| ObjectiveDiabetic cardiomyopathy(DCM)has been defined as ventricle dysfunction accompanied by the development of cardiomyocyte hypertrophy,myocardial fibrosis and apoptosis independent of coronary artery diseases or hypertension.According to our previous study,we had explored that Tripterygium glycosides(TG)elicited immune regulation and anti-inflammatory response effects on diabetic nephropathy(DN),whereas TG inhibited NF-?B signaling pathway and suppressed the activation of T lymphocytes,then prevented renal fibrosis.Consideration of the relevant mechanisms and similar signaling pathways between renal fibrosis in DN and myocardial fibrosis in DCM,chronic inflammatory response and immunologic regulations both played critical role in the development of diabetes and its late complication including DN and DCM.Methods75 male Sprague-Dawley rats were chosen as the research objects and select 15 rats of them randomly as normal control group(NC group),fed with regular diet.The other 60 rats were given high-fat diet for 8 weeks to induce insulin resistance,then in combination with low dose STZ(30mg/kg)injected to establish the rat model of DM.Furthermore,successfully induced DM rats were randomly divided into 4 groups:Diabetic group(DM group)and Diabetic rats treated with TG(1,3,or 6 mg/kg/day resp,named as DM+TL group,DM+TM group and DM+TH group)for 8 weeks.At the end of this study,rats were sacrificed,their bloods were collected and their hearts were harvested for further experiments.Cardiac function was performed by echocardiography,cardiac apoptosis was evaluated by Tunel method,and histopathology of the hearts was examined with HE,Masson staining and scanning electron microscopy.Immune regulation mediators,macrophage infiltrations,inflammatory related cytokines,cardiac fibrosis and cardiac apoptosis mediators were measured by q RT-PCR,Western blot and Immunohistochemistry staining.Results1.The level of blood lipids including triglyceride and total cholesterol,fasting insulin,HOMA-IR and HOMA-? in high-fat diet fed group were significantly higher than NC group(P<0.05).2.Biochemical examinations: Body Weight(BW)and blood glucose: After 8weeks treatment,the BW in DM group was decreased(P<0.05),the blood glucose and triglyceride in DM group were increased compared with NC group.There existed no significant difference between DM group and TG treated groups(P>0.05).3.Echocardiography: The ventricular dilatation(LVEDD),the LV systolic parameters(FS and EF),and LV diastolic function(E/A ratio)significantly imparied in DM group compared with NC group(P<0.05).After 8 weeks of treatment,medium and high dosage TG treated groups significantly attenuated LV systolic dysfunction(EF and FS)as well as diastolic function(E/A ratio and LVEDD)(P<0.05).5.Heart weight index(HW/BW): DM group displayed much higher HW/BW radio compared with NC group(P<0.05).TG treatment displayed a significant reduction in the HW/BW ratio in medium and high dose TG treated groups(P<0.05).6.Myocardial pathological structure and cardiac ultrastructure changes: There were significant alterations in DM group,which including disarrangement of myofilament bundles,destruction of myofibrils,obviously interstitial collagen fibers.In contrast,medium and high dosage TG treated groups displayed improved morphology in HE staining and electron microscopy.7.Using ELISA to detect the levels of NF-?B,IL-1?,TNF-?,MCP-1 and VCAM-1 in serum: The levels of those cytokines in serum were all significantly increased in DM group(P<0.05).After 8 weeks of treatment,the levels of those cytokines were significantly decreased in three TG-treated groups(P<0.05).8.In DM group,the expressions of TLR4,NF-?B,pro-inflammatory cytokines(TNF-?,MCP-1 and VCAM-1)were up-regulated compared with NC group(P<0.05).Interestingly,they were all significantly inhibited when treated with medium and high dosage TG compared with DM group(P<0.05).9.The cardiac fibrosis mediators TGF-?1,?-SMA and vimentin expressions were significantly increased in DM group(P<0.05).While with medium and high dose TG treatment,indicators of myocardial fibrosis including TGF-?1,?-SMA andvimentin were significantly inhibited(P<0.05).10.It revealed that GRP78/PERK/ATF4/CHOP apoptosis pathway was activated in DM group,GRP78 up-regulated expression of p-PERK,p-e IF2?,ATF4,CHOP and Bax/Bcl-2 coupled with cardiac apoptosis compared with NC group(P<0.05).Furthermore,we observed that apoptosis mediators including GRP78,p-PERK/PERK,p-e IF2?/e IF2?,ATF4,CHOP and Bax/Bcl-2 were significantly suppressed when treated with medium and high dosage TG compared with DM group(P<0.05).Conclusions1.In DCM rats,after 8 weeks of treatment,medium and high dosage TG treated groups significantly attenuated LV systolic and diastolic function.2.In DCM rats,medium and high dose TG treatment could significantly down regulate TLR4/NF-?B/IL-1? pathway and NF-?B/TNF-?/VCAM-1 inflammatory pathway,coupled with decreased inflammatory-related cytokines.3.In DCM rats,TGF-?1/?-SMA/Vimentin myocardial fibrosis pathway was inhibited by medium and high dose TG treatment,with which the pathological disarrangements of myocardial tissues were significantly attenuated.4.In DCM rats,myocardial apoptosis GRP78/PERK/ATF4/CHOP pathway was suppressed when treated with medium and high dosage TG,which was associated with reduced downstream cytokines,coupled with decreased cardiac apoptosis shown by Tunel staining. |
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