Abstract： Objective To explore whether Xinshuikang Capsule(心衰康胶囊)can improve myocardial fibrosis in diabetic rats by regulating transforming growth factor-β1(TGF-β1)/mitogen-activated protein kinase p38 antibody(p38MAPK)/cAMP response element binding protein(CREB)signaling pathway.Methods Thirty-two SPF male rats were randomly divided into con-trol group,model group,Xinshuaikang Capsule group(1.0g·kg-1·d-1)and valsartan group(30 mg·kg-1·d-1).In ad-dition to the control group,streptozotocin(STZ)with a concentration of 1 mg/mL was intraperitoneally injected at a body mass of 30 mg/kg to prepare diabetes model rats.Both the control group and the model group were given normal saline by gavage.Hema-toxylin-eosin(HE)staining was used to observe the pathological changes of myocardial tissue in diabetic rats.The immunohisto-chemical method was used to detect the protein expressions of TGF-β1.The enzyme-linked immunosorbent assay(ELISA)was used to detect the protein levels of TGF-β1,B-cell lymphoma factor 2(Bcl-2)and cysteine protease 3(Caspase-3).Western Blot was used to detect the expressions of TGF-β1,phosphorylation-p38MAPK(p-p38MAPK)and CREB.Results Compared with those of the control group,the myocardial arrangement of the rats in the model group was disordered,with tissue swelling and a large amount of inflammatory cell infiltration.The expression levels of Bcl-2 and p-CREB proteins were significantly reduced(P＜0.01),and the expressions of TGF-β1,Caspase-3 and p-p38MAPK proteins were significantly increased(P＜0.05,P＜0.01).Compared with those of the model group,the myocardial fibers of the rats in the Xinshuaikang Capsule group were more neatly arranged and the inflammatory infiltration was reduced.There was no obvious edema in the interstitial space.The pro-tein expression levels of TGF-β1,p-p38MAPK and Caspase-3 decreased significantly(P＜0.01,P＜0.05),while the protein expression levels of p-CREB and Bel-2 increased(P＜0.05,P＜0.01).Conclusion Xinshuaikang Capsule can inhibit myo-cardial fibrosis and apoptosis in diabetic rats,and its improvement may be related to the regulation of TGF-β1/p38MAPK/CREB signaling pathway.