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To investigate the effect of mild hypothermia on neurons autophagy and apoptosis after cerebral ischemia reperfusion (I/R) in Sirt1 knockout mice.
The global cerebral ischemia-reperfusion injury model in Sirt1 knockout mice was established, which were divided into normal temperature group (NT, 37°C) and mild hypothermia group (MH, 34°C); The expressions of Sirt1, FoxO1, Rab7, P53 and autophagy related genes such as Beclin1, LC3 were detected by Q-PCR at each time point; The protein levels of those genes were detected by western blot; The LC3 granules were tested by immunofluorescence; The neurons apoptosis were tested by TUNEL.
Sirt1 knockout mice were identificated by Q-PCR, and Sirt1-/- homozygous were chosen for Subsequent experiments. Western blot showed that，compared with wild-type mice, the expressions of Sirt1, P-FoxO1, Rab7, Beclin1 and LC3II/Iwere decreased obviously in Sirt1 knockout mice，P＜0.05; However, P53 was increased obviously, P＜0.05; Immuno-fluorescence test showed that, compared with wild-type mice, LC3 particles of cerebral cortex in Sirt1 knockout mice were decreased significantly, LC3 particles were more induced at 12h after I/R, P<0.05; Mild hypothermia could not increase the expression of LC3, P＞0.05; TUNEL detection showed that, compared with wild-type mice, neurons apoptosis were increased in Sirt1 knockout mice, neurons apoptosis were more apparent at 72h after I/R, P<0.05; however, Mild hypothermia treatment could not reduce neurons apoptosis after ischemia reperfusion in Sirt1 knockout mice (P＞0.05), which showed that the effect of mild hypothermia on neural protection was abated in Sirt1 knockout mice.
The neurons autophagy were more insufficient and apoptosis were significantly increased after cerebral ischemia reperfusion in Sirt1 knockout mice, the neural protection of mild hypothermia was decreased significantly; It was speculated that Sirt1 may be one key factor of regulating autophagy in the process of ischemia reperfusion injury, and mild hypothermia may regulate autophagy and apoptosis through Sirt1 and its downstream gene, so as to play a role of neuroprotection.