Alterations In The Expression Of The Second Secretory Pathways Ca²⁺-ATPase （SPCA2） After Focal Cerebral Ischemia/Reperfusion Injury In Rats

Background and purpose:The Golgi apparatus (GA) is affected by changes that take place during and after a stroke. The secretory-pathway Ca2+-ATPases (SPCAs) present on the GA are phosphorylation-type ATPases. SPCA2is an isoform of SPCA. The expressions of SPCA2mRNA were present along the gastrointestinal tract, and also in prostate, bone marrow, lung, trachea and neutrophil granulocytes.The endogenous expression of SPCA2protein could only be demonstrated in the intestinal goblet cells, hippocampal neurons, neutrophils, and the secretory acini of the mouse mammary gland up till now.[1] Understanding the changes in of SPCA2expression during and after Ischemia/Reperfusion injury (IRI) may help in defining the role of Ca2+-ATPases in oxidative stress. The purpose of our experiment is to evaluate the effect of brain ischemia/perfusion on SPCA2gene and protein expression.Methods:Sixty male Sprague-Dawley rats were randomly divided into five groups:a control group(C), an ischemia group (I), and groups of ischemia followed by1,3, and24h of reperfusion (I1R, I3R, and I24R). Ischemia was induced by unilateral middle cerebral artery occlusion (MCAO) for90minutes followed by reperfusion (n=6for each group). Ischemic damage by MCAO was confirmed by staining with triphenyl tetrazolium chloride method (TTCM). Gene expression in the cortex of brain was examined using quantitative real-time (RT)-PCR, while the amount of SPCA2protein was analysed by immunohistochemistry.Results:Compared with the control group, the expression of SPCA2mRNA in the brain of male S-D rats did not change during ischemia period. However, SPCA2mRNA was significantly decreased to44%after1h reperfusion (P<0.05),33%after3h reperfusion (P<0.01), and31%after24h reperfusion (P<0.01), compared to the control group. SPCA2protein expression was also reduced in the reperfusion period, although there was a slight, but not significant, increase in the3h reperfusion groups (P>0.05).Conclusions:This research has determined the SPCA2expression pattern in brain cortex. Lower SPCA2activity during reperfusion following ischemia-reperfusion injury reduces Ca uptake and causes overload of cytoplasmic [Ca2+], which is one of the consequences of oxidative stress.