ABSTRACT
Objective: To study the effects of vibration on the expression of mitochondrial fusion and fission genes and ultrastructure of skeletal muscle in rabbits. Methods: Thirty-two 3.5-month-old New Zealand rabbits were randomly divided into low-intensity group, medium-intensity group, high-intensity group and control group, with 8 rabbits in each group. The rabbits in the experimental group were subjected to hind limb vibration load test for 45 days. The vibration intensity of the high intensity group was 12.26 m/s(2), the medium intensity group was 6.13 m/s(2), and the low intensity group was 3.02 m/s(2) according to the effective value of weighted acceleration[a(hw (4))] for 4 hours of equal energy frequency. The control group was exposed to noise only in the same experimental environment as the medium-intensity group. The noise levels of each group were measured during the vibration load experiment. After the test, the mRNA expression of mitochondrial fusion gene (Mfn1/Mfn2) and fission gene (Fis1, Drp1) by RT-PCR in the skeletal muscles were measured and the ultrastructure of the skeletal muscles were observed in high intensity group. Results: The mRNA expression of mitochondrial in the skeletal muscle tissues of control group, low intensity group, medium intensity group and high intensity group were Mfn1: 3.25±1.36, 3.85±1.90, 4.53±2.31 and 11.63±7.68; Mfn2: 0.68±0.25, 1.02±0.40, 0.94±0.33 and 1.40±0.45; Fis1: 1.05±0.62, 1.15±0.59, 1.53±1.06 and 2.46±1.51 and Drp1: 3.72±1.76, 2.91±1.63, 3.27±2.01 and 4.21±2.46, respectively. Compared with the control group, the expressions of Mfn1 mRNA, Mfn2 mRNA and Fis1 mRNA in the high-intensity group increased significantly (P<0.05) , and the expressions of Mfn2 mRNA in the medium-intensity group and the low-intensity group increased significantly (P<0.05) . Compared with the control group, the ultrastructure of skeletal muscle of high intensity group showed mitochondrial focal accumulation, cristae membrane damage, vacuole-like changes; Z-line irregularity of muscle fibers, and deficiency of sarcomere. Conclusion: Vibration must be lead to the abnormal mitochondrial morphology and structure and the disorder of energy metabolism due to the expression imbalance of mitochondrial fusion and fission genes in skeletal muscles of rabbits, which may be an important target of vibration-induced skeletal muscle injury.
Subject(s)
Animals , Rabbits , Hindlimb/metabolism , Mitochondria/metabolism , Mitochondrial Dynamics , Mitochondrial Proteins/pharmacology , Muscle, Skeletal , Vibration/adverse effectsABSTRACT
OBJECTIVE@#To investigate the protective effects of dexmedetomidine (DEX) against cerebral ischemia/reperfusion (I/R) injury in mice and its relation with mitochondrial fusion and fission.@*METHODS@#Male ICR mice were randomly divided into sham-operated group, I/R group, I/R+DEX group and I/R+DEX+dorsomorphin group. Mouse models of cerebral I/R injury were established by modified thread occlusion of the middle cerebral artery. DEX (50 μg/kg) was injected intraperitoneally at 30 min before cerebral ischemia, which lasted for 1 h followed by reperfusion for 24 h. The neurobehavioral deficits of the mice were evaluated based on Longa's scores. The volume of cerebral infarction was detected by TTC staining. The changes in mitochondrial morphology of the brain cells were observed with transmission electron microscopy. Western blotting was performed to detect the expressions of phosphorylated AMP-activated protein kinase (p-AMPK), mitochondrial fusion protein (Mfn2) and mitochondrial fission protein (p-Drp1) in the brain tissues.@*RESULTS@#DEX pretreatment significantly reduced the neurobehavioral score and the percent volume of cerebral infarction in mice with cerebral I/R injury. Treatment with dorsomorphin (an AMPK inhibitor) in addition to DEX significantly increased the neurobehavioral score and the percent volume of cerebral infarction in the mouse models. Transmission electron microscopy showed that DEX obviously reduced mitochondrial damage caused by cerebral I/R injury and restored mitochondrial morphology of the brain cells, and such effects were abolished by dorsomorphin treatment. Western blotting showed that DEX pretreatment significantly increased the expressions of p-AMPK and Mfn2 protein and decreased the expression of p-Drp1 protein in the brain tissue of the mice, and these changes were also reversed by dorsomorphin treatment.@*CONCLUSIONS@#Preconditioning with DEX produces protective effects against cerebral I/R injury in mice possibly by activating AMPK signaling to regulate mitochondrial fusion and fission in the brain cells.
Subject(s)
Animals , Male , Mice , Brain Ischemia , Dexmedetomidine , Mice, Inbred ICR , Mitochondrial Dynamics , Reperfusion InjuryABSTRACT
Objective To investigate the role of silent mating type information regulation 2 homolog 1(SIRT-1) in lipopolysaccharide (LPS)-induced mitochondrial injury on INS-1(insulinoma cell lines-1)cells. Methods INS-1 cells were divided into 5 groups: control group, 1 mg/L LPS group, LPS group with 10 μmol/L RSV (resveratrol) pretreatment for 1 h, LPS group with 20 μmol/L EX527 pretreatment for 1 h, LPS group together with EX527 pretreatment for 1 h, then incubated these INS-1 cells with RSV and LPS for 24 h. The cell viability and ATP generation were detected, then total, cytoplasmic and mitochondrial protein were isolated from INS-1 cells. The protein expression of SIRT1, TLR4, acetylated FoxO1, and cytochrome C (CytC), Mfn1 (mitofusion1), Mfn2 (mitofusion2), and Fis1 (fission1) were tested by Western-blot. Mfn1, Mfn2, and Fis1 genes expression were detected by real-time PCR. The comparison of multiple groups was performed by one-way ANOVA. LSD-t method was used to compare between every two groups. Results After 1 mg/L LPS stimulation for 24 h, there was decreased cell viability (n=4, F=13.98, P<0.01) and ATP generation (n=4, F=27.92, P<0.05) in INS-1 cells. RSV pretreatment could maintain ATP production, but it could not reverse the EX527-induced ATP decrease (P>0.05). Furthermore, RSV upregulated gene and protein expression of SIRT1, Mfn1 and Mfn2, whereas decreased TLR4 and Fis1 expression. LPS-induced CytC released to cytoplasm was alleviated by RSV (P<0.01), but there was no significant change about FoxO1 protein expression (P>0.05). Conclusions RSV may regulate FoxO1 acetylation followed by its effects on SIRT1 activity, which may be partly the mechanism of mitochondrial damage induced by LPS on INS-1 cells.
ABSTRACT
Sepsis is a systemic inflammatory response syndrome caused by infection,and further development can lead to septic shock and multiple organ dysfunction syndrome.Clinical research of sepsis morbidity and mortality is a hot topic in this field.Subcellular related studies in recent years show that mitochondrial damage plays a very important role in the development of sepsis,especially septic shock.Mitochondria are highly dynamic organelles in the cell.They continue to merge and divide within cells,forming a dynamic equilibrium network structure.In sepsis,imbalance of mitochondrial fusion and fission leads to disorders of the intracellular molecules,cells,and organs.This article reviews the progress in the investigation of mitochondrial fusion and fission in the pathogenesis of sepsis.