Deposition and mobilization of fatty acids in adipose tissue

Abstract

Changes in epididymal fatty acid content were estimated by differences in the content of the left pad removed at the start of the experiment and the right pad removed at a later time. The amounts of specific fatty acids mobilized, deposited from the diet or synthesized depend in part upon the length of the experiment and in part upon the amount of new fat deposited in the fat pad. Multiple regression analysis was used to estimate the effects of time and weight change. In one feeding regimen the percentage of linoleic acid in the fat pad fell progressively from 63 to 24 per cent during a 90-day period. This fall in per cent linoleic acid was accomplished, however, with essentially no change in the total linoleic acid content of the fat pad and was due to deposition of other fatty acids. Turnover rates calculated from percentage composition data alone may have little significance when fat is being deposited or mobilized. Animals fed a saturated fat (coconut oil) maintain some degree of unsaturation in the fat by conservation of linoleic acid and synthesis of monounsaturated fatty acids. The data indicate that synthesis of monounsaturated is inhibited by feeding highly unsaturated fats. Multiple regression analysis indicates that most fatty acids in the tissue tend to be retained when fat is being actively deposited. The rate of change of the amount of adipose tissue as well as time must be considered in attempting to define those factors which control the turnover of fatty acids and the composition of adipose tissue.