Influence of amount of dietary fat and protein on esterase-1 (ES-1) activities of plasma and small intestine in rats

Abstract

The objective of the present study was to characterize nutritionally esterase-1 (ES-1). For this purpose, the effects of replacement of dietary carbohydrates by isoenergetic amounts of either fat or protein on ES-1 activities of plasma and small intestine were studied in male rats. Purified diets differing in the amounts of maize starch plus dextrose, casein and various types of fat were used. Plasma and jejunal ES-1 activities were found to be increased with increasing fat intakes. As to the type of fat, increasing plasma ES-1 activities were induced by coconut fat, olive oil, maize oil and medium-chain triacylglycerols, in this order. Maize oil induced higher jejunal ES-1 activities than coconut fat and olive oil, but had similar effects to medium-chain triacylglycerols. Maize oil was more powerful in increasing plasma ES-1 activity than isoenergetic amounts of casein, but with respect to jejunal ES-1 activity these dietary components were equally effective. It is concluded that the amounts of fat and protein in the diet are important determinants of ES-I activities in plasma and jejunum.Dietary fat: Esterase-I: Plasma: Intestine: Rat Esterases (EC 3.1.1 .) form a complex system of non-specific enzymes present in most living organisms (Krisch, 1971). They can be detected in most tissues, but are most abundant in liver, intestine, kidney and plasma. The esterases catalyse the hydrolysis of artificial organic esters such as a-naphthylacetate and p-nitrophenylacetate. Isozymes of esterase catalyse the hydrolysis of a wide range of xenobiotic carboxylesters and aromatic amides, including various anaesthetics (Mentlein & Heymann, 1984).The function of the esterases with respect to natural substrates is still obscure, but there is some evidence that they are involved in lipid metabolism. In vitro studies have shown that rat liver esterases can hydrolyse various classes of lipids, including monoacylglycerols (Mentlein et al. 1985). Involvement of esterases in lipid metabolism is also indicated by in vivo studies. Replacement of isoenergetic amounts of carbohydrates by either maize oil or coconut fat in the diet of rats caused a slight increase in plasma total esterase activity, as measured with p-nitrophenylacetate as substrate (Van Lith et al. 1989). This increase was associated with a pronounced increase of the so-called ES-1 isozyme, an anodal, fastmoving esterase zone in the plasma zymogram. Lewis & Hunter (1966) reported that administration of fat by stomach tube caused an increase in the activity of esterase of high electrophoretic mobility in intestinal lymph of rats. It could be suggested that ES-1 is involved in fat absorption and that it is released from the intestine during this process. Three dietary trials with rats have been carried out in order to obtain clues as to this H. A. V A N L I T H A N D O T H E R Ssuggestion and to characterize plasma and jejunal ES-1 activities nutritionally. The amount and type of fat and the amount of protein in the diet have been focussed on as possible determinants of ...

Feeding and digestive responses to fatty acid intake in two South American passerines with different food habits

“…The magnitude of the esterase activities appears to be related to Fa metabolism. For example, a chronic intake of unsaturated fatty acids (UFa)-rich diets, such as omega-3 (linolenic acid) and omega-6 (linoleic acid) induced a rise in intestinal esterase activity in rats (Van lith et al 1992). a comparative study conducted on fifty-five species of free-living birds belonging to eight orders revealed that passerines with wider dietary diversity (i.e., mixed diets) had the highest hydrolytic activity of liver esterase amongst all birds assessed (Bush et al 1973).…”