Abstract
Male rats were made deficient in essential fatty acids by feeding them a fat-free diet supplemented with 4% tripalmitin for 8-12 wk from the time of weaning. After feeding 0.5 ml of [(14)C]triolein or [(3)H]oleic acid, 72-hr stool recoveries of radioactivity were significantly greater in deficient rats than in chow-fed controls. Essential fatty acid deficiency did not reduce the absorptive capacities for triolein or for a medium-chain fat, trioctanoin, measured after 3 and 2 hr of maximal-rate duodenal infusion. In everted jejunal slices from essential fatty acid-deficient rats, uptake of micellar [(14)C]oleic acid at 0-1 degrees C was similar to that of controls, but the rate of incorporation of fatty acid into triglyceride after rewarming to 37 degrees C was significantly reduced. The specific activities of the microsomal esterifying enzymes, acyl CoA:monoglyceride acyltransferase and fatty acid CoA ligase in jejunal mucosa were 30% lower in essential fatty acid-deficient rats. However, the total microsomal enzyme activity adjusted to constant weight did not differ significantly in deficient rats compared with controls. After intraduodenal perfusion of triolein, accumulation of lipid in the intestinal wall was increased in the deficient rats. Because over 90% of the absorbed mucosal lipid was present as triglyceride, essential fatty acid deficiency appears to affect the synthesis or release of chylomicron lipid from the intestine. Analysis of regions of intestine showed that this delay in transport was most marked in the midportion of the small intestine.
Highlights
Male rats were made deficient in essential fatty acids by feeding them a fat-free diet supplemented with 4% tripalmitin for 8-12 wk from the time of weaning
Examinations of the fatty acid composition of lecithins extracted from bile, intestinal mucosa, and the lecithin fractions of jejunal microsomes confirmed the presence of Essential fatty acid (EFA) deficiency as judged by the significant reduction of linoleic and arachidonic acid content and the increase in the content of eicosatrienoic acid-after 10-12 wk (Table 1)
We have studied various stages of the absorption process in normal and EFA-deficient rats
Summary
Male rats were made deficient in essential fatty acids by feeding them a fat-free diet supplemented with 4% tripalmitin for 8-12 wk from the time of weaning. In everted jejunal slices from essential fatty aciddeficient rats, uptake of micellar [14C]oleicacid at 0-1°C was similar to that of controls, but the rate of incorporation of fatty acid into triglyceride after rewarming to 37°C was significantly reduced. Because over 90% of the absorbed mucosal lipid was present as triglyceride, essential fatty acid deficiency appears to affect the synthesis or release of chylomicron lipid from the intestine. Essential fatty acid (EFA) deficiency results in considerable alteration in the chemical structure of phospholipids, as well as other lipids, in many tissues and has been associated with a number of pathophysiological effects [3]. Studies of ion transport through artificial lecithin membranes prepared from tissues of several animals suggested that sodium efflux was greater through EFA-deficient membranes than through lecithin membranes prepared from control animals [5]. A portion of this work was presented at the Eastern Sectional Meeting of the American Federation of Clinical Research in December 1970 and published in abstract form [1]
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