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Objective To investigate the neurons autophagy and apoptosis after cerebral ischemia reperfusion (I/R) injury in mice,and to explore the effect of mild hypothermia on neurons autophagy and apoptosis.Methods The global cerebral ischemia-reperfusion injury model in C57 mice was established with carotid artery ligation method.Ninety-six C57 mice were randomly (random number) divided into 8 groups (n =12 in each group),namely control group (C0),sham group,normal body temperature group (NT,37 ℃) after I/R 6 h (C6 h),normal body temperature group after I/R 12 h (C12 h),normal body temperature group after I/R 72 h (C72 h),mild hypothermia group (MH,34 ℃) after I/R6 h (C6 h +MH),mild hypothermia group after I/R12 h (C12 h + MH),mild hypothermia group after I/R 72 h (C72 h + MH).The protein expressions of Sirt1,P-FoxO1,Rab7,P53 and autophagy related genes such as Beclin1,LC3 were detected by Western blot at given intervals.The LC3 granules were assayed by immunofluorescence.The neurons apoptosis was detected by TUNEL.The software of SPSS13.0 was used for statistical analysis.Measurement data was expressed with mean ± SD,and comparison between two groups was carried out with Student's t test,One-way ANOVA was used for comparisons among groups,and P ＜ 0.05 was considered statistically significant.Results The global cerebral ischemia-reperfusion injury model in C57 mice was established successfully with bilateral carotid arteries ligation method.Compared with the control group,the protein expressions of Sirt1,P-FoxO1,Rab7,Beclin1 and LC3 Ⅱ / Ⅰ were gradually reduced,especially at 12 h after I/R in NT group (P ＜ 0.05),while the expression of P53 was obviously increased (P ＜0.05).In MH group,the expressions of Sirt1,P-FoxO1,Rab7,Beclin1,LC3 Ⅱ / Ⅰ were higher than those in NT group (P ＜ 0.05).And the expression of P53 was lower than that in NT group (P ＜0.05).Immuno-fluorescence test showed that compared with the control group,the LC3 particles of neurons cells were decreased significantly in group C12 (at 12 h after I/R 6.0 ± 1.5 vs.18.1 ±2.5,P ＜0.05).Nevertheless,LC3 particles were increased in MH group compared with NT group (36.1 ± 4.5 vs.6.0 ± 1.5,P ＜ 0.05).The results of TUNEL test showed that compared with the control group,neurons cells apoptosis were significantly increased in C72 group (at 72 h after I/R,54.8％ ±7.5％ vs.5.5％ ±1.2％,P ＜ 0.05).However,compared with NT group,neurons apoptosis were decreased in MH group (28.8％ ±4.5％ vs.54.8％ ±7.5％,P＜0.05).Conclusions The neuron autophagy was significantly reduced and apoptosis was significantly increased after ischemia reperfusion injury (I/R) in mice.However,mild hypothermia could increase the expression of Sirt1,FoxO1,beclin1 and LC3,so as to promote neurons autophagy and reduce apoptosis,which would provide therapy target for neurons injury after hypoxia and provide soundly theoretical basis for mild hypothermia for clinical application.
RESUMO
Objective To investigate the neurons autophagy and apoptosis after cerebral ischemia reperfusion (I/R) injury in mice,and to explore the effect of mild hypothermia on neurons autophagy and apoptosis.Methods The global cerebral ischemia-reperfusion injury model in C57 mice was established with carotid artery ligation method.Ninety-six C57 mice were randomly (random number) divided into 8 groups (n =12 in each group),namely control group (C0),sham group,normal body temperature group (NT,37 ℃) after I/R 6 h (C6 h),normal body temperature group after I/R 12 h (C12 h),normal body temperature group after I/R 72 h (C72 h),mild hypothermia group (MH,34 ℃) after I/R6 h (C6 h +MH),mild hypothermia group after I/R12 h (C12 h + MH),mild hypothermia group after I/R 72 h (C72 h + MH).The protein expressions of Sirt1,P-FoxO1,Rab7,P53 and autophagy related genes such as Beclin1,LC3 were detected by Western blot at given intervals.The LC3 granules were assayed by immunofluorescence.The neurons apoptosis was detected by TUNEL.The software of SPSS13.0 was used for statistical analysis.Measurement data was expressed with mean ± SD,and comparison between two groups was carried out with Student's t test,One-way ANOVA was used for comparisons among groups,and P ＜ 0.05 was considered statistically significant.Results The global cerebral ischemia-reperfusion injury model in C57 mice was established successfully with bilateral carotid arteries ligation method.Compared with the control group,the protein expressions of Sirt1,P-FoxO1,Rab7,Beclin1 and LC3 Ⅱ / Ⅰ were gradually reduced,especially at 12 h after I/R in NT group (P ＜ 0.05),while the expression of P53 was obviously increased (P ＜0.05).In MH group,the expressions of Sirt1,P-FoxO1,Rab7,Beclin1,LC3 Ⅱ / Ⅰ were higher than those in NT group (P ＜ 0.05).And the expression of P53 was lower than that in NT group (P ＜0.05).Immuno-fluorescence test showed that compared with the control group,the LC3 particles of neurons cells were decreased significantly in group C12 (at 12 h after I/R 6.0 ± 1.5 vs.18.1 ±2.5,P ＜0.05).Nevertheless,LC3 particles were increased in MH group compared with NT group (36.1 ± 4.5 vs.6.0 ± 1.5,P ＜ 0.05).The results of TUNEL test showed that compared with the control group,neurons cells apoptosis were significantly increased in C72 group (at 72 h after I/R,54.8％ ±7.5％ vs.5.5％ ±1.2％,P ＜ 0.05).However,compared with NT group,neurons apoptosis were decreased in MH group (28.8％ ±4.5％ vs.54.8％ ±7.5％,P＜0.05).Conclusions The neuron autophagy was significantly reduced and apoptosis was significantly increased after ischemia reperfusion injury (I/R) in mice.However,mild hypothermia could increase the expression of Sirt1,FoxO1,beclin1 and LC3,so as to promote neurons autophagy and reduce apoptosis,which would provide therapy target for neurons injury after hypoxia and provide soundly theoretical basis for mild hypothermia for clinical application.
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Objective To establish the cardiac arrest-cardiopulmonary resuscitation model in rats, and to observe the effect of mild hypothermia on autophagy in hippocampal CA1 neurons after ROSC.Methods A total of 36 Wistar rats were randomly divided into two groups: normal temperature treatment group(NT group) and mild hypothermia treatment group(HT group).To establish the cardiac arrest-cardiopulmonary resuscitation(CA-CPR) model in rats by epicardial electrical stimulation induced ventricular fibrillation, and to sacrifice 3 animals in each group to obtain the brain cortex in 2nd and 4th hours after ROSC in order to observe the expression of p-AMPK by electron microscope and LC3 granules through Western blot.The neurological deficit score(NDS) was assessed in 24、48、72 hours respectively after ROSC.To sacrifice the animals so as to take the cerebrum in 72 hours after ROSC, then calculate the apoptotic index of the hippocampal CA1 neurons, which were dyed through TUNEL method.Results The expression of p-AMPK、Beclin-1 and LC3-Ⅱ/LC3-Ⅰratio in Normothermia group were all lower than the Mild hypothermia group(P<0.05), the neurons plasma of hippocampal CA1 area in the Hypothermia group demonstrated obvious LC3 granules formation, the NDS score of the Normothermia group and the Mild hypothermia group in ROSC24h、ROSC48h、ROSC72h were 320vs205、285vs140、266vs120, respectively.The apoptotic index of the hippocampal CA1 area in the Normothemia group in ROSC72h was higher than the Mild hypothermia group,(P<0.05).Conclusions Mild hypothermia after cardiopulmonary resuscitation promotes autophagy of the hippocampal CA1 area neurons in rats and reduce neuronal apoptosis.