The effects of long- or medium-chain fat diets on glucose tolerance and myocellular content of lipid intermediates in rats.
Accumulation of triacylglycerols (TAGs) and acylcarnitines in skeletal muscle upon high-fat (HF) feeding is the resultant of fatty acid uptake and oxidation and is associated with insulin resistance. As medium-chain fatty acids (MCFAs) are preferentially β-oxidized over long-chain fatty acids, we examined the effects of medium-chain TAGs (MCTs) and long-chain TAGs (LCTs) on muscle lipid storage and whole-body glucose tolerance. Rats fed a low-fat (LF), HFLCT, or an isocaloric HFMCT diet displayed a similar body weight gain over 8 weeks of treatment. Only HFLCT increased myocellular TAG (42.3 ± 4.9, 71.9 ± 6.7, and 48.5 ± 6.5 µmol/g for LF, HFLCT, and HFMCT, respectively, P < 0.05) and long-chain acylcarnitine content (P < 0.05). Neither HF diet increased myocellular diacylglycerol (DAG) content. Intraperitoneal (IP) glucose tolerance tests (1.5 g/kg) revealed a significantly decreased glucose tolerance in the HFMCT compared to the HFLCT-fed rats (802 ± 40, 772 ± 18, and 886 ± 18 area under the curve for LF, HFLCT, and HFMCT, respectively, P < 0.05). Finally, no differences in myocellular insulin signaling after bolus insulin injection (10 U/kg) were observed between LF, HFLCT, or HFMCT-fed rats. These results show that accumulation of TAGs and acylcarnitines in skeletal muscle in the absence of body weight gain do not impede myocellular insulin signaling or whole-body glucose intolerance.
De Vogel-van den Bosch
Johan
J
Top Institute Food and Nutrition, Wageningen, The Netherlands.
Hoeks
Joris
J
Timmers
Silvie
S
Houten
Sander M
SM
van Dijk
Paul J
PJ
Boon
Wendy
W
Van Beurden
Denis
D
Schaart
Gert
G
Kersten
Sander
S
Voshol
Peter J
PJ
Wanders
Ronald J A
RJ
Hesselink
Matthijs K
MK
Schrauwen
Patrick
P
D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D001835:Body Weight; D002331:Carnitine / Q000031:analogs & derivatives* / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D004075:Diglycerides / Q000032:analysis; D004734:Energy Metabolism; D005227:Fatty Acids / Q000493:pharmacokinetics*; D018149:Glucose Intolerance / Q000378:metabolism*; D005951:Glucose Tolerance Test; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D015227:Lipid Peroxidation; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000493:pharmacokinetics*
C011439:1,2-diacylglycerol; D001786:Blood Glucose; D004041:Dietary Fats; D004075:Diglycerides; D005227:Fatty Acids; D007328:Insulin; D014280:Triglycerides; C116917:acylcarnitine; D002331:Carnitine