Expression of CTRP3, a novel adipokine, in rats at different pathogenic stages of type 2 diabetes mellitus and the impacts of GLP-1 receptor agonist on it

Abstract

This study aimed to investigate the expression of C1q/TNF-related protein-3 (CTRP3) in rats at different pathogenic stages of type 2 diabetes mellitus (T2DM) and the impacts of glucagon-like peptide-1 (GLP-1) receptor agonist on it. Male wistar rats were fed with high-fat diet for 10 weeks to induce insulin resistance (IR) and then were given low-dose streptozotocin (STZ) intraperitoneal injection to induce T2DM. Exendin-4 (Ex-4), a GLP-1 receptor agonist, was subcutaneous injected to the IR rats and T2DM rats for 4 weeks. The expression of CTRP3 mRNA and protein in epididymis adipose tissue of rats at the stage of IR was lower significantly than that of normal control (NC) rats and decreased more when they were at the stage of overt T2DM (all P < 0.05 or P < 0.01). After the treatment with Ex-4, the mRNA and protein expressions of CTRP3 were increased by 15.5% (P < 0.01) and 14.8% (P < 0.05), respectively, in IR rats and increased by 20.6% (P < 0.01) and 16.5% (P < 0.05), respectively, in T2DM rats. Overall, this study found that the expression of CTRP3 in visceral adipose tissue was progressively decreased in a T2DM rat model from the pathogenic stage of IR to overt diabetes, while Ex-4 treatment increased its expression in such animals.

Figure 1

The curve of rats' body weight. NC: normal control group; IR: insulin resistance group; DM: diabetes mellitus group; IR + Ex-4: insulin resistance plus Exendin-4 treatment group; DM + Ex-4: diabetes mellitus plus Exendin-4 treatment group.

Figure 2

CTRP3 mRNA expression at the different stages of T2DM pathogenesis. NC: normal control group; IR: insulin resistance group; DM: diabetes mellitus group; IR + Ex-4: insulin resistance plus Exendin-4 treatment group; DM + Ex-4: diabetes mellitus plus Exendin-4 treatment group; ^∗ P < 0.01, ^# P < 0.05.

Figure 3

CTRP3 protein expression at the different stages of T2DM pathogenesis. NC: normal control group; IR: insulin resistance group; DM: diabetes mellitus group; IR + Ex-4: insulin resistance plus Exendin-4 treatment group; DM + Ex-4: diabetes mellitus plus Exendin-4 treatment group; ^∗ P < 0.01, ^# P < 0.05.