Effect of high-fat diet on cholesterol metabolism in rats and its association with Na⁺/K⁺-ATPase/Src/pERK signaling pathway

Mechanical properties of blood exosomes and lipoproteins after the rat whole blood irradiation with X-rays in vitro explored by atomic force microscopy

Blood is a two-component system with two levels of hierarchy: the macrosystem of blood formed elements and the dispersed system of blood nanoparticles. Biological nanoparticles are the key participants in communication between the irradiated and non-irradiated cells and inducers of the non-targeted effects of ionizing radiation. The work aimed at studying by atomic force microscopy the structural, mechanical, and electrical properties of exosomes and lipoproteins (LDL/VLDL) isolated from rat blood after its exposure to X-rays in vitro.

MATERIALS AND METHODS

The whole blood of Wistar rats fed with a high-fat diet was irradiated with X-rays (1 and 100 Gy) in vitro. The structural and mechanical properties (the elastic modulus and nonspecific adhesion force) of exosome and lipoprotein isolates from the blood by ultracentrifugation method were studied using Bruker Bioscope Resolve atomic force microscope in PF QNM mode, their electric properties (the zeta-potential) was measured by electrophoretic mobility.

RESULTS

Lipoproteins isolated from non-irradiated blood were softer (Me(LQ; UQ): 7.8(4.9;12.1) MPa) compared to blood nanoparticles of its exosome fraction (34.8(22.6;44.9) MPa) containing both exosomes and non-membrane nanoparticles. X-ray blood irradiation with a dose of 1 Gy significantly weakened the elastic properties of lipoproteins. Exposure of the blood to 100 Gy X-rays made lipoproteins stiffer and their nonspecific adhesive properties stronger. The radiation effects on the mechanical parameters of exosomes and non-membrane nanoparticles in exosome fractions differed. The significant radiation-induced change in electric properties of the studied nanoparticles was detected only for lipoproteins in the blood irradiated with 1 Gy X-rays. The low-dose radiation-induced changes in zeta-potential and increase in lipoprotein size with the appearance of a soft thick surface layer indicate the formation of the modified lipoproteins covered with a corona from macromolecules of irradiated blood.

CONCLUSION

Our data obtained using the nanomechanical mapping mode of AFM are the first evidence of the significant radiation-induced changes in the structural and mechanical properties of the dispersed system of blood nanoparticles after the X-ray irradiation of the blood.

The effect of maternal period nutritional status on oro-sensorial fat perception and taste preference in rats

CD36 and GPR120 play an important role in the perception and preference for fat-rich food consumption. We aimed to investigate the relationship between oro-gustatory perception of lipids, fatty taste preference, and maternal (Gestation + Lactation)-maturation period nutrition status in offspring Sprague-Dawley rats. In our study, mother rats were fed with control (C) or high-fat diets (HFD) during gestation (21 days) and lactation (21 days) periods. After weaning, the offspring were fed with control (C) or high-fat diets (HFD) during the maturation (120 days) period. Daily calorie intake and weekly body weight measurements were monitored. Two-bottle preference (TBPT) and licking tests measured the fat perceptions and preferences. Plasma levels of insulin, leptin, glucose, and triglyceride were measured. The protein and mRNA expressions of CD36 and GPR120 in the circumvallate papillae (CVP) were determined. The 48 h TBPT results revealed that maternal HFD-exposed offspring rats significantly preferred 2% rapeseed oil solution regardless of the type of maturation diet. According to the licking test, C/C group (C diet exposed group in maternal and maturation periods) offspring licked 0.1% oleic acid-containing water more than C/HFD (C diet exposed in maternal period and HFD exposed group in maturation period) and HFD/HFD group. (HFD exposed group in maternal and maturation periods) groups. Plasma insulin and leptin concentrations significantly increased in HFD/HFD groups compared to C/C group. CD36 protein expressions were significantly lower in HFD/HFD than C/HFD and HFD/C groups. GPR120 and GNAT3 mRNA expressions in HFD/C group were significantly higher than in C/HFD group. Our results suggest that HFD exposure during maternal and maturation period may play a role in fat perception/preference through oral lipid sensors.

High manganese exposure decreased the risk of high triglycerides in workers: a cross-sectional study

Background

Manganese (Mn) participates in lipid metabolism. However, the associations between Mn exposure and dyslipidaemia is unclear.

Methods

This was a cross-sectional study. Data were collected from the 2017 the Mn-exposed workers healthy cohort (MEWHC). Finally, 803 occupationally Mn-exposed workers included in the study. The workers were divided into two groups. The grouping of this study was based on Mn-Time Weighted Averages (Mn-TWA). The high-exposure group included participants with Mn-TWA greater than 0.15 mg/m³. The low-exposure group included participants with Mn-TWA less than or equal to 0.15 mg/m³. Mn-TWA levels and dyslipidaemia were assessed.

Results

After adjustment for seniority, sex, cigarette consumption, alcohol consumption, high-fat diet frequency, medicine intake in the past two weeks, egg intake frequency, drinking tea, WHR, and hypertension, Mn-TWA levels was negatively correlated with high triglycerides (TG) risk in workers overall (OR = 0.51; 95% CI: 0.36, 0.73; p <  0.01). The results of males and females were consistent (OR = 0.53; 95% CI: 0.34, 0.81; p <  0.01) and (OR = 0.47; 95% CI: 0.24, 0.94; p <  0.01), respectively. By performing interactions analyses of workers overall, we observed no significant interactions among confounders. Mn-TWA levels and pack-years on high TG risk (relative excess risk for the interactions (RERI = 2.29, 95% CI: − 2.07, 6.66), (RERI) = 2.98, 95% CI: − 2.30, 8.26). Similarly, smoking status, drinking status, high-fat diet frequency, and Waist-to-Hip Ratio (WHR) showed non-significant interactions with Mn-TWA levels on high TG risk.

Conclusions

This research indicates that high Mn exposure was negatively related to high TG risk in workers.

Evaluation of the effect of cafeteria diet on the kidney Na,K-ATPase activity, and oxidative stress

In this study, renal tissue, subdivided into the cortex and medulla of Wistar rats subjected to a cafeteria diet (CAF) for 24 days or to normal diet, was used to analyze whether the renal enzyme Na,K-ATPase activity was modified by CAF diet, as well as to analyze the α1 subunit of renal Na,K-ATPase expression levels. The lipid profile of the renal plasma membrane and oxidative stress were verified. In the Na,K-ATPase activity evaluation, no alteration was found, but a significant decrease of 30% in the cortex was detected in the α1 subunit expression of the enzyme. There was a 24% decrease in phospholipids in the cortex of rats submitted to CAF, a 17% increase in cholesterol levels in the cortex, and a 23% decrease in the medulla. Lipid peroxidation was significantly increased in the groups submitted to CAF, both in the cortical region, 29%, and in the medulla, 35%. Also, a reduction of 45% in the glutathione levels was observed in the cortex and medulla with CAF. CAF showed a nearly two-fold increase in glutathione peroxidase (GPX) activity in relation to the control group in the cortex and a 59% increase in the GPx activity in the medulla. In conclusion, although the diet was administered for a short period of time, important results were found, especially those related to the lipid profile and oxidative stress, which may directly affect renal function.

Therapeutic Effect of Chitooligosaccharide Tablets on Lipids in High-Fat Diets Induced Hyperlipidemic Rats

Chitooligosaccharide is beneficial for inhibiting dyslipidemia and reducing atherosclerotic and hyperlipidemic risk. The purpose of this study was to investigate the cholesterol-regulating effects and potential mechanisms of Chitooligosaccharide tablets (CFTs) in high-fat diet-induced hyperlipidemic rats. The results revealed that CFTs can regulate serum lipid levels in hyperlipidemic rats in a dosage-dependent manner. Synchronously, gene expressions related to cholesterol excretion were upregulated in a dosage-dependent manner, including cholesterol 7α-hydroxylase (CYP7A1), liver X receptor α (LXRA), peroxisome proliferation-activated receptor-α (PPARα) and low-density lipoprotein receptor (LDLR), whereas cholesterol synthetic gene expressions including 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) and sterol-responsive element binding protein-2 (SREBP2) were reduced. This work highlights that CFTs have potential as natural products to prevent and treat metabolic hyperlipidemia syndrome, probably due to the reduction of cholesterol biosynthesis and through cholesterol elimination; they also improve the pathological changes of liver tissue in rats, alleviate liver damage, maintain normal lipid metabolism in the liver, ameliorate hepatic glycolipid disorders and accelerate TC operation, and reduce blood lipid levels.

Synergistic effects of prenatal nicotine exposure and post-weaning high-fat diet on hypercholesterolaemia in rat offspring of different sexes

Hypercholesterolaemia is considered a disease with intrauterine origin. Recently, we reported that prenatal nicotine exposure (PNE) induced an abnormal level of total cholesterol in rat offspring before and after birth. However, there were little data about sex differences in serum cholesterol level in PNE offspring. In addition, many previous studies reported that blood cholesterol is associated with daily diet. This study was designed to analyse the interaction among PNE, high-fat diet (HFD) and sex on cholesterol metabolism in the rat. Pregnant Wistar rats were administered 2 mg/kg nicotine subcutaneously from gestational day (GD) 11 until parturition. After weaning, pups were fed with normal diet or HFD till 24 weeks, and then, serum cholesterol phenotypes and hepatic cholesterol metabolism-related genes were tested. Results showed that PNE manifested a distinct programming effect on cholesterol phenotype and cholesterol metabolism-related genes. HFD aggregated PNE-induced hypercholesterolaemia in adult offspring and exacerbated liver cholesterol metabolism dysfunction in PNE offspring. There was no sex difference in serum cholesterol level, but there were interactions among PNE, HFD and sex on cholesterol metabolic genes in adult offspring, which indicates that cholesterol metabolism in female offspring is more likely to be affected by PNE and HFD. In conclusion, HFD exacerbated PNE-induced hypercholesterolaemia, and sex differences existed in liver cholesterol metabolic genes in PNE- or HFD-treated offspring.

Effect of different intensities of physical activity on cardiometabolic markers and vascular and cardiac function in adult rats fed with a high-fat high-carbohydrate diet

BACKGROUND

Physical activity (PA) and diet are 2 lifestyle factors that affect cardiometabolic risk. However, data on how a high-fat high-carbohydrate (HFHC) diet influences the effect of different intensities of PA on cardiometabolic health and cardiovascular function in a controlled setting are yet to be fully established. This study investigated the effect of sedentary behavior, light-intensity training (LIT), and high-intensity interval training (HIIT) on cardiometabolic markers and vascular and cardiac function in HFHC-fed adult rats.

METHODS

Twelve-week-old Wistar rats were randomly allocated to 4 groups (12 rats/group): control (CTL), sedentary (SED), LIT, and HIIT. Biometric indices, glucose and lipid control, inflammatory and oxidative stress markers, vascular reactivity, and cardiac electrophysiology of the experimental groups were examined after 12 weeks of HFHC-diet feeding and PA interventions.

RESULTS

The SED group had slower cardiac conduction (p = 0.0426) and greater thoracic aortic contractile responses (p < 0.05) compared with the CTL group. The LIT group showed improved cardiac conduction compared with the SED group (p = 0.0003), and the HIIT group showed decreased mesenteric artery contractile responses compared with all other groups and improved endothelium-dependent mesenteric artery relaxation compared with the LIT group (both p < 0.05). The LIT and HIIT groups had lower visceral (p = 0.0057 for LIT, p = 0.0120 for HIIT) and epididymal fat (p < 0.0001 for LIT, p = 0.0002 for HIIT) compared with the CTL group.

CONCLUSION

LIT induced positive adaptations on fat accumulation and cardiac conduction, and HIIT induced a positive effect on fat accumulation, mesenteric artery contraction, and endothelium-dependent relaxation. No other differences were observed between groups. These findings suggest that few positive health effects can be achieved through LIT and HIIT when consuming a chronic and sustained HFHC diet.

ATP synthase β-subunit abnormality in pancreas islets of rats with polycystic ovary syndrome and type 2 diabetes mellitus

This study investigated the abnormal expression of ATP synthase β-subunit (ATPsyn-β) in pancreas islets of rat model of polycystic ovary syndrome (PCOS) with type 2 diabetes mellitus (T2DM), and the secretion function changes after up-regulation of ATP5b. Sixty female SD rats were divided into three groups randomly and equally. The rat model of PCOS with T2DM was established by free access to the high-carbohydrate/high-fat diet, subcutaneous injections of DHEA, and a single injection of streptozotocin. The pancreas was removed for the detection of the ATPsyn-β expression by immunohistochemical staining, Western blotting and reverse transcription-PCR (RT-PCR). The pancreas islets of the rats were cultured, isolated with collagenase V and purified by gradient centrifugation, and the insulin secretion after treatment with different glucose concentrations was tested. Lentivirus ATP5b was successfully constructed with the vector of GV208 and transfected into the pancreas islets for the over-expression of ATPsyn-β. The insulin secretion and intracellular ATP content were determined after transfection of the PCOS-T2DM pancreas islets with Lenti-ATP5b. The results showed that the expression of ATPsyn-β protein and mRNA was significantly decreased in the pancreas of PCOS-T2DM rats. The ATP content in the pancreas islets was greatly increased and the insulin secretion was improved after the up-regulation of ATPsyn-β in the pancreas islets transfected with lenti-ATP5b. These results indicated that for PCOS, the ATPsyn-β might be one of the key factors for the attack of T2DM.

Specialized Functional Diversity and Interactions of the Na,K-ATPase

Na,K-ATPase is a protein ubiquitously expressed in the plasma membrane of all animal cells and vitally essential for their functions. A specialized functional diversity of the Na,K-ATPase isozymes is provided by molecular heterogeneity, distinct subcellular localizations, and functional interactions with molecular environment. Studies over the last decades clearly demonstrated complex and isoform-specific reciprocal functional interactions between the Na,K-ATPase and neighboring proteins and lipids. These interactions are enabled by a spatially restricted ion homeostasis, direct protein-protein/lipid interactions, and protein kinase signaling pathways. In addition to its "classical" function in ion translocation, the Na,K-ATPase is now considered as one of the most important signaling molecules in neuronal, epithelial, skeletal, cardiac and vascular tissues. Accordingly, the Na,K-ATPase forms specialized sub-cellular multimolecular microdomains which act as receptors to circulating endogenous cardiotonic steroids (CTS) triggering a number of signaling pathways. Changes in these endogenous cardiotonic steroid levels and initiated signaling responses have significant adaptive values for tissues and whole organisms under numerous physiological and pathophysiological conditions. This review discusses recent progress in the studies of functional interactions between the Na,K-ATPase and molecular microenvironment, the Na,K-ATPase-dependent signaling pathways and their significance for diversity of cell function.