SAA Inhibiting Expression Of Lipoprotein-associated Phospholipase A2 In AS Rats And Research Of The Related Mechanism

Objective To observe the intervention effects of salvianolic acid A(SAA)on atherosclerosis(AS)model rats and effects of SAA on expression of lipoprotein-associated phospholipase A2(Lp-PLA2)in AS rats,and also preliminarily study the mechanism about SAA regulating expression of Lp-PLA2 from PI3K/P38 MAPK pathway,which can support experimental basis for SAA preventing and treating cardiovascular disease.Methods 60 male SD rats,weighing 220-250g,were taken.54 of them were fed with high-fat diets and injected 4.0×104IU/kg Vitamin D3(VD3)i.p..Carotid artery ballon injury was operated after 2 weeks.Next day,36 rats with successful operation were selected,randomly divided into 6 groups according to weights,namely model group(Model,NS 5mL·kg-1),SAA group(SAA,SAA lmg·kg-1),DB group(DB,Darapladib 30mg·kg-1),ATV group(ATV,ATV 5mg·kg-1),SAA+ATV group(SAA+ATV,SAA 1 mg·kg-1+ATV 5mg·kg-1),DB+ATV group(DB+ATV,Darapladib 30mg·kg-1+ATV 5mg·kg-1).Another 6 were used as control group(Control,NS 5mL·kg’1),fed with common diets.The rats were given corresponding drugs respectively,once per day,for 4 weeks.Except for control group,other groups were again injected 1.0×104 IU/kg VD3 i.p.before drug administration and at 2 weeks of drug administration.General signs of rats in each group were observed during experiment.Content of TG,TC,HDL-C,LDL-C,hsCRP,IL-6,TNF-α and Lp-PLA2 and activity of Lp-PLA2 in serum was detected after administration ended,and ratio of TC/HDL-C and arteriosclerosis index(AI)were calculated.Rats were killed and 2 samples of thoracic aorta were taken,one for HE staining and CD68 macrophages immunohistochemical observation.And another for extracting mRNA and protein,RT-PCR was used to test IL-6,IL-1β,TNF-α,MCP-1,VCAM-1 and ICAM-1 mRNA expression.And Western blot was used to test Lp-PLA2,AKT,p-AKT,P38 and p-P38 protein expression.Results(1)Compared to control group,thoracic aorta in AS model showed obviously lipid deposition,atherosclerotic plaques and serious macrophage infiltration through pathology observation.TC,LDL-C contents,ratio of TC/HDL-C and AI were significantly increased(P<0.05),but HDL-C level was decreased obviously(P<0.05).Content of hsCRP,IL-6 and TNF-α in serum was rised notably(P<0.05).IL-6,IL-1β,TNF-α,MCP-1 and VCAM-1 mRNA expression in aorta was increased obviously(P<0.05).Content and activity of Lp-PLA2 in serum and its protein expression in aorta were rised significantly(P<0.05).p-AKT and p-P38 protein levels were notably rised in aorta(P<0.05).(2)Compared to model group,atherosclerotic plaque was alleviated and macrophage infiltration was reduced in drug groups.TC and LDL-C in serum in drug groups were notably decreased(P<0.05),as with ratio of TC/HDL-C and AI in SAA+ATV and DB+ATV.HsCRP,IL-6,and TNF-α in serum in drug groups were reduced notably(P<0.05).IL-6,IL-1β and VCAM-1 mRNA expression in drug groups was reduced notably(P<0.05),TNF-α mRNA expression in SAA,DB,SAA+ATV and DB+ATV groups was notably decreased(P<0.05),MCP-1 mRNA expression in ATV,SAA+ATV and DB+ATV groups was decreased remarkably(P<0.05).Lp-PLA2 content in drug groups was significantly reduced(P<0.05),while Lp-PLA2 activity in SAA,DB and DB+ATV was obviously decreased(P<0.05).Meanwhile,Lp-PLA2 protein expression was decreased in SAA,DB,SAA+ATV and DB+ATV groups(P<0.05).p-P38 protein expression in SAA,DB,SAA+ATV and DB+ATV was significantly reduced(P<0.05).(3)Compared to SAA group,TC level was significantly reduced in SAA+ATV(P<0.05).LDL-C level,ratio of TC/HDL-C and AI were notably decreased in DB+ATV,as well as the Lp-PLA2 activity in DB and DB+ATV(P<0.05).(4)Compared to ATV group,HDL-C in DB+ATV was notably rised(P<0.05),and Lp-PLA2 activity was notably reduced in DB and DB+ATV(P<0.05).Conclusions SAA can alleviate rats AS lesions effectively.The mechanism,on the one hand,may be related to effects of SAA on inhibiting macrophage infiltration,regulating lipid metabolism and resisting inflammation.On the other hand,it may be associate with the function of SAA lowering content,activity and 什么 protein expression of Lp-PLA2 in aorta.Meanwhile,SAA can notably down-regulated phosphorylation level of P38 protein in P38 MAPK pathway in AS rats,suggesting that SAA inhibiting Lp-PLA2 expression may be related to inhibition of P38 MAPK pathway activation.