title: In vitro palmitate treatment of myotubes from postmenopausal women leads to ceramide accumulation, inflammation and affected insulin signaling.
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.
authors.affiliation: The Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases and CMRC, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Julie
authors.initials: J
authors.lastname: Abildgaard
authors.affiliation: Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
authors.forename: Darren C
authors.initials: DC
authors.lastname: Henstridge
authors.affiliation: Department of Gynaecology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Anette T
authors.initials: AT
authors.lastname: Pedersen
authors.affiliation: Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
authors.forename: Katherine G
authors.initials: KG
authors.lastname: Langley
authors.affiliation: The Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases and CMRC, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Camilla
authors.initials: C
authors.lastname: Scheele
authors.affiliation: The Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases and CMRC, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
authors.affiliation: The Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Department of Infectious Diseases and CMRC, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Lindegaard
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism*; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D010168:Palmitates / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism; D017698:Postmenopause / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D002518:Ceramides; D018840:HSP70 Heat-Shock Proteins; D007328:Insulin; D010168:Palmitates; D010750:Phosphoproteins; D048031:JNK Mitogen-Activated Protein Kinases