Carbohydrate type and amount alter intravascular processing and catabolism of plasma lipoproteins in guinea pigs

Abstract

To test the effects of exchanging dietary complex and simple carbohydrate for fat calories on lipoprotein metabolism, guinea pigs were fed two different fat/carbohydrate ratios: 2.5:58% (w/w) or 25:29% (w/w) with either sucrose or starch as the carbohydrate source. Animals fed high-fat had higher plasma low-density lipoprotein (LDL) and hepatic cholesterol concentrations than animals fed low-fat diets (P < 0.01). The cholesteryl ester content per particle was higher, and the number of triacylglycerol (TAG) molecules was lower in very low density lipoprotein (VLDL) and LDL from animals fed high-fat diets. Intake of high-fat/sucrose resulted in higher plasma LDL concentrations than intake of high-fat/starch, and animals fed low-fat/starch had the highest plasma TAG concentrations associated with VLDL particles containing more TAG molecules, as well as a TAG-enriched LDL. The activity of plasma lecithin cholesteryl:acyl transferase (LCAT) was highest in animals fed high-fat/sucrose, and heart lipoprotein lipase (LPL) activity was higher in animals fed high-fat diets. Hepatic apoprotein B/E (apo B/E) receptor number (Bmax) was increased 21% with low-fat diets (P < 0.01). These results suggest that the hypercholesterolemia induced by high-fat and by sucrose intake are associated with a higher plasma LCAT activity which results in a cholesteryl ester-enriched VLDL which, by the action of LPL, might be more readily converted to LDL through the delipidation cascade leading to downregulation of hepatic apo B/E receptors. The hypertriglyceridemia associated with low-fat intake may result from increased production of VLDL TAG, which would explain the increased TAG content and the higher TAG/CE ratio of VLDL from animals fed the low-fat/starch diet.

High-fat but not sucrose intake is essential for induction of dyslipidemia and non-alcoholic steatohepatitis in guinea pigs

“…Accordingly, we found that LDL-C and VLDL-C increased upon high-fat feeding, regardless of dietary content of sucrose. This contradicts previous findings of a sucrose imposed elevation of TC and LDL-C when added to a high-fat diet in male guinea pigs [ 13 , 36 ]. The observed dissimilarity may be due to differences in dietary composition as the latter high-fat diets did not contain excess cholesterol [ 13 , 36 ] and/or a gender associated effect, as female rats—in contrast to males—proved resistant to sucrose-induced hypertriglyceridemia [ 37 ].…”

Olive oil and rapeseed oil differ in their effect on plasma low-density lipoprotein metabolism in the guinea-pig

“…Although high fat compared with low fat, polyunsaturated compared with saturated fat, and rapeseed oil compared with olive oil increase LPL activity (Pawar & Tidwell, 1968;Jansen et al 1975;Weisenburg Delorme & Hams, 1975;Cryer et al 1978;Kiens et al 1987), plasma LDL levels are higher in the former and lower in the latter situation suggesting that the contribution of LPL activity to plasma LDL concentrations differs depending on the dietary treatment. For example, in guinea-pigs the increases in cardiac LPL induced by high fat intake have been associated with cholesteryl-esterenriched VLDL which are readily converted to LDL particles resulting in an expanded plasma LDL pool (Fernandez et al 1995). In contrast, the higher LPL activity with rapeseed oil intake observed in the present study might be related to an increased conversion of VLDL to smaller LDL particles which are rapidly cleared from plasma resulting in lower plasma LDL levels.…”

Initiation of Hyperinsulinemia and Hyperleptinemia is Diet Dependent in C57BL/6 Mice

“…In guinea pigs, this is due to reduced amounts of triglyceride molecules in VLDL particles [23]. In mice, heparin-releasable [24,25] and adipose [6] lipoprotein lipase are increased.…”