Effects Of Metoprolol On Antioxidant Function And ENOS Uncoupling In Psychologically Stress Rats

Part1EFFECT OF METOPROLOL ON ANTIOXIDANT FUNCTION IN PSYCHOLOGICALLY STRESS RATSOBJECTIVE:To establish a rat psychologically stress model induced by empty bottle stimulation and observe the impacts of metoprolol on antioxidant function in psychologically stress rats,so that to lay a foundation for the further mechanisms research of endothelial protection of metoprolol.METHODS:Healthy adult SD rats as the research objects were randomly divided into control group,model group and metoprolol group(12 rats in each group,male and female,half and half).The rat model of psychologically stress was established by the empty bottle stimulation.After 7 days adaptive phase during which water supply was regular(experimental 1th-7th),the experiment turned to a molding phase(experimental 8th-22th).The metoprolol group and model group were accepted unregular water supply/empty bottle stimulation according a random number table,and were injected intraperitoneally metoprolol(2mg/kg,ltime/day)and saline(2ml/kg,ltime/day)respectively,while,control group was still accepted regular water supply and injected saline(2ml/kg,ltime/day)per day.In the modeling ending day(experimental 23th),the rat behavior were evaluated through an open-field test.ELISA method was used for the measurement of plasma levels of the adrenaline(Adr),cortisol(COR),NADPH oxiase 1(NOX1),Xanthine oxidase(XOD),colorimetry were used to analyze the plasma levels of hydrogen peroxide(H202),catalase(CAT),superoxide dismutase(SOD),glutathione peroxidase(GSH-PX).RESULTS:Compared with control group,not only the frequency of crossing and rearing behavior increased significantly(<0.05),but also the level of COR,Adr in the plasma increased significantly in model and Metoprolol group(P<0.01);Compared with control group,the level of H2O2 NOX1,XOD in the plasma increased significantly in model group(P<0.05)and the level of SOD,GSH-PX,CAT reduced significantly(P<0.05).Compared with model group,the level of H202,NOX1,XOD in the plasma reduced significantly in Metoprolol group(P<0.05)and the level of SOD,GSH-PX,CAT increased significantly(P<0.05).CONCLUTION:Metoprolol can enhance the antioxidant function of psychologically stress rats.Part2 EFFECT OF METOPROLOL ON eNOS UNCOUPLING IN PSYCHOLOGICALLY STRESS RATSOBJECTIVE:To explore the effect of metoprolol on the expression of eNOS and its uncoupling in the aortae of psychologically stress rats,to provide experimental evidence for the new application exploit of adrenergic β1 receptor blockers.METHODES:Healthy adult SD rats as the research objects were randomly divided into control group,model group and metoprolol group(10 rats in each group,male and female,half and half).The rat model of psychologically stress was established by the empty bottle stimulation.After 7 days adaptive phase during which water supply was regular(experimental 1th-7th),the experiment turned to a molding phase(experimental 8th-22th).The metoprolol group and model group were accepted unregular water supply/empty bottle stimulation according a random number table,and were injected intraperitoneally metoprolol(2mg/kg,ltime/day)and saline(2ml/kg,1time/day)respectively,while,control group was still accepted regular water supply and injected saline(2ml/kg,ltime/day)per day.ELISA method was used for the measurement of plasma levels of Natric Oxide(NO).Aortae of rats were separated,ELISA method was used for the measurement of aortae levels of Tetrahydrobiopterin(BH4),L-arginine(L-Arg)and the activity of endothelia nitric oxide synthase(eNOS).Western blotting were used to analyze the protein expression of eNOS in the aortae.RESULTS:Comparing with control group,the levels of NO,BH4,L-Arg,eNOS activity and eNOS expression obviously decrease(P<0.05)in model group.Comparing with model group,the levels of NO,BH4,L-Arg,eNOS activity and eNOS expression obviously increase(P<0.05)in metoprolol group.CONCLUTION:On the one hand,metoprolol can enhance eNOS expression.On the other hand,metoprolol can upregulate the level of BH4,L-Arg to reduce the factors of eNOS uncoupling.It is beneficial to improve the activity of eNOS and raise the level of NO.