Metformin ameliorates diabetic nephropathy in a rat model of low-dose streptozotocin-induced diabetes

Mechanism and application of metformin in kidney diseases: An update

Metformin is an oral antihyperglycemic drug widely used to treat type 2 diabetes mellitus (T2DM), acting via indirect activation of 5' Adenosine monophosphate-activated Protein Kinase (AMPK). Beyond the anti-diabetic effect, accumulative pieces of evidence have revealed that metformin also everts a beneficial effect in diverse kidney diseases. In various acute kidney diseases (AKI) animal models, metformin protects renal tubular cells from inflammation, apoptosis, reactive oxygen stress (ROS), endoplasmic reticulum (ER) stress, epithelial-mesenchymal transition (EMT) via AMPK activation. In diabetic kidney disease (DKD), metformin also alleviates podocyte loss, mesangial cells apoptosis, and tubular cells senescence through AMPK-mediated signaling pathways. Besides, metformin inhibits cystic fibrosis transmembrane conductance regulator (CFTR)-mediated fluids secretion and the mammalian target of rapamycin (mTOR)-involved cyst formation negatively regulated by AMPK in autosomal dominant polycystic kidney disease (APDKD). Furthermore, metformin also contributes to the alleviation of urolithiasis and renal cell carcinoma (RCC). As the common pathway for chronic kidney disease (CKD) progressing towards end-stage renal disease (ESRD), renal fibrosis is ameliorated by metformin, to a great extent dependent on AMPK activation. However, clinical data are not always consistent with preclinical data, some clinical investigations showed the unmeaningful even detrimental effect of metformin on T2DM patients with kidney diseases. Most importantly, metformin-associated lactic acidosis (MALA) is a vital issue restricting the application of metformin. Thus, we conclude the application of metformin in kidney diseases and uncover the underlying molecular mechanisms in this review.

Kaempferol attenuates diabetic nephropathy in streptozotocin-induced diabetic rats by a hypoglycaemic effect and concomitant activation of the Nrf-2/Ho-1/antioxidants axis

This study examined the protective effect of Kaempferol against streptozotocin-induced diabetic nephropathy (DN) in rats and studies the underlying mechanisms. Rats were divided into 4 groups as control, control + Kaempferol, STZ, and STZ + Kaempferol. All treatments were conducted for 8 weeks daily after the induction of diabetes. Kaempferol prevented STZ-induced weight and food loss and attenuated renal damage and the alterations in all biochemical related parameters. Concomitantly, Kaempferol reduced renal levels of TNF-α and IL-6, cleaved caspase-3, p38, and Bax, suppressing JNK phosphorylation and NF-κB p65 transactivation, and upregulation of Bcl-2. In both control and STZ-diabetic rats, Kaempferol reduced fasting glucose levels, increased fasting insulin levels and HOMA-β, reduced the levels of ROS and MDA, stimulated SOD and GSH levels, and increased the expression of Nrf2 and HO-1. In conclusion, Kaempferol prevents STZ-induced diabetic nephropathy, mainly, by antioxidant potential, mediated by the upregulation of the Nrf-2/HO-1 axis.

Metformin Attenuates Renal Fibrosis in a Mouse Model of Adenine-Induced Renal Injury Through Inhibiting TGF-β1 Signaling Pathways

It is well-known that all progressive chronic kidney disease (CKD) is pathologically characterized by tubulointerstitial fibrosis process. Multiple studies have shown the critical role of inflammation and fibrosis in the development of CKD. Hence strategies that target inflammatory and fibrotic signaling pathways may provide promising opportunities to protect against renal fibrosis. Metformin has been used as the first-line glucose-lowering agent to treat patients with type 2 diabetes mellitus (T2DM) for over 50 years. Accumulating evidence suggests the potential for additional therapeutic applications of metformin, including mitigation of renal fibrosis. In this study, the anti-fibrotic effects of metformin independent of its glucose-lowering mechanism were examined in an adenine -induced mouse model of CKD. Expressions of inflammatory markers MCP-1, F4/80 and ICAM, fibrotic markers type IV collagen and fibronectin, and the cytokine TGF-β1 were increased in adenine-induced CKD when compared to control groups and significantly attenuated by metformin treatment. Moreover, treatment with metformin inhibited the phosphorylation of Smad3, ERK1/2, and P38 and was associated with activation of the AMP-activated protein kinase (AMPK) in the kidneys of adenine-treated mice. These results indicate that metformin attenuates adenine-induced renal fibrosis through inhibition of TGF-β1 signaling pathways and activation of AMPK, independent of its glucose-lowering action.

The impact of ellagic acid on some apoptotic gene expressions: a new perspective for the regulation of pancreatic Nrf-2/NF-κB and Akt/VEGF signaling in CCl4-induced pancreas damage in rats

OBJECTIVE

The aim of this study was to evaluate the potential effect of ellagic acid (EA) in the treatment of pancreatic injury. EA has been found to have strong anti-inflammatory, antioxidative, and anticancer properties. The effects of EA on pancreati˜c star cell (PSC) activation and cell functions have been evaluated and it has been shown that it inhibits the activation of basic cell functions and PSCs and^. it has antidiabetic activity through its effect on β-pancreas cells.

MATERIALS AND METHODS

In this work, 36 Wistar albino rats (n = 36, 8 weeks old) were used. Rats were divided to 4 groups and 9 rats were each group. Groups: Group 1: control group; Group 2: EA group; Group 3: carbon tetrachloride (CCl₄) group; Group 4: EA + CCl₄ group. Animals were decapitated after 8 weeks and their pancreas tissue samples were taken and researched. In pancreas tissue, NF-κB, TNF-α, Nrf-2, VEGF, Bcl-2, caspase-3, and Akt proteins expression ratios were analyzed by western blotting method, CAT activity and GSH levels were determined by spectrophotometer and ROS production was detected by MDA.

RESULTS

In our results, the Nrf-2 and caspase-3 protein expressions, catalase activities and GSH levels increased, TNF-α, NF-κB, Bcl-2, VEGF, and Akt protein expressions and MDA levels reduced in EA + CCl₄ group comparable to the CCl₄ group.

CONCLUSIONS

These findings reveal that EA decreases pancreas tissue injury in rats and that EA may also be used as a drug against pancreas tissue injury in the future.

A Review on Cellular and Molecular Mechanisms Linked to the Development of Diabetes Complications

Modern lifestyle, changing eating habits and reduced physical work have been known to culminate into making diabetes a global pandemic. Hyperglycemia during the course of diabetes is an important causative factor for the development of both microvascular (retinopathy, nephropathy and neuropathy) and macrovascular (coronary artery disease, stroke and peripheral artery disease) complications. In this article, we summarize several mechanisms accountable for the development of both microvascular and macrovascular complications of diabetes. Several metabolic and cellular events are linked to the augmentation of oxidative stress like the activation of advanced glycation end products (AGE) pathway, polyol pathway, Protein Kinase C (PKC) pathway, Poly-ADP Ribose Polymerase (PARP) and hexosamine pathway. Oxidative stress also leads to the production of reactive oxygen species (ROS) like hydroxyl radical, superoxide anion and peroxides. Enhanced levels of ROS rescind the anti-oxidant defence mechanisms associated with superoxide dismutase, glutathione and ascorbic acid. Moreover, ROS triggers oxidative damages at the level of DNA, protein and lipids, which eventually cause cell necrosis or apoptosis. These physiological insults may be related to the microvascular complications of diabetes by negatively impacting the eyes, kidneys and the brain. While underlying pathomechanism of the macrovascular complications is quite complex, hyperglycemia associated atherosclerotic abnormalities like changes in the coagulation system, thrombin formation, fibrinolysis, platelet and endothelial function and vascular smooth muscle are well proven. Since hyperglycemia also modulates the vascular inflammation, cytokines, macrophage activation and gene expression of growth factors, elevated blood glucose level may play a central role in the development of macrovascular complications of diabetes. Taken collectively, chronic hyperglycemia and increased production of ROS are the miscreants for the development of microvascular and macrovascular complications of diabetes.

The effect of Nigella sativa oil and metformin on male seminal parameters and testosterone in Wistar rats exposed to an obesogenic diet

Obesity is a significant global health and socio-economic challenge, and considered an important risk factor for poor health outcomes including male reproductive dysfunction and infertility. As excess adiposity causes testicular dysfunction and infertility, novel therapeutic strategies require investigation. Nigella sativa (Ns) seed oil and metformin have both demonstrated a potential positive effect on obesity, although both remain poorly investigated in male fertility. Therefore, this study aimed to determine the effect of Ns oil and metformin on total body weight (TBW), mitochondrial membrane potential (MMP), serum testosterone and semen parameters in an obese animal model. Wistar rats (n = 54) were divided into six groups: normal chow (NC), high sugar diet (HSD) only, HSD and saline, HSD and metformin (75 mg/Kg/day), HSD and Ns (200 mg/Kg/day) (NS200), HSD and Ns (400 mg/Kg/day) (NS400). Intervention was force fed for the last 8 weeks of the 14 weeks dietary exposures. Results showed that the HSD increased TBW (P = 0.001) and reduced sperm concentration (P = 0.013) and progressive motility (P = 0.009) compared to the NC group. Metformin, NS200 and NS400 improved TBW (P = 0.035, P = 0.006 and P = 0.005, respectively) and testosterone (P < 0.001) compared to the HSD saline group, where metformin and NS400 improved sperm concentration (P < 0.001 and P = 0.049, respectively) and MMP (P < 0.001). There were no changes in sperm motility and viability for all experimental exposures, although NS400 (P = 0.047) negatively affected sperm viability. Metformin and Ns may be novel treatment options in obesity-induced infertility, although a potential negative impact on viability is cautioned for high dose Ns. These results warrant further investigation of Ns and Metformin for the management of obese infertile males.

Metformin Protects against Podocyte Injury in Diabetic Kidney Disease

Metformin is the most commonly prescribed drug for treating type 2 diabetes mellitus (T2D). Its mechanisms of action have been under extensive investigation, revealing that it has multiple cellular targets, either direct or indirect ones, via which it regulates numerous cellular pathways. Diabetic kidney disease (DKD), the serious complication of T2D, develops in up to 50% of the individuals with T2D. Various mechanisms contribute to the development of DKD, including hyperglycaemia, dyslipidemia, oxidative stress, chronic low-grade inflammation, altered autophagic activity and insulin resistance, among others. Metformin has been shown to affect these pathways, and thus, it could slow down or prevent the progression of DKD. Despite several animal studies demonstrating the renoprotective effects of metformin, there is no concrete evidence in clinical settings. This review summarizes the renoprotective effects of metformin in experimental settings. Special emphasis is on the effects of metformin on podocytes, the glomerular epithelial cells that are central in maintaining the glomerular ultrafiltration function.

Effects of HuoxueJiangtang decoction alone or in combination with metformin on renal function and renal cortical mRNA expression in diabetic nephropathy rats

CONTEXT

HuoxueJiangtang decoction (ZY) is a traditional Chinese medicine for the treatment of diabetes.

OBJECTIVE

The protective effect of ZY on renal injury in diabetic nephropathy rats was investigated in this study.

MATERIALS AND METHODS

Fifty 4-week-old SPF Wistar male rats were selected to construct diabetic nephropathy model rats (DN) group by continuous high-fat feeding for 4 weeks, followed by a tail vein injection of 30 mg/kg streptozotocin for 1 week. The experimental rats were divided into six groups of 10 rats: normal (control), DN, DN + ZY, DN + metformin, DN + metformin + ZY, and DN + metformin + captopril (positive control) groups. Among the groups, 6.25 g/kg ZY, 250 mg/kg metformin, and 17.5 mg/kg captopril were given to the rats by gavage once a day for 16 weeks. Blood glucose, dietary behaviour, biochemical indicators, and gene expression changes were measured in each group.

RESULTS

Metformin + ZY treatment significantly lowered blood glucose, water intake, urine total protein, urine albumin, urine volume, serum triglyceride, and serum cholesterol levels in the DN group. The pathological changes of kidney tissue showed that the DN + metformin + ZY group had a protective effect on kidney tissue damage. And ZY and metformin + ZY treatments repaired the expression of genes in the DN group.

DISCUSSION AND CONCLUSION

The ZY and metformin combined treatment showed a clear therapeutic effect on kidney damage in DN. This study provides a potential mechanism for the treatment of diabetic nephropathy with ZY combined with metformin.

Protective effects of Artemisia judaica extract compared to metformin against hepatorenal injury in high-fat diet/streptozotocine-induced diabetic rats

Diabetes mellitus (DM) is one of the most dangerous incurable diseases that affects a large number of people worldwide. Artemisia species have various protective activities and are widely used for the control of diabetes in folkloric medicine. Therefore, the current study was designed to illustrate the protective effect of oral administration of Artemisia judaica extract (AjE) against hepatorenal damage in a high-fat diet/streptozotocin (HFD/STZ) rat model of hyperlipidemia and hyperglycemia. Animals were divided into five groups-control, AjE, HFD/STZ, HFD/STZ-AjE (300 mg/kg), and HFD/STZ-MET (100 mg/kg)-and treated daily for 28 days. The results revealed that STZ-injected rats showed marked hyperglycemia and hypoinsulinemia in addition to high levels of cholesterol, triglycerides, and low- and high-density lipoproteins compared to control rats. Significant elevations in hepatic (AST and ALT) and renal (urea, uric acid, and creatinine) function markers were observed in the serum of diabetic rats. Additionally, STZ injection caused remarkable elevations in lipid peroxidation and nitric oxide levels as well as suppression of antioxidant markers (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione). Marked elevations in TNF-α and Bax levels with a decline in Bcl-2 levels were detected after STZ injection. Furthermore, TGF-β1 expression levels were significantly upregulated in the liver and kidney tissues. Rats that received AjE or MET showed significant improvement in most of the aforementioned parameters, and the protective efficacy was higher for AjE than for MET. Histopathological screening confirmed the biochemical findings. Conclusively, our results illustrated the antihyperglycemic, antihyperlipidemic, antioxidant, anti-inflammatory, and antiapoptotic activities of AjE against hepatorenal injury in HFD/STZ-induced diabetes.

Comparing prophylactic effect of exercise and metformin on cognitive brain functions in rats with type 3 diabetes mellitus

Introduction

Type 2 diabetes mellitus (DM) and Alzheimer's disease (AD) are two major medical conditions that constitute a significant financial burden on most healthcare systems. Due to AD sharing "insulin resistance" mechanistic features with DM, some scientists have proposed "type 3 DM" terminology for it. This study aims to compare the prophylactic effect of exercise and metformin on cognitive brain functions in rats with type 3 DM.

Material and methods

Two groups of rats were included in the study: the control group (n = 15) and the streptozotocin-induced type 2 diabetic group (n = 45). The diabetic group was subdivided into three equal subgroups: a sedentary non-treated diabetic group, an exercised group, and a metformin-treated group. We estimated step-down avoidance task latency, serum glucose, insulin, free fatty acids (FFA), cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides (TG), brain Aβ-42 and glucose, histological changes by toluidine blue, and immunohistochemistry for brain Aβ-42 and tau-positive cells.

Results

Serum glucose, FFA, TG, cholesterol, LDL, brain Aβ-42, brain glucose, the number of hippocampal dark and degenerated cells, and brain Aβ-42 and tau-positive cells, were all significantly lower. In contrast, serum insulin and HDL, the number of hippocampal granular cells, and latency of the step-down avoidance task were significantly higher in exercised and metformin-treated groups compared to the diabetic group. There were significantly higher values of serum insulin and brain/plasma glucose ratio and number of brain tau-positive cells in the metformin-treated group than in the exercised group.

Conclusions

We can conclude that exercise can be as effective as metformin regarding prophylaxis against the deleterious effects of type 3 DM on cognitive brain functions.

Oral Spirulina Platensis Attenuates Hyperglycemia and Exhibits Antinociceptive Effect in Streptozotocin-Induced Diabetic Neuropathy Rat Model

Introduction

Diabetic neuropathy is a common consequence of diabetes. Hyperalgesia is one of the main symptoms of diabetic neuropathy. In response to noxious stimuli, streptozotocin (STZ)-induced diabetic rats show exaggerated hyperalgesic behavior, while Spirulina platensis has anti-inflammatory, antioxidant, and insulin-like effects. To assess the antinociceptive effect of oral Spirulina platensis (SP) powder on formalin-induced nociceptive responses in STZ-induced diabetic rats.

Methods

Sixty mature male albino rats were randomly allocated into six equal groups (10 in each group). Group 1 (control non-diabetic group) received 0.9% saline; group 2 was given oral pure SP powder-treated as a non-diabetic control group, group 3 was sodium salicylate-treated rats and used as a positive non-diabetic control group, group 4 managed as vehicle-treated diabetic rats, group 5 considered as SP-treated-diabetic group, and sodium salicylate-treated-diabetic rats used as a diabetic positive control group (group 6). STZ-diabetic rats were orally given SP in a dose of 500 mg kg/day for 1 month. The formalin test was implemented in two phases: the early phase in the first 10-min post-formalin injection, and the late phase was considered in the 15–60 min post-formalin injection time interval.

Results

Pain scores were increased in the diabetic groups during both phases of the experiment. Blood glucose was significantly reduced in diabetic rats that received oral SP, P < 0.01. Besides, SP-treated rats had lower pain scores during both phases of the experiment than untreated diabetic ones. However, in the sodium salicylate group, the pain score was reduced only during the second phase. An exaggerated nociceptive response occurred in diabetic rats after the formalin test. A significant antinociceptive effect appeared in SP-treated control and diabetic rats.

Discussion

The findings suggest that oral Spirulina platensis could have a potential therapeutic role for managing induced painful diabetic neuropathy in rats.

Modulation of reproductive dysfunctions associated with streptozocin-induced diabetes by Artemisia judaica extract in rats fed a high-fat diet

We investigated the palliative effect of Artemisia judaica extract (AjE) on testicular deterioration induced by DM in high-fat diet/streptozocin (HFD/STZ)-injected rats. Forty rats were allocated to the following five groups: control, AjE, HFD/STZ, HFD/STZ-AjE, and HFD/STZ-metformin. HFD/STZ-diabetic rats showed a marked decrease in testicular weight and male sex hormones. There was significant suppression of testicular antioxidant enzymes and glutathione content in HFD/STZ-diabetic rats. However, rats that had received the STZ injection and the high-fat diet displayed increased malondialdehyde content and nitric oxide levels as well as tumour necrosis factor-alpha. High levels of Bax and low levels of Bcl-2 were detected after the STZ injection. Obvious pathological alterations were found in the testicular tissue of the HFD/STZ-diabetic rats. Thus, the administration of AjE attenuated the biochemical, molecular, and histopathological changes in the testes of the diabetic rats. The obtained findings showed that AjE treatment attenuated the diabetes-induced reprotoxicity in male rats via its antioxidant, anti-inflammatory, and antiapoptotic properties.

The role of Artemisia turanica extract on renal oxidative and biochemical markers in STZ-induced diabetes in rat

OBJECTIVE

The aim of the current study was to investigate the protective effect of Artemisia turanica (AT) against diabetes- induced renal oxidative stress in rats.

MATERIALS AND METHODS

Fifty male Wistar rats were randomly divided into five groups: control, STZ-induced diabetic rats, diabetic rats+ metformin, diabetic rats + AT extract, diabetic rats+ metformin+ AT extract. In the present study, diabetes was induced by a single-dose (55 mg/kg, ip) injection of streptozotocin (STZ). Diabetic rats were daily treated with metformin (300 mg/kg), AT extract (70 mg/kg) and metformin+ AT extract for 4 consecutive weeks. Tissue activities of superoxide dismutase (SOD) and catalase and the levels of malondialdehyde (MDA) and total thiol content were measured in kidney tissue. Serum concentrations of glucose, creatinine, and urea, as well as, lipid profile were also measured.

RESULTS

STZ significantly increased the levels of glucose, triglyceride, urea and MDA compared to the control group. Total thiol content, as well as, catalase and SOD activities showed significant decreases in diabetic group when compared with the control animals. Serum glucose, triglyceride, cholesterol and renal MDA showed a significant decrease and renal total thiol and the activities of antioxidant enzymes showed significant increases in AT+STZ group compared with the diabetic group. In diabetic rats received AT+ metformin, serum LDL and HDL, renal MDA and SOD and catalase activities significantly improved compared with the diabetic rats.

CONCLUSION

These findings suggested that AT extract has therapeutic effects on renal oxidative damage and lipid profile in diabetes, that possibly may be due to its antioxidant and hypolipidemic effects.

Selenium cleome droserifolia nanoparticles (Se-CNPs) and it's ameliorative effects in experimentally induced diabetes mellitus

Diabetes mellitus is a group of metabolic disorders with great challenge in its treatment due to its pathological complication. In recent decade, there is extensive use of applying nanotechnology to medicinal plants as a trend in diabetes treatment due to phytochemical constituents. The present study aimed to evaluate the hypoglycemic effect of selenium cleome droserifolia nanoparticles (Se-CNPs) and/or Galvus met® treatment on streptozotocin induced diabetes mellitus in male rats. Fifty male Wistar rats were divided equally into five groups: control group, control diabetic group, diabetic group treated with Se-CNPs, diabetic group treated with Galvus met® and diabetic group treated with Se-CNPs plus Galvus met®. Glucose and insulin levels, Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST), Total Cholesterol (TC), Triacylglycerols (TG), High Density Lipoprotein (HDL-c), Very Low Density Lipoprotein cholesterol (VLDL-c), Low Density Lipoprotein cholesterol (LDL-c) and (NEFAs), urea and creatinine were evaluated. Also, histopathological changes in pancreatic tissue were examined. The results showed significant elevation in serum glucose concentration, ALT and AST activities, TG, LDL-c, VLDL-c and Non Esterified Fatty Acids (NEFAs), urea and creatinine levels while a significant decrease in serum insulin and HDL-c concentration in untreated diabetic rats when compared with control. Meanwhile, daily administration of Se-CNPs and/or Galvus met® to diabetic rats showed significant amelioration of these parameters.

Geniposide alleviates diabetic nephropathy of mice through AMPK/SIRT1/NF-κB pathway

Geniposide (GE) can effectively inhibit diabetic nephropathy (DN), but its mechanism is unclear. The objective of this study was to explore the antidiabetic nephropathy effects of GE both in high fat diet/streptozotocin-induced DN mice and in high glucose-induced podocyte model. Renal function in DN mice was evaluated by levels of serum creatinine (Scr) and blood urea nitrogen (BUN). Renal inflammation was appraised by pro-inflammatory cytokines: Tumor necrosis factor α (TNF-α), Interleukin 6 (IL-6) and IL-1β via ELISA assay. Renal histopathology analysis was conducted via hematoxylin and eosin, Masson and periodic acid-silver metheramine staining. Cellular viability was measured by Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay. Moreover, the related proteins p-NF-κB, ASC, Cleave-IL-1β, NLRP3, Cleave-Caspase-1 and GSDMD-N in AMPK/SIRT1/NF-κB pathway were assayed by Western blotting. In order to further investigate the effects of GE on podocytes, we also assessed these protein levels in AMPK/SIRT1/NF-κB pathway after siRNA-AMPK intervention by Western blotting. GE alleviated renal dysfunction as evidenced by decreased levels of Scr, BUN, TNF-α, IL-6 and IL-1β. Histological examination revealed GE effectively attenuated kidney damage, including glomerular basement membrane thickening and inflammatory cells infiltration. AMPK, p-AMPK and SIRT1 levels were obviously decreased both in DN mice and in podocyte model, but GE reversed these changes. The protein expressions in APMK/SIRT1/NF-κB pathway were significantly decreased by GE treatment. These results suggested that GE could efficiently block oxidative stress and inflammatory responses accompanied with pyroptosis, thus inhibiting the development of DN, and its mechanism might be related to APMK/SIRT1/NF-κB pathway.

Tetrandrine mediates renal function and redox homeostasis in a streptozotocin-induced diabetic nephropathy rat model through Nrf2/HO-1 reactivation

Background

Diabetic nephropathy (DN) is the leading cause of morbidity and mortality in diabetic patients. Tetrandrine (Tet), a bisbenzylisoquinoline alkaloid isolated from the roots of Stephania tetrandra, possesses anti-oxidative, anti-hypertensive, anti-inflammatory capacities. In this study, the maintenance role of Tet in DN was evaluated in streptozotocin (STZ)-induced diabetic rats.

Methods

In vitro study, rats were divided into five groups (n=10): the control group, the DN model group, the Tet-treatment group (5, 15, 30 mg/kg). DN damage was assessed by levels of blood glucose, serum creatinine (CRE), proteinuria, and urea nitrogen. ELISA assay was used to detecte tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6) and IL-10 levels. Kits were used to detecte contents of malondialdehyde (MDA), lactate dehydrogenase (LDH) and superoxide dismutase (SOD). Dichlorofluorescein (DCF) staining was used to detecte reactive oxygen species (ROS). HE staining assessed pathological damage. TUNEL staining assessed tissue apoptosis. Western Blot (WB) was used to detecte levels of Ki67, Survivin, Bax, Bcl-2, caspase-3, -9, c-Myc, nuclear factor erythroid-derived 2-related factor 2 (Nrf2), p-Nrf2, and heme oxygenase-1 (HO-1).

Results

Compared with the control group, STZ-induced significantly inhibited proliferation proteins’ level, activated oxidative stress, aggravated tissue inflammation and promoted tissue apoptosis. STZ-induced further aggravated DN damage. Of note, these anomalies were restored by Tet pretreatment. Additionally, Tet upgraded the expression of p-Nrf2 and HO-1.

Conclusions

These results indicated that Tet could significantly restrain diabetic process and renal damage. Tet is a potential therapeutic agent in DN treatment via the reactivation of the Nrf2/HO-1.

Accelerated Kidney Aging in Diabetes Mellitus

With aging, the kidney undergoes inexorable and progressive changes in structural and functional performance. These aging-related alterations are more obvious and serious in diabetes mellitus (DM). Renal accelerated aging under DM conditions is associated with multiple stresses such as accumulation of advanced glycation end products (AGEs), hypertension, oxidative stress, and inflammation. The main hallmarks of cellular senescence in diabetic kidneys include cyclin-dependent kinase inhibitors, telomere shortening, and diabetic nephropathy-associated secretory phenotype. Lysosome-dependent autophagy and antiaging proteins Klotho and Sirt1 play a fundamental role in the accelerated aging of kidneys in DM, among which the autophagy-lysosome system is the convergent mechanism of the multiple antiaging pathways involved in renal aging under DM conditions. Metformin and the inhibitor of sodium-glucose cotransporter 2 are recommended due to their antiaging effects independent of antihyperglycemia, besides angiotensin-converting enzyme inhibitors/angiotensin receptor blockers. Additionally, diet intervention including low protein and low AGEs with antioxidants are suggested for patients with diabetic nephropathy (DN). However, their long-term benefits still need further study. Exploring the interactive relationships among antiaging protein Klotho, Sirt1, and autophagy-lysosome system may provide insight into better satisfying the urgent medical needs of elderly patients with aging-related DN.

Evaluation of the neuro-protective effect of Artemisia judaica extract in a murine diabetic model

Chronic hyperglycemia is associated with several negative outcomes including neuronal injury. Medicinal plants supplementation has been widely applied to treat or decrease diabetic complications. Here, the possible neuroprotective effect of Artemisia judaica extract (AjE. 300 mg kg^-1  day^-1 ) against neuronal deficits in diabetes model induced by high-fat diet (HFD) administration and streptozotocin (STZ, 30 mg/Kg) injection in rats was investigated. Diabetic rats showed a disturbance in the neuronal redox homeostasis as confirmed by the elevated lipoperoxidation and nitric oxide formation along with the decreased antioxidant molecules. In addition, a state of neuroinflammation and apoptosis were recorded in the brain tissue in diabetic rats. Furthermore, HFD/STZ provoked neurochemical alterations. However, AjE administration was found to abrogate significantly the neuronal impairments associated with diabetes. This neuroprotective effect comes from its strong antioxidant, anti-inflammatory, antiapoptotic, and neuromodulatory activity; suggesting that AjE may be applied to alleviate neurological impairments in diabetic patients. PRACTICAL APPLICATIONS: Diabetes mellitus (DM) is a metabolic disorder characterized by high blood glucose level comes from the dysregulation of insulin production and/or its action. The persisted hyperglycemia is correlated with the progression of several physical complications including renal, hepatic, vascular, retinal, and neuronal dysfunction. Artemisia is used in the nutritional and medicinal proposes due to the enriched bioactive molecules such as essential oil, flavonoids, phenolics, sesquiterpenoids, triterpenoids, and artemisinin. And we found that Artemisia judaica extract (AjE) administration was able to abrogate significantly the neuronal impairments associated with diabetes. This neuroprotective effect comes from its strong antioxidant, anti-inflammatory, anti-apoptotic and neuromodulatory activity; suggesting that AjE may be applied to alleviate neurological impairments in diabetic patients.

The physiological and molecular mechanisms to maintain water and salt homeostasis in response to high salt intake in Mongolian gerbils (Meriones unguiculatus)

Desert rodents are faced with many challenges such as high dietary salt in their natural habitats and they have evolved abilities to conserve water and tolerate salt. However, the physiological and molecular mechanisms involved in water and salt balances in desert rodents are unknown. We hypothesized that desert rodents regulated water and salt balances by altering the expression of AQP2 and α-ENaC in the kidney. Mongolian gerbils (Meriones unguiculatus), a desert species, were acclimated to drinking water with different salt contents: (0, control; 4% NaCl, moderate salt, MS; 8% NaCl, high salt, HS) for 4 weeks. The gerbils drinking salty water had lower body mass, food intake, water intake, metabolic water production and urine volume. The HS gerbils increased the expression of arginine vasopressin (AVP) in the hypothalamus, and also enhanced the expression of AQP2 and cAMP/PKA/CREB signaling pathway in the kidney. In addition, these gerbils reduced serum aldosterone levels and α-ENaC expression in the kidney. Creatinine clearance was lower in the HS group than that in the control group, but serum and urine creatinine levels did not change. These data indicate that desert rodents rely on AVP-dependent upregulation of AQP2 and aldosterone-dependent downregulation of α-ENaC in the kidney to promote water reabsorption and sodium excretion under high salt intake.

Significance of Metformin Use in Diabetic Kidney Disease

Metformin is a glucose-lowering agent that is used as a first-line therapy for type 2 diabetes (T2D). Based on its various pharmacologic actions, the renoprotective effects of metformin have been extensively studied. A series of experimental studies demonstrated that metformin attenuates diabetic kidney disease (DKD) by suppressing renal inflammation, oxidative stress and fibrosis. In clinical studies, metformin use has been shown to be associated with reduced rates of mortality, cardiovascular disease and progression to end-stage renal disease (ESRD) in T2D patients with chronic kidney disease (CKD). However, metformin should be administered with caution to patients with CKD because it may increase the risk of lactic acidosis. In this review article, we summarize our current understanding of the safety and efficacy of metformin for DKD.

Destruction of the blood-retina barrier in diabetic retinopathy depends on angiotensin-converting enzyme-mediated TGF-β1/Smad signaling pathway activation

Diabetes mellitus (DM) is a systemic, chronic metabolic disease that is related to heredity and autoimmunity and is often accompanied by complications of retinopathy. However, the causative mechanism involved in the pathological process remains unclear. In this research, treatment with fosinopril or LY2109761 was found to be responsible for the improvement of the pathological processes, serum biochemical indexes and retinopathy in rats with streptozotocin-induced diabetes. In addition, the upregulation of angiotensin-converting enzyme (ACE) in the serum and the increased expression of TGF-β1 in the pathological outer nuclear layer (ONL) and inner nuclear layer (INL) of the retina were also reduced. In vitro experiments demonstrated that ACE enhanced cell damage and TGF-β1/Smad signaling pathway activation in retinal capillary endothelial cells (RCECs) under high glucose conditions. In addition, the activity of ACE was also considered to be related to the increasing levels of activated TGF-β1 in both rat retinal Müller cells (RMCs) and RCECs, but ACE activity had no effect on the high glucose-mediated upregulation of total TGF-β1 in RMCs. Coculture experiments with RCECs and RMCs showed that the barrier that was established under normal conditions was significantly impaired when exposed to high glucose combined with ACE, and damage of barrier can be prevented by adding fosinopril or LY2109761. Finally, a similar auxiliary effect of ACE was also observed in the activated TGF-β1-mediated barrier damage in blood-retinal barrier model in vitro. In summary, ACE-mediated TGF-β1/Smad signaling pathway activation was found to be involved in the destruction of the blood-retina barrier during diabetic retinopathy in a model of streptozotocin-induced diabetes, and these data may provide evidence to guide the treatment of the complications of diabetes mellitus.

Metformin modulates immune cell infiltration into the kidney during unilateral ureteral obstruction in mice

Metformin is today the first choice treatment for type‐2 diabetes, but has also protective effects in several renal disease models. Previously, we have demonstrated that the protective effects in response to unilateral ureteral obstruction (UUO) are independent of organic cation transporters (OCTs), the transporters responsible for the metformin uptake into the renal cells. The mechanisms behind the renoprotective effects are incompletely understood, but our previous results indicate that the renoprotective effects at least partly could be dependent on actions of metformin outside the renal cells. In this study, we investigate whether the renoprotective effects of metformin can be mediated via systemic immunomodulatory actions. We demonstrated that metformin can affect the immune system in the kidney as well as in the peripheral blood and spleen following UUO. UUO kidneys showed infiltration of immune cells including monocytes, B cells, and T cells, but metformin limited infiltration of all cell types. UUO animals had increased spleen sizes, but this increase was attenuated by metformin. Metformin treatment surprisingly resulted in a higher proportion of monocytes with infiltratory capacity 7 days after UUO. Other studies have suggested that metformin regulates monocyte maturation through signal transducer and activator of transcription 3 (STAT3) activation, as also indicated by our results. In conclusion, our results demonstrate that metformin limits the infiltration of immune cells into the kidney, as well as modulates immune cell composition at a systemic level.

Role of Impaired Nutrient and Oxygen Deprivation Signaling and Deficient Autophagic Flux in Diabetic CKD Development: Implications for Understanding the Effects of Sodium-Glucose Cotransporter 2-Inhibitors

Growing evidence indicates that oxidative and endoplasmic reticular stress, which trigger changes in ion channels and inflammatory pathways that may undermine cellular homeostasis and survival, are critical determinants of injury in the diabetic kidney. Cells are normally able to mitigate these cellular stresses by maintaining high levels of autophagy, an intracellular lysosome-dependent degradative pathway that clears the cytoplasm of dysfunctional organelles. However, the capacity for autophagy in both podocytes and renal tubular cells is markedly impaired in type 2 diabetes, and this deficiency contributes importantly to the intensity of renal injury. The primary drivers of autophagy in states of nutrient and oxygen deprivation-sirtuin-1 (SIRT1), AMP-activated protein kinase (AMPK), and hypoxia-inducible factors (HIF-1α and HIF-2α)-can exert renoprotective effects by promoting autophagic flux and by exerting direct effects on sodium transport and inflammasome activation. Type 2 diabetes is characterized by marked suppression of SIRT1 and AMPK, leading to a diminution in autophagic flux in glomerular podocytes and renal tubules and markedly increasing their susceptibility to renal injury. Importantly, because insulin acts to depress autophagic flux, these derangements in nutrient deprivation signaling are not ameliorated by antihyperglycemic drugs that enhance insulin secretion or signaling. Metformin is an established AMPK agonist that can promote autophagy, but its effects on the course of CKD have been demonstrated only in the experimental setting. In contrast, the effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors may be related primarily to enhanced SIRT1 and HIF-2α signaling; this can explain the effects of SGLT2 inhibitors to promote ketonemia and erythrocytosis and potentially underlies their actions to increase autophagy and mute inflammation in the diabetic kidney. These distinctions may contribute importantly to the consistent benefit of SGLT2 inhibitors to slow the deterioration in glomerular function and reduce the risk of ESKD in large-scale randomized clinical trials of patients with type 2 diabetes.

Salidroside ameliorates diabetic nephropathy in rats by activating renal AMPK/SIRT1 signaling pathway

This study investigated if the nephroprotective effect of Salidroside T1DM rats involves activation of AMPK/SIRT1. Rats were divided into control or T1DM and treated with vehicle or Salidroside (100 mg/kg) for 56 days. Mesangial cells were cultured in LG or HG media with or without Salidroside (100 µM/L) for 24 hr. Also, HG + Salidroside-treated cells were pre-incubated with EX-527 or compound C (CC) for 1 hr. With reducing glucose levels, Salidroside improved kidney structure/function in the T1DM rat. It also increased GSH and Bcl-2 levels in control and T1DM rats and inhibited ROS, increased activation of AMPK and nuclear SIRT1, and lowered acetylation of P53 and FOXO-1 in control and T1DM rats and in LG and HG-treated cells. These effects were abolished by EX-527 and CC. Also, CC decreased the nuclear levels of SIRT1. In conclusion, Salidroside attenuates DN in T1DM rats by activation of AMPK and subsequently, SIRT1. PRACTICAL APPLICATIONS: This animal and pre-clinical study shows that Salidroside is able to ameliorate DN in T1DM-induced rats and showed that it mainly acts by a hypoglycemic effect and activation of renal AMPK/SIRT1 axis. Given the wide tissue stimulatory effect of AMPK on peripheral glucose utilization, lipogenesis, and other cell signaling pathways, these data are encouraging to investigate the anti-diabetic effect of glycoside in more clinical trials.

Combined effects of metformin and photobiomodulation improve the proliferation phase of wound healing in type 2 diabetic rats

We determined the impact of Photobiomodulation (PBM) and metformin administration alone and combined on the inflammation and proliferation steps of wound healing of incisions in type two diabetes mellitus (T2DM) rats. 40 rats were divided into 4 groups (n = 10 each group). A non-genetic model of T2DM was induced in all rats, and an incision was made on each rat. There were 4 groups as follows: Group 1 was control group. Group 2 received PBM alone (890 nm, 80 Hz, 0.324 J/cm², daily). Group 3 received metformin alone (50 mg/kg, i.p., daily) and the fourth group received combination of PBM + metformin. At inflammation (day 4) and proliferation (day 7) steps, tensiometerical, stereological, and immunohistochemical examinations were performed. PBM and PBM + metformin treatments significantly increased wound strength at inflammation and proliferation steps of wound healing respectively. PBM, metformin, and PBM + metformin groups significantly decreased inflammatory cells at inflammation and proliferation steps of wound healing. PBM, metformin, and PBM + metformin groups significantly improved granulation tissue formation by increasing fibroblasts, and new blood vessel formation at inflammation and proliferation steps of wound healing. Metformin significantly increased M2 macrophages than other treatment groups at inflammation and proliferation steps of wound healing. Simultaneously, PBM significantly decreased M2 macrophages than control group. We concluded PBM and PBM + metformin treatments significantly hastened repair at the inflammation and proliferation steps of repairing skin injury in a non-genetic model of T2 DM. PBM + metformin showed a synergistic impact. There were not a positive relation between M2 macrophage number and wound strength in the studied groups. The details of the molecular mechanisms of PBM, and PBM + metformin treatments of repairing wounds in animals, and treatment of DFUs of patients with T2 DM should be elucidated by further research.

Mangiferin Alleviates Renal Interstitial Fibrosis in Streptozotocin-Induced Diabetic Mice through Regulating the PTEN/PI3K/Akt Signaling Pathway

Renal interstitial fibrosis is considered to be the typical manifestation of diabetic nephropathy (DN). Mangiferin has shown positive effect on the prevention or treatment of diabetes and its complications. The aim of this study was to explore the inhibitive effect and mechanism of mangiferin on renal interstitial fibrosis in diabetic mice. Streptozotocin- (STZ-) induced diabetic mice were treated with mangiferin (15, 30, and 60 mg/kg/d) for 4 weeks. The morphology of kidneys was observed by Masson's trichrome staining, and the biochemical parameters (fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), blood urea nitrogen (BUN), serum creatinine (SCr), and urine protein) were determined by kits. In addition, the levels of inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin- (IL-) 6, and IL-1β), antioxidant enzymes (SOD, CAT, and GSH-Px), MDA, and ROS were assessed. Furthermore, the expressions of fibronectin (FN), collagen I (Col I), and α-SMA were measured by immunohistochemistry. Regulations of TGF-β1 and the PTEN/PI3K/Akt pathway were detected by Western blotting. Treatment with mangiferin significantly ameliorated renal dysfunction in diabetic mice, as evidenced by the increase in body weight and decreases in FBG, TG, TC, BUN, SCr, urine protein, and the kidney to body weight ratio (KW/BW). Furthermore, mangiferin treatment prevented renal interstitial fibrosis evidenced by decreases in the positive expression of FN, Col I, and α-SMA, in comparison with morphological changes in the renal tissue. Meanwhile, mangiferin increased antioxidant enzymes, reduced the TNF-α, IL-6, and IL-1β, as well as MDA and ROS. Additionally, mangiferin administration also downregulated TGF-β1, upregulated PTEN, and decreased the phosphorylation of both PI3K and Akt. These findings demonstrate that mangiferin may reduce inflammation and oxidative stress in DN, thereby inhibiting the renal interstitial fibrosis by reducing the TGF-β1-mediated elevation of Col I, FN, and α-SMA through the PTEN/PI3K/Akt pathway.

Effect of a polyherbal formulation in streptozotocin-induced diabetic nephropathy in wistar rats

OBJECTIVES:

Chronic kidney failure among people with diabetes mellitus (DM) is a burgeoning health problem that affects up to 25% of patients with type 2 DM. Current pharmacological treatment for diabetic nephropathy (DN) does not stop the attainment of renal complications. The intention of the current study was to explore the role of a polyherbal formulation (PHF) in diabetic-induced nephropathy in experimental animals.

MATERIALS AND METHODS:

Diabetic rats were grouped as follows and underwent the following treatment for about 16 weeks: Group I – normal rats – no treatment, Group II – DN rats – only vehicle (p.o), and Group III and IV – DN rats – PHF orally at 250 and 500 mg/kg, respectively. After the treatment, the animals were sacrificed, and lipid, renal function, and inflammatory markers were estimated. The observed microscopic changes in kidney were analyzed.

RESULTS:

Animals administered with PHF exhibited noteworthy decrease in triglycerides, total cholesterol, very low-density lipoprotein (LDL), LDL, serum creatinine, urinary protein, urinary albumin excretion rate, advanced glycation end products, type IV collagen excretion, interleukin-6, transforming growth factor-ß, and tumor necrosis factor-alpha and showed significant increase in high-density lipoprotein, urine volume, urinary urea, and urine creatinine. Histopathological examination established that administration of PHF prohibited kidney damage.

CONCLUSION:

Treatment with PHF showed beneficial effect on DN which may be due to the improvement of renal function parameters and hyperlipidemic and inflammatory mediators.

Urinary metabolomics analysis reveals the anti-diabetic effect of stachyose in high-fat diet/streptozotocin-induced type 2 diabetic rats

As a new platform of systems biology, metabolomics provides a powerful approach to discover therapeutic biomarkers and mechanism of metabolic disease. Type 2 diabetes mellitus (T2DM) is a global metabolic disease, thus, a urinary metabolomics profiling was analyzed to study the anti-diabetic effects and mechanism of stachyose (ST) on high-fat diet- and low dose streptozotocinc-induced T2DM rats. The results showed that ST treatment regulated the level of insulin, low-density lipoprotein cholesterol, and triglycerides, which demonstrates improvement in T2DM on ST treatment. Urinary samples from the ST and T2DM group were enrolled in metabolomics study, 21 differential metabolites were identified from urinary metabolomics analysis, indicating that the ST treatment partly exerted the anti-diabetes activity by regulating energy metabolism, gut microbiota changes and inflammation. A metabolomics strategy is both suitable and reliable for exploring the anti-diabetes effects and understanding the mechanisms of ST treatment against T2DM.

Oxidative stress in autosomal dominant polycystic kidney disease: player and/or early predictor for disease progression?

Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations in PKD1 or PKD2 genes, is the most common hereditary renal disease. Renal manifestations of ADPKD are gradual cyst development and kidney enlargement ultimately leading to end-stage renal disease. ADPKD also causes extrarenal manifestations, including endothelial dysfunction and hypertension. Both of these complications are linked with reduced nitric oxide levels related to excessive oxidative stress (OS). OS, defined as disturbances in the prooxidant/antioxidant balance, is harmful to cells due to the excessive generation of highly reactive oxygen and nitrogen free radicals. Next to endothelial dysfunction and hypertension, there is cumulative evidence that OS occurs in the early stages of ADPKD. In the current review, we aim to summarize the cardiovascular complications and the relevance of OS in ADPKD and, more specifically, in the early stages of the disease. First, we will briefly introduce the link between ADPKD and the early cardiovascular complications including hypertension. Secondly, we will describe the potential role of OS in the early stages of ADPKD and its possible importance beyond the chronic kidney disease (CKD) effect. Finally, we will discuss some pharmacological agents capable of reducing reactive oxygen species and OS, which might represent potential treatment targets for ADPKD.

Metformin attenuates renal medullary hypoxia in diabetic nephropathy through inhibition uncoupling protein-2

BACKGROUND

The purpose of the study is to examine the effect of metformin on oxygen metabolism and mitochondrial function in the kidney of an animal model of insulinopenic diabetes in order to isolate any renoprotective effect from any concomitant effect on blood glucose homeostasis.

METHODS

Sprague-Dawley rats were injected with streptozotocin (STZ) (50 mg kg^-1 ) and when stable started on metformin treatment (250 mg kg^-1 ) in the drinking water. Rats were prepared for in vivo measurements 25 to 30 days after STZ injection, where renal function, including glomerular filtration rate and sodium transport, was estimated in anesthetized rats. Intrarenal oxygen tension was measured using oxygen sensors. Furthermore, mitochondrial function was assessed in mitochondria isolated from kidney cortex and medulla analysed by high-resolution respirometry, and superoxide production was evaluated using electron paramagnetic resonance.

RESULTS

Insulinopenic rats chronically treated with metformin for 4 weeks displayed improved medullary tissue oxygen tension despite of no effect of metformin on blood glucose homeostasis. Metformin reduced UCP2-dependent LEAK and differentially affected medullary mitochondrial superoxide radical production in control and diabetic rats.

CONCLUSIONS

Metformin attenuates diabetes-induced renal medullary tissue hypoxia in an animal model of insulinopenic type 1 diabetes. The results suggest that the mechanistic pathway to attenuate the diabetes-induced medullary hypoxia is independent of blood glucose homeostasis and includes reduced UCP2-mediated mitochondrial proton LEAK.

Relationship between transforming growth factor-β1 and type 2 diabetic nephropathy risk in Chinese population

BACKGROUND

Diabetes mellitus (DM) is divided into four different etiological categories: type 1 DM (T1DM), type 2 DM (T2DM), other specific types, and gestational DM. One severe complication of T2DM is type 2 diabetic nephropathy (T2DN). The possible association of serum transforming growth factor-β1 (TGF-β1) levels and the TGF-β1 T869C gene polymorphism with patient susceptibility to T2DN in Chinese population is unclear at present. This study was conducted to assess these relationships in Chinese population by a meta-analysis.

METHODS

Association reports were searched and pulled from the Cochrane Library, the China Biological Medicine Database (CBM), and PubMed on March 1, 2018, and eligible studies were selected and used for calculations. The results were expressed as weighted mean differences (MD) for continuous data. Odds ratios (OR) were used to express the results for dichotomous data. Additionally, 95% confidence intervals (CI) were calculated.

RESULTS

Forty-eight reports for the relationship between serum TGF-β1 levels and the risk of T2DN and 13 studies on the association of the TGF-β1 T869C gene polymorphism with susceptibility to T2DN in Chinese population were retrieved from this study. Serum TGF-β1 levels in the T2DM group were higher than those in the normal control group (MD = 17.30, 95% CI: 12.69-21.92, P < 0.00001). The serum TGF-β1 level in the T2DN group was significantly higher than that in the normal control group (MD = 70.03, 95% CI: 60.81-79.26, P < 0.00001;). The serum TGF-β1 level in the T2DN group was significantly higher than that in the T2DM group (MD = 56.18, 95% CI: 46.96-65.39, P < 0.00001). Serum TGF-β1 levels in T2DM patients with microalbuminuria were increased when compared with those in T2DM patients with normoalbuminuria. Furthermore, serum TGF-β1 levels in T2DM patients with macroalbuminuria were increased when compared with those in T2DM patients with microalbuminuria. The TGF-β1 T allele, TT allele and CC genotype were associated with T2DN susceptibility in Chinese population (T: OR = 0.74, 95% CI: 0.59-0.92, P = 0.007; TT: OR = 0.55, 95% CI: 0.31-0.96, P = 0.04; CC: OR = 1.38, 95% CI: 1.14-1.67, P = 0.001).

CONCLUSIONS

High levels of TGF-β1 are associated with susceptibility to T2DM, T2DN and the progression of proteinuria in T2DN patients in Chinese population. Further, the TGF-β1 T allele, and TT genotype were protective factors against the onset of T2DN and CC genotype was a risk factor for the susceptibility of T2DN in Chinese populations.

Thymoquinone Attenuates Cardiomyopathy in Streptozotocin-Treated Diabetic Rats

Diabetic cardiomyopathy is a diabetic complication due to oxidative stress injuries. This study examined the protecting influence of thymoquinone (TQ) on diabetes-caused cardiac complications. The intracellular means by which TQ works against diabetes-caused cardiac myopathy in rats is not completely understood. In this study, Wistar male rats (n = 60) were assigned into four groups: control, diabetic (diabetes induced by IP infusion of streptozotocin, 65 mg/kg), diabetic + TQ (diabetic rats given TQ (50 mg/kg) administered once per day by stomach gavage), and TQ (50 mg/kg) for 12 weeks. TQ supplementation appreciably recovered the cardiac parameters alongside significant declines in plasma nitric oxide concentrations and total superoxide dismutase (T.SOD) activities. Importantly, TQ downgraded expression of cardiac-inducible nitric oxide synthase in addition to significantly upregulating vascular endothelial growth factor and erythropoietin genes and nuclear factor-erythroid-2-related factor 2 (Nrf2) protein. TQ normalized plasma triacylglycerol and low-density lipoprotein-cholesterol and significantly improved the high-density lipoprotein-cholesterol levels. Additionally, TQ administration improved the antioxidant ability of cardiac tissue via significantly increased cardiac T.SOD and decreased cardiac malondialdehyde levels. Oral supplementation with TQ prevented diabetic-induced cardiomyopathy via its inhibitory effect on the E-selectin level, C-reactive protein, and interleukin-6. The TQ protecting effect on the heart tissue was shown by normalization of the plasma cardiac markers troponin I and creatine kinase. This experiment shows the aptitude of TQ to protect cardiac muscles against diabetic oxidative stress, mainly through upregulation of Nrf2, which defeated oxidative damage by improvement of the antioxidant power of cardiac muscle that consequently protected the cardiac muscles and alleviated the inflammatory process.

Evaluation of Osteopontin Gene Expression in Endometrium of Diabetic Rat Models Treated with Metformin and Pioglitazone

Background

Osteopontin (Opn) is one of the co-factors involved in cell adhesion and invasion during the implantation process. Several reports have shown Opn expression changes in diabetic condition in several tissues. In addition, an increased incidence of spontaneous abortion is reported in diabetic women. We, therefore, designed a study to evaluate the effects of diabetes on Opn expression at implantation time after treatment with metformin and pioglitazone.

Materials and Methods

In this interventional and experimental study, 28 rats were randomly divided into four groups, namely control, diabetic, pioglitazone-treated diabetic rats and metformin-treated diabetic rats. Streptozotocin (STZ) and nicotinamide (NA) were used to induce type 2 diabetes (T2D). During the implantation window, the endometrium was removed and the expression of Opn was analysed by reverse transcription quantitative polymerase chain reaction (RT-qPCR).

Results

Opn expression was significantly higher (30.70 fold-changes) in the diabetic group in comparison with the control group (P=0.04). Furthermore, the expression of Opn was significantly lower in the diabetic group treated with pioglitazone when compared with the diabetic group (P=0.04).

Conclusion

According to the high Opn expression and the possibility of increased adhesion of endometrial epithelial cells, the invasion of blastocyst may be affected and thus reduced. As pioglitazone significantly reversed the upregulation of Opn in diabetic rats, it may be considered as a therapeutic compound for treating T2D.

HL156A, a novel pharmacological agent with potent adenosine-monophosphate-activated protein kinase (AMPK) activator activity ameliorates renal fibrosis in a rat unilateral ureteral obstruction model

Background

Renal fibrosis is characterized by excessive production and deposition of extracellular matrix (ECM), which leads to progressive renal failure. Adenosine-monophosphate-activated protein kinase (AMPK) is a highly conserved kinase that plays a key role in Smad-3 signaling. Here, we examined the effect of a novel AMPK activator, HL156A, on the inhibition of renal fibrosis in in vivo and in vitro models.

Methods

Unilateral ureteral obstruction (UUO) was induced in male Wistar rats. Rats with UUO were administered HL156A (20mg/kg/day), and then the kidneys were harvested 10 days after ligation for further analysis.

Results

In the rat UUO model, HL156A attenuated ECM protein deposition. After HL156A treatment, expressions of TGF-β1, p-Smad3, α-SMA, fibronectin, and type IV collagen were suppressed, and E-cadherin expression was up-regulated. In the in vitro experiment, NRK52E cells were treated with HL156A before TGF-β1 stimulation. The inhibitory effects of HL156A upon the signaling pathways and markers of the epithelial-to-mesenchymal transition (EMT) were analyzed. In TGF-β1-treated NRK-52E cells, HL156A co-treatment inhibited the TGF-β1-induced Smad3 signaling pathway and EMT markers.

Conclusion

Taken together, the above findings suggest that HL156A, a novel AMPK activator, ameliorates renal fibrosis in vivo and in vitro.

Metformin attenuates folic-acid induced renal fibrosis in mice

Progressive tubulointerstitial fibrosis has been recognized as a common pathological process that leads to the progression of all chronic kidney disease (CKD). Innovative strategies are needed to both prevent and treat CKD. Inflammatory and fibrotic signaling pathways play central roles in the progression of CKD regardless of aetiology. Hence, targeting inflammatory and fibrotic responses holds promise to limit renal fibrosis. Metformin has been the most prescribed glucose-lowering medicine worldwide, and its potential for many other therapeutic applications is also being explored intensively. Increasing evidence indicates metformin may limit renal fibrosis. However, the exact mechanisms whereby metformin limits renal injury are not fully understood. The anti-fibrotic effects of metformin, independent of improved glycaemic control was examined in a folic acid-induced mouse model of nephropathy for 14 days. Human proximal tubular cells (HK2 cells) exposed to TGF-β1 were used in in vitro models to examine mechanistic pathways. Folic acid induced nephropathy was associated with the overexpression of inflammatory markers MCP-1, F4/80, type IV collagen, fibronectin and TGF-β1 compared to control groups, which were partially attenuated by metformin treatment. In vitro studies confirmed that metformin inhibited TGF-β1 induced inflammatory and fibrotic responses through Smad3, ERK1/2, and P38 pathways in human renal proximal tubular cells. These results suggest that metoformin attenuates folic acid-induced renal interstitial fibrogenesis through TGF-β1 signaling pathways.

Stachyose Improves Inflammation through Modulating Gut Microbiota of High-Fat Diet/Streptozotocin-Induced Type 2 Diabetes in Rats

SCOPE

The present study is undertaken to assess the effects of stachyose (STS) on type 2 diabetes in rats and changes in the gut microbiota compared to metformin (MET).

METHODS AND RESULTS

The type 2 diabetic model is successfully established via a high-fat diet /streptozotocin in Wistar rats, and STS or MET is administered for 4 weeks. Blood is collected to analyze biochemical parameters, pancreas for mRNA expression of related gene, and contents of colon for gut microbiota. STS or MET decreases serum LPS, mRNA expression of IL-6, and tumor necrosis factor-α (TNF-α). In addition, STS and MET show a similar shifting of the structure of the gut microbiota and a selective enrichment of key species. At the genus level, STS shows selective enrichment of Phascolarctobacterium, Bilophila, Oscillospira, Turicibacter, and SMB5, but MET demonstrates a selective effect on Sutterella, Prevotella, 02d06, and rc4. The correlation analysis indicates that STS and MET decrease IL-6 and TNF-α and increase Akt/PI3K expression, which are relative to key species of gut microbiota.

CONCLUSION

STS decreases pancreatic mRNA expression of IL-6 and TNF-α via key species of gut microbiota. The mechanism of this effect is similar to that of MET.