Effect of essential fatty acid deficiency on lipid metabolism in isolated fat cells of epididymal fat pads of rats |
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Authors: | D I Demeyer W C Tan O S Privett |
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Affiliation: | (1) The Hormel Institute, University of Minnesota, 55912 Austin, Minnesota;(2) Present address: Department of Nutrition, Faculty of Agricultural Sciences, Ghent, Belgium |
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Abstract: | Lipogenesis, lipolysis, and stimulation of glucose conversion into lipid by insulin or prostaglandin E1 were studied in isolated fat cells of the epididymal fat pads of rats fed a fat-free diet or this diet supplemented with
10% hydrogenated coconut oil or 10% safflower seed oil. Changes in fatty acid composition, characteristic of an essential
fatty acid deficiency, were well advanced in the neutral lipid but had only started in the polar lipid of the fat cells of
the epididymal fat pads of animals 3 months after weaning. Cellularity of the epididymal fat pads, as indicated by protein
to lipid ratio of the fat cells, was influenced greatly by hydrogenated coconut oil in the diet irrespective of an essential
fatty acid deficiency. Lipogenesis was increased in the fat cells of the animals fed the hydrogenated coconut oil diet 5 weeks
after weaning but was not significantly different from that of the safflower fed animals 3 months after weaning. Incorporation
of glucose into lipid, oxidation to CO2, and basal lipolysis were not significantly different in the fat cells of the essential fatty acid deficient animals from
those fed safflower oil 3 months after weaning, except in animals of the fat-free group based upon cell lipid. However, conversion
of glucose to free fatty acid was significantly greater in the isolated fat cells of animals fed either the hydrogenated coconut
oil or the fat-free diet than in those of animals fed the safflower oil supplement. The incorporation of glucose into lipid
by isolated fat cells was stimulated significantly by insulin in young animals fed a fat-free diet, but the effect on lipogenesis
appeared to be reversed in the fat cells of animals receiving safflower seed oil 3 months after weaning. Prostaglandin E1 also appeared to stimulate the incorporation of glucose into lipid in the fat cells of the older animals receiving safflower
seed oil. Differences in osmolarity produced large differences in utilization of glucose and release of lipid from isolated
fat cells, but no significant differences were observed between the cells from animals fed the fat-free diet and those from
the controls fed safflower oil. The results demonstrated the effects of diets containing fat or no fat on enzyme activities
and membrane properties of fat cells of the epididymal fat pads of essential fatty acid deficient rats. |
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