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Open Access Research article

Guava leaf extracts promote glucose metabolism in SHRSP.Z-Leprfa/Izm rats by improving insulin resistance in skeletal muscle

Xiangyu Guo1, Hisae Yoshitomi2, Ming Gao2*, Lingling Qin1, Ying Duan3, Wen Sun1, Tunhai Xu4, Peifeng Xie1, Jingxin Zhou1, Liansha Huang1 and Tonghua Liu4*

Author Affiliations

1 Department of Endocrinology, Dongfang Hospital of Beijing University of Chinese Medicine, No.6, 1st Area Fangxing Yuan, 100078, Fangzhuang Fengtai District, Beijing, China

2 School of Pharmaceutical Sciences of Mukogawa Women’s University, 11-68 Koshien-Kyuban-cho, 663-8179, Nishinomiya, Hyogo, Japan

3 Department of Chinese Medicine, Tongren Hospital of Capital Medical University, No.2, Chongwenmennei Street, 100730, Dongcheng District, Beijing, China

4 Department of Science and Technology, Beijing University of Chinese Medicine, No.11, North 3rd-ring East Road, 100029, Chao Yang District, Beijing, China

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BMC Complementary and Alternative Medicine 2013, 13:52  doi:10.1186/1472-6882-13-52

Published: 1 March 2013

Abstract

Background

Metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM) have been associated with insulin-resistance; however, the effective therapies in improving insulin sensitivity are limited. This study is aimed at investigating the effect of Guava Leaf (GL) extracts on glucose tolerance and insulin resistance in SHRSP.Z-Leprfa/Izm rats (SHRSP/ZF), a model of spontaneously metabolic syndrome.

Methods

Male rats at 7 weeks of age were administered with vehicle water or treated by gavage with 2 g/kg GL extracts daily for six weeks, and their body weights, water and food consumption, glucose tolerance, and insulin resistance were measured.

Results

Compared with the controls, treatment with GL extracts did not modulate the amounts of water and food consumption, but significantly reduced the body weights at six weeks post treatment. Treatment with GL extracts did not alter the levels of fasting plasma glucose and insulin, but significantly reduced the levels of plasma glucose at 60 and 120 min post glucose challenge, also reduced the values of AUC and quantitative insulin sensitivity check index (QUICKI) at 42 days post treatment. Furthermore, treatment with GL extracts promoted IRS-1, AKT, PI3Kp85 expression, then IRS-1, AMKP, and AKT308, but not AKT473, phosphorylation, accompanied by increasing the ratios of membrane to total Glut 4 expression and adiponectin receptor 1 transcription in the skeletal muscles.

Conclusions

These data indicated that GL extracts improved glucose metabolism and insulin sensitivity in the skeletal muscles of rats by modulating the insulin-related signaling.