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Objective To investigate the effect of extracellular signal-regulated kinases (ERKs) on cell cycle regulation after ischemia. Methods Ischemic model was induced by photochemistry method. Animals were divided randomly into cerebral ischemia groups (control and treatment groups) and sham group. Rats in treatment group were subjected to U0126 solution injection at 30 rain pre-ischemia through caudal veins, and animals in control group were subjected to identical volume DMSO solution without U0126. Positive immunostaining for CyclinD1 and CyclinE were detected by immunohistofluorescence method. Expressions of phosphorylated ERK1/2 (pERK1/2), CyclinD1, and CyclinE proteins were examined by Western blot in ischemic slide of brain cortex. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression of transcription factor E2F mRNA in ischemic slide of brain cortex. Results The numbers of CyclinD1 and CyclinE positive cells were highly decreased in the U0126-treated group (P<0.05 vs vehicle-treated group). Expression of pERK1/2 protein in the ischemic group was significantly higher than that in the U0126-treated group, which peaked at 4h, and decreased to the baseline at 12 after ischemia. While the expression levels of CyclinD1 and CyclinE in the U0126-treated group were increased at 6h post injury, peaked at 12 after injury (P<0.05 vs that in vehicle-treated group). In addition, expression of E2F mRNA in the vehicle-treated group was significantly higher than those in the sham-operated group and the U0126-treated group (P<0.05). Conclusions ERK pathway plays a very important role in cerebral ischemia. Inhibiting ERK1/2 phosphorylation post-ischemia reduces the expressions of CyclinD1, CyclinE and E2F, which indicates that ERK can affect cell cycle regulation.
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Objective To observe the effects of cell cycle inhibitor on astrocytic proliferation and scar formation and to study neuronal apoptosis after focal cerebral ischemia in rats.Methods Ischemic model was established by photochemistry method.T_2-weighted MRI was performed on the 3rd, 7th, and 30th day after focal cerebral ischemia.The expression of glial fibrillary acidic protein(GFAP)and apoptosis was observed by immunofluorescence.The protein levels of GFAP and proliferation cell nuclear antigen (PCNA), CyelinA and CyclinB1 were measured by Western blotting from the ischemic and sham animals finished on the 3rd, 7th, and 30th day.Results A marked and significant reduction of brain infarction volume was found in Olomoucine-treated ischemic animals(2.27%?0.28% , 1.87%?0.19%, 1.08%? 0.18%)as compared with controls(5.10%?0.35%, 4.60%?0.26%, 3.96%?0.28%, P