Effect of hypoxic preconditioning on neural cell apoptosis and expression of Bcl-2 and bax in cerebral ischemia-reperfusion in rats

Abstract

In order to investigate the protective effect of hypoxic preconditioning on the cerebral ischemia-reperfusion injury, the expression of Bcl-2 and Bax was detected by using immunohistochemical staining after 3h cerebral ischemia followed by 1, 6, 12, 24 and 48h reperfusion respectively in rats treated with or without hypoxic preconditioning before cerebral ischemia. In addition, the apoptosis of neural cells and the behavioral scores for neurological functions recovery were evaluated by TUNEL staining and “crawling method”, respectively. Compared with control group (cerebral ischemia-reperfusion without hypoxic preconditioning), the expression of Bcl-2 was significantly increased, but that of Bax decreased in the hypoxic preconditioning group (cerebral ischemia-reperfusion with hypoxic preconditioning), bothP<0.05. The pre-treatment with hypoxic preconditioning could reduce the apoptosis of neural cells and promote the neurological function recovery as compared to control group. It was suggested that hypoxic preconditioning may have protective effects on the cerebral ischemia-reperfusion injury by inhibiting the apoptosis of neural cells, increase the expression of Bcl-2 and decrease the expression of Bax.

Keywords

hypoxic preconditioning / cerebral ischemia / apoptosis / Bcl-2 / Bax

References

[1] MillerB A, PerezR S, ShahA R, et al.. Cerebral protection by hypoxic preconditioning in a murine model of focal ischemia-reperfusion. Neuroreport, 2001, 12(8): 1663-1669

[2] LiY, ChoppM, PowersC, et al.. Apoptosis and protein expression after focal cerebral ischemia in rat. Brain Res, 1997, 765: 301-312

[3] ShibataM, HattoriH, SasakiT, et al.. Subcellular localization of a promoter and an inhibitor of apoptosis (Smac/DIABLO and XIAP) during brain ischemia reperfusion. NeurorEPOrt, 2002, 13: 1985-1988

[4] WuL Y, DingA S, MaQ, et al.. Correlation between enhanced anoxic tolerance induced by hypoxic preconditioning and the stability of mitochondrial membrane potential in cultured hypothalamic cells. Sheng Li Xue Bao (Chinese), 2001, 53(2): 93-96

[5] BernaudinM, NedelecA S, DivouxD, et al.. Normobaric hypoxia induces tolerance to focal permanent cerebral ischemia in association with an increased expression of hypoxia-inducible factor-1 and its target genes, erythropoetin and VEGF, in the adult mouse brain. J Cerebral Blood Flow and Metabolism, 2002, 22: 393-403

[6] LongaE Z, WeinsteinP R, CarlsonS, et al.. Reversible middle cerebral artery occlusion without craniectomy in rats. Stroke, 1989, 20: 84-91

[7] BrailowskyS, KnightR T, BlookK, et al.. Y-Aminobutyric acid-induced prentiation of cortical hemipegia. Brain Res, 1986, 362: 322-330

[8] AhmadS, AhmadA, GerasimovskayaE, et al.. Hypoxia protects human lung microvascular endothelial and epithelial-like cells against oxygen toxicity: role of phosphatidylinositol 3-kinase. Am J Respir Cell Mol Biol, 2003, 28: 179-187

[9] AyI, SugimoriH, FinklesteinS P, et al.. Intravenous basic fibroblast growth factor decreases DNA fragmentation and prevents down regulation of Bcl-2 expression in the ischemic brain following middle cerebral artery occlusion in rats. Brain Res Mol, 2001, 87: 71-80

[10] WangE, GuoQ L, TanX J. Bcl-2 and bax expression in rat cerebral ischemic preconditioning. Hunan Yi Ke Da Xue Xue Bao, 2001, 26(3): 217-218

[11] ChrysisD, CalikogluA S, YeP, et al.. Insulin-like growth factor-1 overexpression attenuates cerebral apoptosis by altering the expression of Bcl family protein in a developmentally specific manner. J Neurosci, 2001, 21: 1481-1489