Abstract
Summary
In this study of spontaneous obesity of pigs, specific metabolic shifts were observed, which explain an increase in fat deposition. Liver tissue utilization of pyruvate and glucose for oxidation and lipogenesis showed no significant difference between lean and obese pigs. Adipose tissue utilization of glucose, acetate and glycerol for triglyceride and fatty acid synthesis was greater in obese pigs than lean pigs (P < 0.01). No significant difference in leucine incorporation into lipid fractions was found. Of the substrates utilized, glucose supplied 86 and 94% of the glyceride-glycerol synthesized in lean and obese pigs, respectively. Glycerol was not a major contributor to glyceride-glycerol synthesis (3.5 to 5.5%), in spite of the presence of adipose tissue glycerokinase. An increase (P < 0.05) in alanine incorporation into glucose was observed in liver tissue from obese pigs. In general, the levels of enzyme activities associated with gluconeogenesis, glycolysis, and lipogenesis supported the findings of in vitro utilization of these substrates.
The authors wish to express their gratitude to V. Hazlett, J. Watkins, P. Lamprey, and P. Hartman for their assistance in conduct of this study and in the preparation of this manuscript.
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