ABSTRACT
Objective To evaluate effect of dexmedetomidine on mitochondrion-dependent apoptosis during hypoxia-reoxygenation (H/R) injury to hippocampal neurons of rats.Methods The primarily cultured hippocampal neurons of Sprague-Dawley rats were divided into 4 groups (n =40 each) using a random number table method:control group (C group),vehicle group (V group),H/R group and dexmedetomidine group (D group).Hippocampal neurons were subjected to oxygen-glucose deprivation followed by restoration of oxygen supply to establish the model of H/R injury.Dexmedetomidine 1 μmol/L was added at 6 h of reoxygenation in D group.The viability of neurons was measured by methyl thiazolyl tetrazolium assay at 20 h of reoxygenation.The ultrastructure of mitochondria was observed by transmission electron microscopy.The expression of cytochrome c (Cyt c),caspase-3,Fis1 and Drp1 was detected by Western blot.The neuronal apoptosis was detected by flow cytometry,and apoptosis rate was calculated.Results Compared with C group,no significant change was found in the viability of neurons in group V (P＞0.05),and the viability of neurons was significantly decreased,the apoptosis rate was increased,the expression of Cyt c,caspase-3,Fis1 and Drp1 was up-regulated (P＜0.05),and the damage to mitochondrial ultrastructure was accentuated in H/R and D groups.Compared with H/R group,the viability of neurons was significantly increased,the apoptosis rate was decreased,the expression of Cyt c,caspase-3,Fis1 and Drp1 was down-regulated (P＜0.05),and the damage to mitochondrial ultrastructure was significantly attenuated in D group.Conclusion The nechanism by which dexmedetomidine reduces the H/R injury to hippocampal neurons is related to inhibiting mitochondrion-dependent apoptosis in rats.
ABSTRACT
Objective To evaluate the role of mitochondrial fission in anoxia-reoxygenation injury to rat hippocampal neurons.Methods Neurons were enzymatically isolated from hippocampi of newborn Sprague-Dawley rats (less than 24 h old).The primary hippocampal neurons were cultured and seeded in 25 mm × 25 mm culture flasks at a density of 7 × 105/ml.The cultured neurons were randomly assigned into 3 groups (n =18 each) using a random number table:control group (C group),anoxia-reoxygenation group (I/R group),and mitochondrial fission inhibitor mdivi-1 group (M group).In group I/R,the vehicle dimethyl sulfoxide (DMSO,final concentration ＜ 0.1％) was added prior to anoxia and the cells were then incubated for 40 min.In group M,mdivi-1 (dissolved in DMSO,final concentration of DMSO ＜ 0.1％) was added prior to anoxia and the cells were then incubated for 40 min.The hippocampal neurons were subjected to oxygen-glucose deprivation (OGD) for 6 h followed by restoration of O2 supply for 20 h.After 20 h of reoxygenation,the level of reactive oxygen species (ROS) (by ELISA),cell apoptosis (using flow cytometry),and expression of mitochondrial fission protein Drp1,Bcl-2 and Bax (by Western blot) were measured.The apoptosis rate and the ratio of Bcl-2 to Bax were calculated.Results Compared with C group,ROS content and apoptosis rate were significantly increased,the expression of Drp1 and Bax was up-regulated,the expression of Bcl-2 was down-regulated,and the ratio of Bcl-2 to Bax was decreased in I/R group (P ＜ 0.05).Compared with I/R group,ROS content and apoptosis rate were significantly decreased,the expression of Drp1 and Bax was down-regulated,the expression of Bcl-2 was up-regulated,and the ratio of Bcl-2 to Bax was increased in M group (P ＜ 0.05).Conclusion Mitochondrial fission is involved in anoxia-reoxygenation injury to rat hippocampal neurons via mitochondria-mediated apoptotic pathway.