期凋亡测定、细胞内钙成像以及线粒体膜电位检测,研究了(D-Ser2)Oxm对Aβ1-42所致细胞毒性的拮抗效应。结果显示,与单独给予Aβ1-42处理的细胞相比,(D-Ser2)Oxm+Aβ1-42处理组的细胞活力明显提高,而加入GLP-1受体抑制剂exendin(9-39)后,细胞活力则显著下降;(D-Ser2)Oxm可有效拮抗Aβ1-42导致的细胞凋亡,并使凋亡相关蛋白caspase3含量显著降低;(D-Ser2)Oxm处理还有效阻止了Aβ1-42引起的海马细胞内钙水平升高、线粒体膜电位去极化以及糖原合成酶激酶-3β(glycogen synthase kinase-3β,GSK-3β)(Y216)的活化。以上结果表明,(D-Ser2)Oxm可能是通过激动GLP-1受体对抗Aβ1-42的神经毒性,并且这种保护效应可能与细胞内钙稳态调节和线粒体膜电位稳定有关。

The accumulation and neurotoxicity of amyloid β protein（Aβ） in the brain is one of major pathological hallmarks of Alzheimer＇s disease（AD）. The effective drugs against Aβ have been still deficient up to now. According to a most recent study,（D-Ser2）Oxm, a new antidiabetic drug, not only improves the disorders in plasma glucose and insulin in type 2 diabetes mellitus（T2DM） rats, but also exerts positive effects on hippocampal neurogenesis and synaptogenesis. However, it is still unclear whether（D-Ser2）Oxm can directly protect cultured neurons against Aβ1-42-induced cytotoxicity. In the present study, we investigated the neuroprotective effects of（D-Ser2）Oxm on the cultured primary hippocampal neurons by testing the cell viability, neuronal apoptosis, mitochondrial membrane potential and intracellular calcium concentration. The results showed that treatment with（D-Ser2）Oxm effectively reversed Aβ1-42-induced decline in cell viability（P 0.001）, and this protective effect could be inhibited by the pretreatment with exendin（9-39）, a GLP-1 receptor blocker.（D-Ser2）Oxm treatment also decreased Aβ1-42-induced neuronal early apoptosis and down-regulated apoptotic protein caspase3. Meantime,（D-Ser2）Oxm treatment inhibited Aβ1-42-induced [Ca2＋]i elevation, mitochondrial membrane potential depolarization, and glycogen synthase kinase-3β（GSK3β） activation. These results suggest that（D-Ser2）Oxm can protect hippocampal neurons against Aβ1-42-induced cytotoxicity and this effect may be related to activation of GLP-1 receptors, regulation of intracellular calcium homeostasis and stabilization of mitochondrial membrane potential.