Effect Of Water-soluble Propolis On Cardiovascular Function And Its Mechanism In High-salt Diet Rat

Objective: To observe the effect of water-soluble propolis on the cardiovascular function and it’s possible mechanism by the model of high-salt inducing hypertensive rat.Methods: Male SD rat,high-salt diet(diet including 4% Na Cl)for 10 weeks,comparing with normal control group(NC group,normal diet,n=10),measuring the rats’ tail artery blood pressure at the same time point of every day.After the success of high-salt diet induced hypertensive rat model,these rats were randomly divided into 5 groups: high-salt hypertension group(SH group),high-salt hypertension and propolis of low concentration group(SH+WSP-L group,50mg/Kg),high-salt hypertension and propolis of medium concentration group(SH+WSP-M group,100mg/Kg),high-salt hypertension and propolis of high concentration group(SH+WSP-H group,200mg/Kg),high-salt hypertension and captopril group(SH+CAP group,50mg/Kg).Drug intervention was performed in each group from the 11 th week: SH+WSP-L group,SH+WSP-M group,SH+WSP-H group and SH+CAP group were given the appropriate dose of drug by gavage administration,while SH group and NC group were given equal volume of distilled water by gavage administration,once a day.Measuring the rats’ tail artery blood pressure at the same time of every day for 4 weeks.The cardiac function of rats in groups(HR,LVDP,± dp / dtmax)were measured by biological signal acquisition system and then thoracic aortic ring tension and relaxtion were detected in each rat;the plasma,heart,kidney and thoracic aortic rings were collected from each group,measuring the levels of nitric oxide(NO)in plasma,and the hydrogenperoxide(H2O2)in vascular homogenate,the activity of catalase(CAT)and endothelial nitric oxide synthase(e NOS),and the levels of interleukin-6(IL-6)and tumor factor-α(TNF-α)in plasma.At the same time,the morphological changes of heart,kidney and blood vessels were observed.The expression of Nox2 and Nox4 in myocardium,kidney and vascular tissue of each group were measured by the method of western blotting(WB)and polymerase chain reaction(PCR).Results: 1.High salt induced changes of blood pressure in rats Compared with the NC group,the blood pressure of the SH group was increased from the third week to the 10 th week,and continued increasing during administration(P<0.05 or P<0.01);the blood pressure of SH + WSP-M group and SH + WSP-H group decreased significantly with increasing drug concentration;the blood pressure of SH+WSP-L was meaningless decreasing.Compared with SH group,the blood pressure of SH + WSP-M group,SH + WSP-H group and SH + CAP group decreased significantly after one week of administration(P<0.05 or P<0.01).2.The change of cardiac function in each group Compared with NC group,LVDP*HR,± dp / dtmax were significantly lower in SH group,SH + WSP-L group and SH + WSP-M group(P<0.05 or P<0.01);and there were no statistically significant in SH + WSP-H group and CAP group(P>0.05).Compared with SH group,cardiac function(LVDP*HR),± dp / dtmax was significantly improved in SH + WSP-M group,SH + WSP-H group and SH + CAP group(P<0.05 or P<0.01),but it was no statistically significant in SH + WSP-L group(P>0.05).3.The changes of thoracic aortic rings in each group(1)Phe on the shrinkage of thoracic aortic rings in rats Compared with NC group,the shrinkage rate of SH group and SH + WSP-L group were significantly increased at Phe(10-8 ~ 10-5)mol / L(P<0.05 or P<0.01);it was significantly increased at Phe(10-8 ~ 10-6)mol / L in SH + WSP-M group(P<0.05 orP<0.01),but there was no statistically significant at the concentration of Phe 10-5mol / L(P>0.05);there were no statistically significant at the concentration of Phe(10-8 ~ 10-6)mol / L in SH + WSP-H group and SH + CAP group(P>0.05).Compared with SH group,it was decrease in shrinkage at the concentration of Phe(10-8 ~ 10-5)mol / L in SH + WSP-L group,but the difference was no statistically significant(P> 0.05);it was no significant difference in Phe concentration(10-8 ~ 10-7)mol / L in SH + WSP-M group(P> 0.05),but the shrinkage rate was significantly decreased at Phe(10-6 ~ 10-5)mol / L(P<0.05 or P<0.01);the shrinkage rate of WSP-H group and SH + CAP group was significantly decreased at Phe(10-8 ~ 10-5)mol / L(P <0.05 or P <0.01).(2)Effect of ACh on the relaxation rate of thoracic aorta in rats Compared with the NC group,relaxation rate of SH group,SH + WSP-L group was significantly lower in ACh concentration of(10-8 ~ 10-5)mol / L(P<0.05 or P<0.01);it was significantly lower in ACh concentration of(10-8 ~ 10-7)mol / L in SH + WSP-M group(P<0.05 or P<0.01),the difference was no statistically significant in ACh concentration of(10-6 ~ 10-5)mol / L(P> 0.05);there was no significant difference in SH + WSP-H group and SH + CAP group at the concentration of ACh(10-8 ~ 10-5)mol / L(P> 0.05).(3)Effects of ACh on the relaxation rate of thoracic aorta in rats after L-NAME incubition At the concentration of ACh(10-8 ~ 10-5),comparing with NC group,relaxation rate has no significant in SH group,SH+WSP-L group,SH+WSP-M group,SH+WSP-H group,and SH+CAP group(P> 0.05).4.Measuring of biochemical indicators(1)NO content in plasma and vascular homogenates of e NOS content Compared with NC group,NO and e NOS content were significantly decreased in SH group,SH + WSP-L group and SH + WSP-M group(P<0.05 or P<0.01),there were no significace in SH + WSP-H group and SH + CAP group.(2)H2O2 content and CAT activity in vascular homogenate Comparing with NC group,the content of H2O2 in SH group,SH + WSP-L group and SH + WSP-M group was significantly higher(P<0.05 or P<0.01),while the activity of CAT was significantly lower in these groups(P<0.05 or P<0.01);the content of H2O2 and the activity of CAT were no significance in SH +WSP-H group and SH + CAP group(P> 0.05).(3)Levels of IL-6 and TNF-α in plasma Comparing with NC group,the levels of IL-6 and TNF-α in SH group,SH + WSP-L group and SH + WSP-M group were significantly increased(P <0.05 or P <0.01),SH + WSP-H group and SH + CAP group were no significant difference(P> 0.05).Compared with SH group,SH + WSP-M group,SH + WSP-H group and SH + CAP group was significantly lower than that in SH group(P <0.05 or P <0.01).(4)ROS content in vascular tissue Comparing with NC group,the content of ROS was significantly higher in SH group,SH + WSP-L group and SH + WSP-M group(P <0.05 or P <0.01),it was no significance in SH + WSP-H group and SH + CAP group(P> 0.05).Compared with SH group,the levels of ROS were significantly decreased in SH + WSP-L group,SH + WSP-M group,SH + WSP-H group and SH + CAP group(P < 0.05 or P < 0.01).5.HE staining was used to observe the morphological changes of heart,kidney and blood vessels The morphology of the aorta was homogeneous and flat,and the mesangial cells were arranged neatly and the thickness of the vessel wall was uniform.The morphological structure of the kidney was normal,and the renal tissue was normal.Small blood vessels no lesions.The myocardium of the rats in the SH group showed the damage of myocardial fibers and the widening of the myocardial fibers.The aorta of the rats showed obvious endometrial injury,thickening of the vessel wall and cell arrangement and morphological changes.In the renal tissue structure,Arterial vitreousdegeneration,renal fissure.Compared with SH group,the pathological changes of SH + WSP-L group,SH + WSP-M group and SH + WSP-H group gradually decreased with the increase of drug concentration.The pathological changes of SH + CAP group Also reduced 6.Detection of Nox2 and Nox4 expression in heart,kidney,and vessels Compared with NC group,the expression of Nox2 and Nox4 were significantly increased in SH group,SH +WSP-L group and SH+WSP-M group by WB and PCR(P <0.05 or P <0.01),SH+WSP-H group and SH+CAP group were no significant difference(P> 0.05).Compared with SH group,the expression of Nox2 and Nox4 were no significant in the group of SH +WSP-L and SH+WSP-M(P> 0.05),SH+ WSP-H group and SH+CAP group were significantly decreade measuring by WB and PCR(P <0.05 or P <0.01).Conclusion: The hypertension rat model that induced by high-salt diet was replicated successfully;water-soluble propolis had a hypotensive effect on blood pressure and a improving effect on cardiac function in hypertensive rats;possibly this effect may be achieved through its antioxidant,anti-inflammatory and improved blood pressure in rats to achieve the endothelial function.