D-ribose-L-cysteine prevents oxidative stress and cardiometabolic syndrome in high fructose high fat diet fed rats

Measurement of blood pressure in rats: Invasive or noninvasive methods?

Experiments should always be based on control values. This assumption fully applies to cardiovascular parameters, such as heart rate (HR) and blood pressure (BP), which are highly sensitive to various external and internal stimuli and can already be significantly altered when an experiment begins. Therefore, it is necessary to determine which values are defined as a starting point (i.e., control and baseline) or compare them with valid reference values if the goal is to evaluate the changes after experimental intervention. A generally accepted principle is a reciprocal relationship between BP and HR, in which one parameter affects the other and vice versa. BP can be measured using two methods-noninvasively (tail-cuff) and invasively (telemetry, direct measurements of BP after introducing the sensor directly into the artery), and HR directly or by extrapolation from BP recordings. This study does not aim to evaluate the results of individual studies, but to review whether there are differences in control (baseline) BP values in normotensive and hypertensive male rats using invasive versus noninvasive methods, and to investigate whether there is a causal relationship between BP and HR in in vivo experiments with male rats.

Mechanism of action of buckwheat quercetin in regulating lipid metabolism and intestinal flora via Toll-like receptor 4 or nuclear factor κB pathway in rats on a high-fat diet

OBJECTIVES

Buckwheat quercetin (QUE) was used as a dietary supplement to investigate the mechanism of QUE on the regulation of lipid metabolism and intestinal flora in hyperlipidemic rats.

METHODS

Here, using a high-fat diet-induced hyperlipidemia model, the intervention was carried out by gavage of QUE at doses of 50, 100, and 200 mg/kg. Serum lipid levels, liver biochemical parameters, and histopathologic changes in the liver and intestinal microorganisms were measured in rats by enzyme-linked immunosorbent assay, hematoxylin-eosin, and high-throughput sequencing, respectively.

RESULTS

Our results found that QUE, at a dose of 200 mg/kg, significantly reduced body weight, liver index, and lipid levels in rats (P < 0.05); improved hepatic oxidative stress; and repaired liver injury. In addition, the upregulation of beneficial bacteria, such as christensenellaceae and Bifidobacterium, in the organism increased the content of short-chain fatty acids, thus interfering with intestinal pH and improving the intestinal environment, while downregulating the relative abundance of Proteobacteria and Eubacterium_coprostanoligenes_group, and regulating the overproduction of butyrate. The real-time fluorescence quantitative polymerase chain reaction results found that QUE inhibited the expression of Toll-like receptor 4 (TLR4) and nuclear factor κB (NF-κB) mRNA content and blocked the activation of the TLR4/NF-κB signaling pathway, thus affecting the downregulation of lipid levels and restoring intestinal homeostasis.

CONCLUSIONS

A QUE dose of 200 mg/kg may improve lipid levels and the composition of intestinal flora through the TLR4/NF-κB pathway, suggesting that proteobacteria and christensenellaceae abundance changes may be biomarkers of potential diseases.

Use of high-fat high-fructose diet for a model of metabolic syndrome in Wistar rats: challenges remain

Metabolic syndrome (MetS) is a global public health challenge and one of the main risk factors for cardiovascular diseases. Its pandemic prevalence created a demand for developing a relevant model system for deep insight into the molecular basis of MetS. Animal models, especially Wistar rats, are commonly used for that purpose. However, there are no standardized protocols in terms of the diet, strain, or age of rats used for the development of MetS. Studies have mostly used a high-fat high-fructose (HFHF) diet in Wistar rats but have reported inconsistent results; thus the main aim of this study was to examine the effects of the HFHF diet on inducing MetS in Wistar rats. We used two different sub-strains of Wistar rats – Hannover and Kyoto – of two different age groups (8 weeks and 4 months). Animals were placed on a modified diet, standard chow diet enriched with 25% fat and 20% fructose. Following 8 weeks of treatment, all groups were tested for indicators of MetS and the treatment was extended to 16 weeks for groups that developed some of the required parameters. None of the tested groups developed MetS after 16 weeks of HFHF diet, suggesting that the HFHF diet is not sufficient to develop at least three out of five (visceral obesity, high fasting glucose, high triglyceride, low HDL-cholesterol, high blood pressure) needed parameters. Based on our results, the addition of some pharmacological agents (e.g., cholic acid) is necessary for establishing a rat model system of MetS.

Caryopteris odorata and its metabolite coumarin attenuate characteristic features of cardiometabolic syndrome in high-refined carbohydrate-high fat-cholesterol-loaded feed-fed diet rats

Caryopteris odorata (D. Don) B.L. Robinson (Verbenaceae family) is an aromaric shrub traditionally used to treat diabetes and related pathologies (diabetic foot ulcer), cancer/tumors, wound healing, and inflammation. It is enriched with flavonoids and phenolics like coumarins, quercetin, gallic acid, coumaric acid, stigmasterol, α-tocopherol, and iridoids. C. odorata has been reported as having α-glucosidase, anti-inflammatory, and anti-oxidant properties. Its effectiveness in preventing cardiometabolic syndrome has not yet been assessed. This study aims to investigate the potential efficacy of C. odorata and coumarin for characteristic features of cardiometabolic syndrome (CMS), including obesity, dyslipidemia, hyperglycemia, insulin resistance, and hypertension by using high-refined carbohydrate-high fat-cholesterol (HRCHFC)-loaded feed-fed rats. Chronic administration of C. odorata and coumarin for 6 weeks revealed a marked attenuation in body and organ weights, with a consistent decline in feed intake compared to HRCHFC diet fed rats. The test materials also caused a significant reduction in the blood pressure (systolic, diastolic, and mean) and heart rate of HRCHFC-diet fed rats. Improved glucose tolerance and insulin sensitivity tests were also observed in test material administered rats compare to only HRCHFC-diet fed rats. C. odorata and coumarin-treated animals produced a marked decline in serum FBG, TC, TG, LFTs, and RFTs, while an increase in serum HDL-C levels was noticed. C. odorata and coumarin also significantly modulated inflammatory biomarkers (TNFα, IL-6), adipokines (leptin, adiponectin, and chemerin), and HMG-CoA reductase levels, indicating prominent anti-inflammatory, cholesterol-lowering, and anti-hyperglycemic potential. Administration of C. odorata and coumarin exhibited a marked improvement in oxidative stress markers (CAT, SOD, and MDA). Histopathological analysis of liver, heart, kidney, pancreas, aorta, and fat tissues showed a revival of normal tissue architecture in C. odorata and coumarin-treated rats compared to only HRCHFC-diet fed rats. These results suggest that C. odorata and coumarin possess beneficial effects against the characteristic features of CMS (obesity, insulin resistance, hypertension, and dyslipidemia) in HRCHFC feed-administered rats. These effects were possibly mediated through improved adipokines, glucose tolerance, and insulin sensitivity, the attenuation of HMG-CoA reductase and inflammatory biomarkers, and modulated oxidative stress biomarkers. This study thus demonstrates a rationale for the therapeutic potential of C. odorata and coumarin in CMS.

Dietary Supplementation with D-Ribose-L-Cysteine Prevents Hepatic Stress and Pro-Inflammatory Responses in Male Wistar Rats Fed a High-Fructose High-Fat Diet

Diets rich in fats and fructose are associated with the pathogenesis of oxidative stress-induced non-alcoholic fatty liver disease. Therefore, we investigated the effect of D-ribose-L-cysteine (DRLC) in high-fructose high-fat (HFHF) diet-fed rats. Twenty rats (n = 5), divided into four groups, were simultaneously exposed to HFHF and/or DRLC (250 mg/kg) orally during the 8 weeks of the study. Results showed that HFHF precipitated pro-inflammation and selective disruption of the oxidative stress markers. There were significant decreases in the level of antioxidants such as superoxide dismutase (SOD), glutathione peroxidase (GPX), total antioxidant capacity (TAC), hepatic SOD and GPX. Significant increases in serum levels of uric acid (UA), tumour necrosis factor-alpha (TNF-α), C-reactive protein (CRP) and hepatic Xanthine oxidase (XO) were observed in the HFHF compared to the control. In the HFHF + DRLC group, oxidative stress was mitigated due to differences in serum levels of SOD, GPX, TAC, TNF-α, liver SOD, and XO relative to control. The administration of DRLC alone caused significant reductions in malondialdehyde, UA and CRP and a significant increase in SOD compared to the control. DRLC prevents hepatic and systemic oxidative stress and pro-inflammatory events in HFHF diet-fed rats.