[Mechanism of Danzhi Jiangtang Capsules on improving liver injury in hyperlipidemia rats based on MAPK pathway].

This study aimed to investigate the protective effect and preliminary mechanism of Danzhi Jiangtang Capsules( DJC) on liver of hyperlipidemic rats. The hyperlipidemia models were successfully made by high-fat diet for 12 weeks in male SD rats,and then divided into model control group and DJC treatment groups( 500 and 1 000 mg·kg~(-1)·d-1) via gavage administration for additional 8 weeks.The levels of serum lipid and liver metabolism indices were detected; HE and oil red O staining were used to observe the pathological changes of liver. Expression levels of extracellular regulated protein kinase 1/2( ERK1/2),c-Jun N-terminal kinase( JNK),and p38 mitogen-activated protein kinase( p38 MAPK) were detected by real-time polymerase chain reaction( RT-PCR). Expression of MCP-1,phosphorylated ERK( p-ERK),phosphorylated JNK( p-JNK),and phosphorylated p38 MAPK( p-p38) were analyzed by immunohistochemistry and Western blot. The results showed that DJC decreased body weight and serum levels of total cholesterol( TC),triglyceride( TG),alanine aminotransferase( ALT),aspartate aminotransferase( AST),increased serum high-density lipoprotein cholesterol( HDL-C) level,ameliorate injury and lipid deposition in the liver induced by the high-fat diet,decreased mRNA expression of ERK1/2,JNK and p-38 MAPK as well as protein expression of p-ERK,p-JNK,p-p38,and MCP-1,somewhat showing a dose-dependent effect. Therefore,DJC has an obvious protective effect on liver of hyperlipidemic rats with certain dose-dependent effect,and the mechanism may be related with inhibiting MAPK pathways and inflammation.

[Study on the mechanism of action of total flavonoids of Litsea coreana for reducing blood glucose level in rat with type 2 diabetes mellitus].

OBJECTIVE: To explore the possible mechanism of total flavonoids of Litsea coreana (TFLC) on reducing blood glucose level in rat with type 2 diabetes mellitus (T2DM). METHODS: Male SD rats of T2DM allocated in two groups were treated with 400 mg/kg TFLC or metformin respectively via gastrogavage for 6 weeks. Blood routine biochemical indices in rats were measured; pathology of rats' liver was examined with HE stain under transmission electron microscopy; levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in liver homogenate were determined, and the expression of protein tyrosine phosphatase 1B (PTP1B) in liver was detected using RT-PCR at the terminal of the experiment. RESULTS: Biochemical measuring showed that the glucose tolerance of rats after treatment was markedly improved in both groups. Meantime, levels of fast blood glucose (FBG), glycohemoglobin (HbA1c), fast blood insulin (FINS), free fatty acid (FFA), total cholesterol (TC), triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C), as well as MDA level in liver were decreased, while levels of high density lipoprotein-cholesterol (HDL-C) in blood and SOD in liver were significantly increased in both groups after treatment, showing insignificant difference between two treatment groups. Light microscopic examination showed markedly fatty degeneration of liver, and electron microscopic examination found mitochondria swelling and endoplasmic reticulum breakage in liver of T2DM rats, but these changes were ameliorated to some extent after treatment. The elevated PTP1B expression in liver of T2DM rats was decreased in the TFLC treated group, but unchanged in the metformin treated group. CONCLUSION: TFLC can significantly decrease the blood levels of glucose and lipid and ameliorate oxidation stress in liver; its mechanism of action in improving insulin resistance might be related with its suppression on PTP1B expression in rat's liver to enhance the insulin signaling pathway.

Antidiabetic effects of total flavonoids from Litsea Coreana leve on fat-fed, streptozotocin-induced type 2 diabetic rats.

This study was initiated to determine the possible antidiabetic effects of total flavonoids of Litsea Coreana leve (TFLC), an alcohol extract from the dried leaves of Litsea Coreana leve, on type 2 diabetic rats. Male Sprague-Dawley rats (n = 40, 160-180 g) were divided into two groups and fed with normal chow diet (Normal Control group) or high-fat diet (HFD) for a period of 4 weeks. After 4 weeks of dietary manipulation, the HFD-fed rats were injected with 30 mg/kg streptozocin (STZ) to induce diabetes 72 hours after STZ injection. These diabetic rats were randomly divided into 3 groups (n = 10): Diabetic Control group, Diabetic + TFLC group and Diabetic + PIO group. Diabetic + TFLC group and Diabetic + PIO group were orally administered with 400 mg/kg TFLC or 10 mg/kg pioglitazone (all suspended in 0.5% CMC-Na) respectively for 6 weeks. All rats were examined for body weight, serum and hepatic biochemical indices, content of malondialdehyde (MDA), activities of superoxide dismutase (SOD) and pathological changes in liver and pancreas, as well as protein tyrosine phosphatase 1B (PTP1B) expression in liver. The diabetic rats became obese, insulin resistant, hyperglycemic and hyperlipidemic. Treatment with TFLC showed a significant increase in insulin sensitivity, serum HDL-C level and SOD activities, meanwhile marked decrease in body weight, serum FFA, TC, TG, LDL-C, CRP, MDA content. TFLC also attenuated pathologic alterations in liver and pancreatic islet. Furthermore, TFLC was found to decrease the expression of PTP1B in diabetic rat liver. These results suggested that TFLC could ameliorate hyperglycemia, hyperlipoidemia, inflammation and oxidation stress, as well as insulin resistance of type 2 diabetic rats.