Nodin Christina, Nilsson Michael, Blomstrand Fredrik
Arvid Carlsson Institute for Neuroscience at the Institute of Clinical Neuroscience, Göteborg University, Sweden.
J Neurochem. 2005 Aug;94(4):1111-23. doi: 10.1111/j.1471-4159.2005.03241.x.
Astrocytes are highly coupled by gap junction channels, which allow transfer of intracellular signalling molecules and metabolites between connected cells. Astrocytic gap junctions remain open during ischemic conditions as previously demonstrated in vitro and in situ. In this study, we investigated the effect of gap junction blockage on iodoacetate-induced ATP depression and cell death progression in astrocytes in primary rat hippocampal cultures. We demonstrated that blockage of gap junctions during iodoacetate-induced inhibition of the glycolysis induced an earlier onset of the ATP depression. Moreover, initiation of apoptotic processes, demonstrated by binding of Annexin V, was critically dependent on the ATP levels. The apoptotic event was also shown to spread and involve neighbouring cells, a process that was inhibited by blockage of gap junction communication. Chelating intracellular calcium using BAPTA-AM decelerated the iodoacetate-induced ATP depression. The chelation also decelerated the spreading of apoptotic processes. Inhibition of caspases did not alter the expansion of cell groups being Annexin V positive. However, the proportion of Annexin V positive cells also being propidium iodide positive was increased after caspase inhibition. The results show that inhibition of gap junctions during cellular metabolic depression interferes with the metabolic status and cell death progression in astrocytes.
星形胶质细胞通过缝隙连接通道高度耦合，缝隙连接通道允许细胞内信号分子和代谢产物在相连细胞之间传递。如先前在体外和原位实验中所证明的，星形胶质细胞的缝隙连接在缺血条件下保持开放。在本研究中，我们调查了缝隙连接阻断对原代大鼠海马培养物中碘乙酸诱导的星形胶质细胞ATP降低和细胞死亡进程的影响。我们证明，在碘乙酸诱导糖酵解抑制期间阻断缝隙连接会导致ATP降低更早发生。此外，通过膜联蛋白V结合所证明的凋亡过程的启动严重依赖于ATP水平。凋亡事件还显示会扩散并累及邻近细胞，这一过程可被缝隙连接通讯阻断所抑制。使用BAPTA-AM螯合细胞内钙可减缓碘乙酸诱导的ATP降低。螯合作用还减缓了凋亡过程的扩散。抑制半胱天冬酶并没有改变膜联蛋白V阳性细胞群的扩展。然而，在抑制半胱天冬酶后，膜联蛋白V阳性且碘化丙啶也阳性的细胞比例增加。结果表明，在细胞代谢抑制期间抑制缝隙连接会干扰星形胶质细胞的代谢状态和细胞死亡进程。
