The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510405, People's Republic of China.
Cell Biol Int. 2012 Nov 1;36(11):1043-8. doi: 10.1042/CBI20120229.
Autophagy is usually up-regulated to provide more ATP in response to starvation or OGD (oxygen-glucose deprivation), but the relationship between autophagy and ATP, [Ca2+]i (intracellular free Ca2+ concentration) or MMP (mitochondrial membrane potential) during reoxygenation is not yet fully clear. The role of autophagy is unknown in PC12 cells subjected to 2 h OGD with different time points of reoxygenation. In the present study, we showed that Beclin-1 was up-regulated beginning at 0 h reoxygenation peaking at 24 h and lasting for 48 h. Cell viability was decreased from 0 to 48 h reoxygenation, reaching its minimum at 10 h reoxygenation. ATP was decreased from 0 to 10 h reoxygenation, reaching its minimum at 4 h reoxygenation. A significant negative correlation was observed between ATP and Beclin-1 (r = -0.61, P<0.05) at 0 h reoxygenation, but ATP was not significant related (r = 0.24, P>0.05) to Beclin-1 at 24 h reoxygenation. Besides, Nimodipine, a calcium antagonist, significantly reduced [Ca2+]i and Beclin-1, but increased MMP in OGD/R-treated cells. At 24 h reoxygenation, Beclin-1 expression reached its maximum, cell viability continued to increase, and ATP was higher than that before OGD. These results suggest that energy metabolism dysfunction can induce autophagy during OGD in PC12 cells. Increased [Ca2+]i and decreased MMP may induce autophagy during reoxygenation in PC12 cells. Autophagy may be a protective effect on PC12 cells treated with different time points of reoxygenation after 2 h OGD.
自噬通常会被上调以在饥饿或 OGD（氧葡萄糖剥夺）时提供更多的 ATP，但自噬与 ATP、[Ca 2+] i（细胞内游离 Ca 2+浓度）或 MMP（线粒体膜电位）在再氧合期间的关系尚不完全清楚。在接受 2 小时 OGD 并在不同再氧合时间点的 PC12 细胞中，自噬的作用尚不清楚。在本研究中，我们表明 Beclin-1 从 0 小时再氧合开始上调，在 24 小时达到峰值并持续 48 小时。细胞活力从 0 到 48 小时再氧合逐渐下降，在 10 小时再氧合时达到最低。ATP 从 0 到 10 小时再氧合逐渐下降，在 4 小时再氧合时达到最低。在 0 小时再氧合时，观察到 ATP 与 Beclin-1 之间存在显著的负相关（r = -0.61，P <0.05），但在 24 小时再氧合时，ATP 与 Beclin-1 没有显著相关（r = 0.24，P > 0.05）。此外，钙拮抗剂尼莫地平可显著降低 [Ca 2+] i 和 Beclin-1，但增加 OGD/R 处理细胞中的 MMP。在 24 小时再氧合时，Beclin-1 表达达到最大值，细胞活力继续增加，ATP 高于 OGD 前水平。这些结果表明，能量代谢功能障碍可在 PC12 细胞 OGD 期间诱导自噬。[Ca 2+] i 的增加和 MMP 的降低可能在 PC12 细胞再氧合期间诱导自噬。自噬可能对接受 2 小时 OGD 后不同再氧合时间点处理的 PC12 细胞具有保护作用。
