title: 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.
abstract: 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.:
authors: Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia. Electronic address:yan.lam@sydney.edu.au.
authors: Yan Y
authors: YY
authors: Lam
authors: Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Alena
authors: A
authors: Janovská
authors: School of Biomedical and Health Sciences, Victoria University, Melbourne, VIC 3000, Australia.
authors: Andrew J
authors: AJ
authors: McAinch
authors: CSIRO Food and Nutritional Sciences, Adelaide, SA 5000, Australia.
authors: Damien P
authors: DP
authors: Belobrajdic
authors: Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia.
authors: George
authors: G
authors: Hatzinikolas
authors: Discipline of Surgery, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Philip
authors: P
authors: Game
authors: Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia.
authors: Gary A
authors: GA
authors: Wittert