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In its initial stages, nonalcoholic fatty liver disease presents hypertriglyceridemia and accumulation of lipids in the liver (hepatic steatosis). Bempedoic acid is an ATP:citrate lyase inhibitor that promotes a dual inhibition of the synthesis of cholesterol and fatty acids. However, its effect in the prevention / treatment of hepatic steatosis and hypertriglyceridemia has not been investigated. The aim of our work has been to elucidate whether bempedoic acid, through a mechanism other than ATP:citrate lyase inhibition, reverses these metabolic alterations.The study was carried out in female Sprague-Dawley rats fed, for three months, with a high fat diet supplemented with fructose (10% w/v) in drinking water. During the last month, bempedoic acid (30mg/kg/day) was administered to a group of animals. Zoometric and plasmatic parameters were analyzed, gene and protein expression analysis were performed in liver samples and PPAR-PPRE binding activity was determined.Our interventional model developed hepatic steatosis and hypertriglyceridemia. Despite an increase in total caloric intake, there was no increase in body weight of the animals. The administration of bempedoic acid significantly reduced hepatic steatosis and promoted a marked hepatocyte hypertrophy. There was a 66% increase in the liver weight of the animals treated with the drug that was not accompanied by modifications in the markers of inflammation, oxidative stress, or endoplasmic reticulum stress. Bempedoic acid activated the peroxisome proliferator activated nuclear receptor (PPARα) and its target genes.Bempedoic acid could be an effective therapy for the treatment of fatty liver and associated cardiovascular risk. Bempedoic acid has other mechanisms of action besides the inhibition of ATP: citrate lyase, such as the activation of PPARα, which could explain the reduction in hepatic steatosis and the increase in liver weight observed in animals treated with the drug.

We previously demonstrated that treatment with BemA (bempedoic acid), an inhibitor of ATP citrate lyase, significantly reduces fatty liver in a model of liver steatosis (HFHFr-female Sprague-Dawley rat fed a high-fat high-fructose diet). Since the hepatic production of the gasotransmitter H

Scope: The aim of this study is to delineate the contribution of dietary saturated fatty acids (FA) versus liquid fructose to fatty liver and hypertriglyceridemia. Methods and results: Three groups of female rats are maintained for 3 months in standard chow (CT); High-fat diet (46.9% of fat-derived calories, rich in palmitic and stearic FA, HFD); and HFD with 10% w/v fructose in drinking water (HFHFr). Zoometric parameters, plasma biochemistry, and liver Oil-Red O (ORO) staining, lipidomics, and expression of proteins involved in FA metabolism are analyzed. Both diets increase ingested calories without modifying body weight. Only the HFHFr diet increases liver triglycerides (x11.0), with hypertriglyceridemia (x1.7) and reduces FA β-oxidation (x0.7), and increases liver FA markers of DNL (de novo lipogenesis). Whereas HFD livers show a high content of ceramides, HFHFr samples show unchanged ceramides, and an increase in diacylglycerols. Only the HFHFr diet leads to a marked increase in the expression of enzymes involved in DNL and triglyceride metabolism, such as carbohydrate response element binding protein β (ChREBPβ, x3.2), a transcription factor that regulates DNL, and patatin-like phospholipase domain-containing 3 (PNPLA3, x2.6), a lipase that mobilizes stored triglycerides for VLDL secretion. Conclusion: The addition of liquid-fructose to dietary FA is determinant in liver steatosis and hypertriglyceridemia production, through increased DNL and PNPLA3 expression, and reduced FA catabolism. This research was funded Grant SAF2017-82369-R funded by MCIN/AEI/ 10.13039/501100011033 and by ERDF A way of making Europe, Generalitat de Catalunya (2017 SGR 38). A.M.V. is a predoctoral fellow, BECAL grant program BCAL04-327, from the Government of Paraguay. A.S.-V. is recipient of the Instituto de Salud Carlos III Miguel Servet fellowship (grant CP II 17/00029).

La enfermedad del hígado graso no alcohólico cursa, en sus fases iniciales, con hipertrigliceridemia y acúmulo de lípidos en el hígado (esteatosis hepática). El ácido bempedoico es un inhibidor de la ATP:citrato liasa que promueve una inhibición dual de la síntesis de colesterol y ácidos grasos. Sin embargo, no se ha investigado su efecto en la prevención/tratamiento de la esteatosis hepática y la hipertrigliceridemia. El objetivo de nuestro trabajo ha sido elucidar si el ácido bempedoico, mediante un mecanismo diferente/alternativo a la inhibición de la ATP:citrato liasa, revierte estas alteraciones metabólicas. Diseño experimental El estudio se realizó con un modelo animal de rata Sprague-Dawley hembra alimentada, durante 3 meses, con una dieta rica en grasa saturada suplementada con fructosa al 10% (p/v) en el agua de bebida. Se administró, durante el último mes, ácido bempedoico (30 mg/kg/día) a un grupo de animales. Se analizaron parámetros zoométricos, se realizaron valoraciones plasmáticas, de expresión génica y proteica en muestras de hígado y se determinó la actividad de unión PPAR-PPRE. Resultados Nuestro modelo de intervención dietética desarrolló esteatosis hepática e hipertrigliceridemia. A pesar de un aumento en la ingesta calórica total, no se observó un incremento de peso corporal de los animales. La administración de ácido bempedoico redujo significativamente la esteatosis hepática y promovió una marcada hipertrofia de los hepatocitos.

Background: Non-alcoholic fatty liver disease (NAFLD) has increased over the last decades and may evolve into hepatocellular carcinoma (HCC). As HCC is challenging to treat, knowledge on the modifiable risk factors for NAFLD/HCC (e.g. hyper caloric diets rich in fructose) is essential. Objective and design: We used a model of diethyl nitrosamine-induced hepatocarcinogenesis to investigate the liver cancer-promoting effects of a diet supplemented with 10% liquid fructose, administered to male and female rats for 11 months. A subset of the fructose-supplemented rats received resveratrol (RVT) in the last 4 months of treatment. Results and discussion: Rat livers showed no de visu or histological evidence of liver tumorigenesis. However, we observed metabolic abnormalities that could be related to cancer development mainly in the female fructose-supplemented rats, such as increases in weight, adiposity and hepatic triglyceride levels, as well as hyperglycaemia, hyperuricemia, hyperleptinemia and a reduced insulin sensitivity index, which were partially reversed by RVT. Therefore, we performed a targeted analysis of 84 cancer-related genes in the female liver samples, which revealed expression changes associated with cancer-related pathways. Analysis of individual genes indicated that some changes increased the risk of hepatocarcinogenesis (Sfrp2, Ccl5, Socs3, and Gstp1), while others exerted a protective/preventive effect (Bcl2 and Cdh1). Conclusion: Our data clearly demonstrate that chronic fructose supplementation, as the sole dietary intervention, does not cause HCC development in rats. Keywords: diethyl nitrosamine; hepatocellular cancer; metabolic syndrome; sugar-sweetened beverages; sugary drinks.

Altres ajuts: Ministerio de Educación (República de Paraguay), BCAL04-451 - 3824321 Scope: Interventions that boost NAD+ availability are of potential therapeutic interest for obesity treatment. The potential of nicotinamide (NAM), the amide form of vitamin B3 and a physiological precursor of nicotinamide adenine dinucleotide (NAD)+, in preventing weight gain has not previously been studied in vivo. Other NAD+ precursors have been shown to decrease weight gain; however, their impact on adipose tissue is not addressed. Methods and results: Two doses of NAM (high dose: 1% and low dose: 0.25%) are given by drinking water to C57BL/6J male mice, starting at the same time as the high-fat diet feeding. NAM supplementation protects against diet-induced obesity by augmenting global body energy expenditure in C57BL/6J male mice. The manipulation markedly alters adipose morphology and metabolism, particularly in inguinal (i) white adipose tissue (iWAT). An increased number of brown and beige adipocyte clusters, protein abundance of uncoupling protein 1 (UCP1), mitochondrial activity, adipose NAD+, and phosphorylated AMP-activated protein kinase (P-AMPK) levels are observed in the iWAT of treated mice. Notably, a significant improvement in hepatic steatosis, inflammation, and glucose tolerance is also observed in NAM high-dose treated mice. Conclusion: NAM influences whole-body energy expenditure by driving changes in the adipose phenotype. Thus, NAM is an attractive potential treatment for preventing obesity and associated complications.

Previous reports suggest that diabetes may differentially affect the vascular beds of females and males. However, there is insufficient evidence to establish the timeline of the vascular dysfunction in diabetes, specifically in relation to sex. Here, we determined whether mesenteric arterial function is altered in UC Davis Type-2 Diabetes Mellitus (UCD-T2DM) rats and if this occurs as early as the pre-diabetic stage of the disease. Specifically, we investigated whether vascular dysfunction differs between pre-diabetic or diabetic status and if this varies by sex. We measured the responses to endothelium-dependent and -independent vasorelaxant as well as vasoconstrictor agents and explored the potential mechanisms involved in sex-specific development of arterial dysfunction in UCD-T2DM rats. In addition, indices of insulin sensitivity were assessed. We report the reduced insulin sensitivity in pre-diabetic males and diabetic females. Vascular relaxation to acetylcholine was impaired to a greater extent in mesenteric artery from males in the pre-diabetic stage than in their female counterparts. In contrast, the arteries from females with diabetes exhibited a greater impairment to acetylcholine compared with diabetic males. Additionally, the sensitivity of mesenteric artery to contractile agents in females, but not in males, after the onset of diabetes was increased. Our data suggest that the reduced insulin sensitivity through AKT may predispose vessels to injury in the pre-diabetic stage in males. On the other hand, reduced insulin sensitivity as well as enhanced responsiveness to contractile agents may predispose arteries to injury in the diabetic stage in females.

Background Low-density lipoprotein receptor-related protein 1 (LRP1) plays a key role in fatty acid metabolism and glucose homeostasis. In the context of dyslipemia, LRP1 is upregulated in the heart. Our aim was to evaluate the impact of cardiomyocyte LRP1 deficiency on high fat diet (HFD)-induced cardiac and metabolic alterations, and to explore the potential mechanisms involved. Methods We used TnT-iCre transgenic mice with thoroughly tested suitability to delete genes exclusively in cardiomyocytes to generate an experimental mouse model with conditional Lrp1 deficiency in cardiomyocytes (TNT-iCre+-LRP1flox/flox). Findings Mice with Lrp1-deficient cardiomyocytes (cm-Lrp1−/−) have a normal cardiac function combined with a favorable metabolic phenotype against HFD-induced glucose intolerance and obesity. Glucose intolerance protection was linked to higher hepatic fatty acid oxidation (FAO), lower liver steatosis and increased whole-body energy expenditure. Proteomic studies of the heart revealed decreased levels of cardiac pro-atrial natriuretic peptide (pro-ANP), which was parallel to higher ANP circulating levels. cm-Lrp1−/− mice showed ANP signaling activation that was linked to increased fatty acid (FA) uptake and increased AMPK/ ACC phosphorylation in the liver. Natriuretic peptide receptor A (NPR-A) antagonist completely abolished ANP signaling and metabolic protection in cm-Lrp1−/− mice. Conclusions These results indicate that an ANP-dependent axis controlled by cardiac LRP1 levels modulates AMPK activity in the liver, energy homeostasis and whole-body metabolism., This work was funded by FIS PI14/01729 and FIS PI18/01584 (to VLl-C), FIS16/00139 (to JCE-G) grants from Instituto Salud Carlos III, co-financed by the European Fund for Regional Development (E.F.R.D.) and by the Ministry of Spain-MINECO (SAF2014-52223-C2-1-R to DS, co-financed by the European Fund for Regional Development (E.F.R.D.). Support was received from Ministerio de Economía y Competitividad to DdG-C (IJCI-2016-29393), Agència de Gestió d'Ajuts Universitaris i de Recerca Grant FI to ERL (FI-DGR 2013/00014), Fundació MARATÓ TV3 Project 201521-10 (to VLl-C) and Project 87/C/2016 to DS. CIBER Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM; CB07/08/0016 (FBV, JCE-G, LC); CB07/08/0017 (AZ), CIBER Fisiopatología de la Obesidad y la Nutrición (CIBEROBN; CB06/03/0001 (DS, LH); CB06/03/0017 (JCL, NR)) and CIBER Enfermedades Cardiovasculares (CIBERCV; CB16/1100403) (DdG-C, VLl-, CS, ERL and AB-G) are Instituto de Salud Carlos III (ISCIII) projects.

Endoplasmic reticulum (ER) homeostasis is crucial to appropriate cell functioning, and when disturbed, a safeguard system called unfolded protein response (UPR) is activated. Fructose consumption modifies ER homeostasis and has been related to metabolic syndrome. However, fructose sweetened beverages intake is allowed during gestation. Therefore, we investigate whether maternal fructose intake affects the ER status and induces UPR. Thus, administrating liquid fructose (10% w/v) to pregnant rats partially activated the ER-stress in maternal and fetal liver and placenta. In fact, a fructose-induced increase in the levels of pIRE1 (phosphorylated inositol requiring enzyme-1) and its downstream effector, X-box binding protein-1 spliced form (XBP1s), was observed. XBP1s is a key transcription factor, however, XBP1s nuclear translocation and the expression of its target genes were reduced in the liver of the carbohydrate-fed mothers, and specifically diminished in the fetal liver and placenta in the fructose-fed mothers. These XBP1s target genes belong to the ER-associated protein degradation (ERAD) system, used to buffer ER-stress and to restore ER-homeostasis. It is known that XBP1s needs to form a complex with diverse proteins to migrate into the nucleus. Since methylglyoxal (MGO) content, a precursor of advanced glycation endproducts (AGE), was augmented in the three tissues in the fructose-fed mothers and has been related to interfere with the functioning of many proteins, the role of MGO in XBP1s migration should not be discarded. In conclusion, maternal fructose intake produces ER-stress, but without XBP1s nuclear migration. Therefore, a complete activation of UPR that would resolve ER-stress is lacking. A state of fructose-induced oxidative stress is probably involved.

Non-alcoholic fatty liver disease is a highly prevalent condition without specific pharmacological treatment, characterized in the initial stages by hepatic steatosis. It was suggested that lipid infiltration in the liver might be reduced by caffeine through anti-inflammatory, antioxidative, and fatty acid metabolism-related mechanisms. We investigated the effects of caffeine (CAF) and green coffee extract (GCE) on hepatic lipids in lean female rats with steatosis. For three months, female Sprague-Dawley rats were fed a standard diet or a cocoa butter-based high-fat diet plus 10% liquid fructose. In the last month, the high-fat diet was supplemented or not with CAF or a GCE, providing 5 mg/kg of CAF. Plasma lipid levels and the hepatic expression of molecules involved in lipid metabolism were determined. Lipidomic analysis was performed in liver samples. The diet caused hepatic steatosis without obesity, inflammation, endoplasmic reticulum stress, or hepatic insulin resistance. Neither CAF nor GCE alleviated hepatic steatosis, but GCE-treated rats showed lower hepatic triglyceride levels compared to the CAF group. The GCE effects could be related to reductions of hepatic (i) mTOR phosphorylation, leading to higher nuclear lipin-1 levels and limiting lipogenic gene expression, (ii) diacylglycerol levels, (iii) hexosylceramide/ceramide ratios, and (iv) very-low-density lipoprotein receptor expression. In conclusion, a low dose of CAF did not reduce hepatic steatosis in lean female rats, but the same dose provided as a green coffee extract led to lower liver triglyceride levels.

One of the most important threats to global human health is the increasing incidences of metabolic pathologies (including obesity, type 2 diabetes and non-alcoholic fatty liver disease), which is paralleled by increasing consumptions of hypercaloric diets enriched in simple sugars. The challenge is to identify the metabolic pathways affected by the excessive consumption of these dietary components when they are consumed in excess, to unravel the molecular mechanisms leading to metabolic pathologies and identify novel therapeutic targets to manage them. Mechanistic (mammalian) target of rapamycin (mTOR) has emerged as one of the key molecular nodes that integrate extracellular signals, such as energy status and nutrient availability, to trigger cell responses that could lead to the above-mentioned diseases through the regulation of lipid and glucose metabolism. By activating mTOR signalling, excessive consumption of simple sugars (such as fructose and glucose), could modulate hepatic gluconeogenesis, lipogenesis and fatty acid uptake and catabolism and thus lipid deposition in the liver. In the present review we will discuss some of the most recent studies showing the central role of mTOR in the metabolic effects of excessive simple sugar consumption.

In the recent decades, there has been a dramatic increase in the dietary intake of simple sugars such as fructose that has largely been attributed to the elevated consumption of sugar-sweetened beverages. This rise in sugar consumption has been paralleled by an increased prevalence of cardiometabolic risk factors, including insulin resistance and nonalcoholic fatty liver disease. In this review, we discuss the role of liquid fructose in the development of these alterations based on the evidence from animal models and clinical studies. The results show the importance of the species used, the type of sugar supplemented, and the duration and route of sugar supplementation. Moreover, we identify several molecular nodes, such as the ChREBP-KHK and the mTORC1-SREBP-1c axes, together with fatty acid β-oxidation and the IRE-1 branch of the endoplasmic reticulum stress response, which could be responsible for the fructose-related effects on liver metabolism.

Scope The effect of chronic supplementation with simple-sugar solutions on leptin signaling in liver, hypothalamus, and visceral white adipose tissue (vWAT) is studied, which is designed to mimic the temporal pattern of consumption by humans. Methods and results Solutions of fructose or glucose are isocalorically supplemented (7 months) in female Sprague-Dawley rats consuming ad libitum rodent chow. After sacrifice, plasma and tissue samples (liver, hypothalamus, and vWAT) are collected. Zoometric parameters, plasma analytes, and the tissue expression and activity of markers of leptin signaling are determined by biochemical and molecular biological methods. The two sugars cause different types of adiposopathy. Both sugars induce increases in plasma nonesterified fatty acids, and leptin resistance in the liver and the hypothalamus. Only fructose-supplemented rats show hyperleptinemia, and increased body weight due to a hypertrophy of vWAT, with no signs of leptin-mediated lipolysis. Glucose-supplemented rats show no significant changes in these parameters but present elevated plasma adiponectin concentrations, lipolysis, and inflammatory markers in vWAT, indicating a shift to a nonexpandable adipose tissue phenotype. Conclusion Chronic consumption of fructose places a greater burden on metabolic homeostasis than equivalent consumption of glucose, inducing hyperleptinemia, generalized leptin resistance, and increased body weight due to expanded, hypertrophic vWAT.

Excessive sugar intake has been related to cognitive alterations, but it remains unclear whether these effects are related exclusively to increased energy intake, and the molecular mechanisms involved are not fully understood. We supplemented Sprague-Dawley female rats with 10% w/v fructose in drinking water or with isocaloric glucose solution for 7 months. Cognitive function was assessed through the Morris water maze (MWM) and the novel object recognition (NOR) tests. Plasma parameters and protein/mRNA expression in the frontal cortex and hippocampus were determined. Results showed that only fructose-supplemented rats displayed postprandial and fasting hypertriglyceridemia (1.4 and 1.9-fold, p < 0.05) and a significant reduction in the discrimination index in the NOR test, whereas the results of the MWM test showed no differences between groups. Fructose-drinking rats displayed an abnormal glucose tolerance test and impaired insulin signaling in the frontal cortex, as revealed by significant reductions in insulin receptor substrate-2 protein levels (0.77-fold, p < 0.05) and Akt phosphorylation (0.72-fold, p < 0.05), and increased insulin-degrading enzyme levels (1.86-fold, p < 0.001). Fructose supplementation reduced the expression of antioxidant enzymes and altered the amount of proteins involved in mitochondrial fusion/fission in the frontal cortex. In conclusion, cognitive deficits induced by chronic liquid fructose consumption are not exclusively related to increased caloric intake and are correlated with hypertriglyceridemia, impaired insulin signaling, increased oxidative stress and altered mitochondrial dynamics, especially in the frontal cortex.

Fructose intake from added sugars correlates with the epidemic rise in metabolic syndrome and cardiovascular diseases. However, consumption of beverages containing fructose is allowed during gestation. Recently, we found that an intake of fructose (10 % wt/vol) throughout gestation produces impaired fetal leptin signaling and hepatic steatosis. Therefore, we have investigated whether fructose intake during pregnancy produces subsequent changes in the progeny, when adult. Fed 261-day-old male and female descendants from fructose-fed, control or glucose-fed mothers were used. Plasma was used to analyze glucose, insulin, leptin, and adiponectin. Hepatic expression of proteins related to insulin signaling was determined. Fructose intake throughout pregnancy did not produce alterations in the body weight of the progeny. Adult male progeny of fructose-fed mothers had elevated levels of insulin without a parallel increase in phosphorylation of protein kinase B. However, they displayed an augmented serine phosphorylation of insulin receptor substrate-2, indicating reduced insulin signal transduction. In agreement, adiponectin levels, which have been positively related to insulin sensitivity, were lower in male descendants from fructose-fed mothers than in the other two groups. Furthermore, mRNA levels for insulin-responsive genes were not affected (phosphoenolpyruvate carboxykinase, glucose-6-phosphatase) or they were decreased (sterol response element-binding protein-1c) in the livers of male progeny from fructose-supplemented rats. On the contrary, adult female rats from fructose-fed mothers did not exhibit any of these disturbances. Maternal fructose, but not glucose, intake confined to the prenatal stage provokes impaired insulin signal transduction, hyperinsulinemia, and hypoadiponectinemia in adult male, but not female, progeny.

Supplementation with 10% liquid fructose to female rats for 2weeks caused hepatic steatosis through increased lipogenesis and reduced peroxisome proliferator activated receptor (PPAR) α activity and fatty acid catabolism, together with increased expression of the spliced form of X-binding protein-1 (Rebollo et al., 2014). In the present study, we show that some of these effects are preserved after sub-chronic (8weeks) fructose supplementation, specifically increased hepatic expression of lipid synthesis-related genes (stearoyl-CoA desaturase, ×6.7-fold; acetyl-CoA carboxylase, ×1.6-fold; glycerol-3-phosphate acyltransferase, ×1.65-fold), and reduced fatty acid β-oxidation (×0.77-fold), resulting in increased liver triglyceride content (×1.69-fold) and hepatic steatosis. However, hepatic expression of PPARα and its target genes was not modified and, further, livers of 8-week fructose-supplemented rats showed no sign of unfolded protein response activation, except for an increase in p-IRE1 levels. Hepatic mTOR phosphorylation was enhanced (×1.74-fold), causing an increase in the phosphorylation of UNC-51-like kinase 1 (ULK-1) (×2.8-fold), leading to a decrease in the ratio of LC3B-II/LC3B-I protein expression (×0.39-fold) and an increase in the amount of the autophagic substrate p62, indicative of decreased autophagy activity. A harmful cycle may be established in the liver of 8-week fructose-supplemented rats where lipid accumulation may cause defective autophagy, and reduced autophagy may result in decreased free fatty acid formation from triglyceride depots, thus reducing the substrates for β-oxidation and further increasing hepatic steatosis. In summary, the length of supplementation is a key factor in the metabolic disturbances induced by fructose: in short-term studies, PPARα inhibition and ER stress induction are critical events, whereas after sub-chronic supplementation, mTOR activation and autophagy inhibition are crucial.

Sugar-sweetened beverage intake is a risk factor for insulin resistance, dyslipidemia, fatty liver, and steatohepatitis (NASH). Sub-chronic supplementation of liquid fructose, but not glucose, in female rats increases liver and plasma triglycerides without inflammation. We hypothesized that chronic supplementation of fructose would cause NASH and liver insulin resistance. We supplemented female Sprague–Dawley rats with water or either fructose or glucose 10% w/v solutions under isocaloric conditions for 7 months. At the end, plasma analytes, insulin, and adiponectin were determined, as well as liver triglyceride content and the expression of key genes controlling inflammation, fatty acid synthesis and oxidation, endoplasmic reticulum stress, and plasma VLDL clearance, by biochemical and histological methods. Although sugar-supplemented rats increased their energy intake by 50–60%, we found no manifestation of liver steatosis, fibrosis or necrosis, unchanged plasma or tissue markers of inflammation or fibrosis, and reduced liver expression of gluconeogenic enzymes, despite both sugars increased fatty acid synthesis, mTORC1, and IRE1 activity, while decreasing fatty acid oxidation and PPARα activity. Only fructose-supplemented rats were hypertriglyceridemic, showing a reduced expression of VLDL receptor and lipoprotein lipase in skeletal muscle and vWAT. Glucose-supplemented rats showed increased adiponectinemia, which would explain the different metabolic outcomes of the two sugars. Chronic liquid simple sugar supplementation, as the sole risk factor, is not enough for female rats to develop NASH and increased liver gluconeogenesis. Nevertheless, under isocaloric conditions, only fructose induced hypertriglyceridemia, thus confirming that also the type of nutrient matters in the development of metabolic diseases.

Sugar intake has dramatically increased during the last few decades. Specifically, there has been a clear trend towards higher consumption of fructose and high fructose corn syrup, which are the most common added sugars in processed food, soft drinks and other sweetened beverages. Although still controversial, this rising trend in simple sugar consumption has been positively associated with weight gain and obesity, insulin resistance and type 2 diabetes mellitus and non-alcoholic fatty liver disease. Interestingly, all of these metabolic alterations have also been related to the development of hepatocellular carcinoma. The purpose of this review is to discuss the evidence coming from epidemiological studies and data from animal models relating the consumption of simple sugars, and specifically fructose, with an increased risk of hepatocellular carcinoma and to gain insight into the putative molecular mechanisms involved.

Fructose ingestion is associated with the production of hepatic steatosis and hypertriglyceridemia. For fructose to attain these effects in rats, simultaneous induction of fatty acid synthesis and inhibition of fatty acid oxidation is required. We aimed to determine the mechanism involved in the inhibition of fatty acid oxidation by fructose and whether this effect occurs also in human liver cells. Female rats were supplemented or not with liquid fructose (10% w/v) for 7 or 14 days; rat (FaO) and human (HepG2) hepatoma cells, and human hepatocytes were incubated with fructose 25 mM for 24 h. The expression and activity of the enzymes and transcription factors relating to fatty acid β-oxidation were evaluated. Fructose inhibited the activity of fatty acid β-oxidation only in livers of 14-day fructose-supplemented rats, as well as the expression and activity of peroxisome proliferator activated receptor α (PPARα). Similar results were observed in FaO and HepG2 cells and human hepatocytes. PPARα downregulation was not due to an osmotic effect or to an increase in protein-phosphatase 2A activity caused by fructose. Rather, it was related to increased content in liver of inactive and acetylated peroxisome proliferator activated receptor gamma coactivator 1α, due to a reduction in sirtuin 1 expression and activity. In conclusion, fructose inhibits liver fatty acid oxidation by reducing PPARα expression and activity, both in rat and human liver cells, by a mechanism involving sirtuin 1 down-regulation.

Fructose intake from added sugars correlates with the epidemic rise in obesity, metabolic syndrome and cardiovascular diseases. Fructose intake also causes features of metabolic syndrome in laboratory animals. Therefore, we have investigated whether fructose modifies lipidemia in pregnant rats and produces changes in their fetuses. Thus, fructose administration (10% wt/vol.) in the drinking water of rats throughout gestation leads to maternal hypertriglyceridemia. This change was not observed in glucose-fed rats, although both carbohydrates produced similar changes in liver triglycerides and in the expression of transcription factors and enzymes involved in lipogenesis. After fasting overnight, mothers fed with carbohydrates were found to be hyperleptinemic. However, after a bolus of glucose, leptinemia in fructose-fed mothers showed no response, whereas it increased in parallel in glucose-fed and control mothers. Fetuses from fructose-fed mothers showed hypotriglyceridemia and a higher hepatic triglyceride content than fetuses from control or glucose-fed mothers. A higher expression of genes related to lipogenesis and a lower expression of fatty acid catabolism genes were also found in fetuses from fructose-fed mothers. Moreover, although hyperleptinemic, these fetuses exhibited increased tyrosine phosphorylation of the signal transducer and activator of transcription-3 (STAT-3) protein, without a parallel increase in the serine phosphorylation of STAT-3 nor in the suppressor of cytokine signaling-3 protein levels whose expression is regulated by leptin through STAT-3 activation. Thus, fructose intake during gestation provoked a diminished maternal leptin response to fasting and refeeding and an impairment in the transduction of the leptin signal in the fetuses, which could be responsible for their hepatic steatosis.

A high consumption of fat and simple sugars, especially fructose, has been related to the development of insulin resistance, but the mechanisms involved in the effects of these nutrients are not fully understood. This study investigates the effects of a Western-type diet and liquid fructose supplementation, alone and combined, on insulin signalling and inflammation in low-density lipoprotein (LDL) receptor-deficient mice (LDL-R−/−). LDL-R−/− mice were fed chow or Western diet ±15% fructose solution for 12 weeks. Plasma glucose and insulin, and the expression of genes related to inflammation in the liver and visceral white adipose tissue (vWAT), were analysed. V-akt murine thymoma viral oncogene homolog-2 (Akt) activation was measured in the liver of the mice after a single injection of saline or insulin. None of the dietary interventions caused inflammation in vWAT, whereas the Western diet induced hepatic inflammation, which was further enhanced by liquid fructose, leading also to a significant increase in fibrogenesis markers. However, there was no change in plasma glucose or insulin, or insulin-induced Akt phosphorylation. In conclusion, hepatic inflammation and fibrogenesis markers induced by a Western diet supplemented with liquid fructose in LDL-R−/− mice are not associated with a significant impairment of hepatic insulin signalling.

Human hepatic lipase (hHL) is mainly localized on the hepatocyte cell surface where it hydrolyzes lipids from remnant lipoproteins and high density lipoproteins and promotes their hepatic selective uptake. Furthermore, hepatic lipase (HL) is closely associated with obesity in multiple studies. Therefore, HL may play a key role on lipid homeostasis in liver and white adipose tissue (WAT). In the present study, we aimed to evaluate the effects of hHL expression on hepatic and white adipose triglyceride metabolism in vivo. Experiments were carried out in hHL transgenic and wild-type mice fed a Western-type diet. Triglyceride metabolism studies included β-oxidation and de novo lipogenesis in liver and WAT, hepatic triglyceride secretion, and adipose lipoprotein lipase (LPL)-mediated free fatty acid (FFA) lipolysis and influx. The expression of hHL promoted hepatic triglyceride accumulation and de novo lipogenesis without affecting triglyceride secretion, and this was associated with an upregulation of Srebf1 as well as the main genes controlling the synthesis of fatty acids. Transgenic mice also exhibited more adiposity and an increased LPL-mediated FFA influx into the WAT without affecting glucose tolerance. Our results demonstrate that hHL promoted hepatic steatosis in mice mainly by upregulating de novo lipogenesis. HL also upregulated WAT LPL and promoted triglyceride-rich lipoprotein hydrolysis and adipose FFA uptake. These data support the important role of hHL in regulating hepatic lipid homeostasis and confirm the broad cardiometabolic role of HL., This work was partly funded by the Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III, and FEDER "Una manera de hacer Europa", grants FIS 08-1147 (to F.B.-V.), CP13- 00070 (to J.J.), FIS 16-00139 (to J.C.E.-G.) and 303/C/2016 (to J.J.) from La Fundacio´ La Marato TV3. J.J. is recipient of a Miguel Servet Type 1 contract. CIBER de Diabetes y Enfermedades Metabólicas Asociadas is an Instituto de Salud Carlos III Project.

Background/objectives: Liquid fructose associates with prevalence of type 2 diabetes mellitus and obesity. Intervention studies suggest that metabolically unfit individuals are more responsive than healthy individuals to liquid fructose. We determined whether mice consuming an obesogenic Western diet were more responsive than chow-fed mice to the alterations induced by liquid fructose supplementation (LFS).Methods: C57BL/6N mice were fed chow or Western diet +/- ad libitum 15% fructose solution for 12 weeks. Food and liquid intake and body weight were monitored. Plasma analytes and liver lipids, histology and the expression of genes related to lipid handling, endoplasmic reticulum stress, inflammation and insulin signaling were analyzed.Results: Western diet increased energy intake, visceral adipose tissue (vWAT), body weight, plasma and liver triglycerides and cholesterol, and inflammatory markers in vWAT vs. chow-fed mice. LFS did not change energy intake, vWAT or body weight. LFS significantly increased plasma and liver triglycerides and cholesterol levels only in Western-diet-fed mice. These changes associated with a potentiation of the increased liver expression of PPAR gamma and CD36 that was observed in Western-fed mice and related to the increased liver mTOR phosphorylation induced by LFS. Furthermore, LFS in Western-diet-fed mice induced the largest reduction in liver IRS2 protein and a significant decrease in whole-body insulin sensitivity.Conclusions: LFS in mice, in a background of an unhealthy diet that already induces fatty liver visceral fat accretion and obesity, increases liver lipid burden, hinders hepatic insulin signaling and diminishes whole-body insulin sensitivity without changing energy intake. (C) 2016 Elsevier Inc. All rights reserved.

Human studies support the relationship between high intake of fructose-sweetened beverages and type 2 diabetes, but there is a debate on whether this effect is fructose-specific or it is merely associated to an excessive caloric intake. Here we investigate the effects of 2 months’ supplementation to female rats of equicaloric 10% w/v fructose or glucose solutions on insulin sensitivity in target tissues. Fructose supplementation caused hepatic deposition of triglycerides and changed the fatty acid profile of this fraction, with an increase in monounsaturated and a decrease in polyunsaturated species, but did not cause inflammation and oxidative stress. Fructose but not glucose-supplemented rats displayed an abnormal glucose tolerance test, and did not show increased phosphorylation of V-akt murine thymoma viral oncogene homolog-2 (Akt) in white adipose tissue and liver after insulin administration. In skeletal muscle, phosphorylation of Akt and of Akt substrate of 160 kDA (AS160) was not impaired but the expression of the glucose transporter type 4 (GLUT4) in the plasma membrane was reduced only in fructose-fed rats. In conclusion, fructose but not glucose supplementation causes fatty liver without inflammation and oxidative stress and impairs insulin signaling in the three major insulin-responsive tissues independently from the increase in energy intake.

Background & Aims Peroxisome proliferator-activated receptor α (PPARα) is a transcription factor activated by ligands that regulates genes related to vascular tone, oxidative stress, and fibrogenesis, pathways implicated in the development of cirrhosis and portal hypertension. This study aims at evaluating the effects of PPARα activation with fenofibrate on hepatic and systemic hemodynamics, hepatic endothelial dysfunction, and hepatic fibrosis in CCl 4 -cirrhotic rats. Methods Mean arterial pressure (MAP), portal pressure (PP), and portal blood flow (PBF) were measured in cirrhotic rats treated with oral fenofibrate (25mg/kg/day, n=10) or its vehicle (n=12) for 7days. The liver was then perfused and dose-relaxation curves to acetylcholine (Ach) were performed. We also evaluated Sirius Red staining of liver sections, collagen-I mRNA expression, and smooth muscle actin (α-SMA) protein expression, cyclo-oxygenase-1 (COX-1) protein expression, and cGMP levels in liver homogenates, and TXB 2 production in perfusates. Nitric oxide (NO) bioavailability and eNOS activation were measured in hepatic endothelial cells (HEC) isolated from cirrhotic rat livers. Results CCl 4 cirrhotic rats treated with fenofibrate had a significantly lower PP (−29%) and higher MAP than those treated with vehicle. These effects were associated with a significant reduction in hepatic fibrosis and improved vasodilatory response to acetylcholine. Moreover, a reduction in COX-1 expression and TXB 2 production in rats receiving fenofibrate and a significant increase in NO bioavailability in HEC with fenofibrate were observed. Conclusions PPARα activation markedly reduced PP and liver fibrosis and improved hepatic endothelial dysfunction in cirrhotic rats, suggesting it may represent a new therapeutic strategy for portal hypertension in cirrhosis.

Resumen Introduccion La suplementacion de la dieta con un 10% (p/v) de fructosa en el agua de bebida durante 14 dias en ratas produce hipertrigliceridemia y esteatosis hepatica como consecuencia de una reduccion en la expresion y en la actividad transcripcional de PPARα en el higado. En el presente trabajo hemos estudiado en un modelo in vitro, la linea celular FaO, el posible mecanismo por el cual la fructosa reduce la expresion de PPARα. Material y metodos Las celulas FaO se incubaron en ausencia o presencia de fructosa 25 mM. Se obtuvieron extractos totales y nucleares para la determinacion de los niveles relativos de ARNm por RT-PCR, y de proteinas por Western Blot, de aquellas enzimas y factores de transcripcion implicados en las alteraciones producidas por la fructosa. Asimismo, se valoro la actividad PP2A. Resultados La incubacion con fructosa redujo la expresion de PPARα y sus genes diana ACO y CYP4A1, e incremento los niveles de proteina ChREBP y ARNm de su gen diana L-PK. El inhibidor de PP2A acido okadaico anulo el incremento de la actividad PP2A mediado por la fructosa y evito parcialmente la induccion de L-PK, pero no modifico la reduccion de la expresion de PPARα, ni tampoco la de ACO y CYP4A1. Conclusiones El aumento de los niveles de proteina ChREBP y de ARNm de L-PK, asi como la represion de PPARα mediados por la fructosa, se reproducen en la linea celular FaO tratada con fructosa 25 mM. Los experimentos realizados en presencia de acido okadaico sugieren que la activacion de PP2A por metabolitos de la fructosa no juega un papel relevante en la reduccion de la expresion de PPARα producida por la fructosa.

Resumen Introduccion Existe una asociacion entre el sindrome metabolico (SM) y el lupus eritematoso sistemico (LES). Los ratones hembra New-Zealand Black-White de primera generacion (BWF1) constituyen un modelo de LES humano y presentan caracteristicas del SM. Hemos estudiado en este modelo la evolucion temporal del SM y marcadores de LES, y su relacion con la proporcion de celulas T reguladoras (Tregs). Metodos Treinta y dos ratones hembra New-Zealand White (control) y 32 ratones hembra BWF1 (grupo LES) se estudiaron durante 28 semanas, determinando el consumo de dieta y el peso corporal. Los animales se sacrificaron a las 8, 16, 24 y 36 semanas de vida, determinando: el peso de tejido adiposo visceral, la proporcion de celulas CD4 + , CD4 + CD25 + y Tregs en linfocitos esplenicos, concentraciones plasmaticas y hepaticas de trigliceridos, concentraciones plasmaticas de glucosa, insulina, leptina, anticuerpos anti-dsDNA y creatinina. Resultados Los ratones LES presentaron, hasta las 16 semanas de vida, signos de alteraciones metabolicas, como hiperfagia, hiperleptinemia y un peso superior a los ratones control, asociado al incremento en la masa de tejido adiposo visceral, asi como una mayor proporcion de celulas Treg. A partir de las 16–24 semanas de vida, se produjo un cambio drastico, con un incremento en los niveles plasmaticos de anticuerpos anti-dsDNA, que coincidio con la desaparicion de las manifestaciones de SM. Conclusiones La presencia de resistencia a la leptina en las primeras semanas de vida explicaria no solo la mayor ingesta de alimento presentada por los ratones LES, sino tambien la mayor proporcion de celulas Tregs.

Introduccion Dietas ricas en fructosa producen, en ratas, hipertrigliceridemia y esteatosis hepatica, como consecuencia de una reduccion en la actividad transcripcional del receptor activado con proliferadores peroxisomicos alfa (PPARα), junto con un estado de resistencia parcial a la leptina. En el presente trabajo, hemos estudiado como la fructosa afecta en el ambito molecular al control del metabolismo energetico hepatico. Material y metodos Se distribuyeron de forma aleatorizada a 16 ratas Sprague-Dawley macho en 2 grupos: control y fructosa (10% peso/volumen en agua de bebida, durante 14 dias). Adicionalmente, se distribuyo a 12 ratas en 3 grupos: control, fructosa y fructosa + 1 β-D ribofuranosido de 5-aminoimidazol 4-carboxamida (AICAR) (500 mg/kg/dia, los ultimos 3 dias de dieta fructosa). Se valoraron los valores plasmaticos de trigliceridos, glucosa, leptina, insulina y adiponectina. En el ambito hepatico se determinaron: contenido de trigliceridos y ceramidas, actividad de β-oxidacion, actividad AMPK (AMP activada proteina cinasa), proteina fosfatasa 2A (PP2A) y valores de expresion proteica y de acido ribonucleico mensajero de diferentes genes implicados en el metabolismo energetico. Resultados Las ratas del grupo fructosa presentaron hipertrigliceridemia (×1,3), hiperleptinemia (×1,9) e hiperadiponectinemia (×1,7), incremento en los trigliceridos (×1,6) y ceramidas hepaticas y en la formacion de complejos PPARα-FoxO1. La administracion de AICAR, aunque incremento en un 30% la actividad AMPK hepatica, no revirtio ninguna de las alteraciones descritas. En ratas fructosa no sometidas a ayuno antes del sacrificio, se detecto en higado un marcado incremento en la subunidad catalitica de PP2A (×1,6) y en la capacidad de union de ChREBP (×1,4). Conclusiones El deficit de oxidacion de acidos grasos producido por el consumo de fructosa en forma liquida no es reversible por activacion de la AMPK hepatica. La activacion de PP2A tras la ingesta de fructosa es la alteracion molecular determinante en la aparicion de los cambios metabolicos inducidos por este monosacarido.

Introduccion En ratas, dietas ricas en fructosa producen hipertrigliceridemia y esteatosis hepatica, como consecuencia de una reduccion en la actividad transcripcional del receptor activado por proliferadores peroxisomicos alfa, junto con un estado de resistencia parcial a la leptina. En el presente trabajo, hemos estudiado como la fructose afecta a la via de senalizacion de la leptina. Material y metodos Se distribuyeron de forma aleatorizada 16 ratas Sprague-Dawley macho en 2 grupos: control y fructosa (10% peso/volumen en agua de bebida, durante 14 dias). Se valoraron los valores plasmaticos de trigliceridos, glucosa, leptina, insulina y adiponectina. En el higado se determinaron: contenido de trigliceridos, actividad de β-oxidacion, actividad AMPK (del ingles AMP-activated protein kinase) y valores de expresion proteica y de acido ribonucleico mensajero de diferentes genes de la via de senalizacion de la leptina. Resultados Las ratas fructosa presentaron un incremento en los valores de leptina plasmatica (1.9X) y de la expresion proteica de STAT-3-PTyr705 (1.9X) respecto las ratas control. No se observaron diferencias en las formas fosforilada y activas de STAT-3-PSer727 y de AMPK. Estas 2 fosforilaciones estan controladas por la via de las MAPK (del ingles mitogen activated protein kinase), que tampoco presentaba modificaciones entre los 2 grupos de estudio. El deficit de fosforilacion es consecuencia de una alteracion en la senalizacion del receptor a la leptina (ObRL) que no se fosforila en el residuo Tyr985, ni fosforila a JAK-2 (del ingles Janus-activated kinase 2), posiciones que controlan la via de las MAPK. SOCS-3 (del ingles supresor of cytokine signaling 3), que presenta un incremento en su expresion proteica (2.8X) en las ratas fructosa, puede ser la causa de la falta de activacion de ObRL-PTyr985 y de JAK-2. Conclusiones La administracion de fructosa provoca un incremento en la expresion proteica de SOCS-3. Como consecuencia, se observa la falta de fosforilacion de los residuos Tyr985 de ObRL y de JAK-2, que parecen ser la causa de la falta de actividad de la via de las MAPK y, por lo tanto, del deficit de actividad de AMPK y de STAT-3.

[Scope]: One of the features of metabolic syndrome caused by liquid fructose intake is an impairment of redox status. We have investigated whether maternal fructose ingestion modifies the redox status in pregnant rats and their fetuses. [Methods and results]: Fructose (10% wt/vol) in the drinking water of rats throughout gestation, leads to maternal hepatic oxidative stress. However, this change was also observed in glucose-fed rats and, in fact, both carbohydrates produced a decrease in antioxidant enzyme activity. Surprisingly, mothers fed carbohydrates displayed low plasma lipid oxidation. In contrast, fetuses from fructose-fed mothers showed elevated levels of plasma lipoperoxides versus fetuses from control or glucose-fed mothers. Interestingly, a clearly augmented oxidative stress was observed in placenta of fructose-fed mothers, accompanied by a lower expression of the transcription factor Nuclear factor-erythroid 2-related factor-2 (Nrf2) and its target gene, heme oxygenase-1 (HO-1), a potent antioxidant molecule. Moreover, histone deacetylase 3 (HDAC3) that has been proposed to upregulate HO-1 expression by stabilizing Nrf2, exhibited a diminished expression in placenta of fructose-supplemented mothers. [Conclusions]: Maternal fructose intake provoked an imbalanced redox status in placenta and a clear diminution of HO-1 expression, which could be responsible for the augmented oxidative stress found in their fetuses., This work was supported by grants from the Instituto de Salud Carlos III Subdireccion General de Evaluacion y Fomento de la Investigacion (PI-09/02192), European Community FEDER funds, as well as the Ayuda a Grupo en Consolidacion Universidad San Pablo-CEU and Banco de Santander (USP-BS-PCON02/2015). Silvia Rodrigo is a FUSP-CEU fellowship. C.Bo. and J.J.A-M conceived and designed the study.

Introduccion Dietas ricas en fructosa producen, en roedores, hipertrigliceridemia y esteatosis hepatica. En el presente estudio, quisimos valorar como afectaba la administracion de este hidrato de carbono a la actividad hepatica de transactivacion y transrepresion del receptor activado por proliferadores peroxisomicos α (PPARα). Material y metodos Se aleatorizo a 24 ratas Sprague-Dawley en 3 grupos de tratamiento: control, fructosa y glucosa (10% peso/volumen [p/v] hidrato de carbono en agua de bebida, durante 14 dias). En plasma se valoraron los valores de trigliceridos, acidos grasos libres, glucosa, insulina y leptina. En tejido hepatico se determino: contenido de trigliceridos, actividad de betaoxidacion de los acidos grasos, valores de expresion (ARN mensajero, proteina y actividad de union proteina-ADN) de los genes objeto de nuestro estudio. Resultados La administracion de fructosa produjo un incremento de 1,9 y 1,8 veces en los valores de trigliceridos plasmaticos y hepaticos, respectivamente. Las concentraciones de leptina se incrementaron 2,4 veces en estos animales, sin que apareciera hiperglucemia ni resistencia a la insulina. La actividad de transactivacion de PPARα se redujo, asi como la actividad de betaoxidacion hepatica de los acidos grasos (48%). La actividad de transrepresion de PPARα tambien se redujo en estos animales, y se produjo un incremento del 30% en la actividad del factor NF-κB en las ratas fructosa frente a animales control. Estos resultados no se observaron tras la administracion de glucosa; no obstante, los 2 hidratos de carbono modificaron de forma similar la expresion hepatica de factores de transcripcion y enzimas clave implicados en la sintesis de acidos grasos. Conclusiones La hipertrigliceridemia y la esteatosis hepatica inducida por la ingesta de fructosa son el resultado de una reduccion en el catabolismo hepatico de los acidos grasos asociado a un deficit de actividad PPARα.

UNLABELLED: Fructose makes up a significant proportion of energy intake in westernized diets; its increased consumption has paralleled the growing prevalence of obesity and metabolic syndrome over the past two decades. In the current study, we demonstrate that fructose administration (10% wt/vol) in the drinking water of rats reduces the trans-activating and trans-repressing activity of the hepatic peroxisome proliferator-activated receptor alpha (PPARalpha). As a consequence, fructose decreases hepatic fatty oxidation and increases pro-inflammatory transcription factor nuclear factor kappaB (NF-kappaB) activity. These changes were not observed in glucose-administered rats (10% wt/vol), although both carbohydrates produced similar changes in plasma adiponectin and in the hepatic expression of transcription factors and enzymes involved in fatty acid synthesis. Fructose-fed, but not glucose-fed, rats were hyperleptinemic and exhibited increased tyrosine phosphorylation of the signal transducer and activator of transcription-3 (STAT-3) transcription factor, although they did not present a similar increase in the serine phosphorylation of nuclear STAT3. Thus, an impairment in the hepatic transduction of the leptin signal could be responsible for the observed alterations in PPARalpha activity in fructose-fed rats. Because PPARalpha activity is lower in human than in rodent liver, fructose ingestion in humans should cause even worse effects, which would partly explain the link between increased consumption of fructose and widening epidemics of obesity and metabolic syndrome. CONCLUSION: Hypertriglyceridemia and hepatic steatosis induced by fructose ingestion result from a reduction in the hepatic catabolism of fatty acids driven by a state of leptin resistance.

Fructose intake from added sugars correlates with the epidemic rise in metabolic syndrome and related events. Nevertheless, consumption of beverages sweetened with fructose is not regulated in gestation. Previously, we found that maternal fructose intake produces in the progeny, when fetuses, impaired leptin signaling and hepatic steatosis and then impaired insulin signaling and hypoadiponectinemia in adult male rats. Interestingly, adult females from fructose-fed mothers did not exhibit any of these disturbances. However, we think that, actually, these animals keep a programmed phenotype hidden. Fed 240-day-old female progeny from control, fructose- and glucose-fed mothers were subjected for 3 weeks to a fructose supplementation period (10% wt/vol in drinking water). Fructose intake provoked elevations in insulinemia and adiponectinemia in the female progeny independently of their maternal diet. In accordance, the hepatic mRNA levels of several insulin-responsive genes were similarly affected in the progeny after fructose intake. Interestingly, adult progeny of fructose-fed mothers displayed, in response to the fructose feeding, augmented plasma triglyceride and NEFA levels and hepatic steatosis versus the other two groups. In agreement, the expression and activity for carbohydrate response element binding protein (ChREBP), a lipogenic transcription factor, were higher after the fructose period in female descendants from fructose-fed mothers than in the other groups. Furthermore, liver fructokinase expression that has been indicated as one of those responsible for the deleterious effects of fructose ingestion was preferentially augmented in that group. Maternal fructose intake does influence the adult female offspring's response to liquid fructose and so exacerbates fructose-induced dyslipidemia and hepatic steatosis.

Introduccion La funcion de la apolipoproteina A-II (apo A-II) en el metabolismo lipoproteico y su relacion con la arteriosclerosis es poco conocida. Los estudios realizados en humanos y ratones modificados geneticamente han demostrado un efecto directo de la apo A-II en el metabolismo de los trigliceridos y los acidos grasos libres (AGL) y la sensibilidad a la insulina. El objetivo principal de este estudio es la identificacion de proteinas diferencialmente expresadas en el higado de ratones transgenicos de apo A-II humana (h) y su potencial relacion con el metabolismo de los trigliceridos y la glucosa. Material y metodos Se realizaron estudios metabolicos de las lipoproteinas ricas en trigliceridos, la betaoxidacion hepatica y la prueba de tolerancia a la glucosa en ratones transgenicos de apo A-IIh y en controles en situacion de ayunas y tras una carga oral de aceite de oliva. Los cambios en el perfil de expresion proteica se analizaron mediante el analisis comparativo de geles bidimensionales y la identificacion de proteinas mediante espectrometria de masas MALDI-TOF. Resultados Los ratones transgenicos de apo A-IIh presentaban un incremento del colesterol y los trigliceridos de las lipoproteinas que contienen apo B, hipertrigliceridemia aumentada tras la carga oral de acido oleico, asi como un aclaramiento acelerado de la glucosa tras la prueba de sobrecarga de glucosa. Estos cambios estaban asociados a una reduccion en el catabolismo de las lipoproteinas ricas en trigliceridos y la tasa de betaoxidacion hepatica, pero sin cambios significativos en la actividad de la lipoproteina lipasa. De las mas de 1.000 manchas resueltas en el rango pH 3 a 10, se identificaron 55 alteraciones significativas en los ratones transgenicos en comparacion con los ratones controles, 16 de las cuales estaban relacionadas directamente con el metabolismo de los AGL y los carbohidratos. Conclusiones La sobreexpresion apo A-IIh en ratones transgenicos induce hipertrigliceridemia posprandial debido, al menos en parte, a un defecto en el catabolismo de las lipoproteinas ricas en trigliceridos. La aproximacion proteomica nos ha permitido detectar y caracterizar diferencias en el proteoma hepatico de los ratones transgenicos de apo A-IIh y establecer proteinas potencialmente involucradas en el metabolismo de los AGL. Se requieren mas estudios bioquimicos y moleculares para investigar el significado funcional de los cambios encontrados.

Old rats are resistant to fibrate-induced hypolipidemia owing to a reduction in hepatic peroxisome proliferator-activated receptor alpha (PPARalpha). We tested whether the age-related decrease in PPARalpha is prevented by atorvastatin (ATV), a hypolipidemic statin. We determined the activity and expression of Liver X receptor alpha (LXRalpha) and PPARalpha in the liver of 18-month-old rats treated with 10 mg kg(-1) of ATV for 21 days. We measured fatty acid oxidation (FAO), the expression of PPARalpha-target genes, liver triglyceride (TG) and cholesteryl ester (CE) contents and plasma concentrations of TG, cholesterol, glucose, nonesterified fatty acids (NEFA), insulin and leptin. While old female rats were practically unresponsive, ATV-treated old males showed lower liver TG (-41%) and CE (-48%), and plasma TG (-35%), glucose (-18%) and NEFA (-39%). Age-related alterations in LXRalpha expression and binding activity were reverted in ATV-treated old males. These changes were related to an increase in hepatic FAO (1.2-fold), and PPARalpha mRNA (2.2-fold), PPARalpha protein (1.6-fold), and PPARalpha-binding activity. Hepatic nuclear factor-4 (HNF-4) and chicken ovalbumin upstream-transcription factor-II participate in the transcriptional regulation of the PPARalpha gene, while peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1) behaves as a PPAR coactivator. Ageing reduced the hepatic content of HNF-4 (74%) and PGC-1 (77%) exclusively in male rats. ATV administration to old males enhanced the hepatic expression and binding activity (two-fold) of HNF-4. ATV-induced changes in hepatic HNF-4 and PPARalpha may be responsible for the improvement of the lipid metabolic phenotype produced by ATV administration to senescent male rats.

We sought to investigate if, similar to what has been described in other rodent tissues, ageing changes the activity of several transcription factors, namely signal transducer and activator of transcription, nuclear factor-kappa B (NFkappaB), activated protein-1 (AP-1) and peroxisome proliferator-activated receptor (PPAR), in cortex of Sprague-Dawley rats. We also investigated if the administration of two hypolipidemic drugs, gemfibrozil (GFB) and atorvastatin (ATV), could prevent those changes. To this purpose, we determined the expression and binding activity of these transcription factors in cortex samples from 3-month and 18-month old male and female rats, and in 18-month old rats of both sexes treated for 21 days with a daily dose of 3mg GFB/kg or 10mg ATV/kg. Ageing increased rat cortex NFkappaB binding activity by 35-40%, and decreased by 22-26% the amount of PPARalpha in rats of both sexes, while cortex AP-1 binding activity and c-Jun content were reduced only in old females (-26 and -50%, respectively). Cortex cyclooxigenase-2 (COX-2) and receptor for activated C-kinase 1 (RACK1) expression was also reduced by old age. Hypolipidemic drugs prevented the age-related decrease of cortex AP-1 in old females and increased AP-1 binding activity and c-Jun protein in cortex from both old male and female rats. GFB increased also by 80% the cortex PPARalpha content in old males. Our data indicate that 18-month old rats show signs of cortex biochemical deterioration related to the ageing process, and that hypolipidemic drug administration partially prevents the appearance of some of the age-related changes in cortex biochemistry.

Fibrate treatment induces adverse changes in biliary-lipid and bile-acid composition. Since the molecular mechanisms underlying these changes are still unclear, we have investigated the effect of fibrate treatment on key factors involved in bile-acid synthesis, biliary-lipid secretion and cholesterol metabolism in gallstone patients.Patients with uncomplicated gallstones and a serum level of low-density lipoprotein (LDL) cholesterol130 mg/dl were randomly assigned to open-label treatment with bezafibrate, fenofibrate, gemfibrozil, or placebo for 8 weeks before elective cholecystectomy. A liver specimen was obtained at operation, and the mRNA relative levels for cholesterol 7alpha-hydroxylase (CYP7A1), hepatocyte nuclear factor-4 (HNF-4), ATP-binding cassette transporters MDR3, ABCG5, and ABCG8, human homologue scavenger receptor BI, sterol response element binding protein-2 (SREBP-2), 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and LDL receptor were determined by means of reverse-transcriptase polymerase chain reaction.Bezafibrate, fenofibrate and gemfibrozil significantly reduced CYP7A1 mRNA levels. The three fibrates tested raised the mRNA levels of ABCG5 and SREBP-2, but only bezafibrate induced significant changes. Although MDR-3 mRNA levels were slightly increased by the three fibrates, no significant differences were obtained.These results show for the first time that fibrate administration to humans downregulates CYP7A1. Although ABCG5 and SREBP-2 mRNA levels were slightly increased by all treatment groups, only bezafibrate induced significant changes.

Introduccion El tratamiento con fibratos provoca cambios tanto en el contenido de lipidos biliares como en la composicion de los acidos biliares, lo que conduce a un incremento de la incidencia de colelitiasis en humanos. Los mecanismos moleculares implicados en estos cambios, observados en pacientes tratados con fibratos durante un largo periodo, todavia no han sido descritos. El objetivo de este estudio ha sido investigar el efecto del tratamiento con fibratos en los factores clave implicados en la sintesis de acidos biliares y en la secrecion biliar de lipidos en pacientes con colelitiasis. Pacientes y metodo Pacientes con colelitiasis y valores de colesterol unido a lipoproteinas de baja densidad (cLDL) elevados (> 130 mg/dl) fueron aleatorizados y asignados al tratamiento con bezafibrato (400 mg/dia), fenofibrato (200 mg/dia), gemfibrozilo (900 mg/dia) o placebo, durante 8 semanas antes de proceder a la intervencion quirurgica (colecistectomia electiva). La obtencion de muestras hepaticas tuvo lugar en el momento de la operacion y mediante RT-PCR se determinaron los valores de ARNm de colesterol 7-α-hidroxilasa (CYP7A1), hepatocyte nuclear factor-4 (HNF-4), transportadores ATP-binding cassette: MDR3, ABCG5, ABCG8 y el homologo humano del receptor scavanger BI (CLA-1). Resultados Fenofibrato, bezafibrato y gemfibrozilo redujeron de forma significativa los valores de cLDL y trigliceridos plasmaticos. Los 3 fibratos ensayados redujeron los valores de ARNm de CYP7A1, pero solo el bezafibrato incremento significativamente los valores de ABCG5. Ninguno de los farmacos por separado produjo cambios importantes en los valores de ARNm de los restantes genes probados, pero los fibratos como grupo incrementaron el ARNm de MDR-3 y ABCG5. Conclusiones Estos resultados muestran por primera vez que la administracion de fibratos a humanos, a dosis similares a las farmacologicas, reduce la expresion de la colesterol 7-α-hidroxilasa e incrementan la expresion de MDR-3 y ABCG5.

Background and Objectives Fibrates induce hepatic peroxisome proliferation and carcinogenesis in rodents by activating peroxisome proliferator-activated receptor α (PPARα). There is no conclusive evidence that humans are unresponsive to peroxisome proliferation, and concern exists about the long-term safety of fibrate treatment. Methods In a university hospital setting, 48 patients with uncomplicated gallstones and a serum level of low-density lipoprotein cholesterol greater than 130 mg/dL were randomly assigned to open-label treatment with bezafibrate (400 mg/d), fenofibrate (200 mg/d), gemfibrozil (900 mg/d), or placebo for 8 weeks before elective cholecystectomy. Serum samples for lipid determinations were obtained at baseline and before surgery. A liver specimen was obtained at operation, and the relative levels of messenger ribonucleic acid (mRNA) for the wild and truncated forms of PPARα, acyl coenzyme A oxidase, liver carnitine palmitoyltransferase I, apolipoprotein A-I, and stearoyl coenzyme A desaturase were determined. Results Fenofibrate, bezafibrate, and gemfibrozil reduced plasma low-density lipoprotein cholesterol levels by 22% (P = .009), 14% (P = .042), and 11% (not significant), respectively. Plasma triglyceride levels decreased significantly (24%-36%; P < .05), whereas high-density lipoprotein cholesterol levels rose nonsignificantly after treatment with the 3 fibrates. Except for a 35% increase of apolipoprotein A-I mRNA after fenofibrate administration (P < .05), none of the individual fibrates induced significant changes in the mRNAs tested, although as a group they increased the mRNA for liver carnitine palmitoyltransferase I by 40%(P = .08; marginally significant). Conclusions Fibrate administration to humans at pharmacologic doses able to activate PPARα and to induce a hypolipidemic effect does not increase the hepatic expression of acyl coenzyme A oxidase, a well-known marker of peroxisome proliferation in rodents. Clinical Pharmacology & Therapeutics (2002) 72, 692–701; doi: 10.1067/mcp.2002.128605

Treatments with high doses of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors may induce the expression of sterol regulatory element binding protein (SREBP)-target genes, causing different effects from those attributed to the reduction of hepatic cholesterol content. The aim of this study was to investigate the effects of high doses of statins on the key enzymes involved in VLDL production in normolipidemic rats. To examine whether the effects caused by statin treatment are a consequence of HMG-CoA reductase inhibition, we tested the effect of atorvastatin on these enzymes in mevalonate-fed rats. Atorvastatin and simvastatin enhanced not only HMG-CoA reductase but also the expression of the SREBP-2 gene itself. As a result of the overexpression of SREBP-2 caused by the statin treatment, genes regulated basically by SREBP-1, as FA synthase and acetyl-coenzyme A carboxylase, were also induced and their mRNA levels increased. DAG acyltransferase and microsomal TG transfer protein mRNA levels as well as phosphatidate phosphohydrolase activity were increased by both statins. Simvastatin raised liver cholesterol content, ACAT mRNA levels, and CTP:phosphocholine cytidylyltransferase activity, whereas it reduced liver DAG and phospholipid content. Mevalonate feeding reversed all changes induced by the atorvastatin treatment. These results show that treatment with high doses of statins induces key enzymes controlling rat liver lipid synthesis and VLDL assembly, probably as a result of SREBP-2 overexpression. Despite the induction of the key enzymes involved in VLDL production, both statins markedly reduced plasma TG levels, suggesting that different mechanisms may be involved in the hypotriglyceridemic effect of statins at high or low doses.