Establishment of a diabetic myocardial hypertrophy model in Mus musculus castaneus mouse

miR-31 ameliorates type 2 diabetic vascular damage through up-regulation of hypoxia-inducible factor-1α/vascular endothelial growth factor-A

AIMS

microRNA may be a new therapeutic direction for diabetes. As a typical tumor marker, miR-31 is involved in a variety of metabolic diseases, but the specific role is still unclear. This study aimed to investigate the effect of miR-31 on type 2 diabetes mellitus and its accompanying vascular injury, as well as on the effects of hypoxia-inducible factor-1α inhibitor (HIF1AN), hypoxia-inducible factor (HIF)-1α, and vascular endothelial growth factor (VEGF)-A expression in vitro and in vivo.

MATERIALS AND METHODS

In vitro, a model of high-fat and high-glucose-induced human aortic endothelial cell (HAEC) injury was established to simulate diabetes mellitus (DM). Cell functions were compared between the control group, the DM damage group, and the group transfected with miR-31 after DM damage. In vivo, overexpressing miR-31 FVB mice and FVB mice were divided into the control and induced type 2 diabetes mellitus groups. Type 2 diabetes mellitus models were induced by a high-fat diet combined with streptozotocin. The lipid metabolism levels, viscera, and vascular damage were compared between the control and type 2 diabetes mellitus groups.

RESULTS

In vitro, miR-31 improved the proliferation ability of damaged cells by targeting HIF1AN and up-regulating the expression of HIF-1α and VEGF-A. In vivo, miR-31 ameliorated the development of type 2 diabetes mellitus, disturbance of glucose and lipid metabolism, and damage to some organs. Meanwhile, miR-31 had a protective effect on vascular damage complicated by type 2 diabetes mellitus by increasing the levels of HIF-1α and VEGF-A.

CONCLUSION

Our experiments show that miR-31 can delay the progression of type 2 diabetes mellitus and ameliorate diabetic vascular injury.

Activation of Kir2.1 improves myocardial fibrosis by inhibiting Ca 2+ overload and the TGF-β1/Smad signaling pathway

The inwardly rectifying potassium channel Kir2.1 is closely associated with many cardiovascular diseases. However, the effect and mechanism of Kir2.1 in diabetic cardiomyopathy remain unclear. In vivo, we use STZ to establish the model, and ventricular structural changes, myocardial inflammatory infiltration, and myocardial fibrosis severity are detected by echocardiography, histological staining, immunohistochemistry, and western blot analysis, respectively. In vitro, a myocardial fibrosis model is established with high glucose. The Kir2.1 current amplitude, intracellular calcium concentration, fibrosis-related proteins, and TGF-β1/Smad pathway proteins are detected by whole-cell patch clamp, calcium probes, western blot analysis, and immunofluorescence, respectively. The in vivo results show that compared to diabetic cardiomyopathy, zacopride (a Kir2.1 selective agonist) significantly reduces the left ventricular systolic diameter and diastolic diameter, increases the left ventricular ejection fraction and left ventricular short-axis shortening, improves the degree of cell necrosis, and reduces the expression of myocardial interstitial fibrosis protein and collagen fibre deposition area. The in vitro results show that the current amplitude and protein expression of Kir2.1 are both decreased in the high glucose-induced myocardial fibrosis model. Additionally, zacopride significantly upregulates the expression of Kir2.1 and inhibits the expressions of the fibrosis-related proteins α-SMA, collagen I, and collagen III. Activation of Kir2.1 reduces the intracellular calcium concentration and inhibits the protein expressions of TGF-β1 and p-Smad 2/3. Activation of Kir2.1 can improve myocardial fibrosis induced by diabetic cardiomyopathy, and the possible mechanism may be related to inhibiting Ca ²⁺ overload and the TGF-β1/Smad signaling pathway.

Chemical Constituents and Antidiabetic Activity of Dichloromethane Extract from Ficus carica Leaves

PURPOSE

To evaluate the dichloromethane extract of Ficus carica leaves (FCL) had a hypoglycemic impact in diabetic mice, as well as to identify the bioactive components in the extract and analyze their anti-hyperglycemia potential in HepG2 cells.

MATERIAL AND METHODS

The antidiabetic activity of dichloromethane extract of Ficus carica leaves was evaluated in diabetic mice induced by streptozotocin (STZ,100 mg/kg) combined with high-fat diet. The fasting blood glucose (FBG), blood lipids, oral glucose tolerance, glycated hemoglobin (HbA1c), and pathological change effects of the extract were measured after administering two doses of the extract (500 and 1000 mg/kg). On the other hand, we used column chromatography to isolate the dichloromethane extract, and we structurally identified the compounds based on ¹H NMR and ³C NMR spectra. The hypoglycemic activity of isolated compounds was investigated in palmitic acid (PA)-induced HepG2 cells.

RESULTS

FCL extract lowers blood glucose and improves blood lipids and the pancreatic β-cell also tend to recover whether the psoralen is removed or not. Meanwhile, three coumarins except psoralen were isolated from dichloromethane extract: 3,4-dihydropsoralen, umbelliferone and 7-hydroxyl-6-methylcoumarin. Psoralen and umbelliferone promoted glucose uptake in HepG2 cells.

DISCUSSION AND CONCLUSION

In vivo experiments, dichloromethane extract of FCL has potential antidiabetic activity, mainly by lowering blood glucose, improving blood lipids, glucose tolerance and repairing pancreatic islet damage, which justifies its use in the treatment of diabetes in Spanish folklore. Additionally, in vitro experiments, psoralen and umbelliferone demonstrated substantial glucose-lowering activity.

Revealing the antiaging effects of cereal- and food oil-derived active substances by a Caenorhabditis elegans model

Cereal grains and oils contain various functional ingredients, such as amino acids, peptides, polyphenols, dietary fiber, linoleic acid, and natural pigments. Their biological activities are of great significance. Benefiting from its robust genetic function and simple cultivation, Caenorhabditis elegans, as one of the most important model organisms has been widely used to screen antiaging substances and investigate the underlying molecular mechanisms. In this paper, the recent advances in the use of C. elegans in antiaging research into active substances from cereals and oils will be assessed, and their potential signal transduction mechanisms will be systematically reviewed. This research aims to provide a theoretical reference for the use of active substances from cereals and oils to prevent and delay aging and aging-associated diseases.

lncRNA uc.48+ regulates immune and inflammatory reactions mediated by the P2X7 receptor in type 2 diabetic mice

Diabetes and non-coding RNAs are receiving increasing attention in contemporary medical research. The present study aimed to explore the role of the long non-coding RNA uc.48+ in the pathological changes of type 2 diabetes mellitus (T2DM) by observing the effects of uc.48+ small interfering RNA (siRNA) on the abdominal cells of a mouse model of T2DM. Mice with T2DM (DM group) were established by feeding with a high-sugar and -fat diet combined with intraperitoneal injections of low-dose streptozotocin. An intraperitoneal injection of uc.48+ siRNA was administered to the diabetic mice, and the serum levels of cytokines together with other clinical parameters, namely blood pressure, heart rate, mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were examined. Following the collection and identification of abdominal cells from the mice, the mRNA levels of uc.48+, mRNA and protein levels of the P2X₇ receptor, and phosphorylation levels of ERK1/2 were evaluated by reverse transcription-PCR and western blotting, respectively. The MWT and TWL were significantly decreased in the DM group compared with the non-diabetic control group. However, the reductions in MWT and TWL were significantly attenuated following uc.48+ siRNA injection. The systolic and diastolic blood pressure, as well as the serum levels of tumor necrosis factor α and interleukin 1β of mice in the DM group were significantly increased compared with those in the control group, whereas these changes were significantly attenuated following the injection of uc.48+ siRNA. In addition, the expression levels of P2X₇ receptor mRNA and protein, and the degree of phosphorylation of ERK1/2 in the abdominal cells were significantly increased in the DM group compared with the control group. These changes were also significantly attenuated following transfection with uc.48+ siRNA in vivo. In conclusion, these data suggest that uc.48+ may play an important role in the pathological changes of blood pressure, neurology and abdominal cell function in T2DM via interaction with the P2X₇ receptor.

Study on the mechanism of Gegen Qinlian Decoction for treating type II diabetes mellitus by integrating network pharmacology and pharmacological evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Gegen Qinlian Decoction (GQD) is a classic traditional Chinese medicine prescription that is widely used to clinically treat diabetes mellitus. It is composed of Pueraria lobata (Willd.) Ohwi (ge gen), Scutellaria baicalensis Georgi (huang qin), Coptidis chinensis Franch. (huang lian), and Glycyrrhiza uralensis Fisch. (gan cao). However, the active ingredients in GQD and their mechanism of action are unclear.

AIM OF THE STUDY

In this study, we aimed to verify the efficacy of GQD in improving insulin resistance (IR) in diabetic mice and used network pharmacology to identify potential targets and pathways underlying its mechanism of action.

MATERIALS AND METHODS

A mouse model of diabetes was created by feeding mice a high-fat diet followed by an intraperitoneal injection of streptozotocin. These type II diabetic mice were administered either a clinical dose or a high dose of GQD, after which blood glucose and serum insulin levels were measured to assess its effects on IR. Network pharmacology was used to construct a 'component-pathway-target' network to elucidate the likely targets and pathways modulated in common by GQD components. Furthermore, mRNA transcript levels and protein expression levels of oestrogen receptor alpha (ESR1) were determined.

RESULTS

The in vivo experiment showed that GQD markedly decreased blood glucose and increased serum insulin levels in type II diabetic mice. Network pharmacology and bioinformatics analysis indicated that GQD regulated 82 corresponding proteins and 59 relevant biological pathways associated with diabetes. One such target was ESR1, which was significantly decreased at both the mRNA and protein levels in diabetic mice, but whose levels were significantly increased by GQD treatment.

CONCLUSIONS

This project provides a scientific basis for understanding the effectiveness of multi-component, multi-target compound formulas, as well as a new strategy for investigating therapeutic drugs for type II diabetes and other diseases.

Metformin Shortens Prolonged QT Interval in Diabetic Mice by Inhibiting L-Type Calcium Current: A Possible Therapeutic Approach

The incidence and mortality of cardiovascular disease in diabetic patients are 2-3 times higher than those in non-diabetic patients. Abnormal function of the L-type calcium channel in myocardial tissue might result in multiple cardiac disorders such as a prolonged QT interval. Therefore, QT prolongation is an independent risk factor of cardiovascular disease in patients with diabetes mellitus. Metformin, a hypoglycemic agent, is widely known to effectively reduce the occurrence of macrovascular diseases. The aim of the present study was to evaluate the effect of metformin on prolonged QT interval and to explore potential ionic mechanisms induced by diabetes. Diabetic mouse models were established with streptozotocin and an electrocardiogram was used to monitor the QT interval after 4 weeks of metformin treatment in each group. Action potential duration (APD) and L-type calcium current (I_Ca-L) were detected by patch-clamp in isolated mice ventricular cardiomyocytes and neonatal cardiomyocytes of mice. The expression levels of CACNA1C mRNA and Cav1.2 were measured by real-time PCR, western blot and immunofluorescence. A shortened QT interval was observed after 4 weeks of metformin treatment in diabetic mice. Patch-clamp results revealed that both APD and I_Ca-L were shortened in mouse cardiomyocytes. Furthermore, the expression levels of CACNA1C mRNA and Cav1.2 were decreased in the metformin group. The same results were also obtained in cultured neonatal mice cardiomyocytes. Overall, these results verify that metformin could shorten a prolonged QT interval by inhibiting the calcium current, suggesting that metformin may play a role in the electrophysiology underlying diabetic cardiopathy.

Activation of 20-HETE/PPARs involved in reno-therapeutic effect of naringenin on diabetic nephropathy

Naringenin is a flavanone compound found in citrus fruits. Recent researches showed that naringenin has many potentially pharmacological effects. However, the therapeutic effect and the potential mechanism of naringenin on diabetic nephropathy (DN) remain to be elucidated. DN model was established by a high-fat diet combined with streptozotocin (STZ), which was confirmed by the levels of fasting blood glucose (FBG, more than 11.1 mmol/L) and urinary albumin (10 times higher than the normal mice). After 5 weeks of STZ injection, the DN was developed in model mice. Then naringenin (25 or 75 mg/kg·d) were supplemented for 4 weeks. At the end of the experiment, the injury of the renal function and structure was deteriorated. Concomitantly, peroxisome proliferators-activated receptors (PPARs) protein expression was down-regulated, and CYP4A expression and 20-hydroxyeicosatetraenoic acid (20-HETE) level were reduced in DN mice. Naringenin administration improved the renal damage of DN mice, and up-regulated PPARs expression, increased CYP4A-20-HETE level. Consistent with the results of in vivo, glucose at 30 mmol/L (high glucose, HG) significantly induced cell proliferation and hypertrophy in NRK-52E cells, following the reductive PPARs protein expression and the downward CYP4A-20-HETE level. Naringenin (0.01, 0.1, 1 μmol/L) reversed these changes induced by HG in a dose-dependent manner. HET0016, a selective inhibitor of 20-HETE synthase, partially blocked the effects of naringenin. In conclusion, naringenin has a therapeutic effect on DN, which may be, at least partly, related to the activation of CYP4A-20-HETE and the up-regulation of PPARs.

Establishment of a diabetic myocardial hypertrophy model in Mus musculus castaneus mouse

The aim of this study was to establish a robust model of diabetic myocardial hypertrophy in Mus musculus castaneus mice. Mice were fed a high-fat diet for four weeks and then given streptozotocin (STZ, 40 mg kg-1  d-1 for 5 days, intraperitoneally) and fasting blood glucose (FBG) levels were tested after seven days. Mice with FBG levels above 11.1 mmol/L were considered diabetic. Diabetic mice continued to have access to the high-fat diet until cardiac hypertrophy developed. FBG and body weight (BW) were measured weekly. Myocardial hypertrophy was confirmed by left ventricle (LV) hypertrophy index (LVHI), LV/BW, LV histopathological observation and atrial natriuretic factor (ANF) mRNA expression. Serum insulin and plasma haemoglobin A1c (HbA1c) levels, total cholesterol (TCH) and triglyceride (TG) were measured, and then an insulin resistance index (HOMA.IR) was calculated. The level of FBG in the model group remained above 11.1 mmol/L, and the BW showed significant weight loss, compared with the control group (P < 0.01). The high levels of HbA1c, HOME.IR, TCH and TG, and the low level of insulin suggested that glucose metabolism was not balanced with insulin resistance; meanwhile, higher TCH and TG showed that dyslipidaemia had also developed. After the diabetic mice were kept on the high-energy diet for another four  weeks, histopathological observation showed myocardial injuries, much more surface area and collagen fibres, higher LVHI and LV/BW, and elevated expression of ANF mRNA (P < 0.01), suggesting that myocardial hypertrophy had appeared in Mus musculus castaneus mice under the current experimental conditions. Thus a robust model of diabetic myocardial hypertrophy was established four  weeks after confirmation of diabetes, which was induced by feeding a high-fat diet for four weeks combined with a repeated low-dose STZ exposure, in Mus musculus castaneus mice.