Fibrosis In Streptozotocin-induced Diabetic Rats Research Articles

Polyphenol-Standardized Aphanamixis polystachya Leaf Extract Ameliorates Diabetes, Oxidative Stress, Inflammation, and Fibrosis in Streptozotocin-Induced Diabetic Rats

Background. Diabetes is a rising disorder that affects millions of people annually. It also creates more complications, such as neuropathy, oxidative stress, and hepatic and kidney impairment. Aphanamixis polystachya plant, which possesses multiple medicinal values, is used in this study to explore its potential in treating diabetes. Methods. A single dose (65 mg/kg) of intraperitoneal streptozotocin injection was utilized to mediate diabetes in Sprague-Dawley rats. Diabetic animals were treated orally with 250 or 500 mg/kg of standardized leaves’ extract of A. polystachya (AP) for 28 days to evaluate the antidiabetic and organ-protective effects of the plant. Different biochemical and histological markers are measured according to the established protocol. Results. Our results demonstrated a significant decrease in blood glucose (p <0.001) and HbA1c (p <0.05) levels in the diabetic animal after administering AP (250 and 500 mg/kg doses) compared to the control groups. AP can also regularize lipids, glycogen, alanine aminotransferase, and aspartate aminotransferase. Furthermore, serum urea nitrogen and creatinine decreased after treatment with AP in diabetic rats. AP also reduced oxidative stress markers and showed a substantial elevation in antioxidant enzymes in diabetic animals. Overall, AP at 500 mg/kg revealed comparable results against the standard antidiabetic drug glyburide. Besides, the histological investigation showed the AP’s efficacy in attenuating kidney tissue inflammation and damage. HPLC data elucidated that the AP leaf extract contains polyphenols with potential antioxidant, antidiabetic, and organ protective agents: gallic acid, rutin hydrate, and quercetin hydrate. Conclusion. Taken together, AP may be one of the potential sources of antidiabetic agents.

Amygdalin alleviates renal injury by suppressing inflammation, oxidative stress and fibrosis in streptozotocin-induced diabetic rats

AimsTo explore the protective efficacies and potent mechanism of amygdalin on high glucose-cultured renal cell HBZY-1 in vitro and streptozotocin (STZ)-induced diabetic nephropathy (DN) rat in vivo. Main methodsThe cellar proliferation and generation of ROS in high-glucose cultured HBZY-1 cell were assessed by MTT and DCFH-DA assay, respectively. The fasting blood glucose levels, renal function and inflammation indexes as well as oxidative stress markers in STZ-induced diabetic rats were all measured. The histologic renal section was stained with Mason and periodic acid-Schiff (PAS) method. Immunohistochemistry and western blotting methods were applied to assess expression levels of extracellular matrix (ECM), epithelial-mesenchymal transition (EMT)-related as well as TGF-β1/Smad signaling pathway-related proteins. Key findingsFirstly, amygdalin significantly suppressed the excessive cell proliferation and ROS generation in HBZY-1 cells cultured with high glucose. The hyperglycemia, 24 h-UP excretion, BUN and Scr of DN rats were significantly attenuated after the chronic treatment of amygdalin. Moreover, MDA, SOD, IFN-γ and IL-12 levels in kidney tissues were all effectively reduced. Besides, amygdalin can suppress the ECM accumulation and EMT transformation by inhibiting Smad/TGF-β pathway to alleviate the renal fibrosis in renal tissues of DN model rats. SignificanceAmygdalin ameliorates excessive oxidative stress, inflammation and renal tissue fibrosis of DN mainly by suppressing TGF-β1/Smad signaling pathway and regulating the key enzymes of ECM degradation.

Retraction Statement.

Retraction Statement.

RETRACTED: Cathelicidin-BF attenuate kidney injury through inhibiting oxidative stress, inflammation and fibrosis in streptozotocin-induced diabetic rats

ObjectiveTo investigate protective efficacies and mechanisms of Cathelicidin-BF (BF-30) peptide on streptozotocin (STZ)-induced diabetic kidney injury. MethodsEffects of BF-30 on hydrogen peroxide induced oxidative damage in HK-2 renal cells were assessed by CCK-8 method. Forty STZ-induced diabetic rats with kidney injury were randomly divided into model control group, BF-30 group at different doses (0.1, 0.3 and 0.9 mg/kg). Blood biochemical and kidney related indexes as well adrenal morphological changes, inflammation related markers of diabetic rats were measured. ResultsCell viability of HK-2 cells with oxidative damage induced by hydrogen peroxide were significantly improved by BF-30 with 0.8 μg/mL for 56.5% and 1.6 μg/mL for 82.3% compared with control. Moreover, the decreased reactive oxygen species (ROS), and increased intracellular antioxidant enzymes GPX1, SOD2 and GSH were showed in BF-30 treated groups. In addition, co-incubation of BF-30 in HK-2 cells promoted the increase of p-AMPK and LC3, decreased activation of p-mTOR, BAX and Caspase 3. Chronic treatment of BF-30 improved the STZ-induced diabetic characteristics of diabetic kidney disease (DKD) model rats. Further renal histopathological examination revealed 12-week treatment of BF-30 effectively improved the morphology of nephropathy in DKD rats. Moreover, BF-30 also could ameliorate excessive oxidative stress, renal cell apoptosis and fibrosis, thereby protects renal tissues. ConclusionBF-30 exerted protective effects on STZ-induced kidney injury mainly through the inhibiting oxidative stress in kidney tissue, reducing renal fibrosis, increasing autophagy, and reducing the renal cell apoptosis related proteins to decrease the cell damage and protect nephrocytes.

Protective effect of exogenous hydrogen sulfide on diaphragm muscle fibrosis in streptozotocin-induced diabetic rats.

Diabetes mellitus is a group of chronic metabolic disorders, which causes serious damage to a variety of organs, such as the retina, heart, and skeletal muscle. The diaphragm is an important skeletal muscle involved in respiration in mammals. Fibrosis of the diaphragm muscle affects its contractility, which in turn impairs respiratory function. Accumulating evidence suggests that exogenous hydrogen sulfide (H2S) exhibits anti-fibrotic activity in diabetes mellitus, but whether and how H2S exerts this anti-fibrotic effect in the diabetic diaphragm remains unclear. The current work for the first time reveals that exogenous H2S attenuates hyperglycemia-induced fibrosis of the diaphragm muscle and strengthens diaphragmatic biomechanical properties in diabetes mellitus, and the mechanism may involve the alleviation of collagen deposition by suppression of the nucleotide-binding oligomerization domain-like receptor protein (NLRP) 3 inflammasome-mediated inflammatory reaction. Therefore, H2S supplementation could be used as an efficient targeted therapy against the NLRP3 inflammasome in the diabetic diaphragm.

Protective Effects of Chromium Picolinate Against Diabetic-Induced Renal Dysfunction and Renal Fibrosis in Streptozotocin-Induced Diabetic Rats.

Diabetic nephropathy (DN) is one of the most important complications of diabetes, and the leading cause of end-stage renal disease (ESRD). While Chromium picolinate (CrPic) supplementation has been found to be effective in treating diabetes, its effects on diabetic-induced nephropathy have not been studied. Therefore, in this study, CrPic (1 mg kg−1 d−1) was administered to a DN rat model by oral gavage for eight weeks to investigate its effects. The results show that CrPic supplementation caused a decrease in levels of blood glucose, serum insulin, blood urea nitrogen (BUN), serum creatinine, and urinary albumin in DN rats. It also reversed renal pathological changes, including renal glomerular sclerosis and interstitial fibrosis. In addition, the oxidative defense system in the kidneys of DN rats was found to be improved; the biological activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) increased; and the content of malondialdehyde (MDA) lowered. Immunohistochemical results reveal that the expression levels of renal transforming growth factor-β1 (TGF-β1), Smad 2, and Smad 3 decreased significantly in the kidneys of rats in the CrPic-treated group. CrPic administration was thus found to ameliorate diabetic nephropathy in SD rats via an antioxidative stress mechanism, as well the ability to inhibit TGF-β1/Smad2/3 expression. This study suggests that CrPic could be a potential renal-protective nutrient against diabetic nephropathy.

Dendropanax morbifera Protects against Renal Fibrosis in Streptozotocin-Induced Diabetic Rats.

The aquatic extract of Dendropanax morbifera (DP) is typically consumed as a beverage in Korea and China and is also used in various traditional medicines. However, the functional role of DP on diabetes-induced renal fibrosis is unclear. Here, the protective effects of DP extract against diabetes-induced renal fibrosis were evaluated. Streptozotocin (STZ, 60 mg/kg) was injected intraperitoneally in rats to induce diabetes. After 5 days, DP extract (25 mg/kg/day) and metformin (50 mg/kg/day) were administered orally to diabetic rats for 28 days. DP administration protected both body and organ weight loss in STZ-treated diabetic rats. Significant improvements in serum blood urea nitrogen (BUN), creatinine, and oxidative stress parameters were observed in diabetic rats by DP administration. DP extract markedly protected diabetic-induced histopathological damages in the kidney and pancreas. A significant reduction was observed in microalbumin, kidney injury molecule-1 (KIM-1), selenium binding protein-1 (SBP1), and pyruvate kinase muscle isozyme M2 (PKM2) levels in the urinary excretion of diabetic rats after the administration of DP extract. The expression of pro-inflammatory cytokines and fibrosis marker levels were significantly reduced in the kidney of diabetic rats. Our results strongly indicate that DP extract exhibits protective activity against diabetes-induced renal fibrosis through ameliorating oxidative stress and inflammation. Therefore, we suggest that DP extract can be used as a preventive agent on the progression of diabetic nephropathy and renal fibrosis.

Protective effect of captopril on cardiac fibrosis in diabetic albino rats: a histological and immunohistochemical study

Background Cardiomyopathy is one of the common complications of diabetes mellitus.Aim The aim of the present study was to investigate the effects of Captopril on myocardial fibrosis in streptozotocin-induced diabetic rats (an animal model of type 1 diabetes mellitus).Materials and methods Forty albino rats were divided into five groups. Group I (control group), group II (untreated diabetic rats), group III (insulin-treated diabetic rats), group IV (Captopril-treated diabetic rats), and group V (insulin and Captopril-treated diabetic rats) were killed at 4 and 8 weeks, and the samples were collected for histological evaluation using hematoxylin and eosin, Masson trichrome, and immunohistochemical staining with anti-P53 for apoptosis, alpha smooth muscle actin (α-SMA) for collagen deposition.Results Treatment of streptozotocin-induced diabetic rats with insulin and Captopril (group V) showed marked decrease in myocardial injury and apoptosis, which was confirmed by marked decrease of sarcoplasmic p53 expression. Group V also showed decreased collagen deposition as confirmed by Masson trichrome staining and α-SMA expression. The results were better after 8 weeks compared with those after 4 weeks.Conclusion The administration of Captopril alone with diabetic rats minimally affected cardiac fibrosis, while the combination of Captopril and insulin markedly improved cardiac fibrosis.

MicroRNA-27a Suppresses Detrusor Fibrosis in Streptozotocin-Induced Diabetic Rats by Targeting PRKAA2 Through the TGF-β1/Smad3 Signaling Pathway

We examined the effects of microRNA-27a (miR-27a) on detrusor fibrosis in streptozotocin (STZ)-induced diabetic rats. Eighty healthy Sprague-Dawley (SD) rats were randomly allocated into control, diabetic, miR-27a mimics, mimics control, miR-27a inhibitors, inhibitors control, siRNA-PRKAA2 (siPRKAA2) and inhibitors + siPRKAA2 groups (the latter 7 groups were established as STZ-induced diabetic rat models and treated in different manners). Detrusor cell apoptosis in bladder tissues was determined through terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) staining. Detrusor cells were assigned to the blank, miR-27a mimics, mimics control, miR-27a inhibitors, inhibitors control, siPRKAA2 and inhibitors + siPRKAA2 groups. Flow cytometry determined the cell cycle stage and apoptosis. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blotting (WB) were used to assess the expression of miR-27a, PRKAA2, TGF-β1, Smad3, p-Smad3, fibronectin (FN), connective tissue growth (CTGF), and collagen-I (COL-I) in tissues and cells. Compared with the control group, the diabetic, miR-27a mimics, and siPRKAA2 groups showed reduced weight and PRKAA2 expression, but elevated blood glucose, serum creatinine (sCr), blood urea nitrogen (BUN), cell apoptosis, and expression of TGF-β1, Smad3, FN, COL-I, CTGF, and p-Smad3. The opposite trend was observed in the miR-27a inhibitors group. PRKAA2 is a target gene of miR-27a. Compared to the blank group, the miR-27a mimics and siPRKAA2 groups indicated markedly increased TGF-β1, Smad3, FN, COL-I, CTGF and p-Smad3 expression; decreased PRKAA2 expression; and increased cell apoptosis. The miR-27a inhibitors group showed the opposite trend. These results indicate that miR-27a may contribute to detrusor fibrosis in STZ-induced diabetic rats by targeting PRKAA2 via the TGF-β1/Smad3 signaling pathway.

Bamboo leaf extract ameliorates cardiac fibrosis possibly via alleviating inflammation, oxidative stress and apoptosis

Previous studies have shown that inflammatory process contributes to the pathogenesis of cardiac damage induced by diabetes mellitus. However, the underlying mechanisms and strategies to alleviate inflammatory injury in the diabetic heart are not fully elucidated. In this study, we investigated the potential role and related mechanism of bamboo leaf extract (BLE) on diabetes-induced cardiac fibrosis in rats. Diabetes was induced by streptozocin (STZ) in rats, blood glucose and glycosylated hemoglobin A1c (HbAlc) were measured. Super oxide dismutase (SOD) activity and malondialdehyde (MDA) level in rat heart homogenates were tested using special kits. Cardiac function was evaluated by echocardiography, and myocardial histology was detected by hematoxylin eosin (HE) staining and Masson’s trichrome staining. Furthermore, expression of transforming growth factor-β1 (TGF-β1), interleukin 6 (IL-6) and Cleaved-cysteinyl aspartate-specific proteinase-3 (Cleaved-caspase-3), and the activity of nuclear factor κB (NF-κB) were examined by western blot analysis. From the data, we found that the BLE treatment inhibits oxidative stress and improved cardiac function in STZ-induced diabetic rats. BLE treatment significantly ameliorated diabetes-induced myocardial morphological changes and cardiac inflammation. Moreover, the protein levels of TGF-β1, IL-6,Cleaved-caspase-3 and the nuclear transcription of NF-κB in the hearts were markedly reduced in diabetic rats result from BLE treatment. In conclusion, this study suggested that BLE ameliorates cardiac fibrosis in streptozotocin-induced diabetic rats, and this protective effect possibly through inhibiting inflammation, oxidative stress and apoptosis. BLE might serve as a potential therapeutic target for the treatment of the cardiac fibrosis in diabetic patients.

Probucol Improves Erectile Function by Restoring Endothelial Function and Preventing Cavernous Fibrosis in Streptozotocin-induced Diabetic Rats

To investigate the effects of probucol on erectile function in streptozotocin-induced diabetic rats and explore the underlying mechanisms. A total of thirty 12-week-old Sprague-Dawley male rats received a 1-time intraperitoneal streptozotocin (60 mg/kg) or vehicle injection after a 12-hour fast. Three days later, the streptozotocin-induced diabetic rats were randomly divided into 2 groups and were treated with daily gavage feedings of probucol at doses of 0 and 500 mg/kg for 12 weeks. A positive control group underwent intraperitoneal injection of saline followed by daily gavage of saline solution. Erectile function was assessed by electrical stimulation of the cavernous nerves with real-time intracavernous pressure measurement. After euthanasia, penile tissue was investigated using immunohistochemistry, Western blot, and ELISA to assess the protein arginine-N-methyltransferase 1/dimethylarginine dimethylaminohydrolase/asymmetric dimethylarginine/nitric oxide synthase metabolism pathway. Superoxide dismutase activity and malondialdehyde levels were detected by colorimetry. We also evaluated penile histological changes such as smooth muscle contents and Masson's trichrome stain. Significant recovery of erectile function was observed in the probucol-treated rats than the untreated diabetic rats. The protein expression of dimethylarginine dimethylaminohydrolase and nitric oxide synthase, cyclic guanosine monophosphate concentrations, and superoxide dismutase activity in cavernous tissue of probucol-treated rats were significantly higher than the untreated diabetic rats. The protein expression of protein arginine-N-methyltransferase 1, asymmetric dimethylarginine concentrations, and malondialdehyde levels in cavernous tissue of probucol-treated rats were significantly lower than the untreated diabetic rats. In addition, probucol treatment markedly augments the cavernous smooth muscle content. Probucol treatment improves erectile function by restoring endothelial function and preventing cavernous fibrosis in streptozotocin-induced diabetic rats.

Klotho gene delivery ameliorates renal hypertrophy and fibrosis in streptozotocin-induced diabetic rats by suppressing the Rho-associated coiled-coil kinase signaling pathway.

The present study aimed to investigate whether klotho gene delivery attenuated renal hypertrophy and fibrosis in streptozotocin-induced diabetic rats. A recombinant adeno-associated virus (rAAV) carrying mouse klotho full-length cDNA (rAAV.mKL), was constructed for in vivo investigation of klotho expression. Diabetes was induced in rats by a single tail vein injection of 60 mg/kg streptozotocin. Subsequently, the diabetic rats received an intravenous injection of rAAV.mKL, rAAV.green fluorescent protein (GFP) or phosphate-buffered saline (PBS). The Sprague-Dawley rat group received PBS and served as the control group. After 12 weeks, all the rats were sacrificed and ELISA, immunohistochemical and histological analyses, fluorescence microscopy, semi-quantitative reverse transcription-polymerase chain reaction and western blottin were performed. A single dose of rAAV.mKL was found to prevent the progression of renal hypertrophy and fibrosis for at least 12 weeks (duration of study). Klotho expression was suppressed in the diabetic rats, but was increased by rAAV.mKL delivery. rAAV.mKL significantly suppressed diabetes-induced renal hypertrophy and histopathological changes, reduced renal collagen fiber generation and decreased kidney hypertrophy index. In addition, rAAV.mKL decreased the protein expression levels of fibronectin and vimentin, while it downregulated the mRNA expression and activity of Rho-associated coiled-coil kinase (ROCK)I in the kidneys of the diabetic rats. These results indicated that klotho gene delivery ameliorated renal hypertrophy and fibrosis in diabetic rats, possibly by suppressing the ROCK signaling pathway. This may offer a novel approach for the long-term control and renoprotection of diabetes.

Tempol ameliorates cardiac fibrosis in streptozotocin-induced diabetic rats: role of oxidative stress in diabetic cardiomyopathy

Long-standing diabetes is associated with increased oxidative stress and cardiac fibrosis. This, in turn, contributes to the progression of cardiomyopathy. The present study was sought to investigate whether the free radical scavenger, 4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl (tempol) can protect against diabetic cardiomyopathy and to explore the specific underlying mechanism(s) in this setting. Diabetes was induced in rats by a single intraperitoneal injection dose of streptozotocin (50 mg/kg). These animals were treated with tempol (18 mg kg(-1) day(-1), orally) for 8 weeks. Our results showed significant increases in collagen IV and fibronectin protein levels and a marked decrease in matrix metalloproteinase-2 (MMP-2) activity measured by gelatin-gel zymography alongside elevated cardiac transforming growth factor (TGF)-β level determined using ELISA or immunohistochemistry in cardiac tissues of diabetic rats compared with control. This was accompanied by an increased in the oxidative stress as evidenced by increased reactive oxygen species (ROS) production and decreased antioxidant enzyme capacity along with elevated lactate dehydrogenase (LDH) and creatine kinase (CK-MB) serum levels as compared with the control. Tempol treatment significantly corrected the changes in the cardiac extracellular matrix, TGF-β, ROS or serum LDH, CK-MB levels, and normalized MMP-2 activity along with preservation of cardiac tissues integrity of diabetic rats against damaging responses. Moreover, tempol normalized the elevated systolic blood pressure and improved some cardiac functions in diabetic rats. Collectively, our data suggest a potential protective role of tempol against diabetes-associated cardiac fibrosis in rats via reducing oxidative stress and extracellular matrix remodeling.

Allicin protects against myocardial apoptosis and fibrosis in streptozotocin-induced diabetic rats

To evaluate the cardioprotective effect of allicin (AL) on myocardial injury of streptozotocin (STZ)-induced diabetic rats and to further explore its underlying mechanisms. Hyperglycemia was induced in rats by single intraperitoneal injection of STZ (40mg/kg). Three days after STZ induction, the hyperglycemic rats (plasma glucose levels ≥16.7mmol/l) were treated with AL by intraperitoneal injection at the doses of 4mg/kg, 8mg/kg, and 16mg/kg daily for 28days. The fasting blood glucose levels were measured on every 7th day during the 28days of treatment. The body weight, blood glucose, and parameter of cardiac function were detected after 4weeks to study the cardioprotective effects of AL on diabetic rats in vivo. The apoptotic index of cardiomyocytes was estimated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The expressions of Fas, Bcl-2, CTGF, and TGF-β1 protein were studied by immunohistochemistry. Laser scanning confocal microscopy technique was utilized to observe the effects of AL on intracellular calcium concentration ([Ca2+]i) in rat ventricular cardiomyocytes. AL at the doses of 4mg/kg, 8mg/kg, and 16mg/kg significantly reduced blood glucose levels in a dose-dependent manner and increased body weight as well compared with the model group. Hemodynamic parameters including left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), and maximum rate of left ventricular pressure rise and fall (+dp/dtmax and −dp/dtmax) were significantly restored back to normal levels in AL-treated (8mg/kg and 16mg/kg) rats compared with diabetic model rats. AL markedly inhibited cardiomyocyte apoptosis induced by diabetic cardiac injury. Further investigation revealed that this inhibitory effect on cell apoptosis was mediated by increasing anti-apoptotic protein Bcl-2 and decreasing pro-apoptotic protein Fas. Additional experiments demonstrated AL abrogated myocardial fibrosis by blocking the expressions of CTGF and TGF-β1 protein. AL shows protective action on myocardial injury in diabetic rats. The possible mechanisms were involved in reducing blood glucose, correcting hemodynamic impairment, reducing Fas expression, activating Bcl-2 expression, decreasing intracellular calcium overload, inhibiting the expressions of TGF-β1 and CTGF, and further improving cardiac function.

Induced Pluripotent Stem (iPS) Cells Inhibit Apoptosis and Fibrosis in Streptozotocin-Induced Diabetic Rats

Recent data suggests that transplanted bone marrow stem cells improve cardiac function in streptozotocin induced diabetic cardiomyopathy (SIDC). However, whether modified embryonic stem (ES) cells, induced pluripotent stem (iPS) cells, or factors released from these cells can inhibit apoptosis and fibrosis remains completely unknown. Therefore, we hypothesized that transplanted ES cells overexpressing pancreatic transcription factor 1 a (Ptf1a), a propancreatic endodermal transcription factor, iPS cells, or their respective conditioned media (CM) will attenuate cardiac remodeling and improve cardiac function in SIDC. Experimental diabetes was induced in male Sprague-Dawley rats (8-10 weeks old) by intraperitoneal injections of streptozotocin (STZ) (65 mg/kg body weight). Animals were divided into different groups including control, STZ, stem cells, and CM. Histology, TUNEL, caspase-3 activity, sarcomeric α-actin, and DHE stainings were performed to assess cardiac apoptosis, fibrosis, and oxidative stress. Animals transplanted with ES cells, iPS cells, or both CM showed a significant (p < 0.05) reduction in apoptosis compared with STZ treated animals. Furthermore, our data also shows that active apoptosis was present in cardiac myocytes as confirmed with combined stainings with TUNEL, sarcomeric α-actin, and active caspase-3 antibodies. Increased oxidative stress as evidenced by DHE staining was significantly (p < 0.05) reduced following stem cell or CM transplantation. Moreover, stem cells or CM also attenuated increased interstitial and vascular fibrosis in SIDC hearts. Echocardiography analysis showed a significant (p < 0.05) improvement in fractional shortening in stem cell and CM transplanted groups compared with respective controls. In conclusion, our data suggest that transplanted stem cells or their CM inhibit apoptosis, reduce fibrosis, and improve cardiac function in STZ-treated diabetic rats.