Myocardial Fibrosis In Diabetic Rats Research Articles

Gaseous signal molecule SO2 regulates autophagy through PI3K/AKT pathway inhibits cardiomyocyte apoptosis and improves myocardial fibrosis in rats with type II diabetes.

Myocardial fibrosis is a key link in the occurrence and development of diabetic cardiomyopathy. Its etiology is complex, and the effect of drugs is not good. Cardiomyocyte apoptosis is an important cause of myocardial fibrosis. The purpose of this study was to investigate the effect of gaseous signal molecule sulfur dioxide (SO2) on diabetic myocardial fibrosis and its internal regulatory mechanism. Masson and TUNEL staining, Western-blot, transmission electron microscopy, RT-qPCR, immunofluorescence staining, and flow cytometry were used in the study, and the interstitial collagen deposition, autophagy, apoptosis, and changes in phosphatidylinositol 3-kinase (PI3K)/AKT pathways were evaluated from in vivo and in vitro experiments. The results showed that diabetic myocardial fibrosis was accompanied by cardiomyocyte apoptosis and down-regulation of endogenous SO2-producing enzyme aspartate aminotransferase (AAT)1/2. However, exogenous SO2 donors could up-regulate AAT1/2, reduce apoptosis of cardiomyocytes induced by diabetic rats or high glucose, inhibit phosphorylation of PI3K/AKT protein, up-regulate autophagy, and reduce interstitial collagen deposition. In conclusion, the results of this study suggest that the gaseous signal molecule SO2 can inhibit the PI3K/AKT pathway to promote cytoprotective autophagy and inhibit cardiomyocyte apoptosis to improve myocardial fibrosis in diabetic rats. The results of this study are expected to provide new targets and intervention strategies for the prevention and treatment of diabetic cardiomyopathy.

Isosorbide mononitrate inhibits myocardial fibrosis in diabetic rats by up-regulating exosomal MiR-378

Purpose: To investigate the effect of isosorbide mononitrate on diabetic cardiomyopathy (DCM), and the potential mechanism of action.Methods: The effects of isosorbide mononitrate and isosorbide mononitrate + GW4869 on cardiac function and myocardial fibrosis in DCM rats were determined via hemodynamics, hematoxylin-eosin (H&E) staining and Masson staining. Exosomes were extracted from the serum, and the differential expressions of microribonucleic acids (miRNAs) related to myocardial fibrosis were determined by reverse transcription-polymerase chain reaction (qRT-PCR). Western blotting was performed to determine the effects of isosorbide mononitrate and isosorbide mononitrate + GW4869 on IGF1R/STAT3 signaling pathway.Results: Isosorbide mononitrate exerted a protective effect against DCM--induced cardiac dysfunction and myocardial fibrosis, while such a protective effect was suppressed by the exosome inhibitor GW4869 (p < 0.05). The expression of miR-378 in exosomes significantly rose in isosorbide mononitrate group. The increased expression of miR-378 in vitro inhibited the proliferation of primary myocardial fibroblasts, and reduced the expression of myocardial fibrosis markers (p < 0.05). Luciferase reporter assay data showed that miR-378 negatively regulated the expression of IGF1R by direct binding to IGF1R mRNA 3'-untranslated region (3'UTR). In primary myocardial fibroblasts, miR-378 mimic significantly reduced the protein expressions of IGF1R, p-STAT3/STAT3 and c-Myc (p < 0.05). Isosorbide mononitrate lowered the protein expressions of IGF1R, p-STAT3/STAT3 and c-Myc, but the inhibitory effect was weakened by the exosome inhibitor, GW4869 (p < 0.05).Conclusion: Isosorbide mononitrate inhibits myocardial fibrosis in diabetic rats by up-regulating exosomal miR-378, and targeting the axis of STAT3/IGF1R. The results of this study may provide a new insight into the treatment of DCM.

Epigallocatechin-3-gallate attenuates myocardial fibrosis in diabetic rats by activating autophagy.

Epigallocatechin-3-gallate (EGCG) possesses anti-fibrotic potential in diverse tissues; however, the molecular mechanisms underlying the impacts of EGCG on diabetes-induced myocardial fibrosis remain unclear. This present study aimed to unravel the anti-fibrotic effects of EGCG on the heart in type 2 diabetic rats and investigate its molecular mechanisms. Rats were randomly assigned to the following four groups: Normal (NOR), diabetic cardiomyopathy (DCM), DCM + 40 mg/kg EGCG, and DCM + 80 mg/kg EGCG groups. After 8 weeks of EGCG treatment, fasting blood glucose, left ventricular hemodynamic indices, heart index, and myocardial injury-related parameters were measured. Hematoxylin and eosin staining and Sirius Red staining were used to evaluate myocardial pathological alterations and collagen accumulation. The contents of myocardial hydroxyproline, collagen-I, collagen-III, transforming growth factor (TGF)-β1, matrix metalloprotease (MMP)-2, and MMP-9 were measured. The gene expression levels of myocardial TGF-β1, MMP-2, and MMP-9 were detected. Autophagic regulators, including adenosine 5'-monophosphate-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR), and autophagic markers, including microtubule-associated protein-1 light chain 3 and Beclin1 were estimated. The results indicated that diabetes significantly decreased cardiac contractile function and aggravated myocardial hypertrophy and injury. Furthermore, diabetes repressed the activation of autophagy in myocardial tissue and promoted cardiac fibrosis. Following ingestion with different doses of EGCG, myocardial contractile dysfunction, hypertrophy and injury were ameliorated; myocardial autophagy was activated, and myocardial fibrosis was alleviated in the EGCG treatment groups. In conclusion, these findings suggested that EGCG could attenuate cardiac fibrosis in type 2 diabetic rats, and its underlying mechanisms associated with activation of autophagy via modulation of the AMPK/mTOR pathway and then repression of the TGF-β/MMPs pathway.

Combined use of systemic quercetin, glutamine and alpha-tocopherol attenuates myocardial fibrosis in diabetic rats

This study aimed to analyze the effects of the quercetin (100 mg/kg), 1% glutamine and 1% α-tocopherol antioxidants in the myocardium of rats with streptozotocin-induced diabetes mellitus. Twenty male rats were subdivided into four groups (n = 5): N (normoglycemic); D (diabetic); NT (normoglycemic treated with antioxidants); and DT (diabetic treated with antioxidants) treated for 60 days. Clinical parameters, oxidative stress markers, inflammatory cytokines, myocardial collagen fibers and immunoexpression of superoxide dismutase 1 (SOD-1), glutathione peroxidase-1 (GPx-1), interleukin-1β (IL-1-β), transforming growth factor-beta (TGF-β), and fibroblast growth factor-2 (FGF-2) were evaluated. Results showed reduced body weight, hyperphagia, polydipsia and hyperglycemic state in groups D and DT. The levels of glutathione (GSH) were higher in NT and DT compared to N (p < 0.01) and D (p < 0.001) groups, respectively. Greater GSH levels were found in DT when compared to N animals (p < 0.001). In DT, there was an increase in IL-10 in relation to N, D and NT (p < 0.05), while GPx-1 expression was similar to N and lower compared to D (p < 0.001). TGF-β expression in DT was greater than N (p < 0.001) group, whereas FGF-2 in DT was higher than in the other groups (p < 0.001). A significant reduction in collagen fibers (type I) was found in DT compared to D (p < 0.05). The associated administration of quercetin, glutamine and α-tocopherol increased the levels of circulating interleukin-10 (IL-10) and GSH, and reduced the number of type I collagen fibers. Combined use of systemic quercetin, glutamine and alpha-tocopherol attenuates myocardial fibrosis in diabetic rats.

The Effect of Curcumin Nano-Suspension on Myocardial Fibrosis in Diabetic Rats

The occurrence of complications of diabetic patients not only increases the difficulty and burden of treatment but also significantly affects the health and safety of patients. Traditional therapeutic drugs are prone to drug resistance, which affects the therapeutic effect. In recent years, the application of plant-derived natural compounds in the treatment of diseases has become a hot spot in the research of diabetes drugs. Curcumin has anti-tumor, anti-inflammation, anti-oxidation and antimicrobial effects, but the mechanism of its effect on cardiomyocytes in diabetic patients is not yet clear. In this study, curcumin was prepared into nano-preparations and its mechanism of action in the process of myocardial fibrosis in diabetic rats was further explored. We found that injection of curcumin nano-suspension can increase the LVIDd and LVFS of rats, while reducing the serum CKMB, LDH, AST and cTnI levels. Further exploration found that curcumin can reduce serum TNF- α and IL-1 β levels in diabetic rats, while increasing the SOD and GSH-Px activities of myocardial tissue, and reducing MDA content. These suggests that curcumin can reduce inflammation and oxidative stress in diabetic rats. Therefore, this study believes that curcumin nano-suspension can effectively inhibit diabetic cardiomyocyte fibrosis, oxidative stress, and inflammation and protect the rat myocardium.

Exogenous Hydrogen Sulfide Ameliorates Diabetic Myocardial Fibrosis by Inhibiting Cell Aging Through SIRT6/AMPK Autophagy.

Stress aging of myocardial cells participates in the mechanism of myocardial fibrosis (MF). Previous studies have shown that hydrogen sulfide (H2S) can improve MF, however the specific internal mechanism remains still unclear. Therefore, this study aims to explore whether H2S can improve myocardial cell aging induced by high glucose and myocardial fibrosis in diabetic rats by activating autophagy through SIRT6/AMPK. We observed that HG (high glucose, 33 mM) induced down-regulation of endogenous H2S-producing enzyme CSE protein expression, increased cell senescence, down-regulation of autophagy-related proteins Beclin1, Atg5, Atg12, Atg16L1, and inhibition of SIRT6/AMPK signaling pathway in H9c2 cardiomyocytes. H2S (NaHS: 400 μM) could up-regulate CSE protein expression, inhibit cell senescence, activate autophagy and SIRT6/AMPK signaling pathway. On the contrary, no above phenomena was achieved upon addition of CSE inhibitor PAG (dl-propargylglycine: mmol/L). In order to further elucidate the relationship between H2S and SIRT6/AMPK signaling pathway, dorsomorphin dihydrochloride (Dor), an inhibitor of AMPK signaling pathway, was added to observe the reversal of H2S’s inhibitory effect on myocardial cell aging. At the same, streptozotocin (STZ; 40 mg/kg) was injected intraperitoneally to build an animal model of diabetic SD rats. The results showed that myocardial collagen fibers were significantly deposited, myocardial tissue senescent cells were significantly increased and the expression of CSE protein was down-regulated, while SIRT6/AMPK signaling pathway and cell autophagy were significantly inhibited. H2S-treated (NaHS; 56 μmol/kg) could significantly reverse the above phenomenon. In conclusion, these findings suggest that exogenous H2S can inhibit myocardial cell senescence and improve diabetic myocardial fibrosis by activating CSE and autophagy through SIRT6/AMPK signaling pathway.

Curcumin analog A13 alleviates oxidative stress by activating Nrf2/ARE pathway and ameliorates fibrosis in the myocardium of high-fat-diet and streptozotocin-induced diabetic rats

BackgroundDiabetes mellitus is an important risk factor for cardiomyopathy. Increasing oxidative stress may be one of the main factors of diabetic cardiomyopathy. A13, a newly synthesized curcumin analog, was proved to be superior to curcumin in biological activity. However, little know about how A13 performed in diabetic models. In this study, we evaluated the ability of curcumin analog A13 to alleviate oxidative stress and ameliorate fibrosis in the myocardium, and explore the underlying mechanisms.MethodsIntraperitoneal injection of streptozotocin (30 mg/kg in 0.1 M sodium citrate buffer, pH 4.5) induced diabetes in high-fat fed rats. The rats were respectively treated with a daily dose of curcumin or A13 via intragastric intubation for 8 weeks. Myocardial tissue sections were stained with hematoxylin–eosin; oxidative stress was detected by biochemical assays; activation of the Nrf2/ARE pathway was detected by Western blot, immunohistochemical staining and RT-qPCR; myocardial fibrosis was identified by Western blot and Masson trichrome staining.ResultsTreatment with curcumin analog A13 reduced the histological lesions of the myocardium in diabetic rats. Curcumin and A13 treatment decreased the malondialdehyde level and increased the activity of superoxide dismutase in the myocardium of diabetic rats. Molecular analysis and immunohistochemical staining demonstrated that dose of 20 mg/kg of A13 could activate the Nrf2/ARE pathway. Molecular analysis and Masson staining showed that curcumin analog A13 treatment significantly ameliorated fibrosis in myocardium of these diabetic rats.ConclusionTreatment with curcumin analog A13 protects the morphology of myocardium, restores the MDA levels and SOD activity, activates the Nrf2/ARE pathway and ameliorates myocardial fibrosis in diabetic rats. It may be a useful therapeutic agent for some aspects of diabetic cardiomyopathy.

Long-term moderate intensity exercise alleviates myocardial fibrosis in type 2 diabetic rats via inhibitions of oxidative stress and TGF-β1/Smad pathway.

Exercise has an effect on the reduction of myocardial fibrosis in diabetic rats as previously reported, in which oxidative stress and the TGF-β1/Smad signaling pathway may play key roles. There is little direct experimental evidence that exercise alleviates myocardial fibrosis in type 2 diabetes mellitus (T2DM). Here we established a type 2 diabetic model by using streptozotocin and a high-fat diet. Rats were divided into groups of normal control (NC), T2DM and T2DM plus exercise (T2DME). The T2DME group received further treadmill training at moderate intensity for 8weeks. Histological and biochemical methods were used to detect the benefits of exercise to T2DM. Results showed that the weight of rats in the T2DM group dropped dramatically, along with significant increases in blood glucose, myocardial fibrosis and oxidative stress, associated with upregulated expression of factors of myocardial fibrosis, except Smad7. Exercise largely reversed T2DM-induced alterations in factors of myocardial fibrosis, including suppressing expression of MMP-2, CTGF, TGF-β1, p-Smad2 and p-Smad3, and increased expression of TIMP-1 and Smad7. Therefore, exercise might be considered an alternative therapeutic remedy for diabetic cardiomyopathy.

H2S attenuates the myocardial fibrosis in diabetic rats through modulating PKC-ERK1/2MAPK signaling pathway.

OBJECTIVETo investigate the roles and underlying mechanism of exogenous HS (hydrogen sulfide) in attenuating the myocardial fibrosis in diabetic rats.METHODS: A total of 40 SD rats were randomly divided into 4 groups: control group, STZ group, STZ HS group and HS group. To build the DM rat model , the rats in the STZ group and STZ HS group were injected streptozotocin (STZ) intraperitoneally, While the rats in the STZ HS group and the HS group received sodium hydrosulfide (NaHS), which provides exogenous HS. Eight weeks later, the myocardial tissues of rats were used to detecting the collagen deposition through Masson staining, as well as some protein expressions related to myocardial fibrosis and signaling pathway by western blotting.RESULTS: Comparing to control group, the collagen deposition of myocardial matrix remarkably increased in the STZ group, and almost all the proteins that are relative to myocardial fibrosis, inflammatory and signaling pathway show an overexpression, except for PPARG and NF-Bp65. When Compared with the STZ group, the collagen deposition was obviously attenuated in STZ HS group, as well as the protein expressions above-mentioned, While PPARG was up-regulated.CONCLUSION: The myocardial fibrosis in DM rats can be attenuated effectively by exogenous HS, and the underlying mechanism is likely to regulating PKC-ERK1/2MAPK signaling pathway, improving the MMPs/TIMPs expression dysregulation and inhibiting inflammatory reaction.

Exogenous H2S mitigates myocardial fibrosis in diabetic rats through suppression of the canonical Wnt pathway

Hydrogen sulfide (H2S) has antifibrotic activity in the kidneys, heart, lungs, and other organs. The present study investigated the protective activity of exogenous H2S against myocardial fibrosis in a rat model of diabetes. Animals were assigned to normal control, diabetes mellitus (DM), DM + sodium hydrosulfide (NaHS; DM + NaHS) and NaHS groups. Fasting blood glucose (FBG), cardiac function and hydroxyproline were monitored. Heart histomorphology and ultrastructure were additionally evaluated. Wnt1-inducible signaling pathway protein (WISP)-1 protein expression in the myocardium was determined by immunohistochemical staining. Matrix metalloprotease (MMP)-2, tissue inhibitor of metalloproteinase (TIMP)-2, collagens, and canonical Wnt and transforming growth factor (TGF)-β1/SMAD family member 3 (Smad3) pathway-related proteins were assessed by western blotting. Cardiac function was decreased, and myocardial injury, hypertrophy and fibrosis were increased in the diabetes model rats. MMP-2 expression was decreased, and the expressions of WISP-1, TIMP-2, collagens, and canonical Wnt and TGF-β1/Smad3 pathway-related proteins were increased in the myocardia of the diabetes model rats. The present results indicated that the canonical Wnt pathway promoted diabetic myocardial fibrosis by upregulating the TGF-β1/Smad3 pathway. Except for FBG, exogenous H2S ameliorated the changes in diabetes-associated indices in rats in the DM + NaHS group. The results are consistent with H2S protection of streptozotocin-induced myocardial fibrosis in the diabetes model rats by downregulation of the canonical Wnt and TGF-β1/Smad3 pathway and decreased myocardial collagen deposition.

Hydrogen sulfide attenuates myocardial fibrosis in diabetic rats through the JAK/STAT signaling pathway.

The aim of the present study was to determine the role of hydrogen sulfide (H2S) in improving myocardial fibrosis and its effects on oxidative stress, endoplasmic reticulum (ER) stress and cell apoptosis in diabetic rats, by regulating the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. A total of 40 male Sprague-Dawley rats were randomly divided into four groups (n=10) as follows: Normal (control group), diabetes mellitus [streptozotocin (STZ) group], diabetes mellitus treated with H2S (STZ + H2S group), and normal rats treated with H2S (H2S group). Diabetes in rats was induced by intra-peritoneal (i.p.) injection of STZ at a dose of 40 mg/kg. NaHS (100 µmol/kg, i.p.), which was used as an exogenous donor of H2S, was administered to rats in the STZ + H2S and H2S groups. After 8 weeks, the pathological morphological changes in myocardial fibers were observed following hematoxylin and eosin and Masson's trichrome staining. Apoptosis of myocardial tissue was analyzed by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Oxidative stress was evaluated through detecting the content of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), glutathione (GSH) and superoxide dismutase (SOD) in the myocardial cells by ELISA. The expression of collagen III, matrix metalloproteinase (MMP)8, MMP14, tissue inhibitor of metalloproteinase (TIMP)2, transforming growth factor (TGF)-β, cystathionine-γ-lyase (CSE), eukaryotic initiation factor 2α (eIF2α), GRP94, Bcl-2, caspase-3, tumor necrosis factor (TNF)-α, nuclear factor-κB (NF-κB) and proteins related to the JAK/STAT pathway, was detected by western blot analysis. The results indicated that the array of myocardial cells was markedly disordered in STZ group rats; compared with the control group, both myocardial interstitial fibrosis and the deposition of collagen III were increased. Furthermore, the expression ratio of MMPs/TIMPs was dysregulated, while the expression levels of TGF-β, eIF2α, GRP94, caspase-3, TNF-α, NF-κB, MDA and 4-HNE were significantly increased. Furthermore, the expressions of JAK-1/2 and STAT1/3/5/6 were also markedly upregulated, while those of CSE, SOD, GSH and Bcl-2 were downregulated. Compared with the STZ group, these changes were reversed in the STZ + H2S group. The results of the present study demonstrated that H2S can improve myocardial fibrosis in diabetic rats, and the underlying mechanism may be associated with the downregulation of the JAK/STAT signaling pathway, thereby suppressing oxidative stress and ER stress, inflammatory reaction and cell apoptosis.

Effect of genistein on myocardial fibrosis in diabetic rats and its mechanism.

The aim of the present study was to investigate the effects of genistein (GEN) on myocardial fibrosis in type 1 diabetic rats and explore the underlying mechanisms. Rats were divided into 4 groups: Normal control (N), diabetic control (D), low-dose GEN treatment (L) and high-dose GEN treatment (H) groups. Following 8 weeks, the ventricular hemodynamic parameters, fasting blood glucose (FBG), heart-weight to body-weight ratio (HW/BW), myocardial hydroxyproline (Hyp) content, serum creatine kinase MB isozyme (CK-MB), lactate dehydrogenase (LDH), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) levels were measured. The histomorphology and ultrastructure of the heart were observed. The protein expression of myocardial transforming growth factor-β1 (TGF-β1), mothers against decapentaplegic homolog (Smad)-3, phosphorylated (p)-Smad3, Smad4, collagen-I and collagen-III were estimated. Compared with the N group, while the cardiac function was decreased, the levels of FBG, HW/BW, Hyp content, CK-MB, LDH, TNF-α, IL-1β and IL-6 were increased in the D group. The myocardial histomorphological alterations and ultrastructure were damaged, and the protein expression of myocardial TGF-β1, Smad3, p-Smad3, Smad4, collagen-I and collagen-III were increased in the D group. Compared with the D group, there were no differences in the ventricular hemodynamic parameters, FBG and p-Smad3 expression in the L group, while HW/BW, Hyp content, CK-MB, LDH, TNF-α, IL-1β and IL-6 levels were decreased. The myocardial histomorphological damage was alleviated and the protein expression of TGF-β1, Smad3, Smad4, collagen-I and collagen-III was decreased in the L group. Compared with L group, excluding FBG, the aforementioned indices were improved in the H group. In conclusion, GEN can attenuate myocardial fibrosis in type 1 diabetic rats, and the underlying mechanisms may be associated with the reduction of CK-MB and LDH leakage, inhibition of the inflammatory reaction, and suppression of the TGF-β1/Smad3 signaling pathway to regulate collagen expression.

Ginsenoside Rh2 Improves Cardiac Fibrosis via PPARδ-STAT3 Signaling in Type 1-Like Diabetic Rats.

Ginsenoside Rh2 (Rh2) is an active principal ingredient contained in ginseng (Panax ginseng Meyer), a medicinal herb used to enhance health worldwide. The present study is designed to investigate the effect of Rh2 on myocardial fibrosis in diabetic rats. In a streptozotocin-induced model of type-1 diabetic rats (STZ-diabetic rats), the increased fasting blood glucose levels and heart weight/body weight (HW/BW) ratio were substantially alleviated by Rh2. Moreover, Rh2 improved cardiac performance in STZ-diabetic rats. Histological results from Masson staining showed that Rh2 attenuated cardiac fibrosis in STZ-diabetic rats. The effects of Rh2 were reversed by GSK0660 at a dose sufficient to inhibit peroxisome proliferator-activated receptor δ (PPARδ) in STZ-diabetic rats. The role of PPARδ was subsequently investigated in vitro. Rh2 restored the decreased PPARδ expression level in high glucose-cultured cardiomyocytes. Moreover, increased protein levels of fibrotic signals, including signal transducer and activator of transcription 3 (STAT3), connective tissue growth factor (CCN2) and fibronectin, were reduced by Rh2 in high glucose-cultured cardiomyocytes. These effects of Rh2 were reversed by GSK0660 or siRNA specific for PPARδ Taken together, PPARδ activation may inhibit STAT3 activation to reduce CCN2 and fibronectin expression in diabetic rats with cardiac fibrosis. Moreover, Rh2 improves cardiac function and fibrosis by increasing PPARδ signaling. Therefore, Rh2 is suitable to develop as an alternative remedy for cardiac fibrosis.

Cryptotanshinone Inhibits STAT3 Signaling to Alleviate Cardiac Fibrosis in Type 1-like Diabetic Rats.

Cryptotanshinone is an active principal ingredient isolated from Salvia miltiorrhiza (Danshen), a medicinal plant used in China to treat cardiac disorders. The objective of this study was to investigate the effect of cryptotanshinone on myocardial fibrosis in diabetic rats. In streptozotocin-induced type 1 diabetic model hyperglycemic rats (STZ-treated rats), fasting blood glucose levels and heart weight/body weight ratio were markedly increased but both were not modified by cryptotanshinone. Additionally, cardiac performance in catheterized STZ-treated rats was improved. The histological results from Masson staining showed that cryptotanshinone attenuated cardiac fibrosis in STZ-treated rats. Moreover, both the mRNA and protein levels of the signal transducer and activator of transcription 3 (STAT3), matrix metalloproteinase-9, and connective tissue growth factor were reduced by cryptotanshinone in high glucose-cultured cardiomyocytes, similar to the reductions observed in the hearts of STZ-treated rats. In conclusion, while STAT3 regulates matrix metalloproteinase-9 and connective tissue growth factor expression in diabetic rats with cardiac fibrosis, cryptotanshinone inhibited fibrosis to improve cardiac function by suppressing the STAT3 pathway. Cryptotanshinone is suitable as an alternative remedy for therapy of cardiac fibrosis. Copyright © 2017 John Wiley & Sons, Ltd.

The mechanism of irbesartan against diabetes induced myocardial fibrosis in rat model

To observe the protective effect of irbesartan on myocardial fibrosis in diabetic rats, and analyze the role of extracellular signal-regulated kinase (ERK) pathway in this protection. Thirty two male SD rats were randomly divided into two groups:normal control group (CON, n=10), experimental group (n=22). Twenty diabetic rats which had modelled successfully were randomly divided into two groups:diabetic group (DM, n=10), irbesartan + DM group (Ir+DM, n=10). After 8 weeks, fasting blood glucose (FBG) level, body weight (BW), the ratio of heart weight/body weight (H/B) and left ventricular weight index (LVWI) were measured. The myocardial morphological and fibrotic changes were observed by Masson staining. Col I and col Ⅲ contents were evaluated using ELISA method, and the protein expressions of ERK1/2, p-ERK1/2 in heart tissue were tested by Western blot. Compared with CON group, in diabetic rats, the levels of FBG, H/B and LVWI were increased while BW was decreased. The contents of col I and col Ⅲ were increased as well as the protein expression of p-ERK1/2 and the ratio of p-ERK1/2/ERK1/2(P<0.05,P<0.01), which had the statistic differences, while ERK1/2 protein expression was not changed. Masson staining showed myocardial collagen was increased, arranged in disorder and uneven distribution. However, in Ir+ DM group, BW was increased obviously, H/B, LVWI, the contents of col I and col Ⅲ were decreased significantly (P<0.05,P<0.01), p-ERK1/2 protein expression and the ratio of p-ERK1/2/ERK1/2 were decreased (P<0.01), which had the statistic differences. Meanwhile myocardial morphology was improved significantly. Diabetes can induce the happening of myocardial fibrosis, and irbesartan can induce the damage of myocardial fibrosis through inhibitting the activation of ERK.

Effects of Tongxinluo on myocardial fibrosis in diabetic rats

BackgroundThe aim of this study was to explore the effect of Tongxinluo on myocardial fibrosis in diabetic rats and its possible mechanism of action. MethodsDiabetic rat models were established and then divided into three groups: control, diabetes, and Tongxinluo groups. Heart function and myocardial interstitial collagen volume fraction were investigated, and the protein and mRNA expression levels of transforming growth factor beta 1 (TGF-β1), Smad3, and Smad7 were measured. ResultsHeart function was clearly abnormal in the diabetes group compared with that in the control group, and the collagen volume fraction and mRNA expression levels of TGF-β1 and Smad3 were higher. However, the protein and mRNA expression levels of Smad7 were lower. In the Tongxinluo group, it was observed that these indicators were improved. ConclusionTongxinluo was effective for the prevention and treatment of myocardial fibrosis in diabetic rats. It probably mediates the expressions of TGF-β1, Smad3, and Smad7 in rat cardiomyocytes to reduce the occurrence of myocardial fibrosis in diabetic rats.

The Protective Effect of Low-Dose Ethanol on Myocardial Fibrosis through Downregulating the JNK Signaling Pathway in Diabetic Rats.

Objective. To investigate the effects of low dose ethanol feeding in diabetic rats and analyze its underlying mechanisms. Methods. Male Sprague-Dawley rats were divided into 4 groups: control (Con), diabetes at 4 weeks (DM4W), diabetes at 8 weeks (DM8W), and EtOH + DM8W. After 8 weeks, hemodynamic parameters were recorded and heart weight/body weight (H/B) and hydroxyproline (Hp) content in myocardium were measured. Morphology of collagen in myocardial tissue was observed with Masson's trichrome staining method and collagen volume fraction (CVF) was analysed. The mRNA expression of ALDH2 was assessed with Real-Time PCR. The protein expressions of p-JNK and JNK were evaluated using western blot. Results. In contrast to Con group, there was no difference in hemodynamic parameters in DM4W group, but mean arterial pressure and heart rate were decreased in DM8W group, and the ratios of H/B, Hp, and CVF were markedly increased. ALDH2 mRNA expression was decreased, while the ratio of p-JNK/JNK were increased. Compared with DM8W group, the above indexes were improved in EtOH + DM8W group. Conclusion. With low dose ethanol intervention, enhanced ALDH2 expression can antagonize the happening of myocardial fibrosis in diabetic rats, which may be relevant with downregulating the JNK pathway.

Effects of hydrogen sulfide on myocardial fibrosis in diabetic rats: Changes in matrix metalloproteinases parameters.

In order to explore the effects of hydrogen sulfide (H2S) on myocardial fibrosis in diabetic rats and its underlying mechanisms, intraperitoneal injections of streptozotocin were used to establish the diabetes models and sodium hydrosulfide (NaHS) was used as an exogenous donor of H2S. Eight weeks later, Van Gieson staining was used to observe pathological changes, and basic hydrolysis methods were adopted to measure hydroxyproline content, while Western Blot was used to determine the expression of MMP2, MMP7, MMP11, MMP13, MMP16, TIMP1 and TGFβ1.The results showed that significant myocardial fibrosis, decreased TIMP1 and MMP2 expression and increased MMP7, MMP11, MMP13, MMP16 expressions occurred in diabetic group, but all these changes were significantly reversed in diabetic rats after NaHS treatment. This suggests that H2S could attenuate cardiac fibrosis induced by diabetes and its mechanisms may be related to its modulation of MMPs/TIMPs expression and regulation of TGFβ1.

Effect of hydrogen sulfide on myocardial fibrosis and expression of PKCα and HSP70 in diabetic rats

To explore the eff ect of hydrogen sulfide (H2S) on protein kinase C α (PKCα) and heat shock protein 70 (HSP70) expression and myocardial fibrosis in diabetic rats. Rats were randomly divided into 4 groups: the control group, diabetes group (STZ group), the H2S intervention group (STZ+H2S group) and the normal rats plus H2S group (the H2S group). Diabetic rats were induced by intraperitoneal injections of streptozotocin (STZ). The pathological morphological changes in myocardial fiber was analyzed by HE staining. The expression of PKCα, HSP70 and type III collagen were analyzed by Western blot. Compared with the control group, the expressions of PKCα, HSP70 and type III collagen in diabetic rats were significantly increased (P<0.05), accompanied by the disordered arrangement of myocardial cells, which were dramatically reversed by H2S treatment (P<0.05). H2S could reduce myocardial fibrosis in diabetic rats, which is related to the inhibition of PKCα and HSP70 expression.

Sitagliptin alleviated myocardial remodeling of the left ventricle and improved cardiac diastolic dysfunction in diabetic rats

ObjectiveSitagliptin, a dipeptidyl peptidase IV (DPP-Ⅳ) inhibitor, has a biological role in improving the serum levels of glucagon-like peptide 1 (GLP-1). Hence, we sought to determine the effect of sitagliptin on myocardial inflammation, collagen metabolism, lipid content and myocardial apoptosis in diabetic rats. Materials and methodsThe type 2 diabetic rat model was induced by low-dose streptozotocin and a high-fat diet. Characteristics of diabetic rats were evaluated by electrocardiography, echocardiography and blood analysis. Cardiac inflammation, fibrosis, cardiomyocyte density, lipid accumulation, and receptor-interacting protein kinase 3 (RIP3) level, related to apoptosis, were detected by histopathologic analysis, RT-PCR and western blot analysis to evaluate the effects of sitagliptin on myocardial remodeling of the left ventricle. ResultsDiabetic rats showed myocardial hypertrophy or apoptosis, inflammation, lipid accumulation, myocardial fibrosis, elevated collagen content, RIP3 overexpression, and left-ventricular dysfunction. Sitagliptin could reverse the overexpression of RIP3 and alleviate cellular apoptosis in myocardial tissues. It could significantly improve left-ventricular systolic pressure and +dp/dt max, reduce the E/E′ ratio, left ventricular end diastolic pressure, −dp/dt max and Tau in diabetic rats. ConclusionsSitagliptin might have a myocardial protective effect by inhibiting apoptosis, inflammation, lipid accumulation and myocardial fibrosis in diabetic rats, for a potential role in improving left-ventricular function in diabetes.