Abstract: Objective To explore the effect and mechanism of insulin-like growth factor 1 (IGF - 1) on cobalt chloride （CoCl2) induced apoptosis of pheochromocytoma (PC12) cells. Methods PC12 cells in logarithmic growth phase were treated with 10, 20, 40 and 80 μmol/L CoCl2 solution and 100, 200, 400 μg/L IGF-1 solution. CCK-8 assay was used to detect cell viability, and the optimal intervention concentrations of CoCl2 and IGF-1 were obtained. According to the selected experimental conditions, PC12 cells were treated with CoCl2 to establish HIE cell model. The experimental cells were divided into control group, CoCl2 treatment group and IGF-1 + CoCl2 treatment group. After 24 h of preincubation in each group, CCK-8 assay was used to detect cell survival rate, TUNEL staining was used to detect the cell apoptosis, and Western blot assay was used to detect the protein expression levels of Bax, Bcl-2 and Caspase-3. Finally, IGF-1 inhibitor 2- methoxyestradiol (2-MeOE2) group and 2-MeOE2+IGF-1 group were added on the basis of the above experiments. Western blot analysis was performed to observe the effects of IGF-1, 2-MeOE2 and both of them on HIF-1α and Bax expressions in PC12 cells. Results CCK-8 assay showed that the optimal concentration of CoCl2 was 40 μmol / L, and the optimal concentration of IGF-1 was 200 μg/L. After 24 h of intervention with the concentration of above groups, the cell survival rate was significantly improved in IGF-1 + CoCl2 group compared with the CoCl2 group, and the number proportion of TUNEL (+) cells was significantly lower in the IGF-1 + CoCl2 group than that of CoCl2 group. The expression of anti-apoptotic protein Bcl-2 was up-regulated in the IGF-1 + CoCl2 group, and the expressions of apoptotic protein Bax, caspase-3 and HIF-1α were significantly down-regulated in the CoCl2+ IGF-1 group compared with the CoCl2 group (P＜0.05). However, after the pretreatment with 2-MeOE2, there were no significant differences in HIF-1α and Bax expressions between CoCl2 + 2- MeOE2 group and 2-MeOE2 + IGF-1 group, but they were significantly down-regulated compared with CoCl2 + IGF-1 group (P＜0.01). Conclusion IGF-1 can inhibit the apoptosis of PC12 cells induced by CoCl2, and its protective effect is related to the down-regulation of HIF-1α expression.

Key words: insulin-like growth factor Ⅰ, hypoxia-ischemia, brain, apoptosis, hypoxia-inducible factor 1, alpha subunit, PC12 cells, CoCl2