These two studies go together...do we want to play the "How"? game?
J Appl Physiol (1985). 2010 Dec;109(6):1653-61. doi: 10.1152/japplphysiol.00598.2010. Epub 2010 Sep 16.
Endurance training-induced accumulation of muscle triglycerides is coupled to upregulation of stearoyl-CoA desaturase 1.
Dobrzyn P, Pyrkowska A, Jazurek M, Szymanski K, Langfort J, Dobrzyn A.
Source
Laboratory of Cell Signaling and Metabolic Disorders, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
[email protected]
Abstract
Stearoyl-CoA desaturase (SCD), a rate-limiting enzyme in the biosynthesis of monounsaturated fatty acids, has recently been shown to be a critical control point in regulation of liver and skeletal muscle metabolism. Herein, we demonstrate that endurance training significantly increases both SCD1 mRNA and protein levels in the soleus muscle, whereas it does not affect SCD1 expression in the EDL muscle and liver. Desaturation index (18:1Δ9/18:0 ratio), an indirect indicator of SCD1 activity, was also significantly higher (3.6-fold) in soleus of trained rats compared with untrained animals. Consistent with greater SCD1 expression/activity, the contents of free fatty acids, diacylglycerol, and triglyceride were elevated in soleus of trained rats. However, training did not affect lipid concentration in EDL and liver. Additionally, endurance training activated the AMP-activated protein kinase pathway as well as increased peroxisome proliferator-activated receptor (PPAR)-δ and PPARα gene expression and activity in soleus and liver. Increased lipid accumulation in soleus was coupled with elevated protein levels of fatty acid synthase, mRNA levels of diacylglycerol acyltransferase and glycerol-3-phosphate transferase, as well as increased levels of proteins involved in fatty acid transport (fatty acid translocase/CD36, fatty acid transport protein 1). Interestingly, sterol regulatory element-binding protein (SREBP)-1c expression and SREBP-1 protein levels were not affected by exercise training. Together, the obtained data suggest that SCD1 upregulation plays an important role in adaptation of oxidative muscle to endurance training.
PMID:
20847127
[PubMed - indexed for MEDLINE]
PLoS One. 2012;7(3):e33815. doi: 10.1371/journal.pone.0033815. Epub 2012 Mar 27.
An ethanol extract of Artemisia iwayomogi activates PPARδ leading to activation of fatty acid oxidation in skeletal muscle.
Cho SY, Jeong HW, Sohn JH, Seo DB, Kim WG, Lee SJ.
Source
Health Science Research Institute, Research and Development Center, AmorePacific Corporation, Bora-dong, Giheung-gu, Yongin-si, Korea.
Abstract
Although Artemisia iwayomogi (AI) has been shown to improve the lipid metabolism, its mode of action is poorly understood. In this study, a 95% ethanol extract of AI (95EEAI) was identified as a potent ligand of peroxisome proliferator-activated receptorδ (PPARδ) using ligand binding analysis and cell-based reporter assay. In cultured primary human skeletal muscle cells, treatment of 95EEAI increased expression of two important PPARδ-regulated genes, carnitine palmitoyl-transferase-1 (CPT1) and pyruvate dehydrogenase kinase isozyme 4 (PDK4), and several genes acting in lipid efflux and energy expenditure. Furthermore, 95EEAI stimulated fatty acid oxidation in a PPARδ-dependent manner. High-fat diet-induced obese mice model further indicated that administration of 95EEAI attenuated diet-induced obesity through the activation of fatty acid oxidation in skeletal muscle. These results suggest that a 95% ethanol extract of AI may have a role as a new functional food material for the prevention and/or treatment of hyperlipidermia and obesity.
PMID:
22479450
[PubMed - indexed for MEDLINE]
PMCID:
PMC3313949