Endocrine Abstracts

Objective: To investigate the effects of C1q/TNF related protein 3 CTRP3 on the insulin sensitivity of adipocyte and its possible mechanisms.

Methods: The insulin resistance model of 3T3-L1 adipocyte was induced by palmic acid (PA) cultivation. Such adipocytes were treated with different concentration of recombinant CTRP3 (0,10,50,250,1250 ng/ml) for 12 h, and for different time (2, 6, 12, 24 h) at the concentration of 250 ng/ml. The glucose consumption was detected by glucose oxidase method. The glucose transport ratio was inspected by 2-deoxidation-H³-glucose intake method. The contents of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in supernatant were detected by enzyme-linked immunosorbent assay (ELISA). The relative expression of TNF-α, IL-6 and glucose transporter-1 (GLUT-4) were measured by fluorescence RT-PCR.

Results: With the increased concentration of CTRP3 (10,50,250,1250 ng/ml), the glucose consumption were increased by 22.1, 42.9, 76.6, and 80.5% respectively (all P<0.01), the glucose intake ratio were increased by 39, 68, 108, and 111% respectively (all P<0.01) in compared with that in control group which were not treated with CTRP3. With the increased duration (2, 6, 12, 24 h) of CTRP3 treatment at the concentration of 250 ng/ml, the glucose intake ratio were increased by 23, 79, 109, and 114 respectively (all P<0.01). The contents of TNF-α and IL-6 in supernatant were decreased by 17.4 and 17.1% respectively (all P<0.01) as treated with CTRP3 at the concentration of 250 ng/ml for 12 h, and the relative expression of TNF-α and IL-6 mRNA were decreased by 26 and 19% respectively (all P<0.01), while the relative expression of GLUT-4 mRNA was increased by 62% (P<0.01).

Conclusion: CTPR3 may increase the insulin sensitivity of adipose tissue though the decreased expression of inflammation factors, improved insulin signal transduction and increased the expression of GLUT-4.

Keywords: CTRP3, 3T3-L1 adipocyte, insulin resistance, inflammation