Effects of Two Highly Monounsaturated Oils on Lipid Composition and Enzyme Activities in Rat Jejunum

Abstract

The effects of two monounsaturated fatty acid (MUFA) oils, olive oil (OO) and high-oleic sunflower oil (HOSO), with high content in oleic acid but differing in their non-fatty acid fraction, on brush-border membrane (BBM) lipid composition and fluidity and on mucosal enzyme activities of rat jejunum were studied. Animals were given semipurified diet with linoleic acid to prevent essential fatty acid deficiency (control group) or semipurified diet containing 10% of either OO or HOSO for 12 weeks. There was a significant decrease in the content of jejunal BBM phospholipids together with an increase in the level of free cholesterol in both oil-fed rats, when compared to control group. Although the increase in the BBM free cholesterol level was not statistically significant in HOSO-fed rats, a significant decrease in the phospholipid/free cholesterol ratio was found in both OO and HOSO-fed animals compared to control group. Rat jejunal BBM had a high level of free fatty acids which was increased in BBM isolated from OO and HOSO-fed animals. There was no statistical significant difference in the phospholipid distribution between the control and the OO group. However, HOSO-fed animals showed the lowest level of phosphatidylethanolamine together with the highest phosphatidylcholine content and the phosphatidylcholine/sphingomyelin ratio. The fatty acid pattern of jejunal BBM lipids was modified according to the major fatty acids in the oils. There was a decrease in both stearic acid (18:0) and linoleic acid (18:2 n-6), together with an increase in oleic acid (18:1 n-9) in jenunal BBM isolated from both oil experimental groups. All these results were accompanied by a significant increase in the BBM fluidity (as assessed by steady-state fluorescence polarization of diphenylhexatriene) isolated from oil-fed rat, when compared to control group. OO and HOSO-fed animals had the lowest activities of sucrase and maltase, while alkaline phosphatase activity only was decreased in HOSO-fed animals. The specific activity of maltase was not modified in any experimental rats. In summary, both MUFA oils induced similar effects on jejunal BBM lipid composition, fluidity, sucrase, maltase and lactase activities. Furthermore, HOSO intake resulted in a lowest alkaline phosphatase activity which was accompanied by changes in individual phospholipid composition. All these results suggest that effects of MUFA oils on jejunal BBM lipid composition and hydrolase activities are most likely due to the presence of high content of oleic acid rather than other components contained in the non-fatty acid of olive oil.

Intestinal alkaline phosphatase: multiple biological roles in maintenance of intestinal homeostasis and modulation by diet

“…A fat‐free diet was found to have a depressive effect on IAP activity while fat intake stimulated IAP expression 81 . Long‐chain saturated triglycerides and medium‐chain triglycerides increased IAP expression and/or activity, 82–85 while unsaturated FAs reduced it 82,86,87 . Trans FAs decreased the AP activity of intestinal brush border membranes when the amount of linoleic acid in the diet was low, whereas no effect was observed with higher amounts of dietary linoleic acid 88 .…”

Intestinal Alkaline Phosphatase: A Review of This Enzyme Role in the Intestinal Barrier Function

“…Triglycerides increase IALP expression and activity in the intestinal lumen; that is, the amount of fat in the diet determines the amount of IALP secretion [81][82][83][84]. On the other hand, the Mediterranean diet, which is rich in unsaturated fatty acids, increases IALP activity [81,85,86]. Different types of unsaturated fatty acids can influence IALP activity [85].…”

Influence of a high-fat diet on gut microbiota, intestinal permeability and metabolic endotoxaemia

“…Mice resistant to obesity were observed to have higher intestinal alkaline phosphatase activity ( 92 ) . Some authors suggest that dietary fat content and specific fatty acids can modulate the enzyme activity in different ways ( 88 , 93 , 94 ) . Thus, more studies are needed to determine the relationship between fat absorption, intestinal alkaline phosphatase activity and LPS clearance.…”