碱性成纤维细胞因子在局灶性脑缺血后内源性神经干细胞增殖过程中对β-catenin的影响

BACKGROUND： The Wnt/β-catenin signaling pathway plays an important role in neural development. ,β-catenin is an important component of the Wnt/β-catenin signaling pathway. The Wnt signaling pathway has been shown to regulate the interaction of neural stem cells with the extracellular matrix.
OBJECTIVE： To investigate the effects of basic fibroblast growth factor （bFGF） on β-catenin protein and mRNA expression, and on hippocampal neural stem cell proliferation in a rat model of cerebral ischemia/reperfusion. DESIGN, TIME AND SETTING： A randomized, controlled, neurobiology experiment was performed in Shenyang Medical College between August 2006 and August 2008. MATERIALS： A total of 72 healthy male Wistar rats, aged 3 months, were used in this study. bFGF was provided by Beijing SL Pharmaceutical Co.,Ltd., China. METHODS： Rats were randomly divided into 3 groups： sham-operated, ischemia/reperfusion, and bFGF-treated （n = 24 per group）. Focal cerebral ischemia/reperfusion was induced in rats from the ischemia/reperfusion group and the bFGF-treated group by 2 hour right middle cerebral artery occlusion and 2 hour restoration of blood flow using the suture method. The ischemia/reperfusion and bFGF-treated groups were intraperitoneally administered 500 IU/mL of bFGF, or the same volume of physiological saline, once a day at postoperative days 1 3, and once every 3 days thereafter. Simultaneously, the sham-operated group underwent experimental procedures identical to the ischemia/reperfusion and bFGF-treated groups, with the exception of ischemia/reperfusion induction and drug administration. At 2 hours, 2, 6, 13, and 20 days after ischemiaJreperfusion induction, 50 mg/kg bromodeoxyuridine （BrdU） was administered to each group, twice daily, to label proliferating neural stem cells. MAIN OUTCOME MEASURES： The effects of bFGF on BrdU labeling, and ,8 -catenin mRNA and protein expression, in neural stem cells were examined by immunohistochemistry, Western blot, RT-PCR, and in situ hybridization techniques. RESULTS： In the sham-operated group, only a few BrdU-immunoreactive neural stem cells were found. In the ischemia/reperfusion group, BrdU-immunoreactive cells began to increase from 3 days after ischemia/reperfusion induction, reached a peak level at 7 days, and gradually reduced from 21 days. At 3, 7, 14, and 21 days after ischemia/reperfusion induction, the numbers of BrdU-immunoreactive cells were significantly greater in the bFGF-treated group than in the ischemia/reperfusion group. The sham-operated group exhibited slight expression of β-catenin and β-catenin mRNA. In the ischemia/reperfusion group, the expression of β-catenin and β-catenin mRNA gradually increased with reperfusion time, peaked at 14 days after reperfusion, and gradually decreased thereafter; by 21 days, the expression was markedly lower. Following bFGF injection, the expression of hippocampal BrdU, β-catenin, and β-catenin mRNA had apparently increased in each group. CONCLUSION： bFGF promotes neural stem cell proliferation, and the expression of β-catenin and β-catenin mRNA in the ischemic brain tissue. These findings indicate that bFGF promotion of neural stem cell proliferation may be mediated by Wnt/β-catenin signaling pathway.

Effects of basic fibroblast growth factor on beta-catenin protein and mRNA expression during the proliferation of endogenous neural stem cells following focal cerebral ischemia

basic fibroblast growth factor β-catenin neural stem cell proliferation rats