Effects of Modified Sanzi Yangqin Decoction on Tyrosine Phosphorylation of IRS-1 in Skeletal Muscle of Type 2 Diabetic Rats.

Ya Wang,Yushan Dong,Xiaojin La,Ji’An Li,Xiujuan Gao,Feng Qi,Changlong Qiu,Chunyu Tian

doi:10.1155/2018/7092140

Abstract

This study aimed to investigate the effect of Modified Sanzi Yangqin Decoction on tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1) in skeletal muscle of type 2 diabetic rats. The rat model of type 2 diabetes was induced by high-fat diet and multiple low-dose streptozotocin injections. Diabetic model rats were randomly divided into 5 groups: the model control group, the metformin group, and Modified Sanzi Yangqin Decoction groups of low, medium, and high doses. OGTT was conducted every two weeks during treatment period. At the end of the treatment, the fasting blood glucose (FBG) level and the fasting C-peptide level were measured to calculate insulin resistance index. The levels of IRS-1, p-IRS-1(Tyr895), and protein tyrosine phosphates 1B (PTP1B) in skeletal muscle were also measured. Modified Sanzi Yangqin Decoction significantly reduced the FBG level, increased the fasting C-peptide level, and lowered the insulin resistance index in type 2 diabetic rats. It also significantly increased the protein level of p-IRS-1(Tyr895) and reduced the PTP1B protein level in skeletal muscle of type 2 diabetic rats. Modified Sanzi Yangqin Decoction increases tyrosine phosphorylation of IRS-1 in skeletal muscle of type 2 diabetic rats, which results from the increase of p-IRS-1(Tyr895) protein and is related to the suppression of PTP1B protein.

Highlights

Type 2 diabetes mellitus (T2DM) is one of the world’s most common health issues and its incidence has been growing at a high rate [1, 2]
We evaluated the improvement of insulin resistance and studied the effect of Modified Sanzi Yangqin Decoction on insulin receptor substrate 1 (IRS-1), p-IRS-1(Tyr895), and protein tyrosine phosphates 1B (PTP1B), key molecules involved in the insulin signal transduction pathway
On day 14 after drug treatment, fasting blood glucose (FBG) levels were significantly increased in all diabetic rats (p < 0.05); 2 h postprandial blood glucose (2 hPG) levels were significantly reduced in MSYD groups (p < 0.05), but it remained at high levels in metformin group (MET) and T2DCn

Summary

Introduction

Type 2 diabetes mellitus (T2DM) is one of the world’s most common health issues and its incidence has been growing at a high rate [1, 2]. T2DM and its complications have high risk of disabilities and mortality rates [1]. Insulin resistance (IR) is an important pathological condition of T2DM, in which the body is still able to produce insulin but the cells become resistant to its effect, making insulin ineffective in regulating blood sugar levels. Insulin levels may become insufficient as well. Both the insulin resistance and deficiency lead to high blood glucose levels. Increasing insulin sensitivity is an important and effective therapy for T2DM [3]

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