Apelin-13 Protects PC12 Cells From Corticosterone-induced Apoptosis Through PI3K And ERKs Activation

Background and Objective: It is widely accepted that environmental stress is a risk factor for mental disorders. Glucocorticoid hormones play a vital role in the regulation of physiological response to stress,there are also studies suggest that the elevated level of glucocorticoid hormones is as sociated with depression and corticosterone may cause nerve cell degeneration or apoptosis.Apelin and its receptor APJ are widely distributed in the central nervous system including limbic structures in volved in stress responses. Apelin exert its physical roles such as protect nerve cells、heart cells、regulation of blood pressure、HPA roles by binding to APJ.However, the role of apelin in the regulation of stress-related disorders is largely unknown. PI3K/Akt and ERKs signaling pathways play an important role in cell proliferation, differentiation, survival and apoptosis. So, we used PC12 cells as nervecell model to investigated whether apelin-13 protects PC12 cells from corticosterone-induced apoptosis through activating PI3K/Akt and ERKs signaling pathwaysMethods: MTT assay was used for cell viability; Hoechst staining and flow cytometry assays was used for cell apoptosis analysis; Western blotting analysis was used for PI3 K,ERK, p-ERK, p-Akt and cleaved caspase-3 expression.Results: 1. Apelin-13 protects against corticosterone-induced PC12 cells v-iability loss PC12 cells were treated with different concentration of corticosterone(200, 400, 600, 800 and 1000 μM) for 24 hs.The results shows that corticosterone dose-dependently inhibited the proliferation of PC12 cells. Besides, when apelin-13(0.25, 0.5, 1, 2 and 4 μM) was added in the cell culture medium 0.5 h prior to 600 μM corticosterone treatment, the survival of PC12 cells significantly increased in a dose-dependent manner. 2. Apelin-13 protects against corticosterone-induced PC12 cells apoptosis PC12 cells were treated with corticosterone(600μM) for 24 hs. The results shows that apoptosis rate were positively correlated with the concentration of corticosterone. Besides, Apelin-13(4 μM) exposure 0.5 h prior to corticosterone treatment significantly reduces the number of apoptotic PC12 cells induced by corticosterone treatment. 3. Apelin-13 attenuates corticosterone-induced down-regulation of p-Akt and p-ERKs PC12 cells were treated with corticosterone 600μM) for 24 hs. The results shows that corticosterone(600 μM) significantly downregulated the levels of p-Akt and p-ERKs expression. Besides, apelin-13(4 μM) exposure 0.5 h prior to corticosterone treatment significantly attenuated corticosterone-induced down-regulation of p-Akt and p-ERKs expression levels. 4.LY294002 and PD98059 block the neuroprotective activity of apelin-13 PC12 cells were pre-treated with LY294002(10 μM) 和PD98059(20 μM) for 30 min, then treated with apelin-13 for 30 min, and co-treated with corticosterone for 24 hs. The results shows apelin-13(4 μM) significantly reduced corticosterone-induced PC12 cells apoptosis, and this reduction was blocked by the pretreatment of LY294002 or PD98059. cleaved caspase-3 involving PI3 K and ERK1/2 signaling pathway PC12 cells were treated with corticosterone 600μM) for 24 hs. The results shows that corticosterone(600 μM) significantly up-regu lated the expression level of cleaved caspase-3. Besides, Apelin-13(4μM) exposure 0.5 h prior to corticosterone treatment significantlyat tenuated corticosterone-induced up-regulation of cleaved caspase-3. Further results showed that apelin-13-induced down-regulation of cleaved caspase-3 was blocked by LY294002 or PD98059 pretreatment 0.5 h prior to aplin-13 exposure. 5. Apelin-13 attenuates corticosterone-induced up-regulation ofConclusion: Apelin-13 protects PC12 cells from corticosterone-induced apoptosis through activating PI3K/Akt and ERKs signaling pathways...