student research day - Case Western Reserve University School of ...

Steven Foy
Extensive triglyceride synthesis in epididymal adipose tissue in the absence of dietary carbohydrate: Evidence in
support of glycerol-glucose cycling.
Steve Foy, Ilya R. Bederman, Visvanathan Chandramouli, James C. Alexander and Stephen F. Previs
Departments of Nutrition, Medicine, and Mathematics
Case Western Reserve University
The obesity epidemic has generated interest in determining the contribution of various pathways to triglyceride
synthesis. We hypothesized that a dietary intervention would demonstrate the importance of glucose vs. nonglucose
carbon sources to triglyceride synthesis in white adipose tissue. C57BL/6J mice were either fed a low-fat,
high-carbohydrate (HC) diet or a high-fat, carbohydrate-free (CF) diet and maintained on 2H2O (to determine total
triglyceride dynamics) or infused with [6,6-2H]glucose (to quantify the contribution of glucose to triglycerideglycerol).
The 2H2O labeling data demonstrate that although de novo lipogenesis contributed ~ 80% vs. ~ 5% to
the pool of triglyceride-palmitate in HC vs. CF fed mice, the epididymal adipose tissue synthesized ~ 1.7-fold more
triglyceride in CF vs. HC fed mice. The [6,6-2H]glucose labeling data demonstrate that ~ 69% and ~ 28% of
triglyceride-glycerol is synthesized from glucose in HC vs. CF fed mice, respectively. Although these data are
consistent with the notion that non-glucose carbon sources (e.g. glyceroneogenesis) can make substantial
contributions toward the synthesis triglyceride-glycerol, these observations raise an important point regarding the
operation of a glycerol-glucose cycle.
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