Effects Of Astragalus Polysaccharides On Myocardial Hypertrophy Induced By Iso-prenaline Via NF-κB And CaMK Ⅱ Signaling Pathway In Neonatal Rats

ObjectiveTo discuss the protective effects and mechanisms of AstragalusPolysaccharide (APS) on cardiomyocytes hypertrophy induced by Isoprenaline(ISO) via TLR4/NF-κB and CaMKⅡsignaling pathways in neonatal rats.MethodsThe primary ventricular myocytes of SD neonatal rats were cultured andinduced hypertrophic response by ISO10μmol/L, the effects of differentconcentration of APS (0.1mg/L,1mg/L,10mg/L), NF-кB inhibitor (BAY11-7082)and CaMK Ⅱinhibitor (KN93) on cardiomyocytes hypertrophy were observed.The volume of cardiomyocytes was measured by digestive isolation andcomputer photograph analysis system; total protein content by coomassiebrilliant blue (Bradford); the expression of tumor necrosis factor α (TNF-α) andinterleukin-6(IL-6) by enzyme-linked immunosorbent assay (ELISA);cytoskeleton and cell nucleus were observed by Rhodamine-phalloidin andHoechst33258staining, respectively; the expression of atrial natriuretic peptide(ANP) mRNA and TLR4mRNA by inverse transcription polymerase chainreaction (RT-PCR); the expression of myocardial cell IκBα、p65、TLR4andCaMKⅡ δprotein expression by Western blot.ResultsCompared with normal control group, ISO10μmol/L significantly increased cell volume, cytoskeleton filaments density, nucleus size, total protein contentand the expression of ANP mRNA. These effects abolished by differentconcentration of APS, BAY11-7082and KN93. Furthermore, APS andBAY11-7082could down-regulate expression of TLR4mRNA、p65and TLR4protein; up-regulate expression of IкBα and reduce the level of TNF-α and IL-6via TLR4/NF-кB inflammatory signaling pathway, respectively. APS and KN93can also attenuate the expression of CaMK Ⅱδ and inflammation induced byISO partially via CaMKⅡ signaling pathway.In addition, CaMK Ⅱ δcouldregulate NF-кB expression The protective effects of APS also showed adose-dependent manner.ConclusionsThe protective effects of APS on cardiomyocytes hypertrophy induced byISO, which is partially via attenuating inflammation through TLR4/NF-кB andCaMKⅡ signaling pathways, and between NF-кB and CaMKⅡhad interactiveeffects.