Correlation between resistin gene expression and insulin sensitivity index in type 2 diabetic rat models

Zaigang YANG; Yun ZHU

ABSTRACT

BACKGROUND:

Resistin decreases insulin's action. Therefore might be a key molecule in the pathogenesis of type 2 diabetes mellitus in obese subjects.

OBJECTIVE:

To investigate the correlation of resistin gone expression and insulin sensitivity index (ISI) in type 2 diabetic rat models, and to explore the effect of rosiglitazone on resistin gone expression in a rat diabetic model.

DESIGN:

Randomized controlled animal study.

SETTING:

Department of Geratology, the First Affiliated Hospital of Zbengzhou University.MATERIALS Thirty 2-month-old healthy female Wistar rats were provided by Animal Center of Tongji Medical College,Huazhong University of Science and Technology. Common diets were provided by Animal Center of Tongji Medical College, Huazhong University of Science and Technology, and the gross calorific value was 14.88 J/g (mass fraction 0.2protein, 0.61 carbohydrate, 0.17 fat); furthermore, high-fat diets were mixed with common diets, saccharobiose, rendered lard, egg, and mild powder, and the gross calorific value was 20.083 J/g (mass fraction 0.09 protein, 0.51 carbohydrate, 0.38fat). Resistin and β -actin were synthesized in Beijing Salbaisheng Company.

METHODS:

This study was performed in the First Affiliated Hospital of Zhengzhou University from October 2006 to October 2007. The experimental for animal manipulation conforms to criteria of the university's ethnic committee. Two weeks after adaptability, rats were randomly divided into normal chew group (n=8) and high-fat diet group (n=22). Rats in the high-fat diet group underwent vena caudalis injection with streptozotoein (25 mg/kg), and two days later they were continued fed with high-fat diet. For normal chew group rats were injected with sodium citrate-citrate buffer solution (1 mL/kg) and continued normal chew. After 12 weeks, 15 rats in the high-fat diet group were hyperglycemic and were randomly divided into rosiglitazone (n=8) and high-fat diet diabetic group (n=7). Rats were lavaged with rosiglitazone (2 mg/kg/d) in the rosiglitazone group and with distilled water (8 mL/kg/d) in high-fat diet diabetic group; for normal chew group rats were lavaged with the same volume of distilled water. Rats were studied for four successive weeks.MAIN OUTCOME

MEASURES:

Fasting serum glucose was measured with glucose oxidase method; insulin by magnetic separation enzyme linked immunosorbent assay; triglyceride and total cholesterol levels by enzymic enzymatic method; ISI was calculated as [1/(fasting serum glucose × fasting insulin)]; resistin mRNA expression in greater omental adipose tissue was examined by RT-PCR; correlation between resistin gene and ISI analyzed by Spearman correlation and multivariate stepwise regression.

RESULTS:

Fifteen high-fat diet rats and eight normal chew rats were included in the final analysis. Resistin gene expression in the greater omental adipose tissue (A value) was 0.27±0.031 in the high-fat diet diabetic group (0.15±0.018) in the normal chew group, and (0.20±0.024) in rosiglitazone group (P < 0.01). Spearman correlation analysis and multiple stepwise regression analysis showed that resistin gene expression was positively correlated with fasting serum glucose (r=0.271, P < 0.01), fasting insulin (r=0.283, P < 0.01), and ISI (r =0.323, P < 0.01), apparent effects of resistin gene expression on ISI was 0.081.

CONCLUSION:

High-fat diet and diabetes increases resistin gene expression and rosiglitazone ameliorate its expression.The expression of resistin is correlated with ISI.