Effect of lipoprotein-associated phospholipase A2 inhibitor on insulin resistance in streptozotocin-induced diabetic pregnant rats

Anti-Diabetic and Insulinotropic Effects of p-Anisic Acid in High-Fat Diet and Streptozotocin Induced Type-2 Diabetic Rats

PURPOSE

To evaluate the antidiabetic effect of p-anisic acid (p-AA) against type 2 diabetes mellitus (T2DM).

METHODS

Thirty-six male rats were utilized for the study. The animals were provided with the high-fat diet (HFD) and T2DM was induced through 35 mg/kg streptozotocin (STZ). Subsequently, the animals were allocated to 6 groups and subjected to the treatments for 4 weeks followed by a 2-week observation. Three treatment groups were administered with p-AA (25 mg/kg, 50 mg/kg or 100 mg/kg). Glibenclamide (3 mg/kg) was provided to the standard control group. The normal control and disease control groups were supplied with 0.1 % carboxymethyl cellulose (CMC). Subsequently, the effects of treatment on body weight (BW), blood glucose level (BGL), glycosylated haemoglobin (HbA1c), insulin, and lipid parameters were measured and the pancreas was isolated for histopathology.

RESULTS

A statistically significant (P-value<0.001) increase in BW was observed in the p-AA (50 mg/kg and 100 mg/kg) groups. The BGL decreased significantly (P-value<0.001) in p-AA groups. p-AA significantly (P-value<0.001) regulated the levels of HbA1c and serum insulin and lipid parameters. A notable improvement in the morphology of the pancreas was observed.

CONCLUSION

Treatment with p-AA exhibited significant antidiabetic effects against STZ-HFD-induced T2DM.

The changes of Lp-PLA2 in patients with gestational diabetes and its clinical significance

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy and associated with adverse pregnancy outcomes. The aim of this study was to investigate the changes of lipoprotein-associated phospholipaseA2 (Lp-PLA2) level and its correlation with biochemical indexes in patients with GDM.This observational cross-sectional study was performed among 52 GDM and 48 healthy pregnant women. Automatic biochemical analyzer was employed to test the biochemical indexes, including fasting plasma glucose (FPG), Hemoglobin A1c (HbA1c), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). The lipoprotein-associated phospholipaseA2 (Lp-PLA2) level was evaluated by enzyme-linked immunosorbent assay, and homeostatic model assessment for insulin resistance (HOMA-IR) was calculated.The levels of FPG, HbA1c, HOMA-IR, TG, TC and LDL-C were significantly increased while high-density lipoprotein cholesterol (HDL-C) level was significantly decreased in the GDM group when compared with those in the control group. Lp-PLA2 level in maternal blood in the GDM group was significantly higher than that in the control group (199.125 ± 23.494 vs165.825 ± 15.576 ng/mL, P < .05) and logistic regression analysis further confirmed the association of Lp-PLA2 levels with GDM. Furthermore, Lp-PLA2 positively correlated with HOMA-IR, TC, and LDL-C.Our results confirmed the association of Lp-PLA2 with GDM. This broadens our knowledge on the pathophysiology of GDM and provides insights into the development of new targets for the prevention and treatment of GDM.

Combination treatment strategies with a focus on rosiglitazone and adriamycin for insulin resistant liver cancer

Insulin resistance promotes the occurrence of liver cancer and decreases its chemosensitivity. Rosiglitazone (ROSI), a thiazolidinedione insulin sensitiser, could be used for diabetes with insulin resistance and has been reported to show anticancer effects on human malignant cells. In this paper, we investigated the combination of ROSI and chemotherapeutics on the growth and metastasis of insulin-resistant hepatoma. In vitro assay, ROSI significantly enhanced the inhibitory effects of adriamycin (ADR) on the proliferation, autophagy and migration of insulin-resistant hepatoma HepG2/IR cells via downregulation of EGFR/ERK and AKT/mTOR signalling pathway. In addition, ROSI promoted the apoptosis of HepG2/IR cells induced by ADR. In vivo assay, high fat and glucose diet and streptozotocin (STZ) induced insulin resistance in mice by increasing the body weight, fasting blood glucose (FBG) level, oral glucose tolerance, fasting insulin level and insulin resistance index. Both the growth of mouse liver cancer hepatoma H22 cells and serum FBG level in insulin resistant mice were significantly inhibited by combination of ROSI and ADR. Thus, ROSI and ADR in combination showed a stronger anti-tumour effect in insulin resistant hepatoma cells accompanying with glucose reduction and might represent an effective therapeutic strategy for liver cancer accompanied with insulin resistant diabetes.

Downregulation of microRNA-873 attenuates insulin resistance and myocardial injury in rats with gestational diabetes mellitus by upregulating IGFBP2

Gestational diabetes mellitus (GDM) is a metabolic disorder characterized by insulin resistance, and patients with GDM have a higher risk of cardiovascular disease. Multiple microRNAs (miRNAs) are reported to be involved in the regulation of myocardial injury. Moreover, miR-873 was predicted to target insulin-like growth factor binding protein 2 (IGFBP2) through bioinformatic analysis, which was further confirmed using a luciferase assay. Thus, our objective was to assess whether microRNA-873 (miR-873) affects insulin resistance and myocardial injury in an established GDM rat model. The GDM rats were treated with miR-875 mimic or inhibitor or IGFBP2 siRNA. The effects of miR-875 and IGFBP2 on the cardiac function, insulin resistance, and myocardial injury were evaluated by hemodynamic measurements, determination of biochemical indices of myocardium and serum, and insulin homeostatic model assessment. The results indicated that downregulation of miR-873 upregulated the expression of IGFBP2 and promoted the activation of phosphatidylinositol-3 kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) axis. With downregulation of miR-873 in GDM rats, the cardiac function was improved and the myocardial apoptosis was inhibited, coupled with elevated activity of superoxide dismutase, carbon monoxide synthase, and the nitric oxide content. In addition, the inhibition of miR-873 in GDM rats modulated the insulin resistance and reduced myocardial apoptosis. Overall, the data showed that inhibition of miR-873 by targeting IGFBP2 may regulate the insulin resistance and curtail myocardial injury in GDM rats through activating the PI3K/AKT/mTOR axis, thus providing a potential means of impeding the progression of GDM.

Metformin alleviates oxidative stress and enhances autophagy in diabetic kidney disease via AMPK/SIRT1-FoxO1 pathway

Metformin, as the basic pharmacological therapy and the first preventive drug in type 2 diabetes mellitus (T2DM), is proved to have potential protection in diabetic kidney disease (DKD). Here, we established a diabetic rat model induced by high-fat diet and low dose streptozotocin, and high glucose cultured rat mesangial cells (RMCs) pre-treated with metformin or transfected with AMPK, SIRT1 and FoxO1 small interfering RNA, and detected oxidative stress and autophagy related factors to explore the molecular mechanisms of metformin on DKD via adenosine monophosphate-activated protein kinase (AMPK)/silent mating type information regulation 2 homolog-1 (sirtuin-1, SIRT1)-Forkhead box protein O1 (FoxO1) pathway. We found that metformin effectively alleviated the disorders of glycolipid metabolism, renal function injury in diabetic rats, and relieved oxidative stress, enhanced autophagy and slowed down abnormal cell proliferation in high glucose cultured RMCs through AMPK/SIRT1-FoxO1 pathway, indicating the protective role of metformin against the pathological process of DKD.