Alteration of phosphatidylinositol transfer protein during global brain ischemia–reperfusion in gerbils

Phosphatidylinositol transfer proteins (PI-TPs) are responsible for the transport of phosphatidylinositol and other phospholipids. Moreover, these proteins are involved in vesicle transport and in the function of cytoskeleton. Our previous data indicated that brain ischemia affected phosphoinositides metabolism and the level of lipid derived second messengers. In this study, the effect of ischemia-reperfusion injury on the level of PI-TPs and of the role of NMDA receptor stimulation on the alteration of these proteins was investigated during reperfusion after 5 min of forebrain ischemia in gerbils. Some groups of animals were injected intraperitoneally with MK-801, an antagonist of NMDA receptor 30 min before ischemia. The levels of both PI-TP isoforms alpha+beta and separately the alpha-isoform were determined in cytosol and membrane fraction from brain cortex and hippocampus using Western blot analysis. In the cytosolic fractions, the concentration of both isoforms of PI-TP was 2 times higher when compared to the membrane fraction. In brain cortex, PI-TP alpha isoform consist about 32-44% but in hippocampus 72-82% of both isoforms (PI-TP alpha+beta) in cytosolic and membrane fraction respectively. Ischemia-reperfusion had no effect on PI-TPs in brain cortex. However, in hippocampus after 5 min ischemia and during whole reperfusion time up till 7 days the level of PI-TP alpha+beta and PI-TP alpha was significantly higher by about 20-55%, respectively when compared to control. MK-801 eliminated ischemia-reperfusion evoked alteration of PI-TPs. To confirm the role of NMDA receptor in PI-TP alteration additional experiments were carried out on PC-12 cells in culture. The results indicated that activation of NMDA receptor enhances significantly the level of PI-TP alpha. The competitive antagonist of NMDA receptor inhibited this effect. These results indicated that activation of NMDA receptor is connected with PI-TPs alteration and plays an important role in modulation of PI-TPs during ischemia-reperfusion injury that may have important physiopathological consequence.