The key target of neuroprotection after the onset of ischemic stroke: secretory pathway Ca^(2+)-ATPase 1

The regulatory mechanisms of cytoplasmic Ca2＋ after myocardial infarction-induced Ca2＋ overload involve secretory pathway Ca2＋-ATPase 1 and the Golgi apparatus and are well understood. However, the effect of Golgi apparatus on Ca2＋ overload after cerebral ischemia and reperfusion remains unclear. Four-vessel occlusion rats were used as animal models of cerebral ischemia. The expression of secretory pathway Ca2＋-ATPase 1 in the cortex and hippocampus was detected by immunoblotting, and Ca2＋ concentrations in the cytoplasm and Golgi vesicles were determined. Results showed an overload of cytoplasmic Ca2＋ during ischemia and reperfusion that reached a peak after reperfusion. Levels of Golgi Ca2＋ showed an opposite effect. The expression of Golgi-specific secretory pathway Ca2＋-ATPase 1 in the cortex and hippocampus decreased before ischemia and reperfusion, and increased after reperfusion for 6 hours. This variation was similar to the alteration of calcium in separated Golgi vesicles. These results indicate that the Golgi apparatus participates in the formation and alleviation of calcium overload, and that secretory pathway Ca2＋-ATPase 1 tightly responds to ischemia and reperfusion in nerve cells. Thus, we concluded that secretory pathway Ca2＋-ATPase 1 plays an essential role in cytosolic calcium regulation and its expression can be used as a marker of Golgi stress, responding to cerebral ischemia and reperfusion. The secretory pathway Ca2＋-ATPase 1 can be an important neuroprotective target of ischemic stroke.

Changes in secretory pathway Ca^(2+)-ATPase 2 following focal cerebral ischemia/reperfusion injury

This study aimed to investigate changes in secretory pathway Ca2＋-ATPase 2 expression following cerebral ischemia/reperfusion injury, and to define the role of Ca2＋-ATPases in oxidative stress. A rat model of cerebral ischemia/reperfusion injury was established using the unilateral middle cerebral artery occlusion method. Immunohistochemistry and reverse transcription-PCR assay results showed that compared with the control group, the expression of secretory pathway Ca2＋-ATPase 2 protein and mRNA in the cerebral cortex and hippocampus of male rats did not significantly change during the ischemic period. However, secretory pathway Ca2＋-ATPase 2 protein and mRNA expression reduced gradually at 1, 3, and 24 hours during the reperfusion period. Our experimental findings indicate that levels of secretory pathway Ca2＋-ATPase 2 protein and mRNA expression in brain tissue change in response to cerebral ischemia/reperfusion injury.