Melatonin and Metformin Diminish Oxidative Stress in Heart Tissue in a Rat Model of High Fat Diet and Mammary Carcinogenesis

Palm oil as part of a high-fat diet: advances and challenges, or possible risks of pathology?

Nutritional status disorders have the most significant impact on the development of cardiovascular and oncologic diseases; therefore, the interest in the study of palm oil as among the leading components of nutrition has been increasing. The data examined in this review were sourced from the Scopus, SCIE (Web of Science), PubMed and PubMed Central, MEDLINE, CAPlus/SciFinder, and Embase databases; experts in the field; bibliographies; and abstracts from review analyses from the past 15 years. This review summarizes recent research data focusing on the quantitative and qualitative composition of nutrition of modern humans; concepts of the relationship between high-fat diets and disorders of insulin functioning and transport and metabolism of fatty acids; analyses of data regarding the palmitic acid (16:0) to oleic acid (18:1) ratio; and the effect of diet based on palm oil consumption on cardiovascular risk factors and lipid and lipoprotein levels. Several studies suggest a potential vector contributing to the transmission of maternal, high-fat-diet-induced, addictive-like behaviors and obesogenic phenotypes across generations. The relationship between cholesterol accumulation in lysosomes that may lead to lysosome dysfunction and inhibition of the autophagy process is analyzed, as is the progression of inflammatory diseases, atherosclerosis, nonalcoholic liver inflammation, and obesity with associated complications. Data are discussed from analyses of differences between rodent models and human population studies in the investigated different effects of palm oil consumption as a high-fat diet component. A conclusion is reached that the results cannot be generalized in human population studies because no similar effects were observed. Although there are numerous published reports, more studies are necessary to elucidate the complex regulatory mechanisms in digestive and nutrition processes, because there are great differences in lipoprotein profiles between rodents and humans, which makes it difficult to reproduce the pathology of many diseases caused by different types of the high-fat diet.

Melatonin in energy control: Circadian time-giver and homeostatic monitor

Melatonin is a neurohormone synthesized from dietary tryptophan in various organs, including the pineal gland and the retina. In the pineal gland, melatonin is produced at night under the control of the master clock located in the suprachiasmatic nuclei of the hypothalamus. Under physiological conditions, the pineal gland seems to constitute the unique source of circulating melatonin. Melatonin is involved in cellular metabolism in different ways. First, the circadian rhythm of melatonin helps the maintenance of proper internal timing, the disruption of which has deleterious effects on metabolic health. Second, melatonin modulates lipid metabolism, notably through diminished lipogenesis, and it has an antidiabetic effect, at least in several animal models. Third, pharmacological doses of melatonin have antioxidative, free radical-scavenging, and anti-inflammatory properties in various in vitro cellular models. As a result, melatonin can be considered both a circadian time-giver and a homeostatic monitor of cellular metabolism, via multiple mechanisms of action that are not all fully characterized. Aging, circadian disruption, and artificial light at night are conditions combining increased metabolic risks with diminished circulating levels of melatonin. Accordingly, melatonin supplementation could be of potential therapeutic value in the treatment or prevention of metabolic disorders. More clinical trials in controlled conditions are needed, notably taking greater account of circadian rhythmicity.

Eubiotic Effect of a Dietary Bio-Aqua® and Sodium Diformate (NaDF) on Salmo trutta caspius: Innate Immune System, Biochemical Indices, Antioxidant Defense, and Expression of Immunological and Growth-Related Genes

The present study investigated the effects of combined and singular oral administration of Bio-Aqua® with different dosages of sodium diformate (NaDF) on biochemical indices, innate immune responses, antioxidant effects, and expressions of immunological related genes of Caspian brown trout (Salmo trutta caspius). Fingerlings Salmo trutta caspius (n = 1800; initial weight 15 ± 3 g) were randomly allocated into five groups (120 fish group-1 in triplicates). Control diet: without any addition, G1, G2, G3, and G4 received diets containing 0.2 g kg-1 commercial probiotic Bio-Aqua® combined with 0, 0.5, 1.0, and 1.5% NaDF to the basal diet for 60 days according to recommended dosages reported in previous studies. Results indicated that serum bactericidal activity (G3 on day 60 and G1 on day 30) and classic complement in all groups (on day 60) (G1 and G2 on day 30) were significantly elevated (P < 0.05). The serum lysozyme, glucose, globulin, and albumin levels showed no significant differences between all groups compared to the control group (P > 0.05). On days 30 and 60 of the sampling, no significant difference was observed in the amount of superoxide disotase (SOD) and catalase (CAT) between the treatments (P > 0.05) but activity of malondialdehyde (MDA) was lower in G1 than the control (P < 0.05). The expression of the immune-regulating genes IL-10, IL-1β, GTP, FATP, and IGF was significantly improved in all probiotic + acidifier-treated groups (P < 0.05). The current findings showed that mixture of Bio-Aqua® and NaDF (1.5% + pro) is beneficial, as it effectively improves some immune parameters and expression of immunological and growth-related genes in Caspian brown trout.

Metformin confers longitudinal cardiac protection by preserving mitochondrial homeostasis following myocardial ischemia/reperfusion injury

PURPOSE

Myocardial ischemia-reperfusion (I/R) injury is associated with systemic oxidative stress, cardiac mitochondrial homeostasis, and cardiomyocyte apoptosis. Metformin has been recognized to attenuate cardiomyocyte apoptosis. However, the longitudinal effects and pathomechanism of metformin on the regulation of myocardial mitohormesis following I/R treatment remain unclear. This study aimed to investigate the longitudinal effects and mechanism of metformin in regulating cardiac mitochondrial homeostasis by serial imaging with the 18-kDa translocator protein (TSPO)-targeted positron emission tomography (PET) tracer ¹⁸F-FDPA.

METHODS

Myocardial I/R injury was established in Sprague-Dawley rats, which were treated with or without metformin (150 mg/kg per day). Serial gated ¹⁸F-FDG and ¹⁸F-FDPA PET imaging were performed at 1, 4, and 8 weeks after surgery, followed by analysis of ventricular remodelling and cardiac mitochondrial homeostasis. The correlation between Hsp60 and ¹⁸F-FDPA uptake was analyzed. After PET imaging, the activity of antioxidant enzymes, immunostaining, and western blot analysis were performed to analyze the spatio-temporal effects and pathomechanism of metformin for cardiac protection after myocardial I/R injury.

RESULTS

Oxidative stress and apoptosis increased 1 week after myocardial I/R injury (before significant progression of ventricular remodelling). TSPO expression was correlated with Hsp60 expression and was co-localized with inflammatory CD68⁺ macrophages in the infarct area, and TSPO uptake was associated with an upregulation of AMPK-p/AMPK and a downregulation of Bcl-2/Bax. However, these effects were reversed with metformin treatment. Eight weeks after myocardial I/R injury (representing the advanced stage of heart failure), ¹⁸F-FDPA uptake in myocardial cells in the distal non-infarct area increased without CD68⁺ expression, whereas the activity decreased with metformin treatment.

CONCLUSION

Taken together, these results show that a prolonged metformin treatment has pleiotropic protective effects against myocardial I/R injury associated with a regional and temporal dynamic balance between mitochondrial homeostasis and cardiac outcome, which were assessed by TSPO-targeted imaging during cardiac remodelling.

Effects of melatonin and metformin in preventing lysosome-induced autophagy and oxidative stress in rat models of carcinogenesis and the impact of high-fat diet

Imbalanced glucose tolerance and insulin resistance remain important as high cancer risk factors. Metformin administration to diabetic patients may be associated with a reduced risk of malignancy. The combined effects of the hormone melatonin and metformin in oncology practice have shown positive results. The relevance of our study is to find out the role of specific biomarkers of lysosome destruction and oxidative stress data in carcinogenesis models. The present study was designed to investigate the comparative synergic effect of peroral antidiabetic metformin (MF) and pineal hormone melatonin (MEL) administered alone and in combination in two different rat’s models of mammary tumour proliferation in vivo (N-methyl-N-nitrosourea, NMU or 7,12-dimethylbenz[a]anthracene, DMBA). We have studied the processes of lysosomal destruction (alanyl aminopeptidase AAP, leucyl aminopeptidase LAP, acid phosphatase AcP, β-N-acetylglucosaminidase NAG, β-galactosidase β-GD and β-glucuronidase β-GR) caused by evaluated oxidative stress in three types of tissues (liver, heart, and spleen) in female Sprague–Dawley rats fed a high-fat diet (10% of total fat: 2.5% from lard and 7.5% from palm olein). Our results revealed an increase in the activity of the studied lysosomal enzymes and their expression in a tissue-specific manner depending on the type of chemical agent (NMU or DMBA). MANOVA tests in our study confirmed the influence of the three main factors, type of tissue, chemical impact, and chemopreventive agents, and the combinations of these factors on the lysosomal activity induced during the process of cancerogenesis. The development and induction of the carcinogenesis process in the different rat models with the high-fat diet impact were also accompanied by initiation of free-radical oxidation processes, which we studied at the initial (estimated by the level of diene conjugates) and final (TBARS products) stages of this process. The combined effects of MEL and MF for the two models of carcinogenesis at high-fat diet impact for AAP, LAP, and AcP showed a significant synergistic effect when they impact together when compared with the effects of one substance alone (either MEL or MF) in the breast cancer model experiments. Synergistic effects of limiting destructive processes of lysosomal functioning β-GD enzyme activity we obtained in experiments with MEL and MF chemoprevention for both models of carcinogenesis for three tissues. The statistical SS test allowed us to draw the following conclusions on the role of each lysosomal parameter analyzed as an integral model: NAG > AcP > β-GD > β-GR > AAP > LAP.

Effect of melatonin on visceral fat deposition, lipid metabolism and hepatic lipo-metabolic gene expression in male rats

Melatonin (MT) influences lipid metabolism in animals; however, the mechanistic effect of melatonin on liver fat and abdominal adipose deposition requires further clarity. In order to study the effects of melatonin on lipid metabolism, and hepatic fat and abdominal adipose deposition in animals, twenty Sprague-Dawley (SD) rats of 6 weeks of age with similar bodyweight were randomly divided into two groups: control (CTL) and MT-treated (10 mg/kg/day). During a 60-day experiment, food intake and bodyweight were measured daily and weekly respectively. At the end of treatment, blood samples were collected to collect plasma to quantify hormones and metabolic indicators of lipid metabolism. In addition, organ and abdominal adipose depots including liver, and omental, perirenal, and epididymal fat were weighed. Liver tissue was sampled for sectioning, long-chain fatty acid (LCFA) quantification, and gene chip and Real-time quantitative PCR (qPCR) analyses. The results showed that liver weight and index (ratio of liver weight to body weight) in MT group reduced by 20.69% and 9.63% respectively; omentum weight and index reduced by 59.88% and 54.93% respectively, and epididymal fat weight reduced by 45.34% (p = 0.049), relative to CTL. Plasma lipid indices, triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL) and total cholesterol (TC) with MT treatment decreased significantly compared with the control. Fat and 8 LCFA content in liver in MT group also decreased. Gene chip and qPCR demonstrated that there were 289 genes up-regulated and 293 genes down-regulated by MT. Further analysis found that the mRNA expression of lipolysis-related genes increased, while the mRNA expression of lipogenesis-related enzymes decreased (p < 0.05) with MT. This study concluded that melatonin greatly affected fat deposition, and hepatic LCFA supply and the expression of genes associated with lipogenesis and lipolysis.

D-allulose provides cardioprotective effect by attenuating cardiac mitochondrial dysfunction in obesity-induced insulin-resistant rats

PURPOSE

Obesity-induced insulin resistant is associated with cardiovascular diseases via impairing cardiac mitochondria. Recently, D-allulose could protect β-islets and improve insulin resistance. However, the effects of D-allulose on the heart and cardiac mitochondrial function under obesity-induced insulin-resistant condition has not been investigated. In this study, we aimed to investigate the effects of D-allulose on metabolic parameters, cardiac function, heart rate variability (HRV), cardiac mitochondrial function, and apoptosis in the heart of obesity-induced insulin-resistant rats induced by chronic high fat diet consumption.

METHODS

Male Wistar rats (n = 24) received a normal fat diet (ND) or high fat diet (HFD) for 12 weeks. Then, HFD group was randomly divided into three subgroups to receive (1) HFD with distilled water, (2) HFD with 3% D-allulose 1.9 g/ kg·BW/ day (HFR), and (3) HFD with metformin 300 mg/kg·BW/ day (HFM) by diluted in drinking water daily for 12 weeks. At week 24, proposed study parameters were investigated.

RESULTS

Chronic HFD consumption induced obesity-induced insulin resistant in rats and high fat diet impaired cardiac function and HRV. HFR rats had improved insulin sensitivity as indicated by decreasing HOMA index, plasma insulin, whereas HFM decreased body weight, visceral fat, plasma cholesterol, and plasma LDL. HFR and HFM provided similar efficacy in improving HRV and attenuating cardiac mitochondrial dysfunction, leading to improved cardiac function.

CONCLUSIONS

Even though this is the first investigation of the D-allulose impact on the heart with a relatively small sample size, it clearly demonstrated a beneficial effect on the heart. D-allulose exerted a therapeutic effect on metabolic parameters except for body weight and lipid profiles and provided cardioprotective effects similar to metformin via attenuating cardiac mitochondrial function in obesity-induced insulin-resistant rats.

The association of rs2233679 in the PIN1 gene promoter with the risk of Coronary Artery Disease in Chinese female individuals

BACKGROUNDS

Vascular atherosclerosis leads to various cardiovascular and cerebrovascular diseases. Nitric oxide (NO) promotes vasodilatation and prevents Coronary Artery Disease (CAD). Pin1 suppresses NO production by down-regulating the activity of endothelial nitric oxide synthase (eNOS). Whether the genetic polymorphisms of the PIN1 gene (encoding Pin1) are implicated in CAD deserves investigations in human beings.

METHODS

A total of 210 CAD patients and control individuals (all females) were enrolled, and their genotypes of rs2233679 (-667C/T, a key SNP in the promoter of PIN1 gene) were sequenced. T-test, chi-square test, odds ratio (OR) and 95% confidence interval (95% CI) were calculated to evaluate Hardy-Weinberg equilibrium, varied genetic distribution and relative CAD risk.

RESULTS

The differences in age, BMI, triglyceride, total cholesterol, low-density and high density cholesterol between the CAD and control groups were not significant (all P>0.05), and Hardy-Weinberg equilibrium was observed in the two groups (both P>0.05). The frequency of -667T allele in the CAD group was higher than that in the control group. The genotype -667TT elicited a higher hazardous risk of CAD compared to the genotype -667CC (OR=1.85, 95% CI: 0.75-4.53) as well as the genotypes CC+CT (OR=1.97, 95% CI: 0.86-4.49).

CONCLUSIONS

We firstly show that the allele -667T in the PIN1 promoter may elicit a higher CAD-risk than -667C, and the -667TT genotype of PIN1 may be a new genetic biomarker for increased incidence of CAD. These novel observations put forward a new understanding of the PIN1-CAD genetic relationship in humans, potentially contributing to both cardiovascular and cerebrovascular disorders.

Chronic exposure to green light aggravates high-fat diet-induced obesity and metabolic disorders in male mice

Light is involved in many critical physiological or biochemical processes of human beings, such as visual sensing and the production of vitamin D. Recent studies have showed that the lights of different wavelengths have a profound influence in life activities. For example, blue light promotes alertness, whereas green light (GL) induces sleep in mice. On the other hand, metabolic homeostasis is regulated by a variety of factors, including dietary habits and light exposure. Our study aims to study whether certain wavelength of light would affect metabolic status of mice. Mice were divided into normal diet-fed group and high-fat diet (HFD)-fed group, and then exposed to various colors of the light. Physiological parameters, such as body weight, food intake and water drinking were regularly measured. Glucose tolerance test and pyruvate tolerance test were simultaneously performed. After mice were humanely sacrificed, liver histology and serologic analysis were performed for detecting lipid levels. We found that GL group showed obvious glucose intolerance and increased levels of serum and liver lipid contents compared to white light group. Meanwhile, the expression levels of lipid metabolism-related genes were almost down-regulated in liver. Furthermore, melatonin receptor-1b and thyroid hormone receptor-β expression levels were significantly lowered in liver of GL-treated obese mice, suggesting that these hormone pathways may mediate the changes of lipid metabolism. Our data indicate that GL has a detrimental effect on the energy metabolism and aggravates HFD-induced obesity in mice. In addition to malnutrition, the colors of the lights also have a profound influence in the metabolic homeostasis and should be taken into consideration in the therapy of metabolic disorders.

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.

Liver antioxidant and aerobic status improves after metformin and melatonin administration in a rat model of high-fat diet and mammary carcinogenesis

Oxidative stress is involved in the development of various cancers. In the present study, the effect of long-term administration of peroral antidiabetic metformin and pineal hormone melatonin on liver antioxidant and aerobic status in female Sprague-Dawley rats carrying mammary tumors induced by N-methyl-N-nitrosourea was evaluated. Both substances were administered in a preventive and curative manner (12 days before and 16 weeks after the carcinogen application). Carcinogen administration induced oxidative stress: the level of thiobarbituric acid reactive substances (TBARS) considered as a marker of reactive oxygen species (ROS) generation in liver increased as well as the level of oxidatively modified protein content (OMP; aldehyde and ketone derivates). Metformin administration restored succinate dehydrogenase and lactate dehydrogenase activity and associated ROS production and OMP content to the level of intact rats, with predominant activation of superoxide dismutase (SOD) and glutathione reductase (GR). Melatonin alone and in combination with metformin also decreased TBARS content. OMP content decreased in all groups receiving chemoprevention. The rise in total antioxidant capacity after melatonin and particularly metformin and melatonin combination might result from the initiation of anaerobic metabolism and increasing SOD, GR, and glutathione peroxidase activity. Long-term administration of metformin and melatonin exerts antioxidant properties in liver, especially in combination.

Mitochondria: Central Organelles for Melatonin's Antioxidant and Anti-Aging Actions

Melatonin, along with its metabolites, have long been known to significantly reduce the oxidative stress burden of aging cells or cells exposed to toxins. Oxidative damage is a result of free radicals produced in cells, especially in mitochondria. When measured, melatonin, a potent antioxidant, was found to be in higher concentrations in mitochondria than in other organelles or subcellular locations. Recent evidence indicates that mitochondrial membranes possess transporters that aid in the rapid uptake of melatonin by these organelles against a gradient. Moreover, we predicted several years ago that, because of their origin from melatonin-producing bacteria, mitochondria likely also synthesize melatonin. Data accumulated within the last year supports this prediction. A high content of melatonin in mitochondria would be fortuitous, since these organelles produce an abundance of free radicals. Thus, melatonin is optimally positioned to scavenge the radicals and reduce the degree of oxidative damage. In light of the "free radical theory of aging", including all of its iterations, high melatonin levels in mitochondria would be expected to protect against age-related organismal decline. Also, there are many age-associated diseases that have, as a contributing factor, free radical damage. These multiple diseases may likely be deferred in their onset or progression if mitochondrial levels of melatonin can be maintained into advanced age.

Melatonin: A Molecule for Reducing Breast Cancer Risk

The objective of this article is to review the basis supporting the usefulness of melatonin as an adjuvant therapy for breast cancer (BC) prevention in several groups of individuals at high risk for this disease. Melatonin, as a result of its antiestrogenic and antioxidant properties, as well as its ability to improve the efficacy and reduce the side effects of conventional antiestrogens, could safely be associated with the antiestrogenic drugs presently in use. In individuals at risk of BC due to night shift work, the light-induced inhibition of melatonin secretion, with the consequent loss of its antiestrogenic effects, would be countered by administering this neurohormone. BC risk from exposure to metalloestrogens, such as cadmium, could be treated with melatonin supplements to individuals at risk of BC due to exposure to this xenoestrogen. The BC risk related to obesity may be reduced by melatonin which decrease body fat mass, inhibits the enhanced aromatase expression in obese women, increases adiponectin secretion, counteracts the oncogenic effects of elevated concentrations of leptin; and decreases blood glucose levels and insulin resistance. Despite compelling experimental evidence of melatonin's oncostatic actions being susceptible to lowering BC risk, there is still a paucity of clinical trials focused on this subject.