Validation of the Antidiabetic and Hypolipidemic Effects of Hawthorn by Assessment of Gluconeogenesis and Lipogenesis Related Genes and AMP-Activated Protein Kinase Phosphorylation

Abstract

Since with the increased use of antidiabetic and antihyperlipidemic effect of phytonutrients for daily supplement has gained considerable attention worldwide, we examine the effect and molecular mechanism of Crataegus pinnatifida Bge. var. major N.E. Br. (hawthorn) by quantifying the expression of hepatic gluconeogenesis and lipogenesis on diabetes and dyslipidemia in high-fat (HF)-fed C57BL/6J mice. Firstly, mice were divided randomly into two groups: the control (CON) group was fed with a low-fat diet, whereas the experimental group was fed a 45% HF diet for 8 weeks. Afterwards, the CON group was treated with vehicle, whereas the HF group was subdivided into five groups and was given orally hawthorn extract (including 0.2, 0.5, 1.0 g/kg/day extracts) or rosiglitazone (Rosi) or vehicle for 4 weeks afterward. Diabetic mice showed an increase in plasma glucose and insulin. Glucose lowering was comparable with Rosi-treated mice. This study demonstrated that hawthorn was effective in ameliorating the HF diet-induced hyperglycemia, hypertriglyceridemia and hypercholesterolaemia. Hawthorn extract significantly increases the hepatic protein contents of AMP-activated protein kinase (AMPK) phosphorylation and reduces expression of phosphenol pyruvate carboxykinase (PEPCK) and glucose production. Furthermore, hawthorn decreased in hepatic triacylglycerol and cholesterol synthesis (including sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), SREBP2). An increase in expressions of apoA-I gene and high-density lipoprotein cholesterol (HDL-C) was detected in HF-fed mice treated with high dose hawthorn. Our data suggest that hawthorn extract are capable of decreasing glucose production and triacylglycerol synthesis by inducing AMPK-phosphorylation and hawthorn is a candidate source of antidiabetic and antihyperlipidemic phytonutrients factors.

Figure 1

Effects of extract of hawthorn on (a) plasma glucose, (b) triglyceride, (c) total cholesterol, and (d) HDL levels at week 12. Mice were fed 45% high-fat diet (HF) or low-fat diet (CON) for 12 weeks. At 8 weeks following HF, the HF mice were treated with vehicle (water; p.o.) or extracts of hawthornor rosiglitazone (p.o.) accompanied with HF diet for 4 weeks. All values are means ± S.E. (n = 9). ^# P < 0.05 compared with the control (CON) group; *P < 0.05, **P < 0.01, ***P < 0.001 compared with the high-fat + vehicle (distilled water) (HF) group by ANOVA.

Figure 2

Histology of the epididymal white adipose tissue (WAT) of mice in the (a) low-fat (LF), (b) high-fat (HF), (c) HF + K1, (d) HF + K2, (e) HF + K3, or (f) HF + Rosi groups. Each image presented is typical and representative of nine mice. Magnification: 10 (ocular) × 40 (object lens). K1: 0.2, K2: 0.5, and K3: 1.0 g/kg bodyweight) extracts of hawthorn; Rosi: rosiglitazone (0.01 g/kg bodyweight).

Figure 3

Semiquantitive RT-PCR analysis on (a) PEPCK, (b) SREBP1c, (c) FAS, (d) apo C-III, (e) apoA-I, and (f) SREBP2 mRNA expression in liver tissue of the mice by oral gavage extracts of hawthorn for 4 weeks. All values are means ± S.E. (n = 9). ^## P < 0.01, ^### P < 0.001 compared with the control (CON) group; *P < 0.05, **P < 0.01, ***P < 0.001 compared with the high-fat + vehicle (distilled water) (HF) group. K1, K2, K3, extracts of hawthorn.

Figure 4

The phospho-AMPK (Thr172) protein contents in liver tissue of the mice by oral gavage extracts of hawthorn for 4 weeks. Protein was separated by 12% SDS-PAGE detected by Western blot. All values are means ± S.E. (n = 9). *P < 0.05, ***P < 0.001 compared with the high-fat + vehicle (distilled water) (HF) group by ANOVA. K1, K2, K3, extracts of hawthorn.

Figure 5

Effects of extract of hawthorn on oral glucose tolerance in normal mice. Animals in all groups received oral glucose 30 minutes after the extract administration. Blood samples were collected and centrifuged at 3000 rpm for 10 minutes. Each point is the mean ± S.E. of 5 separate mice. *P < 0.05, **P < 0.01, ***P < 0.001 are significantly different compared with the control group in the same time by ANOVA.