Dietary ω3 fatty acids and cholesterol modify enterocyte microsomal membrane phospholipids, cholesterol content and phospholipid enzyme activities in diabetic rats
Lipids(1994)
摘要
Diabetes-associated changes in intestinal uptake of nutrients are modified by isocaloric variations in the type of dietary
lipids, and are associated with alterations in the phospholipid and fatty acyl content of the intestinal brush border membrane.
The present study was designed to test the hypothesis that diet- and diabetes-associated changes in enterocyte microsomal
membrane phospholipids are due to variations in the activity of two phospholipid metabolizing enzymes, 1,2-diacylglycerol:
CDP choline cholinephosphotransferase (CPT) and phosphatidylethanolamine methyltransferase (PEMT). Adult female Wistar rats
were fed one of four semisynthetic diets—beef tallow low in cholesterol (BT), beef tallow high in cholesterol (BTC), fish
oil low in cholesterol (FO) or fish oil high in cholesterol. In half of the animals, diabetes mellitus was produced by injection
of streptozotocin. Jejunal and ileal enterocyte microsomes (EMM) were isolated and analyzed for cholesterol and phospholipids,
as well as for CPT and PEMT activities. In control animals, feeding FO reduced EMM total phospholipids including phosphatidylcholine
(PC), phosphatidylethanolamine (PE) and phosphatidylinositol. Feeding FO resulted in a greater than 95% reduction in the activity
of CPT. Diabetes was associated with increased jejunal EMM total phospholipids including sphingomyelin (SM) and PE, without
associated changes in CPT or PEMT. Dietary cholesterol supplementation did not effect EMM total cholesterol or phospholipid
composition in control rats fed BT or FO, but was associated with an increase in EMM cholesterol in diabetic rats fed BT or
FO. A decrease in total phospho-lipids due to a decline in SM, PC and PE in diabetic rats fed FO was not associated with changes
in the activities of CPT or PEMT in EMM. Thus (i) enterocyte microsomal membrane cholesterol and phospholipid contents are
influenced by diabetes, dietary cholesterol and the type of fatty acid in the diet, and (ii) changes in phospholipid composition
are not fully explained by alterations in the activities of CPT and PEMT.
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关键词
diabetes mellitus,brush border membrane,fatty acid,enzyme,enzyme activity
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