STZ-induced Rats Research Articles

The Comparative Effectiveness of Phaleria macrocarpa (Scheff.) Boerl. Pericarp Ethanol Extract and Metformin in Reducing Blood Sugar Levels and Ameliorating the Langerhans Islets Degeneration in Diabetic Rat Models

Phaleria macrocarpa (Scheff.) Boerl. has been widely used in the treatment of diabetes mellitus but its effectiveness is still inconclusive so it needs to be compared with standard drugs such as metformin. This study aims to analyze the effects of P. macrocarpa fruit extracts on blood sugar levels and the repairing of the pancreatic Langerhans islets of diabetic rat models. The study was conducted experimentally by pre and post-test design with a control group. Thirty white rats were divided into 6 groups. All rats were treated with 40 mg/200 g BW of streptozotocin (STZ) to induce hyperglycemia, except group I. Group II as a negative control was given with aquadest. Group III, IV, and V were given with ethanol extract of P. macrocarpa pericarps at doses of 200, 250, and 300 mg/200 g BW/day, respectively. Group VI was given with metformin at a dose of 150 mg/200 g BW/day. On the 22nd day of treatment, blood specimens were taken for examination of fasting blood sugar levels and pancreatic organs were analyzed for histopathological examination of the islets of pancreatic Langerhans. The data were statistically analyzed with α<0.05; CI95%. Paired sample t-test results showed a significant decrease in blood sugar levels before and after treatment in group V (p-value=0.048). One way anova and post hoc Least Significant Difference (LSD) test results showed a significant difference in mean blood sugar levels after the final treatment between groups I and II (p-value=0.013), I and III (p-value=0.004), I and IV (p-value=0.002), I and VI (p-value=0.000), II and VI (p-value=0.031), and V with VI (p-value=0.005); one way anova and post hoc LSD test results showed a significant difference in the mean area of islets of pancreatic Langerhans between group I and all treatment groups (p-value=0.000), II with V and VI (p-value=0.000 and 0.009), III with V and VI (p-value=0.000 and 0.001), and IV with V (p-value=0.003). It can be concluded that the extract of P. macrocarpa pericarps showed a hypoglycemic effect and repaired the damage in Langerhans islets of STZ-induced rat in a dose-dependent manner.

Therapeutic effect of integrin-linked kinase gene-modified bone marrow-derived mesenchymal stem cells for streptozotocin-induced diabetic cystopathy in a rat model

BackgroundDiabetic cystopathy (DCP) is a chronic complication of diabetes mainly within the submucosal and muscular layers of the bladder due to the hyperglycemia-induced ischemia. As no effective therapies are currently available, the administration of optimized mesenchymal stem cells (MSCs) provides a potential treatment of DCP. Thus far, new strategy, such as genetic modification of MSCs, has been developed and has shown promising outcomes of various disorders.MethodsThis study was conducted using integrin-linked kinase (ILK) gene-modified bone marrow-derived stem cells (BMSCs) for streptozotocin (STZ)-induced diabetic cystopathy in a rat model. In total, 68 male Sprague-Dawley rats were randomized into five groups: sham control (control group, n = 10); DCP model alone (DM group, n = 10); DCP rats intravenously treated with BMSCs (BMSC group, n = 16); DCP rats accepted adenoviral vector-infected BMSCs (Ad-null-BMSC group, n = 16) and DCP rats accepted ILK adenoviral vector-infected BMSCs (Ad-ILK-BMSC group, n = 16). Diabetic rats accepted cell transplantation in the experimental group (2 rats per group) were sacrificed for the bladder tissue on the third day, 7th day, and 14th day of treatment respectively ahead of schedule. At 4 weeks after treatment, all rats in five groups accepted urodynamic studies to evaluate bladder function and were sacrificed for bladder tissue.ResultsOur data showed that the underactive bladder function was significantly improved in DCP rats intravenously treated with ILK gene-modified BMSCs compared to those in the DM, BMSCs, and Ad-null-BMSC group. Meanwhile, we found that gene-modified BMSC treatment significantly promoted the activation of the AKT/GSK-3β pathway by increasing phosphorylation and led to the enhancement of survival. In addition, the expression levels of angiogenesis-related protein vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and stromal cell-derived factor-1 (SDF-1) were significantly higher in the Ad-ILK-BMSC group than that in the DM, BMSCs, and Ad-null-BMSC group as assessed by enzyme-linked immunosorbent assay and western blot. As two indicators of vascular endothelial cell markers, the expression of von Willebrand factor (vWF) and CD31 by western blot and immunofluorescent staining revealed that the percentage of the vascular area of the bladder tissue significantly increased in Ad-ILK-BMSC group compared with the BMSCs and Ad-null-BMSC group on the 14th day of treatment. Histological and immunohistochemical staining (hematoxylin and eosin (HE), vWF, Ki67, and TUNNEL) on the bladder tissue revealed statistically different results between groups.ConclusionILK gene-modified BMSCs restored the bladder function and histological construction via promoting the process of angiogenesis and protecting cells from high glucose-associated apoptosis in STZ-induced DCP rat model, which provides a potential for the treatment of patients with DCP.

α-Glucosidase Inhibitory, Anti-Oxidant, and Anti-Hyperglycemic Effects of Euphorbia nivulia-Ham. in STZ-Induced Diabetic Rats.

In this study, we aimed to investigate the antidiabetic effects of Euphorbia nivulia (En), native to Cholistan Desert area of Bahawalpur, Pakistan. First, we performed high-performance liquid chromatography analysis and found that this plant contains ferulic acid, gallic acid, quercetin, benzoic acid, polyphenols, and flavonoids. Then, we performed in vitro and in vivo studies to assess its effects on diabetic Wistar rat model. The experiments were performed and compared with control drug glibenclamide. The 70% hydroalcoholic extract of En exhibited 97.8% in vitro α-glucosidase inhibitory effect at a dose of 1.0 mg/mL. We orally administered the extract of En and control drug to the streptozotocin (STZ)-induced diabetic rats and analyzed its antidiabetic effects. We found that the extract of En with a dose of 500 mg/kg/body weight exhibited significant effect to reduce blood glucose in STZ-induced rats as compared with the control group (P < .001). Our histological data also showed that the extract significantly improved the histopathology of pancreas. Collectively, both in vitro and in vivo studies revealed that En possesses α-glucosidase inhibitory, antioxidant, and anti-hyperglycemic effect in STZ-induced diabetic rats.

The bone marrow-derived mesenchymal stem cells (BMSCs) alleviate diabetic peripheral neuropathy induced by STZ via activating GSK-3β/β-catenin signaling pathway

BackgroundDiabetic peripheral neuropathy, a common complication of diabetic mellitus, has brought a threaten on patients’ health. The bone marrow-derived mesenchymal stem cells (BMSCs) were reported to play an important role in diverse diseases. Nevertheless, the specific function of BMSCs in diabetic peripheral neuropathy remained uncharacterized. MethodsA wide range of experiments including RT-qPCR, western blot, H&E staining, oxidative stress assessment, measurement of thermal sensitivity, ELISA, urine protein and CCK-8 assays were implemented to explore the function and mechanism of BMSCs in vivo and vitro. ResultsThe experimental results displayed that BMSCs improve STZ-induced diabetes symptoms in rats by decreasing blood glucose and urinary protein. Functionally, BMSCs ameliorate oxidative stress, painful diabetic neuropathy, neurotrophic status and angiogenesis in STZ-induced rats. Moreover, BMSCs participate in the regulation of sciatic neuro morphology in diabetic neuropathy rat model. In mechanism, BMSCs alleviate diabetic peripheral neuropathy via activating GSK-3β/β-catenin signaling pathway in rats and improve Schwann's cells viability by activating GSK-3β/β-catenin signaling pathway under high glucose. ConclusionsWe verified that BMSCs alleviate diabetic peripheral neuropathy of rats induced by STZ via activating GSK-3β/β-catenin signaling pathway, which implied a novel biomarker for diabetic peripheral neuropathy treatment.

P0989VDR/ATG3 AXIS REGULATES SLIT DIAGRAM TO TIGHT JUNCTION TRANSITION VIA P62-MEDIATED AUTOPHAGY PATHWAY IN DIABETIC NEPHROPATHY

Abstract Background and Aims Vitamin D receptor (VDR) loss, slit diagram (SD) to tight junction (TJ) transition and impaired autophagic flux contribute to podocyte injury in diabetic nephrology. This study aims to examine the effect and mechanism of VDR on autophagic flux and SD-TJ transition in diabetic nephropathy. Method Renal biopsy tissues from DN patients at stage IIa, IIb, III, IV and patients with minimal lesions were used to evaluate the expression of VDR, autophagic flux and SD-TJ transition glomeruli. In vitro, cultured podocytes were treated with serum starvation (SS), autophagic inhibitors (3-methyladenine 3-MA or chloroquine CQ) to determine the degradation pathway of TJ marker ZO-1. Meanwhile, db/db mice and STZ-induced rats were used to explore the therapeutic effect and mechanism of VDR agonist in diabetic nephropathy. Results SD-TJ transition between foot processes could be observed under electron microscopy in DN patients at all stages, whereas foot processes were separated by the filtration slit and appeared to be single cross-strands in the normal glomeruli. There was a trend of increasing expression of autophagic marker p62 and ZO-1 and the expression of p62 is positively correlated with the changes of ZO-1 in the glomeruli of DN patients. In vitro, inhibiting autophagy with 3-MA and CQ resulted in the accumulation of ZO-1 in cultured podocytes. In addition, Co-IP experiments further convinced the interaction between p62 and ZO-1, which was enhanced by the activation of autophagy. Podocytes apoptosis and the activity of caspase 3 and caspase 8 were significantly increased in the presence of 3-MA or CQ, while these effects were rescued by silencing p62. According to VDR gene expression data in GEO database, VDR expression was decreased in diabetic nephropathy patients compared with normal people. Knocking down VDR lowered the expression of atg3 and leaded to the blockage of autophagy, which could be reversed by over-expressing Atg3. Podocytes treated with high glucose resulted in the decrease of VDR and Atg3, impaired autophagic flux and aggravated podocytes injury. However, VDR agonist treatment partially reversed all the changes. In vivo, db/db mice and STZ-induced rats (DN animal models) exhibited SD-TJ transition, massive proteinuria, decreased expression of VDR and podocin and the increased accumulation of p62 and ZO-1, all of which could be partially reversed by VDR agonist. Conclusion VDR loss contributed to the impairment of autophagic flux and SD-TJ transition via down-regulation Atg3 in diabetic nephropathy. Here, we identified a new mechanism and evidence for VDR agonist to treat diabetic nephropathy.

Palbinone alleviates diabetic retinopathy in STZ-induced rats by inhibiting NLRP3 inflammatory activity.

Diabetic retinopathy (DR) is the primary cause of blindness and visual impairment in diabetes patients worldwide. However, laser and surgical therapies at DR have short-term effectiveness and cause side effects. Treatment with natural products is a reasonable alternative treatment for DR. The main objective of this investigation is to explore the efficacy of a bioactive compound such as palbinone (PB) in DR. Experimental rats were injected intraperitoneally with streptozotocin (STZ, 65 mg/kg), and these established experimental rats were treated with PB (20 mg/kg/bw) for 42 days. The observed results showedthat PB considerably reduced the proinflammatory cytokine(interleukin-18 [IL-18] and IL-1β) production as well as improved the activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) particularly in the retinal region of STZ-induced DR rats. In addition, PB treatment improved nuclear factor erythroid 2-related factor 2 (Nrf2) accumulation and enhanced the heme oxygenase-1 expression, and major antioxidants downregulatedNrf2in the damaged retina. Also, the expression levels of nod-like receptor family pyrin domain containing 3 (NLRP3), cleaved-caspase-1, IL-1β, and apoptosis-associated speck-like protein containing CARD in the retinal region were notably upregulated in STZ-induced DR,which was eliminated by PB interference. PB administration exerted efficient antioxidant activities, Nrf2 pathway activation, and inhibition of NLRP3 inflammasome. This current investigation concluded that PB considerablyreduced the retinal inflammation and oxidative stress stimulated via high glucose, and also activated the antioxidative Nrf2 pathway and inhibited the NLRP3 inflammasome formation in rats.

Momordica charantia L. Fruit Fractions inhibit Malondialdehyde Level and Regenerate Hepatic Damage of Hyperglycemic Rats

BACKGROUND: Chronic hyperglycemia causes an increase of free radical production and in longterm, the hyperglycemia increases oxidative stress. Among medicinal plants, Momordica charantia L. fruit has been known to overcome hyperglycemia. However, role of M. charantia L. fruit on oxidative stress is not well understood. Therefore, current study was conducted to investigate the effect of M. charantia L. fruit extract on malondialdehyde (MDA) level and hepatic damage in hyperglicemic rat model.METHODS: Twenty five white rats (Rattus novergicus) were induced with Streptozotocin (STZ) and treated with/without glibenclamide, sodium carboxymethyl cellulose (Na-CMC), or M. charantia L. fruit ethanol/ethyl acetate/ n-hexane fraction. After the treatment, rat’s livers were collected and separated for histopathological examination and MDA analysis.RESULTS: The MDA level average of rats before the STZ induction was 1.37 μg/mL. MDA level average was markedly increased (23.85 μg/mL) in rats induced with STZ and treated with Na-CMC merely. The MDA level average of STZ-induced glibenclamide-treated rats was 3.12 μg/mL. Meanwhile, the MDA level averages of STZ-induced M. charantia L. fruit ethanol, ethyl acetate and n-hexane fractions-treated rats were 14.95, 8.98 and 5.37 μg/mL, respectively. The histopathology results of this study showed that adipocytes, dilated sinusoids and central vein thickening were mostly observed in STZ-induced Na-CMC-treated rats. Meanwhile, the STZ-induced ethanol/ethyl acetate/n-hexane fraction-treated rats did not exhibitthose expressions.CONCLUSION: M. charantia L. fruit fractions inhibit the MDA level average in liver tissue and regenerate hepatic damage of STZ-induced rats, especially the n-hexane fraction which could be a potential hepatic antioxidant and regenerative agent.KEYWORDS: Momordica charantia L., malondialdehyde, oxidative stress, hyperglycemia, diabetes mellitus

Protective Effect of Hydroxysafflor Yellow A on Nephropathy by Attenuating Oxidative Stress and Inhibiting Apoptosis in Induced Type 2 Diabetes in Rat.

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus, and its prevalence has been increasing all over the world, which is also the leading cause of end-stage renal failure. Hydroxysafflor yellow A (HSYA) is the main active chemical component of Carthamus tinctorius L., and it is commonly used in patients with cardiovascular and cerebrovascular diseases in China. The aim of this study was to investigate the renal protective effects and molecular mechanisms of HSYA on high-fat diet (HFD) and streptozotocin- (STZ-) induced DN in rats. The DN rats were treated with HSYA for eight weeks. We assessed creatinine (CR), urea nitrogen (UN), glomerular volume, podocyte number, renal inflammation, oxidative stress, and cells apoptosis markers after HSYA treatment. The number of apoptotic cells was measured by the TUNEL assay, and apoptosis-related proteins BAX, caspase-3, and BCL-2 in the renal tissue were analyzed by western blot. The treatment with HSYA significantly decreased fasting blood glucose, CR, UN, and blood lipid profile, including triglyceride and total and low-density lipoprotein cholesterol, even though it did not change the rats' body weights. The western blot results indicated that HSYA reversed the upregulation of BAX and caspase-3 and significantly increased BCL-2 in renal tissue. Moreover, the levels of TNF-α and the inflammatory products, including free fatty acids (FFA) and lactic dehydrogenase (LDH) in the HSYA group, were significantly decreased. For the oxidative stress marker, the superoxide dismutase (SOD) markedly increased in the HSYA treatment group, while the malondialdehyde (MDA) in the serum and kidney tissue evidently decreased. In conclusion, HSYA treatment preserved kidney function in diabetic nephropathy in the HFD- and STZ-induced rats. The potential mechanism of renal protective effect of HSYA might be through inhibiting oxidative stress, reducing inflammatory reaction, and attenuating renal cell apoptosis. Our studies present a promising use for Hydroxysafflor yellow A in the treatment of type 2 diabetes mellitus.

Research on the pathological mechanisms of nerve decompression in relieving tactile allodynia in diabetic rats

Objectives To explore the pathological mechanism of peripheral nerve decompression in relieving tactile allodynia in diabetic rats. Methods Healthy adult male Sprague Dawley rats were randomly divided into 5 groups for different interventions: group Ⅰ (healthy control, n=10), group Ⅱ (diabetes model, n=20), group Ⅲ (diabetes model with latex tube placement, n=10), group Ⅳ (diabetes model with latex tube placement and nerve decompression, n=10), group V (diabetes model with latex placement and merely operational area exposure, n=10). The diabetes model was induced by intraperitoneal injection of streptozotocin (STZ). Nerve decompression was performed by removal of latex tube encircling the sciatic nerve at 3 weeks post model establishment. The paw withdrawal threshold was tested 3 days after modeling with the use of up-down method. Diabetic rats with tactile allodynia in 4 experimental groups (groups Ⅱ-Ⅳ) were preserved. Morphometric analysis of myelinated and non-myelinated nerve fibers was performed with the use of projection electron microscope. Western blot and immunofluorescence were used to localized and determined the expression of GABAB receptor protein in spinal dorsal horn. Results Three weeks after operation, the incidence of tactile allodynia in STZ-induced rats[55.0%(11/20)] was lower than that in diabetic rats with latex tube placement (groups Ⅲ, Ⅳ and Ⅴ) [86.7%(26/30), χ2=6.254, P=0.012]. The paw withdrawal threshold in group Ⅰ (13.41±1.88 g) was higher than those in groups Ⅱ-Ⅳ (4.06±1.28 g, 3.09±1.43 g, 4.02±1.96 g, 4.15±1.87 g respectively, P<0.05). At 5 weeks post operation, the paw withdrawal threshold in group Ⅳ was higher than those of group Ⅱ, Ⅲ and Ⅴ(all P<0.05). When compared with group Ⅰ, smaller myelinated fibers area and density, as well as higher g-ratio were revealed by electron microscope in each experimental group (all P<0.05). Larger myelinated fiber area and density, as well as lower g-ratio were noted in group Ⅳ when compared with those in group Ⅱ and Ⅴ (all P<0.05). The results of western blot showed that lower expression of GABAB receptor was noted in experimental groups (Ⅱ, Ⅲ, Ⅳ and Ⅴ) when compared with group Ⅰ (all P<0.05), and higher expression of GABAB receptor in both NF-200+ areas and neurons of spinal dorsal horn was noted in group Ⅳ when compared with group V (P<0.05) at 3 weeks post nerve decompression. The results of immunofluorescence showed that lower expression of GABAB receptor in both NF-200+ areas and neurons of spinal dorsal horn was noted in experimental groups (Ⅱ, Ⅲ, Ⅳ and Ⅴ) when compared with group Ⅰ (all P<0.05). Conclusions Peripheral nerve decompression can relieve the tactile allodynia of diabetic rats mainly by removing the compression damage of myelinated nerve fibers, lifting the GABAB receptor downregulation-mediated central sensitivity, thereby relieving the pathological state of elevated spinal excitability. Key words: Diabetes mellitus; Disease models, animal; Tactile allodynia; Nerve decompression

Antihyperglycemic Effect of the Aqueous Extract of Foeniculum vulgare in Normal and Streptozotocin-induced Diabetic Rats.

Diabetes mellitus is associated with high blood glucose levels due to insulin shortcoming (insulinopenia) or defective insulin action. The objective of the study was to investigate the antidiabetic and antioxidant effects of Foeniculum vulgare in streptozotocin-induced diabetic rat. The effects of the leaves aqueous extract (LAE) of Foeniculum vulgare (F. vulgare) at a dose of 10 mg/kg on blood glucose levels were evaluated in normal and streptozotocin (STZ)- induced diabetic rats. Histopathological changes were also evaluated in liver in STZ-induced rats. Single oral administration of F. vulgare LAE reduced blood glucose levels 6 h after administration in STZ diabetic rats (p<0.0001). Furthermore, blood glucose levels were decreased in both normal (p<0.05) and STZ diabetic rats (p<0.0001) after the fifteenth day of treatment. During this test, both groups did not show any significant change in their body weight. Moreover, this aqueous extract improved oral glucose tolerance in diabetic rats and revealed a positive effect on liver histology. On the other hand, the extract used in this experiment showed an inhibitory concentration (IC50) of 50% of free radicals with a concentration of 43±1.19 µg/ml. While the synthetic antioxidant (BHT) had an IC50 equal to 22.67±2.17µg /ml. This study demonstrates the antihyperglycemic, hypoglycemic and antioxidant effects of the leaves of F. vulgare in normal and diabetic rats.

Diabetic nephropathy execrates epithelial-to-mesenchymal transition (EMT) via miR-2467-3p/Twist1 pathway

Although diabetic nephropathy (DN) is induced by a complicate interplay of multiple factors, the underlying mechanisms remain poorly characterized, even the treatment. Herein, we show that both of DN patients and STZ-induced type 1 diabetic rat exhibit the reduction both of urinary and circulating miR-2467-3p. We identify a negative correlation between miR-2467-3p levels and renal dysfunction. Administration of miR-2467-3p prevents diabetes-induced renal dysfunction and represses renal fibrosis in STZ-induced type 1 diabetic rats. Conversely, anti-miR-2467 overexpression exacerbates renal dysfunction and fibrosis in STZ-induced rats. In diabetic condition, the reduction of miR-2467-3p promotes expression of Twist1, inducing epithelial-to-mesenchymal transition (EMT), resulting in renal fibrosis and kidney dysfunction. Together, our study presents miR-2467/Twist1/EMT as a regulatory axis of renal dysfunction in DN.

Molecular docking analysis and anti-hyperglycaemic activity of Synacinn™ in streptozotocin-induced rats.

Synacinn™ is a standardized polyherbal supplement formulated from Cinnamomum zeylanicum Blume, Curcuma zanthorrhiza Roxb., Syzygium polyanthum (Wight) Walp., Orthosiphon stamineus Benth. and Andrographis paniculata (Burm.f.) Nees. It is designed for the synergistic treatment of diabetes mellitus and its complications. Although the beneficial effects are yet to be verified scientifically, it is traditionally used to improve general health in patients with diabetes. This study aimed to evaluate the anti-hyperglycemic effects of Synacinn™ in a streptozotocin-induced type 1 diabetes rat model. Initially, Synacinn™ was used for in vivo acute oral toxicity tests and 14 day repeated dose toxicity tests to determine the toxicity levels. An efficacy study of Synacinn™ was carried out via the oral administration of 10, 50, 100, 250, and 250 (b.i.d.) mg kg−1 doses to streptozotocin-induced diabetic rats. After 28 days, blood serum was collected to measure the fasting blood glucose, triglyceride, cholesterol, alanine aminotransferase, alkaline phosphatase, creatinine, and uric acid levels. The liver, kidney, and pancreas structures were histopathologically analyzed. In silico binding interaction studies of five phytochemicals in Synacinn™ identified via HPLC with glucokinase were performed using molecular docking analysis. The results showed that although no mortality was observed during the acute oral toxicity tests, notable damage to the liver and kidney occurred during the 14 day repeated dose testing at Synacinn™ levels of 600 mg kg−1 and 2000 mg kg−1. Treatment with 250 mg kg−1 (b.i.d.) Synacinn™ of the streptozotocin-induced type 1 diabetic rats significantly (p < 0.05) improved the fasting blood glucose (59%), triglyceride (58%), cholesterol (47%), alanine aminotransferase (60%), alkaline phosphatase (90%), and creatinine (32%) levels. Synacinn™ also improved the relative weights of liver (35%), kidney (36%), and pancreatic (36%) tissue. Histological analysis showed improvements in the conditions of the central vein of the liver, the kidney Bowman's capsule and glomerulus, and the pancreatic islets of Langerhans. HPLC analysis of a standardized extract identified five active phytochemicals: andrographolide (17.36 mg g−1), gallic acid (11.5 mg g−1), curcumin (2.75 mg g−1), catechin (3.9 mg g−1), and rosmarinic acid (5.54 mg g−1). Molecular docking studies with glucokinase showed that andrographolide yields the highest binding energy (−12.1 kcal mol−1), followed by catechin (−10.2 kcal mol−1), rosmarinic acid (−8.6 kcal mol−1), curcumin (−7.8 kcal mol−1), and gallic acid (−5.6 kcal mol−1). These current findings suggest that Synacinn™ at a dose of 250 mg kg−1 was non-toxic to rats. A twice-daily 250 mg kg−1 dose of Synacinn™ is an effective anti-hyperglycemic agent, lowering blood glucose, triglyceride, and cholesterol levels, and assisting the recovery of organ impairment caused by streptozotocin in type 1 diabetic rats.

Schisandrin ameliorates cognitive deficits, endoplasmic reticulum stress and neuroinflammation in streptozotocin (STZ)-induced Alzheimer’s disease rats

Schisandrin, an active component extracted from Schisandra chinensis (Turcz.) Baill has been reported to alleviate the cognitive impairment in neurodegenerative disorder like Alzheimer’s disease (AD). However, the mechanism by which schisandrin regulates the cognitive decline is still unclear. In our study, intracerebroventricular injection of streptozotocin (STZ) was employed to establish AD model in male Wistar rats, and indicated dose of schisandrin was further administered. The Morris water maze test was performed to evaluate the ability of learning and memory in rats with schisandrin treatment. The results indicated that schisandrin improved the capacity of cognition in STZ-induced rats. The contents of pro-inflammatory cytokines in brain tissue were determined by ELISA, and the expressions of these cytokines were assessed by western-blot and immunohistochemistry. The results showed that treatment of schisandrin significantly reduced the production of inflammation mediators including tumor necrosis factor-α, interleukin-1β and interleukin-6. Further study suggested a remarkable decrease in the expressions of ER stress maker proteins like C/EBP-homologous protein, glucose-regulated protein 78 and cleaved caspase-12 in the presence of schisandrin, meanwhile the up-regulation of sirtuin 1 (SIRT1) was also observed in the same group. Additionally, the results of western-blot and EMSA demonstrated that schisandrin inhibited NF-κB signaling in the brain of STZ-induced rats. In conclusion, schisandrin ameliorated STZ-induced cognitive dysfunction, ER stress and neuroinflammation which may be associated with up-regulation of SIRT1. Our study provides novel mechanisms for the neuroprotective effect of schisandrin in AD treatment.

Protective effect of ferulic acid on STZ-induced diabetic nephropathy in rats.

Diabetic nephropathy (DN) is a major and severe complication of diabetes mellitus. Ferulic acid (FA), a phenolic compound widespread in fruits and plants, displays a variety of pharmacological activities including regulating blood glucose and lipids, anti-oxidation, anti-inflammation and anti-fibrosis. The study was aimed to investigate the renal protective effects of FA on diabetic rats and elucidate the underlying mechanisms. FA (100 mg kg-1, i.g., once a day) was administered to DN rats for 8 weeks. The organ coefficient of kidneys was calculated. Levels of UP, BUN, Cr, FBG, TC and TG in serum were measured. Activities of SOD, CAT and GPx and the content of MDA in renal tissues were assayed. Pathological changes in renal tissues were observed by HE staining, PAS staining, PASM staining, Masson staining and transmission electron microscopy. p-NF-κB p65, TNF-α, TGF-β1, collagen IV, nephrin and podocin protein expressed in renal tissues were determined by immunohistochemistry and western blotting. Results showed that FA significantly improved the kidney organ coefficient, decreased the UP, BUN, Cr, FBG, TC and TG levels in serum, increased SOD, CAT and GPx activities, reduced MDA content in renal tissues and alleviated pathological injury of the renal tissues. What's more, long-term treatment with FA considerably down-regulated the expressions of p-NF-κB p65, TNF-α, TGF-β1 and collagen IV proteins, and up-regulated the expressions of nephrin and podocin proteins in renal tissues. FA could be a renoprotective agent by attenuating oxidative stress, inflammation, and fibrosis, as well as improving podocyte injury in STZ-induced DN rats.

Effect of dapagliflozin alone and in combination with insulin in a rat model of type 1 diabetes

Dapagliflozin is a selective sodium-glucose cotransporter 2 (SGLT2) inhibitor; it reduces glucose reabsorption via the kidney and increases the glucose excretion in urine. This inhibitor functions through a unique insulin-independent mechanism, and is therefore a potential new approach for the treatment of hyperglycemia in patients with diabetes. In this study, we evaluated the effectiveness of the SGLT2 inhibitor, dapagliflozin, by using a rat model of type 1 diabetes. Type 1 diabetes was induced by a single intraperitoneal injection of 60 mg/kg streptozotocin (STZ). The STZ-induced rats showed marked hyperglycemia and other metabolic abnormalities. We clarified the hypoglycemic effect of the combination treatment of dapagliflozin with a low dose of insulin compared with dapagliflozin alone and insulin alone in 3-week and 8-week studies. Our results showed that dapagliflozin in combination with a low dose of insulin significantly lowered hyperglycemia, hypercholesterolemia, and hypertriglyceridemia. Furthermore, the antioxidant status and body weight were improved. In contrast, treatment with dapagliflozin alone did not improve the blood glucose levels, lipid profile, antioxidant status, or body weight. These findings suggested that in type 1 diabetes, dapagliflozin was effective in combination with a low dose of insulin; however, the administration of dapagliflozin alone did not achieve a significant effect.

Ethyl Vanillin Protects against Kidney Injury in Diabetic Nephropathy by Inhibiting Oxidative Stress and Apoptosis.

Diabetes-induced oxidative stress and apoptosis is regarded as a critical role in the pathogenesis of diabetic nephropathy (DN). Treating diabetes-induced kidney damage and renal dysfunction has been thought a promising therapeutic option to attenuate the development and progression of DN. In this study, we investigated the renoprotective effect of ethyl vanillin (EVA), an active analogue of vanillin isolated from vanilla beans, on streptozotocin- (STZ-) induced rat renal injury model and high glucose-induced NRK-52E cell model. The EVA treatment could strongly improve the deterioration of renal function and kidney cell apoptosis in vivo and in vitro. Moreover, treating with EVA significantly decreased the level of MDA and reactive oxygen species (ROS) and stabilized antioxidant enzyme system in response to oxidative stress by enhancing the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in vivo and in vitro. Furthermore, EVA also markedly suppressed cleaved caspase-3, Bax, and nuclear transcription factor erythroid 2-related factor (Nrf2) expression in STZ-induced rats. Therefore, these results of our investigation provided that EVA might protect against kidney injury in DN by inhibiting oxidative stress and cell apoptosis.

Cyclocarya paliurus triterpenic acids fraction attenuates kidney injury via AMPK-mTOR-regulated autophagy pathway in diabetic rats

BackgroudDiabetic nephropathy is the most serious complication of diabetes. Cyclocarya paliurus (CP), an herbal plant in China, has been reported the biological activity of anti-hyperglycemia. However, its effects on the diabetic nephropathy (DN) remain unclear. PurposeWe aimed to investigate the potential role of CP and its underlying mechanisms on DN. Study designIn this study, the effects of triterpenic acids-enriched fraction from CP (CPT) on DN was evaluated in streptozotocin (STZ)-induced rats and high glucose (HG)-induced HK-2 cells models. MethodsAfter oral administration with or without CPT for 10 weeks, body weight, glucose, microalbumin, serum creatinine and blood urea in STZ-induced rats were detected. Histological analysis was performed to evaluate renal function of mice. Moreover, the level of autophagy was detected by western blot or immunostaining. In vitro, HG-induced HK-2 cell was conducted to evaluate the renal protection and mechanism of CPT. ResultsCPT dramatically decreased the levels of microalbumin, serum creatinine and blood urea nitrogen and ameliorated increased mesangial matrix and glomerular fibrosis. In addition, we found the CPT prevented renal damage and cell apoptosis through the autophagy. Furthermore, CPT could increase the phosphorylation of AMPK and decrease its downstream effector phosphorylation of mTOR. Besides, the expression of LC3-II were locked by AMPK inhibitor dorsomorphin dihydrochloride (compound C), implying that the autophagy may be regulated with AMPK activation. ConclusionThese findings suggested that CPT might be a desired candidate against diabetes, potentially through AMPK-mTOR-regulated autophagy pathway.

Phosphorylated Glycogen Synthase Kinase-3β (GSK-3β) Improves Cognition in Rats with Diabetes-Associated Cognitive Decline.

BackgroundThe serine/threonine kinase glycogen synthase kinase-3β (GSK-3β) is involved in a broad range of cellular processes, including cell proliferation, apoptosis, and inflammation. GSK-3β has been considered to play an important role in the pathogenesis of T2DM and AD, which is activated in both the periphery and central nervous system. However, the upstream and downstream factors and the underlying regulatory mechanisms of GSK-3β in T2DM and AD are unclear.Material/MethodsHere, we investigated the production of cytochrome C, Caspase-3, and Caspase-9 in in the hippocampus of DM rats and clarify the role of GSK-3β in these processes. Streptozotocin (STZ)-induced DM rats presented increased GSK-3β activity.ResultsWe found that cytochrome C, Caspase-3, and Caspase-9 were overproduced in the hippocampus. Furthermore, the cytochrome C, Caspase-3, and Caspase-9 levels were restored after GSK-3β inhibitors Licl treatment.ConclusionsOur results show that GSK-3β regulates the production of cytochrome C, Caspase-3, and Caspase-9 in STZ-induced rat brain and may therefore contribute to DM-caused cognitive dysfunction via inhibition of neural cell apoptosis.

Puerarin alleviates streptozotocin (STZ)-induced osteoporosis in rats through suppressing inflammation and apoptosis via HDAC1/HDAC3 signaling

Diabetic osteoporosis is a severe public health concern in the world. Puerarin (PU) is extensively attractive due to its superior bioactivities. In the study, we found that PU protected against streptozotocin (STZ)-induced osteoporotic changes in rats. PU treatment improved STZ-induced diabetes in rats, as evidenced by the reduced serum glucose and insulin levels. PU administration markedly attenuated bone loss and tartarate-resistant acid phosphatase (TRAP) activity in STZ-induced rats. Bone mineral density (BMD) was significantly decreased in diabetic rats, while being prevented by PU. STZ-induced impairments in microarchitecture of femoral tissues were markedly alleviated by PU treatment. In addition, bone-specific alkaline phosphatase (BALP), osteoprotegerin (OPG) and Runt-related transcription factor 2 (Runx2) levels in serum or tibia were improved by PU in STZ-injected rats; however, TRACP isoform 5b (TRACP-5b), carboxy-terminal collagen cross-links (β-CTX) and receptor activator of nuclear factor-κB ligand (RANKL) levels were decreased. Further, PU treatment inhibited inflammation and apoptosis in STZ-treated rats. Additionally, STZ injection increased histone deacetylase (HDAC)-1 and -3 expressions in femoral heads of rats, which were relieved by PU treatment. Notably, both HDAC1 and HDAC3 could enhance osteoporosis in vitro, as proved by the decreased ALP and Runx2 levels and the increased TRAP expression. Inflammation and apoptosis were exacerbated by HDAC1/3 over-expression, which were markedly diminished by PU treatment. In contrast, suppressing HDAC1/3 significantly abrogated fructose (Fru)-elicited inflammation and apoptosis in cells. Collectively, our data illustrated that PU is a potential therapeutic option to prevent diabetic osteoporosis by inhibiting HDAC1/HDAC3 signaling.

Diabetic Wound Healing Biosurfactants Dialkyl Alginate Cream on TNF-α TGF-β Expression, Reepithelization, and Collagenization

Diabetic wound healing is delayed by many factors, including high TNF-α expression and low TGF-β expression which can affect the formation of new epithelial tissue and collagen as the main goal of the wound healing process. One of the diabetic wound healing agent is biosurfactant dialkyl alginate where so far its use in cream form for diabetic wound has never been reported. This study aimed to determine TNF-α, TGF-β, reepithelization and the collagenization of biosurfactant dialkyl alginate cream in diabetic biopsy wounds in STZ-induced rat. Biosurfactant dialkyl alginate was made in cream form and applied to biopsy wounds on the backs of rat twice a day for 9 days. Observation of TNF-α and TGF-β expression were performed by immunohistochemical staining, while epithelial and collagen with staining HE and Mallory. The results showed that the biosurfactant dialkyl alginate cream had an activity to decrease TNF-α expression, increase TGF-β expression and reepithelization but did not have any significant activity on collagenization. These results suggest that the biosurfactant dialkyl alginate cream can accelerate the healing of diabetic wound.