ABSTRACT
Objective To explore whether brimonidine has a protective effect on retinal ganglion cells (RGCs) through improving mitochondrial function under the oxidative stress.Methods Mouse RGC-5 cells were cultured in DMEM medium containing low concentration of glucose (1 g/L),10％ fetal bovine serum and 100 U/ml penicillin-streptomycin solution.The cells were divided into normal control group,H2O2-treated group and brimonidine+ H2O2 group.H2O2 at the concentration of 800 μmol/L was added into the medium in the H2O2-treated group,and 1 μmol/L brimonidine was added into the medium for 2 hours prior to the addition of H2O2 in the brimonidine+H2O2 group.The cells were sequently cultured for 24 hours.The morphology of the cell nucleus was examined by Hoechst fluorscence staining.The expressions of apoptosis-related protein in the cells were detected by Western blot assay.Mitochondrial membrane potential was assessed by JC-1 staining.Results The cell nuclei showed round or oval in shape with consistent size in the normal control group.The pycnosis and karyorrhexis of the cell nuclei were seen in the H2O2-treated group,and less abnormal nuclei were found in the brimonidine+H2O2 group.The relative expression level of bcl-2 protein in the cells was 0.76±0.15,0.50±0.13 and 0.75±0.17 in the normal control group,H2O2-treated group and brimonidine + H2O2 group,respectively,and the expression of bcl-2 protein in the H2O2-treated group was significantly lower than that in the normal control group and brimonidine+H2O2 group (both at P＜0.05).The relative expression level of bax protein in the cells was 0.65±0.13,0.83±0.07 and 0.70±0.10 in the normal control group,H2O2-treated group and brimonidine+H2O2 group,respectively,and the expression of bax protein in the H2O2-treated group was significantly higher than that in the normal control group and brimonidine+H2O2 group (both at P＜0.05).A strong orange fluorescence was seen in the mitochondrial membrane of RGC-5 in the normal control group with a coexpression with the green fluorescence of cell membrane.In the H2O2-treated group,the orange fluorescence intensity in the cells was evidently weakened,and the number of JC-1 responsed cells was considerably increased and the orange fluorescence intensity was enhanced in the brimonidine + H2O2 group.Conclusions Brimonidine can prevent RGCs from oxidative-stress damage by improving the mitochondrial function and therefore play a potential neuroprotective effect on optic nerve.
ABSTRACT
Diabetes mellitus is a common disease of serious harmful to human health,but its pathogenesis is not entirely clear.Mitochondria are the important organelles to generate energy in eukaryocytes,and play a pivotal role in the regulation of reactive oxygen species generation,intracellular calcium homeostasis,and apoptosis signal transduction.The possible causes of mitochondrial dysfunction include oxidative stress,Ca2+ disturbances,reduction of mitochondrial biosynthesis,opening of mitochondrial permeability transition pore,mitochondrial DNA mutations,and etc..Many studies demonstrate that mitochondrial dysfunction is associated with β-cell dysfunction of type 1 diabetes mellitus and insulin resistance of type 2 diabetes mellitus.Moreover,mitochondrial dysfunction plays important roles in the development of diabetic cardiomyopathy.This present article reviewed the current status of studies on the relationship of mitochondrial dysfunction and diabetes mellitus and diabetic cardiomyopathy.It is very important to understand and study mitochondrial dysfunction and its important roles in diabetes mellitus and diabetic cardiomyopathy in order to clarify the pathogenesis of diabetes mellitus and explore new approaches of prevention and treatment for diabetes mellitus.