In vitro palmitate treatment of myotubes from postmenopausal women leads to ceramide accumulation, inflammation and affected insulin signaling

PLoS One. 2014 Jul 7;9(7):e101555. doi: 10.1371/journal.pone.0101555. eCollection 2014.

Abstract

Menopause is associated with an increased incidence of insulin resistance and metabolic diseases. In a chronic palmitate treatment model, we investigated the role of skeletal muscle fatty acid exposure in relation to the metabolic deterioration observed with menopause. Human skeletal muscle satellite cells were isolated from premenopausal (n = 6) and postmenopausal (n = 5) women. In an in vitro model, the myotubes were treated with palmitate (300 µM) for one-, two- or three days during differentiation. Effects on lipid accumulation, inflammation and insulin signaling were studied. Palmitate treatment led to a 108% (CI 95%: 50%; 267%) increase in intramyocellular ceramide in the myotubes from the postmenopausal women (post-myotubes) compared with a 26% (CI 95%: -57%; 96%) increase in myotubes from the premenopausal women (pre-myotubes), (p<0.05). Furthermore, post-myotubes had a 22% (CI 95%: 4%; 34%) increase in pJNK (p = 0.04) and a 114% (CI 95%: 50%; 177%) increase in Hsp70 protein expression (p = 0.03) after three days of palmitate treatment, compared with pre-myotubes, in which no increase in either pJNK (-12% (CI 95: -26%; 2%)) or Hsp70 (7% (CI 95: -78%; 91%)) was detected. Furthermore, post-myotubes showed a blunted insulin stimulated phosphorylation of AS160 in response to chronic palmitate treatment compared with pre-myotubes (p = 0.02). The increased intramyocellular ceramide content in the post-myotubes was associated with a significantly higher mRNA expression of Serine Palmitoyltransferase1 (SPT1) after one day of palmitate treatment (p = 0.03) in post-myotubes compared with pre-myotubes. Our findings indicate that post-myotubes are more prone to develop lipid accumulation and defective insulin signaling following chronic saturated fatty acid exposure as compared to pre-myotubes.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / drug effects
  • Adipose Tissue / metabolism
  • Ceramides / metabolism*
  • Female
  • HSP70 Heat-Shock Proteins / metabolism
  • Humans
  • Insulin / metabolism*
  • Insulin Resistance
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Lipid Metabolism / drug effects
  • Middle Aged
  • Muscle Fibers, Skeletal / cytology*
  • Muscle Fibers, Skeletal / drug effects
  • Muscle Fibers, Skeletal / metabolism*
  • Oxidative Stress / drug effects
  • Palmitates / pharmacology*
  • Phosphoproteins / metabolism
  • Postmenopause / drug effects
  • Postmenopause / metabolism*
  • Signal Transduction / drug effects*

Substances

  • Ceramides
  • HSP70 Heat-Shock Proteins
  • Insulin
  • Palmitates
  • Phosphoproteins
  • JNK Mitogen-Activated Protein Kinases

Grants and funding

The Centre of Inflammation and Metabolism (CIM) is supported by a grant from the Danish National Research Foundation (DNRF55). The Centre for Physical Activity Research is supported by a grant from Trygfonden. This study was further supported by grants from Augustinusfonden. CIM is part of the UNIK Project: Food, Fitness & Pharma for Health and Disease, supported by the Danish Ministry of Science, Technology, and Innovation. CIM is a member of DD2 - the Danish Center for Strategic Research in Type 2 Diabetes (the Danish Council for Strategic Research, grant no. 09-067009 and 09-075724). The Copenhagen Muscle Research Centre is supported by a grant from the Capital Region of Denmark. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.