Journal of Lipid Research, Vol 24, 1310-1320, Copyright © 1983 by Lipid Research, Inc.
Effect of ethanol on intestinal lipid absorption in the rat
CM Mansbach 2d
The effect of ethanol infusion on intestinal lipid absorption was studied
in rats with a duodenal cannula. Rats were infused with ethanol overnight
and ethanol was included in a trioleoylglycerol emulsion infusion given for
3 hr the next day. These rats were compared to control animals infused with
glucose (isocalorically). The ethanol- infused rats had a greatly impaired
lipid absorptive capacity. The monoacylglycerol and free fatty acid
contents in the intestinal lumen in the ethanol-infused rats were 4- and
7-fold greater, respectively, than controls. The inhibition of absorption
was not due to an effect of ethanol on lipolytic activity. The lipase
content of the ethanol- infused rats was greater than controls and the
separate infusion of monoacylglycerol and fatty acids demonstrated impaired
absorption of these end products of lipolysis as compared to controls. To
observe if these changes were due to an effect of ethanol on the enterocyte
brush border membrane, the membrane lipids were analyzed. The
phosphatidylcholine, lysophosphatidylcholine, and phosphatidylethanolanine
content was reduced but not the neutral lipids, sphingomyelin, or
phosphatidylserine. The uptake of fatty acid into intestinal rings was also
shown to be impaired by ethanol infusion. Lastly, the specific activity of
the neutral lipids remaining in the intestinal lumen after
[3H]glycerol-labeled trioleoylglycerol- infusion was similar to controls
even though the mass was much greater. It is concluded that ethanol impairs
neutral lipid absorption due to an effect on the enterocyte brush border
membrane and by increasing the efflux of low specific activity lipid from
the enterocyte back out into the intestinal lumen. A potential pathway for
this efflux is the recently described increased porosity of the apical
junctional complex in response to ethanol infusion.