Palm-based tocotrienol-rich fraction (TRF) supplementation modulates cardiac sod1 expression, fxr target gene expression, and tauro-conjugated bile acid levels in aleptinemic mice fed a high-fat diet.

Tocotrienol-rich fraction (TRF) has been reported to protect the heart from oxidative stress-induced inflammation. It is, however, unclear whether the protective effects of TRF against oxidative stress involve the activation of farnesoid X receptor (fxr), a bile acid receptor, and the regulation of bile acid metabolites. In the current study, we investigated the effects of TRF supplementation on antioxidant activities, expression of fxr and its target genes in cardiac tissue, and serum untargeted metabolomics of high-fat diet-fed mice. Mice were divided into high-fat diet (HFD) with or without TRF supplementation (control) for 6 weeks. At the end of the intervention, body weight (BW), waist circumference (WC), and random blood glucose were measured. Heart tissues were collected, and the gene expression of sod1, sod2, gpx, and fxr and its target genes shp and stat3 was determined. Serum was subjected to untargeted metabolomic analysis using UHPLC-Orbitrap. In comparison to the control, the WC of the TRF-treated group was higher (p >0.05) than that of the HFD-only group, in addition there was no significant difference in weight or random blood glucose level. Downregulation of sod1, sod2, and gpx expression was observed in TRF-treated mice; however, only sod1 was significant when compared to the HFD only group. The expression of cardiac shp (fxr target gene) was significantly upregulated, but stat3 was significantly downregulated in the TRF-treated group compared to the HFD-only group. Biochemical pathways found to be influenced by TRF supplementation include bile acid secretion, primary bile acid biosynthesis, and biotin and cholesterol metabolism. In conclusion, TRF supplementation in HFD-fed mice affects antioxidant activities, and more interestingly, TRF also acts as a signaling molecule that is possibly involved in several bile acid-related biochemical pathways accompanied by an increase in cardiac fxr shp expression. This study provides new insight into TRF in deregulating bile acid receptors and metabolites in high-fat diet-fed mice.

Untargeted serum metabolites profiling in high-fat diet mice supplemented with enhanced palm tocotrienol-rich fraction using UHPLC-MS.

Excessive high fat dietary intake promotes risk of developing non-alcoholic fatty liver disease (NAFLD) and predisposed with oxidative stress. Palm based tocotrienol-rich fraction (TRF) has been reported able to ameliorate oxidative stress but exhibited poor bioavailability. Thus, we investigated whether an enhanced formulation of TRF in combination with palm kernel oil (medium-chain triglycerides) (ETRF) could ameliorate the effect of high-fat diet (HFD) on leptin-deficient male mice. All the animals were divided into HFD only (HFD group), HFD supplemented with ETRF (ETRF group) and HFD supplemented with TRF (TRF group) and HFD supplemented with PKO (PKO group). After 6 weeks, sera were collected for untargeted metabolite profiling using UHPLC-Orbitrap MS. Univariate analysis unveiled alternation in metabolites for bile acids, amino acids, fatty acids, sphingolipids, and alkaloids. Bile acids, lysine, arachidonic acid, and sphingolipids were downregulated while xanthine and hypoxanthine were upregulated in TRF and ETRF group. The regulation of these metabolites suggests that ETRF may promote better fatty acid oxidation, reduce oxidative stress and pro-inflammatory metabolites and acts as anti-inflammatory in fatty liver compared to TRF. Metabolites regulated by ETRF also provide insight of its role in fatty liver. However, further investigation is warranted to identify the mechanisms involved.

Understanding the Impact of Perfluorinated Compounds on Cardiovascular Diseases and Their Risk Factors: A Meta-Analysis Study.

Perfluorinated compounds (PFCs) are non-biodegradable synthetic chemical compounds that are widely used in manufacturing many household products. Many studies have reported the association between PFCs exposure with the risk of developing cardiovascular diseases (CVDs). However, those reports are still debatable, due to their findings. Thus, this review paper aimed to analyse the association of PFCs compound with CVDs and their risk factors in humans by systematic review and meta-analysis. Google Scholar, PubMed and ScienceDirect were searched for PFCs studies on CVDs and their risk from 2009 until present. The association of PFCs exposure with the prevalence of CVDs and their risk factors were assessed by calculating the quality criteria, odds ratios (ORs), and 95% confidence intervals (CIs). CVDs risk factors were divided into serum lipid profile (main risk factor) and other known risk factors. The meta-analysis was then used to derive a combined OR test for heterogeneity in findings between studies. Twenty-nine articles were included. Our meta-analysis indicated that PFCs exposure could be associated with CVDs (Test for overall effect: z = 2.2, p = 0.02; Test for heterogeneity: I2 = 91.6%, CI = 0.92-1.58, p < 0.0001) and their risk factors (Test for overall effect: z = 4.03, p < 0.0001; Test for heterogeneity: I2 = 85.8%, CI = 1.00-1.14, p < 0.0001). In serum lipids, total cholesterol levels are frequently reported associated with the exposure of PFCs. Among PFCs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) exposure increased the risk of CVDs than other types of PFCs. Although the risk of PFOA and PFOS were positively associated with CVDs and their risk factors, more observational studies shall be carried out to identify the long-term effects of these contaminants in premature CVDs development in patients.

Bile acids and their respective conjugates elicit different responses in neonatal cardiomyocytes: role of Gi protein, muscarinic receptors and TGR5.

Bile acids are recognised as bioactive signalling molecules. While they are known to influence arrhythmia susceptibility in cholestasis, there is limited knowledge about the underlying mechanisms. To delineate mechanisms underlying fetal heart rhythm disturbances in cholestatic pregnancy, we used FRET microscopy to monitor cAMP release and contraction measurements in isolated rodent neonatal cardiomyocytes. The unconjugated bile acids CDCA, DCA and UDCA and, to a lesser extent, CA were found to be relatively potent agonists for the GPBAR1 (TGR5) receptor and elicit cAMP release, whereas all glyco- and tauro- conjugated bile acids are weak agonists. The bile acid-induced cAMP production does not lead to an increase in contraction rate, and seems to be mediated by the RI isoform of adenylate cyclase, unlike adrenaline-dependent release which is mediated by the RII isoform. In contrast, bile acids elicited slowing of neonatal cardiomyocyte contraction indicating that other signalling pathways are involved. The conjugated bile acids were found to be partial agonists of the muscarinic M2, but not sphingosin-1-phosphate-2, receptors, and act partially through the Gi pathway. Furthermore, the contraction slowing effect of unconjugated bile acids may also relate to cytotoxicity at higher concentrations.

Heart and bile acids - Clinical consequences of altered bile acid metabolism.

Cardiac dysfunction has an increased prevalence in diseases complicated by liver cirrhosis such as primary biliary cholangitis and primary sclerosing cholangitis. This observation has led to research into the association between abnormalities in bile acid metabolism and cardiac pathology. Approximately 50% of liver cirrhosis cases develop cirrhotic cardiomyopathy. Bile acids are directly implicated in this, causing QT interval prolongation, cardiac hypertrophy, cardiomyocyte apoptosis and abnormal haemodynamics of the heart. Elevated maternal serum bile acids in intrahepatic cholestasis of pregnancy, a disorder which causes an impaired feto-maternal bile acid gradient, have been associated with fatal fetal arrhythmias. The hydrophobicity of individual bile acids in the serum bile acid pool is of relevance, with relatively lipophilic bile acids having a more harmful effect on the heart. Ursodeoxycholic acid can reverse or protect against these detrimental cardiac effects of elevated bile acids.

Ursodeoxycholic acid prevents ventricular conduction slowing and arrhythmia by restoring T-type calcium current in fetuses during cholestasis.

BACKGROUND: Increased maternal serum bile acid concentrations in intrahepatic cholestasis of pregnancy (ICP) are associated with fetal cardiac arrhythmias. Ursodeoxycholic acid (UDCA) has been shown to demonstrate anti-arrhythmic properties via preventing ICP-associated cardiac conduction slowing and development of reentrant arrhythmias, although the cellular mechanism is still being elucidated. METHODS: High-resolution fluorescent optical mapping of electrical activity and electrocardiogram measurements were used to characterize effects of UDCA on one-day-old neonatal and adult female Langendorff-perfused rat hearts. ICP was modelled by perfusion of taurocholic acid (TC, 400µM). Whole-cell calcium currents were recorded from neonatal rat and human fetal cardiomyocytes. RESULTS: TC significantly prolonged the PR interval by 11.0±3.5% (P<0.05) and slowed ventricular conduction velocity (CV) by 38.9±5.1% (P<0.05) exclusively in neonatal and not in maternal hearts. A similar CV decline was observed with the selective T-type calcium current (ICa,T) blocker mibefradil 1µM (23.0±6.2%, P<0.05), but not with the L-type calcium current (ICa,L) blocker nifedipine 1µM (6.9±6.6%, NS). The sodium channel blocker lidocaine (30µM) reduced CV by 60.4±4.5% (P<0.05). UDCA co-treatment was protective against CV slowing induced by TC and mibefradil, but not against lidocaine. UDCA prevented the TC-induced reduction in the ICa,T density in both isolated human fetal (-10.2±1.5 versus -5.5±0.9 pA/pF, P<0.05) and neonatal rat ventricular myocytes (-22.3±1.1 versus -9.6±0.8 pA/pF, P<0.0001), whereas UDCA had limited efficacy on the ICa,L. CONCLUSION: Our findings demonstrate that ICa,T plays a significant role in ICP-associated fetal cardiac conduction slowing and arrhythmogenesis, and is an important component of the fetus-specific anti-arrhythmic activity of UDCA.

Melatonin ameliorates the adverse effects of leptin on sperm.

This study examined the effects of melatonin on leptin-induced changes in sperm parameters in adult rats. Five groups of Sprague-Dawley rats were treated with either leptin or leptin and melatonin or melatonin for 6 weeks. Leptin was given daily via the intraperitoneal route (60 µg kg-1 body weight) and melatonin was given in drinking water (10 mg kg-1 or 20 mg kg-1 body weight per day). Upon completion, sperm count, sperm morphology, 8-hydroxy-2-deoxyguanosine, Comet assay, TUNEL assay, gene expression profiles of antioxidant enzymes, respiratory chain reaction enzymes, DNA damage, and apoptosis genes were estimated. Data were analyzed using ANOVA. Sperm count was significantly lower whereas the fraction of sperm with abnormal morphology, the level of 8-hydroxy-2-deoxyguanosine, and sperm DNA fragmentation were significantly higher in rats treated with leptin only. Microarray analysis revealed significant upregulation of apoptosis-inducing factor, histone acetyl transferase, respiratory chain reaction enzyme, cell necrosis and DNA repair genes, and downregulation of antioxidant enzyme genes in leptin-treated rats. Real-time polymerase chain reaction showed significant decreases in glutathione peroxidase 1 expression with increases in the expression of apoptosis-inducing factor and histone acetyl transferase in leptin-treated rats. There was no change in the gene expression of caspase-3 (CASP-3). In conclusion, the adverse effects of leptin on sperm can be prevented by concurrent melatonin administration.

Dysregulation of Glucose Homeostasis Following Chronic Exogenous Administration of Leptin in Healthy Sprague-Dawley Rats.

INTRODUCTION: Impaired glucose utilization is seen in chronic hyperleptinaemia associated conditions such as obesity and type 2 diabetes mellitus. It is unclear if this impaired glucose utilization is due to the effect of persistent hyperleptinaemia on insulin secretion from the beta cells of pancreas. AIM: To examine the effects of chronic leptin administration on plasma glucose regulation in rats. MATERIALS AND METHODS: Glucose challenge curves were plotted for male Sprague-Dawley rats treated with either normal saline (Control; n=8) or subcutaneous leptin injection for 42 days (60 µg/kg body weight/day; n=8). Plasma glucose and plasma insulin levels were measured at 0, 5, 10, 15, 20 and 25 minutes after glucose challenege. Skeletal muscle tissue was collected at the end of a glucose challenge for glucose transporter-4 protein content, insulin receptor and glucose transporter-4 mRNA expression. Data were analysed using repeated measures and one-way ANOVA with post-hoc analysis. RESULTS: Chronic leptin treatment caused significantly higher fasting insulin level. Post glucose challenge, there was a significant increase in blood glucose levels and insulin level in the leptin treated rats. There was no significant difference in the skeletal muscle glucose transporter-4 content. However, leptin treated rats showed decreased mRNA expression of Insulin Receptor and glucose transporter-4 in the skeletal muscle. CONCLUSION: Leptin administration for 42 days caused hyperinsulinaemia and decreased the expression of insulin receptors in insulin sensitive tissues leading to the development of an insulin resistance-like state in the rats.