The impact of high fructose on cardiovascular system: Role of α-lipoic acid

The Impact of the High-Fructose Corn Syrup on Cardiac Damage via SIRT1/PGC1-α Pathway: Potential Ameliorative Effect of Selenium

High-fructose corn syrup (HFCS) has been a subject of intense debate due to its association with cardiovascular risks. This study investigates the potential protective effects of selenium (Se) supplementation against cardiac damage induced by HFCS. Thirty-two male Wistar albino rats were divided into four equal groups: control, CS (20%-HFCS), CS with Se (20%-HFCS, 0.3 mg/kg-Se), and Se (0.3 mg/kg-Se) only. After a 6-week period, heart and aorta tissues were collected for histopathological, immunohistochemical, biochemical, and genetic analyses. HFCS consumption led to severe cardiac pathologies, increased oxidative stress, and altered gene expressions associated with inflammation, apoptosis, and antioxidant defenses. In the CS group, pronounced oxidative stress within the cardiac tissue was concomitant with elevated Bcl-2-associated X protein (Bax) expression and diminished expressions of B-cell-lymphoma-2 (Bcl-2), nuclear factor erythroid 2-related factor 2 (Nrf2), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), and silenced information regulator 1 (SIRT1). Se supplementation mitigated these effects, showing protective properties. Immunohistochemical analysis supported these findings, demonstrating decreased expressions of caspase-3, tumor necrosis factor-alpha (TNF-α), IL-1β, and vascular endothelial growth factor (VEGF) in the CS + Se group compared to the CS group. The study suggests that Se supplementation exerts anti-inflammatory, antioxidant, and antiapoptotic effects, potentially attenuating HFCS-induced cardiovascular toxicity. These findings highlight the importance of dietary considerations and selenium supplementation in mitigating cardiovascular risks associated with HFCS consumption.

The Role of Hyperuricemia in Cardiac Diseases: Evidence, Controversies, and Therapeutic Strategies

Hyperuricemia (HUA) may lead to myocardial cell damage, thereby promoting the occurrence and adverse outcomes of heart diseases. In this review, we discuss the latest clinical research progress, and explore the impact of HUA on myocardial damage-related diseases such as myocardial infarction, arrhythmias, and heart failure. We also combined recent findings from basic research to analyze potential mechanisms linking HUA with myocardial injury. In different pathological models (such as direct action of high uric acid on myocardial cells or combined with myocardial ischemia-reperfusion model), HUA may cause damage by activating the NOD-like receptor protein 3 inflammasome-induced inflammatory response, interfering with cardiac cell energy metabolism, affecting antioxidant defense systems, and stimulating reactive oxygen species production to enhance the oxidative stress response, ultimately resulting in decreased cardiac function. Additionally, we discuss the impact of lowering uric acid intervention therapy and potential safety issues that may arise. However, as the mechanism underlying HUA-induced myocardial injury is poorly defined, further research is warranted to aid in the development novel therapeutic strategies for HUA-related cardiovascular diseases.

Intermittent exposure of cultured endothelial cells to physiologically relevant fructose concentrations has a profound impact on nitric oxide production and bioenergetics

Hyperglycaemia is known to induce endothelial dysfunction and changes in metabolic function, which could be implicated in diabetes-induced cardiovascular disease. To date, however, little is known about the impact of physiologically relevant concentrations of fructose on endothelial cells. A novel in vitro model was devised to establish the impact of substitution of a small proportion of glucose with an equal concentration (0.1 mM or 1 mM) of fructose on EA.hy926 endothelial cells during periodic carbohydrate “meals” superimposed on a normoglycaemic (5.5 mM) background. Parallel experiments were conducted using meals consisting of normoglycaemic glucose, intermediate glucose (12.5 mM) or profound hyperglycaemia (25 mM), each delivered for 2 h, with and without substituted fructose over 50 h. Outcome measures included nitrite as a surrogate marker of the mediator of healthy endothelial function, nitric oxide (NO), and a range of bioenergetic parameters using a metabolic analyser. Despite its relatively low proportion of carbohydrate load, intermittent fructose induced a substantial reduction (approximately 90%) in NO generation in cells treated with either concentration of fructose. Cell markers of oxidative stress were not altered by this treatment regimen. However, the cells experienced a marked increase in metabolic activity induced by fructose, irrespective of the glucose concentration delivered simultaneously in the “meals”. Indeed, glucose alone failed to induce any metabolic impact in this model. Key metabolic findings were a 2-fold increase in basal oxygen consumption rate and a similar change in extracellular acidification rate–a marker of glycolysis. Non-metabolic oxygen consumption also increased substantially in cells exposed to fructose. There was no difference between results with 0.1 mM fructose and those with 1 mM fructose. Low, physiologically relevant concentrations of fructose, delivered in a pattern that mimics mealtime consumption, had a profound impact on endothelial function and bioenergetics in an in vitro cell model. The results suggest that endothelial cells are exquisitely sensitive to circulating fructose; the potential ensuing dysfunction could have major implications for development of atherosclerotic disease associated with high fructose consumption.

The Role of Perivascular Adipose Tissue in Early Changes in Arterial Function during High-Fat Diet and Its Combination with High-Fructose Intake in Rats

The aim of the current study was to evaluate the influence of a high-fat diet and its combination with high-fructose intake on young normotensive rats, with focus on the modulatory effect of perivascular adipose tissue (PVAT) on the reactivity of isolated arteries. Six-week-old Wistar–Kyoto rats were treated for 8 weeks with a control diet (10% fat), a high-fat diet (HFD; 45% fat), or a combination of the HFD with a 10% solution of fructose. Contractile and relaxant responses of isolated rat arteries, with preserved and removed PVAT for selected vasoactive stimuli, were recorded isometrically by a force displacement transducer. The results demonstrated that, in young rats, eight weeks of the HFD might lead to body fat accumulation and early excitation of the cardiovascular sympathetic nervous system, as shown by increased heart rate and enhanced arterial contractile responses induced by endogenous noradrenaline released from perivascular sympathetic nerves. The addition of high-fructose intake deteriorated this state by impairment of arterial relaxation and resulted in mild elevation of systolic blood pressure; however, the increase in arterial neurogenic contractions was not detected. The diet-induced alterations in isolated arteries were observed only in the presence of PVAT, indicating that this structure is important in initiation of early vascular changes during the development of metabolic syndrome.

Protective Effect of Alpha-Lipoic Acid against Liver Damage Induced by Cigarette Smoke: An in vivo Study

Background:

Long-term cigarette smoking damages the liver tissue. Alpha-lipoic acid (ALA) is used as a therapeutic agent in a number of conditions and is known to have ameliorative effects against oxidative stress in the liver.

Objective:

To investigate the ameliorative effects of ALA on cigarette smoke (CS)-induced oxidative liver damage by examining histopathological, immunohistopathological changes and biochemical parameters in an animal model.

Materials and Methods:

Twenty-eight female Sprague–Dawley rats were randomly divided into three groups. In the control group (n = 8), rats were exposed to fresh air twice a day and given 0.1 ml of saline by gavage once a day for 8 weeks. In the smoking group (n = 10), rats were exposed to CS for 1 h in the morning and afternoon and given 0.1 ml of saline by gavage once a day for 8 weeks. In the smoking + ALA group (n = 10), CS exposure was same as the smoking group in addition to 100 mg/kg of ALA per day for 8 weeks through gavage. Oxidative damage in the liver tissue was determined by evaluating malondialdehyde (MDA), catalase (CAT) and superoxide dismutase (SOD) levels. Aspartate aminotransferase (AST), alanine aminotransaminase (ALT), alkaline phosphatase (ALP), direct bilirubin and total bilirubin levels were measured in the blood. Histopathological and immunohistochemical examinations were performed.

Results:

MDA (P = 0.011), AST (P = 0.018) and total bilirubin levels (P < 0.001) were increased, while CAT activity (P = 0.009) and the efficiency of SOD (P = 0.010) were decreased in the smoking group compared with the control group. CAT activity was increased (P = 0.017) and AST (P = 0.018) and total bilirubin levels (P < 0.001) were decreased in ALA-treated group compared with the smoking group. We observed vascular dilatation and hemorrhagic areas in the smoking group. TNF-α expression was increased in the smoking group compared with the control group. However, TNF-α expression was high in some preparations in the ALA-treated group.

Conclusions:

ALA can enhance antioxidant activity, but studies with different doses of ALA are required to determine the extent of its hepatoprotective effect.

Research on the effects of L-carnitine and trans-chalcone on endoplasmic reticulum stress and oxidative stress in high-fructose corn syrup-fed rats

Purpose

The debate on the metabolic effects of high fructose corn syrup (HFCS) continues. The deterioration of endoplasmic reticulum (ER) homeostasis is called ER stress. Glucose-regulated protein-78 (GRP-78) and X-box binding protein-1 (XBP-1) are key markers of ER stress and the therapeutic targets of diseases. Sterol regulatory element binding protein-1c (SREBP-1c) is the most important transcription factor that regulates the expression of enzymes for fatty acid synthesis. The purpose of this paper is to research the effects of L-carnitine and trans-chalcone on ER stress and oxidative stress parameters, and to explore the therapeutic potential of L-carnitine and trans-chalcone molecules.

Design/methodology/approach

Forty male wistar albino rats randomly selected were divided into five groups. All groups are fed with standard chow (ad libitum). While Group I was fed with drinking water, Group II, III, IV and V were fed with water containing 15% HFCS. L-carnitine was given to Group IV and trans-chalcone to Group V, and both were dissolved with DMSO and given intraperitoneally. Group III was not given anything additional.

Findings

While the amount of water consumption of HFCS-fed rats has increased, the amount of feed consumption has decreased. The weights of rats in Group II and Group III have increased significantly compared to Group I (p = 0.001, p = 0.001 respectively). In Group III, GRP78, XBP-1; malondialdehyde level (p < 0.001, p = 0.001, p = 0.041); total cholesterol, triglyceride, LDL levels (p = 0.001, p < 0.001, p = 0.009, p = 0.001, respectively) have increased significantly.

Originality/value

To the best of the authors’ knowledge, this study is the first report to show that excessive HFCS consumption causes oxidative stress and ER stress. The antioxidant and antiobesity properties of trans chalcone have been demonstrated. Extensive experimental and clinical studies should be conducted.

Melatonin protects the heart and endothelium against high fructose corn syrup consumption-induced cardiovascular toxicity via SIRT-1 signaling

High fructose corn syrup (HFCS) has been shown to cause cardiovascular toxicity via oxidative stress and inflammation. The aim of this study is to demonstrate the protective effects of melatonin (MLT) against HFCS-induced endothelial and cardiac dysfunction via oxidative stress and inflammation. Thirty-two Sprague Dawley male rats were distributed into three groups as control, HFCS, and HFCS + MLT. HFCS form F55 was prepared as 20% fructose syrup solution and given to the rats through drinking water for 10 weeks, and MLT administrated 10 mg/kg/day orally for last 6 weeks in addition to F55. After decapitation, blood and half of the heart samples were collected for biochemical analysis and other half of the tissues for histopathological and immunohistochemical analysis. Aspartate transaminase, creatine kinase MB, lactate dehydrogenase, total oxidant status and oxidative stress index, and caspase-3 levels increased and total antioxidant status levels decreased significantly in HFCS group. MLT treatment reversed all these parameters. Histopathologically, hyperemia, endothelial cell damage and increased levels of angiogenin, C-reactive protein, inducible nitric oxide synthase, myeloperoxidase and decreased sirtuin-1 (SIRT-1) expressions were observed in HFCS group. MLT ameliorated all these changes. MLT has an anti-inflammatory, antioxidant, antiapoptotic effects on HFCS-induced cardiovascular toxicity through enhancing the expression of SIRT-1.

The effects of high-fructose corn syrup consumption on testis physiopathology-The ameliorative role of melatonin

This study investigated the ameliorative role of melatonin (MLT) and the effects of a long-term intake of high-fructose corn syrup (HFCS) on the male reproductive system. Thirty-six male Sprague Dawley rats were randomly divided into 3 groups as follows: Control, HFCS and HFCS + MLT. Testis and epididymal weights were measured. Malondialdehyde (MDA) levels, superoxide dismutase (SOD) and catalase (CAT) activities, total testosterone levels, testicular histopathological damage scores were evaluated, and immunohistochemical analyses were performed on testicular tissue. Epididymal weights were significantly lower in the HFCS + MLT group than those of the control and HFCS groups. MDA was significantly increased, while SOD and CAT activities were reduced in the HFCS group compared with the control group. Administration of melatonin significantly increased SOD and CAT activities in the HFCS + MLT group. Histopathological evaluation revealed slight hyperaemia and oedema in the stromal tissue of rat testes in the HFCS group. Sperm count and Johnsen's testicular biopsy score (JTBS) were significantly decreased in the HFCS group. Immunohistochemical analysis revealed that HSP, iNOS, MDA, OPN and VEGF values were significantly increased in the HFCS group. However, melatonin ameliorated the immunohistochemical scoring. Our results showed that a long-term intake of HFCS caused testicular damage. Melatonin may be a promising pharmacological agent against testicular toxicity induced by HFCS.

Alpha-lipoic acid and its protective role in fructose induced endocrine-metabolic disturbances

In recent decades a worldwide increase has been reported in the consumption of unhealthy high calorie diets associated with marked changes in meal nutrient composition, such as a higher intake of refined carbohydrates, which leads to the speculatation that changes in food habits have contributed to the current epidemic of obesity and type 2 diabetes. Among these refined carbohydrates, fructose has been deeply investigated and murine models of high fructose diet have emerged as useful tools to study dietary-induced insulin resistance, impaired glucose tolerance, dyslipidemia and alterations in glucose metabolism. Since oxidative stress has been demonstrated to play a key pathogenic role in the alterations described above, several lines of research have focused on the possible preventive effects of antioxidant/redox state regulation therapy, among which alpha-lipoic acid has been extensively investigated. The following references discussed support the fact that co-administration of alpha-lipoic acid normalized the changes generated by fructose rich diets, thereby making this compound a good therapeutic tool, also administered as a food supplement, to prevent endocrine-metabolic disturbances triggered by high fructose associated with obesity and type 2 diabetes at an early stage of development (prediabetes).

The effects of chronic smoking on lung tissue and the role of alpha lipoic acid

We investigated the effects of alpha lipoic acid (ALA) on blood and lung tissue exposed chronically to cigarette smoke (CS). Female Sprague-Dawley rats were divided into three groups. Group 1 was the control group (CON): fresh air was supplied twice daily and 0.1 ml physiological saline was given orally for 8 weeks. Group 2 was exposed to CS: 12 cigarettes were smoked daily at two sessions for 1 h and 0.1 ml saline was given orally for 8 weeks. Group 3 (CS + ALA) was exposed to 12 cigarettes daily in two sessions for 1 h and 100 mg/kg/day ALA was given orally for 8 weeks. DNA damage was assessed using comet analysis; oxidative damage was assessed using ischemia-modified albumin (IMA) from blood; and total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI) were measured in blood and lung tissue. Histopathological and immunohistochemical evaluation of hypoxia-inducible factor (HIF)-1α, and -2α, caspase-3, vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF₂) were conducted using lung tissue. The oxidative markers, TOS, OSI and IMA, and the comet analysis score were increased and the TAS level was decreased in the blood of the CS group compared to the CON group. IMA levels in blood, and TOS and OSI levels in the lung were decreased significantly in the CS + ALA group compared to the CS group. We observed increased septal wall thickness, marked and diffuse inflammatory reaction, emphysema, and necrotic cell debris in bronchial and bronchiolar lumens in the CS group. HIF-1α, HIF-2α, caspase-3 and FGF₂ expressions were increased, while VEGF expression decreased in the lung tissues of the CS group compared to the CON group. ALA slightly ameliorated the damage caused by chronic exposure to CS in the lungs, but further investigation is needed to determine its possible protective effects at different dosages.

New arguments for beneficial effects of alpha-lipoic acid on the cardiovascular system in the course of type 2 diabetes

PURPOSE

Alpha-lipoic acid (ALA), widely known as an antioxidant, modifies also serum levels of angiogenic factors in type 2 diabetic patients. These pharmacological activities may influence the status of the cardiovascular system. Taking into consideration that diabetes is related to the increased cardiovascular risk we investigated several effects of ALA on angiogenic factors in the myocardium and in the aortal wall using a rat model of type 2 diabetes.

METHODS

Diabetes was induced in Wistar rats by a fat-rich diet and by intraperitoneal injection of a small dose of streptozotocin (30 mg/kg). Animals were divided into 3 groups: ALA-treated type 2 diabetes rat model, placebo-treated type 2 diabetes rat model and placebo-treated non-diabetic rats. ALA was administered orally once a day, 20 mg/kg, for 8 consecutive weeks. mRNA VEGF, VEGF-R1 and VEGF-R2 expression was measured in the myocardium and the aortal wall, simultaneously with circulating VEGF and circulating endothelial cells (cEC) and endothelial progenitor cells (cEPC).

RESULTS

ALA induced pro-angiogenic effect in the myocardium of rats with diabetes increasing mRNA VEGF expression and decreasing mRNA VEGFR-1 expression, while in the aortal wall ALA increased mRNA VEGFR-2 and VEGFR-1 expression. cVEGF in the ALA-treated group was higher comparing to both control groups. It was revealed that cEC percentage in the ALA-treated group was decreased with no effect on the percentage of cEPC.

CONCLUSIONS

In summary, the current data provide novel findings about potential beneficial effects of ALA on angiogenic factors in the cardiovascular system, especially on myocardium, in the course of type 2 diabetes.

Cardioprotective effect of Phyllanthus amarus against high fructose diet induced myocardial and aortic stress in rat model

Increased number of population with heart stroke/attack is attributed to sedentary lifestyle and consumption of high-sugar diets, especially fructose. The objective of this study is to investigate the cardio-protective activity of aqueous extract of Phyllanthus amarus (PAAE) against high-fructose (HF) diet induced cardiac damage in Wistar rats. Male Wistar rats were randomly assigned into five groups of six animals each: Control (C), Control treated with PAAE (C+PAAE), High fructose diet fed (F), High fructose diet fed treated with PAAE (F+PAAE) and High fructose diet fed treated with Pioglitazone (F+Pio). PAAE was orally administered at a dosage of 200mg/kg body weight/day to C+PAAE and F+PAAE group rats for 60days. Pioglitazone (10mg/kg body weight/day) was used to compare the efficacy of PAAE. After 60days, heart and aorta samples were collected for biochemical and histological analysis. Co-administration of PAAE along with HF-diet for 60days prevented the increase in levels of cardiac and aortic lipids i.e., total lipids, triglycerides, total cholesterol and free fatty acids and decreased phospholipids. Further, enhanced activities of cardiac aldose reductase (15.3%) and sorbital dehydrogenase (6.9%) and decreased activity of creatine kinase (35.6%) in group-F were also prevented by PAAE treatment with the recovery of 126% for AR, 122% for SDH and 118% for CK. PAAE treatment showed protection from HF-diet induced increase in stress markers (LPO and PO), decreased non-enzymatic (GSH and Vit-C) and enzymatic (GR, GPx, GST, SOD, and CAT) antioxidants in the heart and aorta. Histopathological examination of the heart and aorta indicated that PAAE/Pio treatment reduced fat deposition and necrosis. The present study clearly indicates the cardio protection efficacy of PAAE against HF-diet induced oxidative stress in rats.

Fructose: Toxic effect on cardiorenal risk factors and redox state

AIM

To investigate the effects of fructose consumption on the antioxidant capacity in heart and kidney, cardiovascular disease risk factors, and evaluation of these variables after its removal.

METHODS

Male Wistar rats (n = 36) were divided into control group (n = 12): standard chow + water or F group: standard chow + fructose in drinking water (30%) for 15 weeks. After, F group was divided to continue receiving standard chow + fructose in drinking water (30%) (n = 12) or standard chow + water (Ex group, n = 12) for 9 weeks. Water, chow and caloric diaries intake, final body weight, adiposity index, plasma glucose and triacylglycerol, systolic blood pressure, and cardiac and renal hydrophilic antioxidant capacity were analyzed.

RESULTS

Control and Ex groups consumed less chow and water compared to F group. Caloric intake was higher in control group. There was no difference in final body weight and adiposity index. Systolic blood pressure and cardiac and renal hydrophilic antioxidant capacity were worst in F group.

CONCLUSION

Prolonged exposure to fructose induces oxidative stress, systolic blood pressure, and increase in triacylglycerol. When stopped fructose consumption, Ex group presented improvement in these variables, suggesting the toxicity effect of fructose when consumed in high amounts and prolonged exposure.

Altered heart proteome in fructose-fed Fisher 344 rats exposed to bisphenol A

Bisphenol A (BPA), is an artificial estrogen initially produced for medical purposes but is today widely used in polycarbonate plastics and epoxy resins. Exposure-related reproductive disorders have been found, but recently it has also been suggested that BPA may be involved in obesity, diabetes, myocardial hypertrophy and myocardial infarction in humans. To mimic a modern lifestyle, female rats were fed with fructose or fructose plus BPA (0.25mg/L drinking water). The myocardial left ventricle proteome of water controls, fructose-fed and fructose-fed plus BPA supplemented rats was explored. The proteome was investigated using nano-liquid chromatography tandem mass spectrometry and two-dimensional gel electrophoresis followed by matrix assisted laser desorption/ionization mass spectrometry identification. In total, 41 proteins were significantly altered by BPA exposure compared to water or fructose controls. Principal component analysis and cellular process enrichment analysis of altered proteins suggested increased fatty acid transport and oxidation, increased ROS generation and altered structural integrity of the myocardial left ventricle in the fructose-fed BPA-exposed rats, indicating unfavorable effects on the myocardium. In conclusion, BPA exposure in the rats induces major alterations in the myocardial proteome.

Protective effects of aspirin and vitamin C against corn syrup consumption-induced cardiac damage through sirtuin-1 and HIF-1α pathway

Objective:

The aim of this study was to investigate the protective effects of aspirin (AS) and vitamin C (VC) against cardiac damage induced by chronic corn syrup (CS) consumption via a mechanism involving sirtuin-1 (ST-1), hypoxia-inducible factor-1a (HIF-1a), and the caspase-3 pathway in rats.

Methods:

Forty male Sprague–Dawley rats (14–16 weeks) that weighed 250–300 g were randomly distributed into 5 groups, each containing 8 rats: control group, CS+AS group, CS+VC group, CS+AS+VC group, and CS group. AS (10 mg/kg/day) and VC (200 mg/kg/day) were orally given to the rats. F30 (30% fructose syrup solution) was given to the rats in drinking water for 6 weeks. The rats were sacrificed by exsanguination 24 h after the last administration. Blood samples and tissue were collected for biochemical, histopathological, and immunohistochemical examinations. Non-parametric Kruskal–Wallis test and Mann–Whitney U test used for the parameters without normal distribution and ANOVA and post-hoc LSD tests were used for parameters with a normal distribution to compare groups.

Results:

Uric acid, creatine kinase (CKMB), and lactate dehydrogenase (LDH) levels were increased in the CS group compared with the control group (1.45±0.39 and p=0.011; 3225.64±598.25 and p=0.004; 3906.83±1064.22 and p=0.002, respectively) and decreased in all the treatment groups. In addition, increased levels of MDA and decreased activity of CAT in the CS group (0.172±0.03 and p=0.000; 0.070±0.005 and p=0.007, respectively) were reversed with AS and VC therapy. A decrease in ST-1 activity and increases in caspase-3 and HIF-1 activities corrected by VC and AS therapy were observed.

Conclusion:

AS and VC, which display antioxidant and antiapoptotic activities, ameliorated cardiac damage induced by chronic fructose consumption by increasing the levels of ST-1 and decreasing the levels of HIF-1a and caspase-3.