期刊
NEUROSCIENCE
卷 226, 期 -, 页码 388-396出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.neuroscience.2012.09.025
关键词
exendin-4; oxygen/glucose deprivation; endoplasmic reticulum stress; unfolded protein response; neurons; rat
资金
- Program of National Natural Science Foundation of China [81070938, 81101905]
- Program for New Century Excellent Talents in University [NCET-10-0406]
- Fundamental Research Funds for the Central Universities [HUST 2010JC028]
Previous studies demonstrated that exendin-4 (Ex-4) may possess neurotrophic and neuroprotective functions in ischemia insults, but its mechanism remained unknown. Here, by using real-time PCR and ELISA, we identified the distribution of active GLP-1Rs in the rat primary cortical neurons. After establishment of an in vitro ischemia model by oxygen/glucose deprivation (OGD), neurons were treated with various dosages of Ex-4. The MTT assay showed that the relative survival rate increased with the dosage of Ex-4 ranging from 0.2 to 0.8 mu g/ml (P < 0.001, vs. OGD group). The apoptosis rate was reduced from (49.47 +/- 2.70)% to (14.61 +/- 0.81)% after Ex-4 treatment (0.4 mu g/ml) 12 h after OGD (P < 0.001). Moreover, immunofluorescence staining indicated that Ex-4 increased glucose-regulated proteins 78 (GRP78) and reduced C/EBP-homologous protein (CHOP). Western blot analysis demonstrated that, after neurons were treated with Ex-4, GRP78 was up-regulated over time (P < 0.01, vs. OGD group), while CHOP levels rose to a peak 8 h after OGD and then decreased (P < 0.05, vs. OGD group). This effect was changed by both the protein kinase A (PKA) inhibitor H89 (P < 0.01, P < 0.05, respectively, vs. Ex-4 group) and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 (P < 0.01, P < 0.01, respectively, vs. Ex-4 group) but not by the mitogen-activated protein kinase (MAPK) inhibitor U0126. Our study also revealed that, compared with the Ex-4 group, inhibition of the PKA signaling pathway significantly decreased the survival rate of neurons, down-regulated the expression of B-cell lymphoma 2 (Bcl-2) and up-regulated the Bax expression 3 h after ODG (P < 0.05, P < 0.01, respectively), while neither PI3K nor MAPK inhibition exerted such effects. Furthermore, Western blotting exhibited that PKA expression was elevated in the presence or absence of OGD insults (P < 0.05). This study indicated that Ex-4 protected neurons against OGD by modulating the unfolded protein response (UPR) through the PKA pathway and may serve as a novel therapeutic agent for stroke. (c) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.
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