The use of adipose tissue-conditioned media to demonstrate the differential effects of fat depots on insulin-stimulated glucose uptake in a skeletal muscle cell line

• Published in: Obesity research & clinical practice Vol. 5; no. 1; pp. e43 - e54
• Main Authors: Lam, Yan Y, Janovská, Alena, McAinch, Andrew J, Belobrajdic, Damien P, Hatzinikolas, George, Game, Philip, Wittert, Gary A
• Format: Journal Article
• Language: English
• Published: Netherlands 01.01.2011
• Subjects: Endocrinology & Metabolism; Internal Medicine; Adipokines; Insulin resistance; Skeletal muscle
• ISSN: 1871-403X
• DOI: 10.1016/j.orcp.2010.12.002

Summary We aimed to study the depot-specific effect of adipose tissue on insulin sensitivity of skeletal muscle in vitro . Adipose tissue-conditioned medium (CM) was generated from visceral and subcutaneous fat from obese subjects. CM from visceral as compared to subcutaneous fat had higher concentrations of interleukin (IL)-6 (15-fold; P < 0.05) and IL-8 (8-fold; P < 0.05). CM from visceral fat (1:128 dilution) reduced insulin-stimulated glucose uptake in L6 myotubes by 19% ( P < 0.05), an effect mediated by a nuclear factor kappa B (NFκB)/mammalian target of rapamycin complex 1 (mTORC1)-dependent pathway and partially reversed by neutralizing IL-6. IL-6 at a concentration comparable to that in CM from visceral fat reduced insulin-stimulated glucose uptake by 53% ( P < 0.05), an effect abolished by inhibiting NFκB or mTORC1. We demonstrated the utility of the CM-myotube system and identified IL-6 as a major cytokine mediating visceral fat-induced muscle insulin resistance.