Rosiglitazone protects diabetic rats from liver destruction

Protective Effects of Reduced Beta 2 Glycoprotein I on Liver Injury in Streptozotocin (STZ)-Diabetic Rats by Activation of AMP-Activated Protein Kinase

Background

Protective effects of reduced beta 2 glycoprotein I (Rβ2GPI) against vascular injury of diabetes mellitus have been extensively investigated. However, the effects of Rβ2GPI on liver injury in diabetic animals have not been reported.

Material/Methods

A diabetic rat model of was produced by systemic injection of streptozotocin (STZ). Rats were divided into a normal control group, a model group, and an Rβ2GPI treatment group (N=6 in each group). After treatments, blood serum and liver tissue were collected to test the protection of Rβ2GPI. AMP-activated protein kinase (AMPK) was detected by immunohistochemistry and Western blotting.

Results

Our results revealed that Rβ2GPI reduced blood glucose, serum creatinine, and urea nitrogen levels, as well as serum inflammation cytokines, including interleukin (IL)-6, tumor necrosis factor (TNF)-a and C-reactive protein in the diabetic rats. Importantly, Rβ2GPI prevented liver injury in the diabetic rats as confirmed by hematoxylin-eosin (H&E) staining, alanine transaminase, aspartate transaminase, and gamma-glutamyl transferase. Reactive oxygen species (ROS) were promoted by diabetic modeling and were attenuated by Rβ2GPI administration. Moreover, Rβ2GPI significantly reduced liver catalase, malondialdehyde, and superoxide dismutase levels in the diabetic rats. Rβ2GPI reduced liver glycolipid storage in STZ diabetic rats. Both immunohistochemistry and Western blotting demonstrated that Rβ2GPI promoted AMPK phosphorylation in the diabetic rats.

Conclusions

Our data proved that Rβ2GPI prevented liver injury in diabetic rats, likely through activating the AMPK signaling pathway.

Effects of Chimonanthus nitens Oliv. Leaf Extract on Glycolipid Metabolism and Antioxidant Capacity in Diabetic Model Mice

The paper investigated the antihyperglycemic and antihyperlipidemic efficacy and antioxidant capacity of Chimonanthus nitens Oliv. leaf extract (COE) in combination of high-glucose-fat diet-fed and streptozotocin-induced diabetic model mice. Various physiological indexes in diabetic model mice were well improved especially by oral administration of high dose of COE; the results were listed as follows. Fast blood glucose (FBG) level and serum triglyceride (TC), total cholesterol (TG), low-density lipoprotein cholesterol (LDLC), and malondialdehyde (MDA) as well as MDA in liver were significantly reduced; fasting serum insulin (FINS) and insulin sensitivity index (ISI) were both increased; high-density lipoprotein cholesterol (HDLC) in serum was significantly increased; total antioxidant capacity (T-AOC), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in serum and liver were apparently enhanced; liver coefficient (LC), liver transaminase, and alkaline phosphatase (ALP) were decreased. Furthermore, pancreas islets and liver in diabetic model mice showed some extend of improvement in morphology and function after 4 weeks of COE treatment. In consequence, COE was advantageous to regulate glycolipid metabolism and elevate antioxidant capacity in diabetic model mice. Thus, the present study will provide a scientific evidence for the use of COE in the management of diabetes and its related complications.

Effects of Chimonanthus nitens Oliv. Leaf Extract on Glycolipid Metabolism and Antioxidant Capacity in Diabetic Model Mice

The paper investigated the antihyperglycemic and antihyperlipidemic efficacy and antioxidant capacity of Chimonanthus nitens Oliv. leaf extract (COE) in combination of high-glucose-fat diet-fed and streptozotocin-induced diabetic model mice. Various physiological indexes in diabetic model mice were well improved especially by oral administration of high dose of COE; the results were listed as follows. Fast blood glucose (FBG) level and serum triglyceride (TC), total cholesterol (TG), low-density lipoprotein cholesterol (LDLC), and malondialdehyde (MDA) as well as MDA in liver were significantly reduced; fasting serum insulin (FINS) and insulin sensitivity index (ISI) were both increased; high-density lipoprotein cholesterol (HDLC) in serum was significantly increased; total antioxidant capacity (T-AOC), activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in serum and liver were apparently enhanced; liver coefficient (LC), liver transaminase, and alkaline phosphatase (ALP) were decreased. Furthermore, pancreas islets and liver in diabetic model mice showed some extend of improvement in morphology and function after 4 weeks of COE treatment. In consequence, COE was advantageous to regulate glycolipid metabolism and elevate antioxidant capacity in diabetic model mice. Thus, the present study will provide a scientific evidence for the use of COE in the management of diabetes and its related complications.

Rosiglitazone protects rat liver against acute liver injury associated with the NF-κB signaling pathway

Rosiglitazone, which is mainly used in the treatment of diabetes mellitus, is also involved in the regulation of inflammation. The peroxisome proliferator-activated receptor (PPAR)-γ receptor subtype appears to play a pivotal role in the regulation of inflammation. However, the exact mechanism for the protective effects of rosiglitazone against inflammation such as liver injury remains unclear. The aim of this study was to investigate the effects of rosiglitazone on inflammation in the liver of rats treated with D-GaIN/LPS. Male Sprague–Dawley rats were injected with D-GaIN/LPS with or without pre-administration of rosiglitazone (3, 10, or 30 mg/kg, intraperitoneal injection). Our data showed that rosiglitazone significantly inhibited D-GaIN/LPS-induced hepatotoxicity in a dose-dependent manner, as indicated by both diagnostic indicators of liver damage (serum aminotransferase activities) and histopathological analysis. Western blot analysis showed that rosiglitazone significantly decreased protein expression levels of COX-2 and production of pro-inflammatory markers, including TNF-α and IL-6, in D-GaIN/LPS-treated rat liver. The results indicated that the inhibition of D-GaIN/LPS-induced inflammation by rosiglitazone can be attributed, at least partially, to its capacity to regulate the the immunoregulatory transcription factor nuclear factor kappa B (NF-κB) signaling pathway.