Journal of Lipid Research, Vol 28, 381-387, Copyright © 1987 by Lipid Research, Inc.
Normal cholesterol absorption in rats deficient in intestinal acyl coenzyme A:cholesterol acyltransferase activity [published erratum appears in J Lipid Res 1987 Sep;28(9):1128]
LL Gallo, JA Wadsworth and GV Vahouny
Acyl coenzyme A:cholesterol acyl transferase and/or cholesterol esterase
may regulate the esterification and absorption of exogenous cholesterol. To
assess this, mucosal acyl coenzyme A:cholesterol acyl transferase activity
was inhibited selectively with three different drugs [Sandoz #58-035,
inhibitor 1; Lederle inhibitor 2 and inhibitor 3] and the effect upon the
absorption of a [4-14C]cholesterol meal was studied in the lymph fistula
rat. Compared to control rats, ACAT activity measured in mucosal
homogenates from the drug-treated rats was reduced 80-90%, 40%, and 30%,
respectively, during the predicted time- frame for maximum mucosal
esterification of cholesterol (i.e., after cholesterol is fed and before it
appears in lymph). In contrast, [14C]cholesterol absorption in the
drug-treated animals was unchanged from controls [5.7 +/- 1.2 (inhibitor 1)
vs. 5.4 +/- 1.6 mumol/6 hr (control); 6.1 +/- 2.1 (inhibitor 2) and 5.2 +/-
1.5 (inhibitor 3) vs. 4.1 +/- 1.3 mumol/6 hr (control)]. Of the absorbed
[14C]cholesterol, approximately 75% was esterified in all groups.
Cholesterol esterase activity measured in the drug-treated rats was
unchanged compared to controls nor did the drugs inhibit this enzyme in
vitro. Under the conditions of this study, drugs causing substantial
inhibition of acyl coenzyme A:cholesterol acyl transferase activity had no
effect on the absorption of exogenous cholesterol.