| The study was conducted to investigate the effect of sodium fluoride(NaF)on the oxidative stress and apoptosis,and relationship between apoptosis and the death receptor pathway as well as oxidative stress involved in the mouse liver by using methods of flow cytometry,quantitative real time polymerase chain reaction(qRT-PCR),western blot,biochemistry and experimental pathology.240 four-week-old ICR mice were randomly divided into 4 groups and exposed to different concentration of NaF(0mg/kg,12mg/kg,24 mg/kg and 48 mg/kg)for a period of 42 days.At 21 and 42 days of the experiment,the relative weight,histopathological changes,liver function indexes in the serum,the percentage of apoptotic cells and relative expression of apoptotic regulatory genes and proteins,and oxidative stress parameters in the mouse liver of every group were observed.Results were as follow:1.Effect of NaF on the growth and development of mouse liver.The relative weight was declined,liver development was arrested,and volume and weight were reduced.Histopathologically,hepatocellular granular degeneration,vacuolar degeneration and necrosis were observed in a dose and time dependent manner.2.Effect of NaF on the liver function indexes.In the NaF-treated groups,activities of ALT,AST and AKP,and contents of TBIL in the serum were significantly increased when compared to the control group(p < 0.05 or p < 0.01).3.Effect of NaF on the hepatocellular ROS production levels and the percentage of apoptotic cells.By flow cytometry,NaF could obviously increase the hepatocellular ROS production levels and the percentage of apoptotic cells in a timeand dose-dependent manner(p < 0.05 or p < 0.01).4.Effect of NaF on the mRNA expression levels of apoptotic parameters associated to death receptor pathway in the mouse liver.The detection results of qRT-PCR showed that NaF could elevated the genes and proteins expression of TNF-R1、FADD、TRADD、caspase-8、caspase-3.At 21 days of the experiment,the mRNA expression of caspase-3 in the 48mg/kg groups,the mRNA expression of TNF-R1、FADD、caspase-8 in the 24,48mg/kg groups,and the mRNA expression of TRADD in the 12,24,48mg/kg groups were higher than the control groups(p < 0.05 or p < 0.01).At 42 days of the experiment,the mRNA expression of FADD in the 24 and 48mg/kg groups were increased obviously(p < 0.05),and the mRNA expression of TNF-R1、TRADD、caspase-8、caspase-3 in the 12,24 and 48mg/kg groups were significantly increased when compared to the control group(p < 0.05 or p < 0.01).5.Effect of NaF on the protein expression levels of apoptotic parameters associated to death receptor pathway in the mouse liver.At 21 days of the experiment,the protein levels of TNF-R1、FADD in the 48mg/kg group,the protein levels of caspase-3 in the 24 and 48mg/kg groups,and the protein levels of TRADD、caspase-8 in the 12,24 and 48mg/kg groups were obviously higher than the control groups(p < 0.05 or p < 0.01).At 42 days of the experiment,the protein levels of TNF-R1、FADD、TRADD、caspase-8、caspase-3 in the NaF-treated groups were increased when compared to the control groups.6.Effect of NaF on the oxidative stress.The results of qRT-PCR and biochemistry experiment proved that activities of SOD、 CAT、 GSH、GST and GSH-PX were significantly decreased(p < 0.05 or p < 0.01),and MDA contents was increased in the NaF-treated groups.The mRNA expression of CuZn-SOD、Mn-SOD、CAT、 GSH、GST and GSH-PX were obviously reduced when compared to the control groups(p < 0.05 or p < 0.01).It was concluded that NaF gavage doses more than 12mg/kg could cause oxidative stress and apoptosis in the mouse liver,which leaded to liver pathological injury and liver function abnormality.NaF could liver apoptosis via death receptor signaling pathway and oxidative stress.Changes of gene,protein expression levels in antioxidative enzymes and apoptotic parameters associated to the death receptor signaling pathway were the molecular basis of NaF-induced liver oxidative stress and apoptosis. |
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