High-Fat and Fructose Intake Induces Insulin Resistance, Dyslipidemia, and Liver Steatosis and Alters In Vivo Macrophage-to-Feces Reverse Cholesterol Transport in Hamsters

Abstract

Reverse cholesterol transport (RCT) promotes the egress of cholesterol from peripheral tissues to the liver for biliary and fecal excretion. Although not demonstrated in vivo, RCT is thought to be impaired in patients with metabolic syndrome, in which liver steatosis prevalence is relatively high. Golden Syrian hamsters were fed a nonpurified (CON) diet and normal drinking water or a high-fat (HF) diet containing 27% fat, 0.5% cholesterol, and 0.25% deoxycholate as well as 10% fructose in drinking water for 4 wk. Compared to CON, the HF diet induced insulin resistance and dyslipidemia, with significantly higher plasma non-HDL-cholesterol concentrations and cholesteryl ester transfer protein activity. The HF diet induced severe liver steatosis, with significantly higher cholesterol and TG levels compared to CON. In vivo RCT was assessed by i.p. injecting ³H-cholesterol labeled macrophages. Compared to CON, HF hamsters had significantly greater ³H-tracer recoveries in plasma, but not HDL. After 72 h, ³H-tracer recovery in HF hamsters was 318% higher in liver and 75% lower in bile (P < 0.01), indicating that the HF diet impaired hepatic cholesterol fluxes. However, macrophage-derived cholesterol fecal excretion was 45% higher in HF hamsters than in CON hamsters. This effect was not related to intestinal cholesterol absorption, which was 89% higher in HF hamsters (P < 0.05), suggesting a possible upregulation of transintestinal cholesterol excretion. Our data indicate a significant increase in macrophage-derived cholesterol fecal excretion in a hamster model of metabolic syndrome, which may not compensate for the diet-induced dyslipidemia and liver steatosis.

Empagliflozin, via Switching Metabolism Toward Lipid Utilization, Moderately Increases LDL Cholesterol Levels Through Reduced LDL Catabolism

“…Lipoprotein total cholesterol profile was assessed using fast protein liquid chromatography analysis using one pooled plasma sample (one pool per treatment group); Western blot analyses for LDL receptor protein expression and fecal cholesterol mass excretion were performed as previously described (7). A second set of hamsters underwent radioactive tracer-based in vivo experiments to measure intestinal cholesterol absorption, LDL cholesteryl esters kinetics, or macrophage-to-feces reverse cholesterol transport as previously described (6,7). Intestinal cholesterol absorption was assessed after administration of 14 C-cholesterollabeled olive oil by oral gavage and intraperitoneal injection of poloxamer-407 (a lipase inhibitor) to measure 14 C-tracer plasma tracer appearance at time 3, 5, and 6 h after oral gavage (6).…”

“…Hamsters were kept fasted for the first 6 h of the kinetic experiment and were then kept in individual cages with access to food and water for feces collection over 72 h. Plasma 3 H-tracer decay curve was monitored over 72 h after injection to calculate 3 H-cholesteryl oleate LDL fractional catabolic rate using Simulation Analysis and Modeling (SAAM II) software. Liver (collected after 72 h) and feces were used to measure 3 H-tracer recovery in cholesterol and bile acid fraction after chemical extraction (6,7).…”

“…Macrophage-to-feces reverse cholesterol transport was measured over 72 h after intraperitoneally injecting 3 H-cholesterol-labeled/oxidized LDL-loaded J774 macrophages (6,7). In this experiment, hamsters were not fasted and had constant access to food and water over 72 h. Plasma 3 H-tracer appearance was measured every 24 h, and liver (collected after 72 h) and feces (collected over 72 h) were used to measure 3 H-tracer recovery in cholesterol and bile acid fraction after chemical extraction.…”

“…However, the transient diuretic effect of SGLT2 inhibitors may not completely contribute to the observed LDL-C increase. We therefore investigated the effects of the SGLT2 inhibitor empagliflozin in the diet-induced insulin-resistant dyslipidemic golden Syrian hamster, a validated preclinical model with cholesterol metabolism similar to that of humans (6,7).…”

Animal Models as Tools for Translational Research: Focus on Atherosclerosis, Metabolic Syndrome and Type-II Diabetes Mellitus

“…Although not established in vivo, RCT is thought to be impaired in patients with MetS, in which liver steatosis prevalence is relatively high. In this sense, Briand and coworkers [80] introduced a hamster model of MetS to study RCT. These scientists with the help of HFT diet containing 27% fat, 0.5% cholesterol, and 0.25% deoxycholate as well as 10% fructose in drinking water for 4 weeks induced promoted IR, dyslipidemia with significantly higher plasma non-HDL-C concentrations and CETP activity, and hepatic steatosis.…”