Hereditary Hypertriglyceridemic Rats Research Articles

The Effect of Ovariectomy and Estradiol Substitution on the Metabolic Parameters and Transcriptomic Profile of Adipose Tissue in a Prediabetic Model.

Menopause brings about profound physiological changes, including the acceleration of insulin resistance and other abnormalities, in which adipose tissue can play a significant role. This study analyzed the effect of ovariectomy and estradiol substitution on the metabolic parameters and transcriptomic profile of adipose tissue in prediabetic females of hereditary hypertriglyceridemic rats (HHTgs). The HHTgs underwent ovariectomy (OVX) or sham surgery (SHAM), and half of the OVX group received 17β-estradiol (OVX+E2) post-surgery. Ovariectomy resulted in weight gain, an impaired glucose tolerance, ectopic triglyceride (TG) deposition, and insulin resistance exemplified by impaired glycogenesis and lipogenesis. Estradiol alleviated some of the disorders associated with ovariectomy; in particular, it improved insulin sensitivity and reduced TG deposition. A transcriptomic analysis of perimetrial adipose tissue revealed 809 differentially expressed transcripts in the OVX vs. SHAM groups, mostly pertaining to the regulation of lipid and glucose metabolism, and oxidative stress. Estradiol substitution affected 1049 transcripts with overrepresentation in the signaling pathways of lipid metabolism. The principal component and hierarchical clustering analyses of transcriptome shifts corroborated the metabolic data, showing a closer resemblance between the OVX+E2 and SHAM groups compared to the OVX group. Changes in the adipose tissue transcriptome may contribute to metabolic abnormalities accompanying ovariectomy-induced menopause in HHTg females. Estradiol substitution may partially mitigate some of these disorders.

Empagliflozin alters lipid metabolism in the myocardium and liver in a prediabetes model with severe dyslipidemia.

Recent studies suggest that empagliflozin reduces total and cardiovascular mortality in both diabetic and nondiabetic subjects. Although the exact mechanism is unclear, it is understood to positively affect myocardial energetics, including the metabolism of ketone bodies, lipids, and fatty acids. In this study, we compared empagliflozin effects on lipid metabolism in the heart and liver in a prediabetic rat model with severe dyslipidemia. Wistar rats served as the control group, while hereditary hypertriglyceridemic (HHTg) rats were used as a nonobese, prediabetic model. Rats were treated with or without empagliflozin at a dose of 10mg/kg body weight (BW) for 8weeks. In HHTg rats, empagliflozin decreased body weight and adiposity, improved glucose tolerance, and decreased serum triacylglycerols (TAGs) (p < 0.001). Empagliflozin decreased the activity and gene expression of the lipogenic enzyme SCD-1 (p < 0.001) in the myocardium, which may have led to a decrease in the ectopic accumulation of TAGs and lipotoxic diacylglycerols and lysophosphatidylcholines (p < 0.001). Changes in the myocardial phosphatidylcholine/phosphatidylethanolamine ratio (p < 0.01) and in the fatty acid profile of myocardial phospholipids may have contributed to the antifibrotic effects of empagliflozin. The anti-inflammatory effects of empagliflozin were evidenced by an increased IL-10/TNFα ratio (p < 0.001), a marked decrease in arachidonic acid metabolites (20-HETE, p < 0.001), and an increase in PUFA metabolites (14,15-EETs, p < 0.001) in the myocardium. However, empagliflozin did not significantly affect either the concentration or utilization of ketone bodies. In the liver, empagliflozin decreased lipogenesis and the accumulation of TAGs and lipotoxic intermediates. Its effect on arachidonic acid metabolites and alterations in n-3 PUFA metabolism was less pronounced than in the myocardium. Our findings suggest that empagliflozin treatment in the heart and liver reduced the accumulation of neutral lipids and lipotoxic intermediates and altered the metabolism of n-3 PUFA. In the heart, empagliflozin altered arachidonic acid metabolism, which is likely associated with the anti-inflammatory and antifibrotic effects of the drug. We assume that these alterations in lipid metabolism contribute to the cardioprotective effects of empagliflozin in prediabetic states with severe dyslipidemia.

Metabolic Syndrome in Hypertriglyceridemic Rats: Effects of Antioxidants.

Long-lasting disturbances in lipid and glucose metabolism present in metabolic syndrome (MetS) lead to serious cardiovascular diseases. The study was aimed to evaluate the effect of natural antioxidant vitamin E (VitE, 100 mg/kg/day, p.o.) on basal biochemical and physiological parameters characterizing MetS and on the changed function of the heart. Furthermore, the possible potentiation of VitE effect by synthetic pyridoindole antioxidant SMe1EC2 (SMe, 15 mg/kg/day, p.o.) was also tested. MetS was induced in hereditary hypertriglyceridemic rats (HTG) by the 5 weeks administration of high-fat fructose diet (HFFD: 1 % cholesterol, 7.5 % pork lard, 10 % fructose). The heart function was tested using Langendorff preparation under constant pressure. The functional parameters of isolated heart, dysrhythmias and evoked fibrillations were evaluated in conditions of ischemia-reperfusion. The HFFD increased body weight gain and serum levels of total cholesterol, low-density lipoproteins and blood glucose. The HFFD significantly increased heart flow and force of contraction, compared to standard diet (SD). During the reperfusion, the HFFD caused the increase of the ventricular premature beats number at the expense of decreasing the duration of serious dysrhythmias (ventricular tachycardias and fibrillations). The addition of VitE, SMe or their combination to the HFFD decreased body weight gain, depressed blood pressure, improved particular biochemical parameters. The combination of VitE and SMe suppressed the occurrence of serious dysrhythmias. Our data indicate that the HFFD-related disturbances led to alterations within pathophysiology in HTG rats. The results showed that a combination of antioxidants might have the potential to amend disorders accompanying MetS.

Hypolipidemic and insulin sensitizing effects of salsalate beyond suppressing inflammation in a prediabetic rat model.

Background and aims: Low-grade chronic inflammation plays an important role in the pathogenesis of metabolic syndrome, type 2 diabetes and their complications. In this study, we investigated the effects of salsalate, a non-steroidal anti-inflammatory drug, on metabolic disturbances in an animal model of prediabetes-a strain of non-obese hereditary hypertriglyceridemic (HHTg) rats. Materials and Methods: Adult male HHTg and Wistar control rats were fed a standard diet without or with salsalate delivering a daily dose of 200mg/kg of body weight for 6weeks. Tissue sensitivity to insulin action was measured ex vivo according to basal and insulin-stimulated 14C-U-glucose incorporation into muscle glycogen or adipose tissue lipids. The concentration of methylglyoxal and glutathione was determined using the HPLC-method. Gene expression was measured by quantitative RT-PCR. Results: Salsalate treatment of HHTg rats when compared to their untreated controls was associated with significant amelioration of inflammation, dyslipidemia and insulin resistance. Specificaly, salsalate treatment was associated with reduced inflammation, oxidative and dicarbonyl stress when inflammatory markers, lipoperoxidation products and methylglyoxal levels were significantly decreased in serum and tissues. In addition, salsalate ameliorated glycaemia and reduced serum lipid concentrations. Insulin sensitivity in visceral adipose tissue and skeletal muscle was significantly increased after salsalate administration. Further, salsalate markedly reduced hepatic lipid accumulation (triglycerides -29% and cholesterol -14%). Hypolipidemic effects of salsalate were associated with differential expression of genes coding for enzymes and transcription factors involved in lipid synthesis (Fas, Hmgcr), oxidation (Pparα) and transport (Ldlr, Abc transporters), as well as changes in gene expression of cytochrome P450 proteins, in particular decreased Cyp7a and increased Cyp4a isoforms. Conclusion: These results demonstrate important anti-inflammatory and anti-oxidative effects of salsalate that were associated with reduced dyslipidemia and insulin resistance in HHTg rats. Hypolipidemic effects of salsalate were associated with differential expression of genes regulating lipid metabolism in the liver. These results suggest potential beneficial use of salsalate in prediabetic patients with NAFLD symptoms.

Hypolipidemic Effects of Beetroot Juice in SHR-CRP and HHTg Rat Models of Metabolic Syndrome: Analysis of Hepatic Proteome

Recently, red beetroot has attracted attention as a health-promoting functional food. Studies have shown that beetroot administration can reduce blood pressure and ameliorate parameters of glucose and lipid metabolism; however, mechanisms underlying these beneficial effects of beetroot are not yet fully understood. In the current study, we analysed the effects of beetroot on parameters of glucose and lipid metabolism in two models of metabolic syndrome: (i) transgenic spontaneously hypertensive rats expressing human C-reactive protein (SHR-CRP rats), and (ii) hereditary hypertriglyceridemic (HHTg) rats. Treatment with beetroot juice for 4 weeks was, in both models, associated with amelioration of oxidative stress, reduced circulating lipids, smaller visceral fat depots, and lower ectopic fat accumulation in the liver compared to the respective untreated controls. On the other hand, beetroot treatment had no significant effects on the sensitivity of the muscle and adipose tissue to insulin action in either model. Analyses of hepatic proteome revealed significantly deregulated proteins involved in glycerophospholipid metabolism, mTOR signalling, inflammation, and cytoskeleton rearrangement.

The Different Insulin-Sensitising and Anti-Inflammatory Effects of Palmitoleic Acid and Oleic Acid in a Prediabetes Model.

Introduction Monounsaturated fatty acids (MUFA) are understood to have therapeutic and preventive effects on chronic complications associated with type 2 diabetes mellitus (T2DM); however, there are differences between individual MUFAs. Although the effects of palmitoleic acid (POA) are still debated, POA can regulate glucose homeostasis, lipid metabolism, and cytokine production, thus improving metabolic disorders. In this study, we investigated and compared the metabolic effects of POA and oleic acid (OA) supplementation on glucose and lipid metabolism, insulin sensitivity, and inflammation in a prediabetic model, the hereditary hypertriglyceridemic rat (HHTg). HHTg rats exhibiting genetically determined hypertriglyceridemia, insulin resistance, and impaired glucose tolerance were fed a standard diet. POA and OA were each administered intragastrically at a dose of 100 mg/kg b.wt. for four weeks. Results Supplementation with both MUFAs significantly elevated insulin and glucagon levels, but only POA decreased nonfasting glucose. POA-treated rats showed elevated circulating NEFA associated with increased lipolysis, lipoprotein lipase gene expression, and fatty acid reesterification in visceral adipose tissue (VAT). The mechanism of improved insulin sensitivity of peripheral tissues (measured as insulin-stimulated lipogenesis and glycogenesis) in POA-treated HHTg rats could contribute increased circulating adiponectin and omentin levels together with elevated FADS1 gene expression in VAT. POA-supplemented rats exhibited markedly decreased proinflammatory cytokine production by VAT, which can alleviate chronic inflammation. OA-supplemented rats exhibited decreased arachidonic acid (AA) profiles and decreased proinflammatory AA-derived metabolites (20-HETE) in membrane phospholipids of peripheral tissues. Slightly increased FADS1 gene expression after OA along with increased adiponectin production by VAT was reflected in slightly ameliorated adipose tissue insulin sensitivity (increased insulin-stimulated lipogenesis). Conclusions Our results show that POA served as a lipokine, ameliorating insulin sensitivity in peripheral tissue and markedly modulating the metabolic activity of VAT including cytokine secretion. OA had a beneficial effect on lipid metabolism and improved inflammation by modulating AA metabolism.

Beneficial Effect of Fenofibrate and Silymarin on Hepatic Steatosis and Gene Expression of Lipogenic and Cytochrome P450 Enzymes in Non-Obese Hereditary Hypertriglyceridemic Rats.

The efficacy of fenofibrate in the treatment of hepatic steatosis has not been clearly demonstrated. In this study, we investigated the effects of fenofibrate and silymarin, administered as monotherapy and in combination to existing hepatic steatosis in a unique strain of hereditary hypertriglyceridemic rats (HHTg), a non-obese model of metabolic syndrome. HHTg rats were fed a standard diet without or with fenofibrate (100 mg/kg b.wt./day) or with silymarin (1%) or with a combination of fenofibrate with silymarin for four weeks. Fenofibrate alone and in combination with silymarin decreased serum and liver triglycerides and cholesterol and increased HDL cholesterol. These effects were associated with the decreased gene expression of enzymes involved in lipid synthesis and transport, while enzymes of lipid conversion were upregulated. The combination treatment had a beneficial effect on the gene expression of hepatic cytochrome P450 (CYP) enzymes. The expression of the CYP2E1 enzyme, which is source of hepatic reactive oxygen species, was reduced. In addition, fenofibrate-induced increased CYP4A1 expression was decreased, suggesting a reduction in the pro-inflammatory effects of fenofibrate. These results show high efficacy and mechanisms of action of the combination of fenofibrate with silymarin in treating hepatic steatosis and indicate the possibility of protection against disorders in which oxidative stress and inflammation are involved.

Cardiovascular, Metabolic and Inflammatory Changes after Ovariectomy and Estradiol Substitution in Hereditary Hypertriglyceridemic Rats.

Background: If menopause is really independent risk factor for cardiovascular disease is still under debate. We studied if ovariectomy in the model of insulin resistance causes cardiovascular changes, to what extent are these changes reversible by estradiol substitution and if they are accompanied by changes in other organs and tissues. Methods: Hereditary hypertriglyceridemic female rats were divided into three groups: ovariectomized at 8th week (n = 6), ovariectomized with 17-β estradiol substitution (n = 6), and the sham group (n = 5). The strain of abdominal aorta measured by ultrasound, expression of vascular genes, weight and content of myocardium and also non-cardiac parameters were analyzed. Results: After ovariectomy, the strain of abdominal aorta, expression of nitric oxide synthase in abdominal aorta, relative weight of myocardium and of the left ventricle and circulating interleukin-6 decreased; these changes were reversed by estradiol substitution. Interestingly, the content of triglycerides in myocardium did not change after ovariectomy, but significantly increased after estradiol substitution while adiposity index did not change after ovariectomy, but significantly decreased after estradiol substitution. Conclusion: Vascular and cardiac parameters under study differed in their response to ovariectomy and estradiol substitution. This indicates different effects of ovariectomy and estradiol on different cardiovascular but also extracardiac structures.

Complex Positive Effects of SGLT-2 Inhibitor Empagliflozin in the Liver, Kidney and Adipose Tissue of Hereditary Hypertriglyceridemic Rats: Possible Contribution of Attenuation of Cell Senescence and Oxidative Stress.

(1) Background: empagliflozin, sodium-glucose co-transporter 2 (SGLT-2) inhibitor, is an effective antidiabetic agent with strong cardio- and nephroprotective properties. The mechanisms behind its cardio- and nephroprotection are still not fully clarified. (2) Methods: we used male hereditary hypertriglyceridemic (hHTG) rats, a non-obese model of dyslipidaemia, insulin resistance, and endothelial dysfunction fed standard diet with or without empagliflozin for six weeks to explore the molecular mechanisms of empagliflozin effects. Nuclear magnetic resonance (NMR)-based metabolomics; quantitative PCR of relevant genes involved in lipid and glucose metabolism, or senescence; glucose and palmitic acid oxidation in isolated tissues and cell lines of adipocytes and hepatocytes were used. (3) Results: empagliflozin inhibited weight gain and decreased adipose tissue weight, fasting blood glucose, and triglycerides and increased HDL-cholesterol. It also improved insulin sensitivity in white fat. NMR spectroscopy identified higher plasma concentrations of ketone bodies, ketogenic amino acid leucine and decreased levels of pyruvate and alanine. In the liver, adipose tissue and kidney, empagliflozin up-regulated expression of genes involved in gluconeogenesis and down-regulated expression of genes involved in lipogenesis along with reduction of markers of inflammation, oxidative stress and cell senescence. (4) Conclusion: multiple positive effects of empagliflozin, including reduced cell senescence and oxidative stress, could contribute to its long-term cardio- and nephroprotective actions.

The combination of atorvastatin with silymarin enhances hypolipidemic, antioxidant and anti-inflammatory effects in a rat model of metabolic syndrome.

Hypolipidemic and cardioprotective effects of statins can be associated with the development of myopathies and new-onset type 2 diabetes. These adverse effects may be related to increased oxidative stress. The plant extract silymarin (SM) is known for its antioxidant and anti-inflammatory actions. We tested the hypothesis that the combination of atorvastatin (ATV) with SM could improve therapy efficacy and eliminate some negative effects of statin on hypertriglyceridemia-induced metabolic disorders. Hereditary hypertriglyceridemic rats were fed a standard diet for four weeks without supplementation; supplemented with ATV (5 mg/kg b. wt./day) or a combination of ATV with 1 % micronized SM (ATV+SM). ATV treatment elevated plasma levels of HDL-cholesterol (p<0.01), glucose and insulin and decreased triglycerides (p<0.001). The combination of ATV+SM led to a significant reduction in insulin, an improvement of glucose tolerance, and the hypolipidemic effect was enhanced compared to ATV alone. Furthermore, ATV supplementation increased skeletal muscle triglycerides but its combination with SM decreased triglycerides accumulation in the muscle (p<0.05) and the liver (p<0.01). In the liver, ATV+SM treatment increased the activities of antioxidant enzymes, glutathione and reduced lipid peroxidation (p<0.001). The combined administration of ATV with SM potentiated the hypolipidemic effect, reduced ectopic lipid accumulation, improved glucose metabolism, and increased antioxidant and anti-inflammatory actions. Our results show that SM increased the effectiveness of statin therapy in a hypertriglyceridemic rat model of metabolic syndrome.

Cerium Oxide-Decorated γ-Fe2O3 Nanoparticles: Design, Synthesis and in vivo Effects on Parameters of Oxidative Stress.

Magnetic γ-Fe2O3/CeOx nanoparticles were obtained by basic coprecipitation/oxidation of iron chlorides with hydrogen peroxide, followed by precipitation of Ce(NO3)3 with ammonia. The appearance of CeOx on the magnetic particle surface was confirmed by X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and elemental analysis; a magnetometer was used to measure the magnetic properties of γ-Fe2O3/CeOx. The relatively high saturation magnetization of the particles (41.1 A·m2/kg) enabled magnetic separation. The surface of γ-Fe2O3/CeOx particles was functionalized with PEG-neridronate of two different molecular weights to ensure colloidal stability and biocompatibility. The ability of the particles to affect oxidative stress in hereditary hypertriglyceridemic (HHTg) rats was tested by biological assay of the liver, kidney cortex, and brain tissues. An improvement was observed in both enzymatic [superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)] and non-enzymatic (reduced (GSH) and oxidized (GSSG) glutathione) levels of antioxidant defense and lipid peroxidation parameters [4-hydroxynonenal (4-HNE) and malondialdehyde (MDA)]. The results corresponded with chemical determination of antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, proving that in the animal model γ-Fe2O3/CeOx@PEG2,000 nanoparticles effectively scavenged radicals due to the presence of cerium oxide, in turn decreasing oxidative stress. These particles may therefore have the potential to reduce disorders associated with oxidative stress and inflammation.

Global DNA methylation in rats´ liver is not affected by hypercholesterolemic diet.

Increased plasma cholesterol levels are listed between the major atherosclerosis risk factors. The final plasma cholesterol levels result from the interplay between the genetic and environmental (diet, physical activity) factors. Little is known, how dietary factor influence epigenetics. We have analyzed, if an over-generation feeding of rat with cholesterol influences total liver-DNA methylation, and if total liver-DNA methylation differ between the different rat strains (Prague hereditary hypercholesterolemic rats, Prague hereditary hypertriglyceridemic rats and Wistar Kyoto rats). The animals were feed with high fat (additional 5 % over normal capacity) high cholesterol (2 %) diet for 14 days. DNA methylation in the liver tissue in different generations was analyzed using the liquid chromatography coupled with tandem mass spectrometry. We have not observed any significant changes in total liver-DNA methylation over the 9 generations of animals feed by fat/cholesterol enriched diet. Additionally, there were no differences in DNA methylation between different rat strains. In animal model, the dietary changes (hypercholesterolemic diet) not significantly influence the total DNA methylation status within the liver.

The Effect of Lipotoxicity on Renal Dysfunction in a Nonobese Rat Model of Metabolic Syndrome: A Urinary Proteomic Approach.

Introduction The development of metabolic syndrome-associated renal dysfunction is exacerbated by a number of factors including dyslipidemia, ectopic deposition of lipids and their toxic metabolites, impairment of lipid metabolism, and insulin resistance. Renal dysfunction is also affected by the production of proinflammatory and profibrotic factors secreted from adipose tissue, which can in turn directly impair kidney cells and potentiate insulin resistance. In this study, we investigated the manifestation of renal lipid accumulation and its effect on renal dysfunction in a model of metabolic syndrome—the hereditary hypertriglyceridemic rat (HHTg)—by assessing microalbuminuria and targeted urinary proteomics. Male Wistar control rats and HHTg rats were fed a standard diet and observed over the course of ageing at 3, 12, and 20 months of age. Results Chronically elevated levels of triglycerides in HHTg rats were associated with increased levels of NEFA during OGTT and over a period of 24 hours (+80%, P < 0.01). HHTg animals exhibited qualitative changes in NEFA fatty acid composition, represented by an increased proportion of saturated fatty acids (P < 0.05) and a decreased proportion of n-3 PUFA (P < 0.01). Ectopic lipid deposition in the kidneys of HHTg rats—triglycerides (+30%) and cholesterol (+10%)—was associated with markedly elevated microalbuminuria as ageing increased, despite the absence of microalbuminuria at the young age of 3 months in these animals. According to targeted proteomic analysis, 3-month-old HHTg rats (in comparison to age-matched controls) exhibited increased urinary secretion of proinflammatory parameters (MCP-1, IL-6, IL-8, P < 0.01) and decreased urinary secretion of epidermal growth factor (EGF, P < 0.01) before manifestation of microalbuminuria. Elevation in the urinary secretion of inflammatory cytokines can be affected by increased relative expression of MCP-1 in the renal cortex (P < 0.05). Conclusions Our results confirm dyslipidemia and ectopic lipid accumulation to be key contributors in the development of metabolic syndrome-associated renal dysfunction. Assessing urinary secretion of proinflammatory cytokines and epidermal growth factor can help in detecting early development of metabolic syndrome-associated renal dysfunction.

1962-P: Comparison of the Effects of Three SGLT2 Inhibitors on Metabolic Parameters and Insulin Sensitivity in a Nondiabetic Rat Model of Metabolic Syndrome

Studies directly comparing metabolic efficacy of various sodium glucose cotransporter-2 inhibitors (SGLT2i) are scarce. To this end, we compared the effect of SGLT2i: Empagliflozin (EMP), Canagliflozin (CAN) and Dapagliflozin (DAP) on biometric, metabolic and hormonal parameters and insulin sensitivity in hereditary hypertriglyceridemic rats (hHTG) - a non-obese model of metabolic syndrome characterized by dyslipidemia, insulin resistance and increased blood pressure. Male rats, 4 months old, were fed standard diet (C) or standard diet enriched by EMP (10mg/kg b.w./day), CAN (100mg/kg b.w./day) or DAP (10mg/kg b.w./day) for 6 weeks. All SGLT2i induced glycosuria which was 8-fold higher in CAN and DAP as compared to EMP group (Mean±SD: EMP:53±6; CAN:416±4; DAP:376±32 mmol/l; P&amp;lt;0.001). CAN decreased body weight relative to C while EMP and DAP had no significant effect. Visceral fat weight decreased in CAN and DAP compared to C (P&amp;lt;0.01). Relative weight of kidneys (g/100g b.w.) was increased in all SGLT2i groups compared to C with a less pronounced effect of EMP relative to CAN and DAP (P&amp;lt;0.01). CAN decreased both fasting and postprandial glycemia relative to other groups. Postprandial triglyceride levels were decreased by all SGLT2i compared to C (EMP: -32%; P&amp;lt;0.01; CAN: -55%; DAP -48%, P&amp;lt;0.001). 14C-palmitic acid oxidation decreased in the myocardium of CAN and DAP compared to C, whereas no significant effect of EMP was noted. CAN and EMP administration reduced liver glycogen content compared to C (P&amp;lt;0.05). Leptin levels decreased in CAN (-79%) and DAP (-56%) compared to C. GLP-1 levels increased in CAN compared to other groups while C-peptide was lower in CAN vs. C group. In conclusion, our results suggest higher efficacy of CAN compared to DAP and EMP in improving insulin sensitivity and decreasing glucose levels in a non-obese model of metabolic syndrome. The differences could be related to higher SGLT1 inhibition activity of CAN. Disclosure J. Trnovska: None. M. Hüttl: None. I. Marková: None. O. Oliyarnyk: None. H. Malinska: None. D. Miklankova: None. H. Kratochvilova: None. P. Svoboda: None. A. Cinkajzlova: None. I. Lankova: None. M. Mraz: None. M. Haluzik: None. Funding MH CZ - DRO; Institute for Clinical and Experimental Medicine (IN00023001)

Fenofibrate Decreases Hepatic P-Glycoprotein in a Rat Model of Hereditary Hypertriglyceridemia.

P-glycoprotein (P-gp) is a membrane-bound transporter encoded by Mdr1a/Abcb1a and Mdr1b/Abcb1b genes in rodents involved in the efflux of cytotoxic chemicals and metabolites from cells. Modulation of its activity influences P-gp-mediated drug delivery and drug-drug interaction (DDI). In the current study, we tested the effects of fenofibrate on P-gp mRNA and protein content in non-obese model of metabolic syndrome. Males hereditary hypertriglyceridemic rats (HHTg) were fed standard laboratory diet (STD) (Controls) supplemented with micronized fenofibrate in lower (25 mg/kg b. wt./day) or in higher (100 mg/kg b. wt./day) dose for 4 weeks. Liver was used for the subsequent mRNA and protein content analysis. Fenofibrate in lower dose decreased hepatic Mdr1a by 75% and Mdr1b by 85%, while fenofibrate in higher dose decreased Mdr1a by 90% and Mdr1b by 92%. P-gp protein content in the liver was decreased by 74% in rat treated with fenofibrate at lower dose and by 88% in rats using fenofibrate at higher dose. These findings demonstrate for the first time that fenofibrate decreases both mRNA and protein amount of P-gp and suggest that fenofibrate could affect bioavailability and interaction of drugs used to treat dyslipidemia-induced metabolic disorders.

Micronized silymarin extract reduced hepatotoxic effect of fenofibrate in hereditary hypertriglyceridemic rats

Aim: Hypolipidemic effect of fibrates, mediated by PPARα activation, can be accompanied by liver damage due to oxidative stress and inflammation. Hepatoprotective effect of silymarin was demonstrated in clinical and experimental studies. We investigated whether silymarin improves negative effect of fenofibrate in experimental model of metabolic syndrome, hereditary hypertriglyceridemic rats (HHTg).

The Effect of Empagliflozin on Metabolic Parameters in Nonobese Nondiabetic Model of Metabolic Syndrome

Empagliflozin (EMPAG), an SGLT2 inhibitor, improves glucose metabolism by increasing urinary glucose output. EMPA-REG OUTCOME study documented cardiovascular (CV) benefits of EMPAG in patients with type 2 diabetes (T2DM) and history of a CV event. This work was undertaken to investigate complex effects of EMPAG in hereditary hypertriglyceridemic rats (HHTg), a non-obese, nondiabetic model of metabolic sydrome. HHTg rats are characterized by the presence of dyslipidemia and insulin resistance without obesity or hyperglycemia. 8 months old male HHTg rats were fed a standard diet (SD) or SD enriched by EMPAG in a dose of 10 mg/kg body weight/day for 6 weeks. EMPAG treatment suppressed an increase in body weight despite greater average food intake in EMPAG relative to control group. EMPAG administration induced glycosuria (+99%; P&amp;lt;0.001) and decreased fasting glycemia (-21%; P&amp;lt;0.02). Plasma lipid profile in postprandial state revealed a decrease in triglycerides (-34%; P&amp;lt;0.001) and insulin (-36%;P&amp;lt;0.01), increase in HDL cholesterol (+17%; P&amp;lt;0.01) and free fatty acids (+36%; P&amp;lt;0.02). Systemic ketone bodies concentrations were unchanged with simultaneous decrease in 14C-palmitic acid oxidation in the myocardium suggesting ketone bodies utilization by this tissue. EMPAG improved parameters of oxidative stress (SOD: +24%; P&amp;lt;0.03; GSH-Px: +31%; P&amp;lt;0.01; TBARS: -17%; P&amp;lt;0.003) in the kidney and decreased glycogen content in the liver and muscle by 39% and 13%; respectively (P&amp;lt;0.01). EMPAG improved insulin sensitivity of white adipose tissue (+13%; P&amp;lt;0.05) and decreased relative weight of perirenal adipose tissue (-13%; P&amp;lt;0.01). In conclusion, in nondiabetic rats with MS, EMPAG improved insulin sensitivity of WAT, dyslipidemia and oxidative stress in the kidney. Combination of these factors may partially explain CV benefits of EMPAG in T2DM and suggests the possibility of similar benefits in patients with metabolic syndrome without diabetes. Disclosure J. Trnovska: None. M. Hüttl: None. I. Marková: None. O. Oliyarnyk: None. H. Malinska: None. L. Kazdova: None. M. Haluzik: None.

Hepatic Transcriptomic Signature of High-Sucrose Diet in Nonobese Model of Metabolic Syndrome and Prediabetes

Both genetic predisposition and nutrition factors, such as high sucrose diet (HSD), are involved in the development of metabolic syndrome and insulin resistance. HSD can cause glucose intolerance and liver steatosis and exert hypertriglyceridemic effect. The aim of this study was to investigate the liver transcriptome profile under standard diet or HSD (70 kcal% as sucrose) in two strains of rats. We used Wistar rats and a strain of hereditary hypertriglyceridemic rats (HHTg) as a polygenic model of metabolic syndrome and insulin resistance. HSD feeding in 2 weeks did not affect body weight, but fasting glucose and AUC were increased (P diet&amp;lt;0.01, P strain&amp;lt;0.05). HSD feeding in both strains led to marked accumulation of hepatic triglycerides (P diet&amp;lt;0.01). However, cholesterol concentrations in the liver were reduced after HSD (P diet&amp;lt;0.01) in both strains. Comparative transcriptomic analyses in the liver identified (FDR&amp;lt;0.05) sets of differentially expressed genes in response to HSD common to both strains (n=959 transcripts) as well as HHTg (n=687) and Wistar (n=1531) specific sets. Network analysis revealed overrepresentation of genes involved in transport, synthesis or regulation of lipid metabolism (SREBF, PPARA, PPARG, SCD), mitochondrial dysfunction, excessive oxidative stress response (NRF2-mediated) and endoplasmic reticulum stress. Expression of genes related to sterol biosynthesis and oxidative phosphorylation was down-regulated, whereas genes involved in fatty acid synthesis (FAS, ACC), oxidative or endoplasmic reticulum stress were up-regulated after HSD. Our results support that HSD induced alterations in the liver transcriptome in both strains, which precede the development and progression of liver steatosis. The top regulated gene networks included lipid metabolism and mitochondrial dysfunction. Most of the major expression shifts due to HSD were similar in direction in both strains but differed in magnitude of expression change. Disclosure I. Marková: None. M. Hüttl: None. H. Malinska: None. O. Seda: None. L. Kazdova: None.

The Different Effect of Sucrose on Transcriptomic Profile in Adipose and Muscle Tissues in Model of Metabolic Syndrome and Insulin Resistance

The development and progression of insulin resistance is driven by genetic and enviromental factors and their interactions. Sucrose belongs to nutrition factors with lipogenic impact, induces de novo lipogenesis, reduces fatty acid oxidation and can deteriorate insulin sensitivity. The aim of study was to investigate transcriptome profile in adipose and muscle tissues under standard or high sucrose diet (HSD) (70 kcal% as sucrose) in two strains of rats - Wistar and a strain of hereditary hypertriglyceridemic rats (HHTg) as a polygenic model of metabolic syndrome and insulin resistance. The transcriptome analysis was evaluated in the context of development and progression of insulin resistance. HSD feeding in 2 weeks increased epididymal adipose tissue (EAT) weight in both strains (P diet&amp;lt;0.05), but not body weight. In addition, HSD feeding resulted in elevated levels of fasting glucose (P diet&amp;lt;0.05), insulin (P diet&amp;lt;0.01) and FFA (P diet&amp;lt;0.05, P strain&amp;lt;0.05), but adiponectin was decreased only in HHTg rats (P&amp;lt;0.01). Insulin sensitivity of EAT was significantly reduced (P diet&amp;lt;0.05, P strain&amp;lt;0.05), but HSD did not change triglycerides or insulin sensitivity in muscle. In skeletal muscle, HSD significantly changed expression (FDR&amp;lt;0.05) of 20 transcripts in HHTg and 21 in Wistar (only 2 common). In EAT, HSD significantly changed expression of 810 transcripts in HHTG and 1823 in Wistar (344 common). The most affected pathways were insulin receptor signaling in HHTg and mitochondrial dysfunction and oxidative phosphorylation in Wistar rats. Major regulator nodes of the mechanistic networks included insulin, SCD and miR-27 for HSD effect in HHTg and LIPE, miR-27 and VEGF in Wistar strain. In conclusion, HSD feeding impaired insulin sensitivity in both rat strains. Transcriptomic alterations in adipose tissue precede muscle changes caused by HSD and show distinct patterns in genetically susceptible HHTg model of metabolic syndrome. Disclosure M. Hüttl: None. I. Marková: None. H. Malinska: None. L. Kazdova: None. O. Seda: None.

Metformin attenuates myocardium dicarbonyl stress induced by chronic hypertriglyceridemia.

Reactive dicarbonyls stimulate production of advanced glycation endproducts, increase oxidative stress and inflammation and contribute to the development of vascular complications. We measured concentrations of dicarbonyls - methylglyoxal (MG), glyoxal (GL) and 3-deoxyglucosone (3-DG) - in the heart and kidney of a model of metabolic syndrome - hereditary hypertriglyceridemic rats (HHTg) and explored its modulation by metformin. Adult HHTg rats were fed a standard diet with or without metformin (300 mg/kg b.w.) and dicarbonyl levels and metabolic parameters were measured. HHTg rats had markedly elevated serum levels of triacylglycerols (p<0.001), FFA (p<0.01) and hepatic triacylglycerols (p<0.001) along with increased concentrations of reactive dicarbonyls in myocardium (MG: p<0.001; GL: p<0.01; 3-DG: p<0.01) and kidney cortex (MG: p<0.01). Metformin treatment significantly reduced reactive dicarbonyls in the myocardium (MG: p<0.05, GL: p<0.05, 3-DG: p<0.01) along with increase of myocardial concentrations of reduced glutathione (p<0.01) and glyoxalase 1 mRNA expression (p<0.05). Metformin did not have any significant effect on dicarbonyls, glutathione or on glyoxalase 1 expression in kidney cortex. Chronically elevated hypertriglyceridemia was associated with increased levels of dicarbonyls in heart and kidney. Beneficial effects of metformin on reactive dicarbonyls and glyoxalase in the heart could contribute to its cardioprotective effects.