Abstrato

Proteomic study of ischemic preconditioning in rat hippocampus

Anna Tomascova

  Myocardial infarction is often accompanied by severe global cerebral ischemia. Only a few minutes of oxygen deprivation in the brain leads to irreversible bioenergetic failure. Subsequent reperfusion, depending on duration and the ischemic period, may cause further damage through increased oxidation stress and inflammation processes. A frequently studied mechanism improving the outcome of ischemic damage is evolutionary conserved neuroprotection, called ischemic tolerance which evokes certain adaptation to lethal ischemia. This can be induced by short-term sublethal ischemia known as preconditioning.

For this study, adult male Wistar rats were randomly divided into three groups: control, ischemia-reperfusion (IR) and preconditioned (IPC), 5 animals per group. Hippocampal homogenates were analysed by 2D-gel electrophoresis with protein identification on MALDI-TOF mass spectrometer (Bruker), western blot analysis and fluorescent immunohistochemistry.

Using protein profiling, we detected 304 proteins and quantitative changes in expression of 28 proteins in the hippocampus of experimental animals undergoing ischemia-reperfusion injury and in preconditioned animals. Proteomic analysis of IR and IPC hippocampus showed enhanced sensitivity to changes in overall redox state. According to our results, preconditioned hippocampus showed lesser deregulation of antioxidation enzymes when compared to the IR group. However, we observed over twofold downregulation in the expression of Peroxiredoxin 5 (PRX5) that plays a role in protection against oxidative stress. According to immunofluorescent staining, PRX5 was predominantly located within the plasmalemma of perikarya and neurons (axons and dendrites). Apart from their beneficial antioxidation function, peroxiredoxins are potentially harmful in the post-ischemic brain where after spilling out of necrotic cells initiate inflammation processes.