Diet-fed Rats Research Articles

High‐fat diet reduced dendritic spine density, but it did not affect cognitive function in spontaneous diabetic torii rats

Diabetes is a known risk factor for dementia, several factors are involved in the pathogenesis of diabetes including genetic predisposition, and high calorie diet consumption. We previously reported that long-term high-fat diet (HFD) consumption led to prediabetes, which associated with cognitive impairments. However, the effects of long-term HFD consumption on metabolic and brain function in genetically type 2 diabetes (T2DM) model have not been investigated. Therefore, we hypothesized that long-term HFD consumption aggravates metabolic and cognitive impairments in T2DM rats. Sixteen Spontaneous Diabetic Torii (SDT) rats, which is a genetically engineered T2DM rats, and eight wild type (WT) rats were used. At the age of 8 weeks old, SDT rats were divided into two dietary groups either normal diet or HFD feeding for 12 weeks. WT rats were received a normal diet entire the study. At 20 weeks old, metabolic parameters, the hippocampal dependent cognitive function using novel object location (NOL) test, and hippocampal dendritic spine density were determined. Our data demonstrated that, at 20 weeks old, SDT rats in both dietary groups exhibited their diabetic characters as indicated by hyperglycemia, hypoinsulinemia, and insulin insensitivity. HFD feeding did not aggravate diabetic status, but it significantly induced body weight gain, visceral fat deposition, hypertriglyceridemia, and hypercholesterolemia (as shown in Figure 1). Unexpectedly, hippocampal dependent cognitive impairments were not observed in both normal diet and HFD-fed SDT rats, when compared with WT rats (Figure 1). However, brain mitochondrial dysfunction and dendritic spine loss were observed in both dietary groups of SDT rats. Interestingly, the reduction of dendritic spine density was greater in HFD-fed SDT rats than normal diet-fed SDT rats (Figure 1). Long-term HFD consumption induced truncal obesity, dyslipidemia, and reduced dendritic spine density in SDT rats, but it did not affect hippocampal dependent cognitive function. It is possible that the duration of HFD feeding was insufficient to promote cognitive impairments in genetically T2DM rats.

Alleviating the effect of quinoa and the underlying mechanism on hepatic steatosis in high-fat diet-fed rats

BackgroundNonalcoholic fatty liver disease (NAFLD) is considered the hepatic component of metabolic syndrome and has attracted widespread attention due to its increased prevalence. Daily dietary management is an effective strategy for the prevention of NAFLD. Quinoa, a nutritious pseudocereal, is abundant in antioxidative bioactive phytochemicals. In the present study, the effects of different amounts of quinoa on the progression of NAFLD and the related molecular mechanism were investigated.MethodsMale SD rats were simultaneously administered a high fat diet (HF) and different amounts of quinoa (equivalent to 100 g/day and 300 g/day of human intake, respectively). After 12 weeks of the intervention, hepatic TG (triglyceride) and TC (total cholesterol) as well as serum antioxidative parameters were determined, and hematoxylin–eosin staining (H&E) staining was used to evaluate hepatic steatosis. Differential metabolites in serum and hepatic tissue were identified using UPLC-QTOF-MSE. The mRNA expression profile was investigated using RNA-Seq and further verified using real-time polymerase chain reaction (RT-PCR).ResultsLow amounts of quinoa (equivalent to 100 g/d of human intake) effectively controlled the weight of rats fed a high-fat diet. In addition, quinoa effectively inhibited the increase in hepatic TG and TC levels, mitigated pathological injury, promoted the increase in SOD and GSH-Px activities, and decreased MDA levels. Nontarget metabolic profile analysis showed that quinoa regulated lipid metabolites in the circulation system and liver such as LysoPC and PC. RNA-Seq and RT-PCR verification revealed that a high amount of quinoa more effectively upregulated genes related to lipid metabolism [Apoa (apolipoprotein)5, Apoa4, Apoc2] and downregulated genes related to the immune response [lrf (interferon regulatory factor)5, Tlr6 (Toll-like receptor), Tlr10, Tlr11, Tlr12].ConclusionQuinoa effectively prevented NAFLD by controlling body weight, mitigating oxidative stress, and regulating the lipid metabolic profile and the expression of genes related to lipid metabolism and the immune response.

Mangrove (Rhizophora sp.) Fruit Extract Inhibits Tumor Growth Factor (TGF)-β1 Expression in High Cholesterol Diet-Fed Rats

Background: Atherosclerosis is a major finding in cardiovascular disease. One of the pro-fibrotic cytokines that play an important role in the atherosclerosis process is Tumor Growth Factor (TGF)-β1, where the presence of high TGF-β1 secretion due to hypercholesterolemia will trigger excessive collagen matrix formation. Objective: To analyze Rhizophora sp fruit extract effect on TGF-β1 expression in high cholesterol diet-fed rats. Material and Methods: Eighteen 10-week-old rats weighing 150-200 g were used in this study. These animals were grouped into 3 groups, each consisting of 6 rats. Group A (normal control) is a group of rats that received a normal diet. Group B (atherogenic control) received a diet that induces atherosclerosis (atherogenic diet). This diet contains 2% cholesterol, 5% goat fat, 0.2% cholic acid and standard diet up to 100%. Atherogenic diet was given for 3 days, and on the first day this group also received vitamin D3 700,000 IU/kg. Group C (treated), apart from receiving an atherogenic diet, was also given Rhizophora sp fruit extract 500 mg/kg body weight. The Rhizophora sp fruit extract effect on TGF-β1 expression was evaluated by immunohistochemical procedure. The area of ​​the expression is calculated using the ImageJ. Results: The results of this study indicate that the expression of TGF-β1 is higher in the group receiving the atherogenic diet than the normal control group (17.3 vs. 8.9; P=0.000). Rhizophora sp fruit extract reduced this expression remarkably (17.3 vs. 11.4; P=0.001). Conclusion: Rhizophora sp fruit extract inhibits the the expression of TGF-β1 in high cholesterol diet-fed rats.

Liraglutide suppresses obesity and promotes browning of white fat via miR-27b in vivo and in vitro.

ObjectiveTo investigate the effect of liraglutide on the browning of white fat and the suppression of obesity via regulating microRNA (miR)-27b in vivo and in vitro.MethodsSprague-Dawley rats were fed a high-fat (HF) diet and 3T3-L1 pre-adipocytes were differentiated into mature white adipocytes. Rats and mature adipocytes were then treated with different doses of liraglutide. The mRNA and protein levels of browning-associated proteins, including uncoupling protein 1 (UCP1), PR domain containing 16 (PRDM16), CCAAT enhancer binding protein β (CEBPβ), cell death-inducing DFFA-like effector A (CIDEA) and peroxisome proliferator-activated receptor-γ-coactivator 1α (PGC-1α), were detected using quantitative real-time polymerase chain reaction and Western blotting.ResultsLiraglutide decreased body weight and reduced the levels of blood glucose, triglyceride and low-density lipoprotein cholesterol in HF diet-fed rats. Liraglutide increased the levels of UCP1, PRDM16, CEBPβ, CIDEA and PGC-1α in vivo and vitro. The levels of miR-27b were upregulated in HF diet-fed rats, whereas liraglutide reduced the levels of miR-27b. In vitro, overexpression of miR-27b decreased the mRNA and protein levels of UCP1, PRDM16, CEBPβ, CIDEA and PGC-1α. Transfection with the miR-27b mimics attenuated the effect of liraglutide on the browning of white adipocytes.ConclusionLiraglutide induced browning of white adipose through regulation of miR-27b.

Nitrogen Balance and Bioavailability of Amino Acids in Spirulina Diet-Fed Wistar Rats.

Spirulina widely known to consumers as a health food is mainly a dried product. Since data for raw spirulina as a protein source are insufficient, the nutritional values of dry and raw spirulina diets in Wistar rats were determined. Digestibility coefficients were significantly lower in the dry (84.1 ± 0.5%) and raw (85.7 ± 0.4%) spirulina diets than that in the casein diet (96.6 ± 0.2%), although biological values of dry (86.3 ± 1.3%) and raw (77.9 ± 2.6%) spirulina diets were significantly higher than that of the casein diet (71.9 ± 2.5%). The protein digestibility-corrected amino acid score of raw spirulina (86.6 ± 0.5%) was significantly higher than that of dry spirulina (85.1 ± 0.5%). Additionally, amino acid profiling of portal/venous blood in spirulina diet-fed rats revealed that Ala, Gly, Val, and Leu/Ile were markedly decreased after systemic circulation. These results suggest that dry and raw spirulina diets may be effective not only as a protein source but also as a supplement to support protein/amino acid bioavailability.

Dietary intake of n-3 polyunsaturated fatty acids alters the lipid mediator profile of the kidney but does not attenuate renal insufficiency

The efficacy of n-3 polyunsaturated fatty acids (PUFAs) in improving outcomes in a renal ischemia-reperfusion injury (IRI) model has previously been reported. However, the underlying mechanisms remain poorly understood and few reports demonstrate how dietary n-3 PUFAs influence the composition of membrane phospholipids in the kidney. Additionally, it has not been elucidated whether perilla oil (PO), which is mainly composed of the n-3 alpha-linolenic acid, mitigates renal IRI. In this study, we investigated the effect of dietary n-3 PUFAs (PO), compared with an n-6 PUFA-rich soybean oil (SO) diet, on IRI-induced renal insufficiency in a rat model. Levels of membrane phospholipids containing n-3 PUFAs were higher in the kidney of PO-rich diet-fed rats than the SO-rich diet-fed rats. Levels of blood urea nitrogen and serum creatinine were significantly higher in the ischemia-reperfusion group than the sham group under both dietary conditions. However, no significant differences were observed in blood urea nitrogen, serum creatinine, or histological damage between PO-rich diet-fed rats and SO-rich diet-fed rats. In the kidney of PO-rich diet-fed rats, levels of arachidonic acid and arachidonic acid-derived pro-inflammatory lipid mediators were lower than SO-rich diet-fed rats. Eicosapentaenoic acid and eicosapentaenoic acid-derived lipid mediators were significantly higher in the kidney of PO-rich than SO-rich diet-fed rats. These results suggest that dietary n-3 PUFAs alter the fatty acid composition of membrane phospholipids and lipid mediators in the kidney; however, this does not attenuate renal insufficiency or histological damage in a renal IRI model.

Astaxanthin attenuates hepatic steatosis in high-fat diet-fed rats by suppressing microRNA-21 via transactivation of nuclear factor erythroid 2-related factor 2.

This study examined whether astaxanthin (ASX) could alleviate hepatic steatosis in rats fed a high-fat diet (HFD) by modulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/miR-21 axis. Rats (n = 8/group) were fed either a standard diet (3.8kcal/g; 10% fat) or HFD (4.6kcal/g; 40% fat) and treated orally with either the vehicle or ASX (6mg/kg) daily for 8days. Another group was fed HFD and treated with ASX and brusatol (an Nrf2 inhibitor) (2mg/kg/twice per week/i.p.). ASX prevented the gain in body and liver weights and attenuated hepatic lipid accumulation in HFD-fed rats. In the control and HFD-fed rats, ASX did not affect food intake, serum free fatty acid (FFA) content, and glucose and insulin levels and tolerance. However, serum triglyceride (TG), cholesterol, and low-density lipoprotein-cholesterol levels; hepatic levels of TGs and FFAs; and hepatic levels of Srebp1, Srebp2, HMGCR, and fatty acid synthase mRNAs and miR-21 were reduced and the mRNA levels of Pparα were significantly increased in both the groups. These effects were associated with a reduction in the hepatic levels of reactive oxygen species, malondialdehyde, tumor necrosis factor-α, and interlukin-6 as well as an increase in superoxide dismutase levels, total glutathione content, and nuclear levels and activity of Nrf2. miR-21 levels were strongly correlated with the nuclear activity of Nrf2. Brusatol completely reversed the effects of ASX. In conclusion, ASX prevents hepatic steatosis mainly by transactivating Nrf2 and is associated with the suppression of miR-21 and Srebp1/2 and upregulation of Pparα expression.

Beneficial Effects of High Intensity Interval Training and/or Linseed Oil Supplementation to Limit Obesity-Induced Oxidative Stress in High Fat Diet-Fed Rats.

High-intensity interval training (HIIT) and linseed oil (LO) supplementation are effective strategies to reduce obesity-induced oxidative stress. Our aim was to determine whether the HIIT + LO combination prevents obesity-induced oxidative stress in high fat diet (HFD)-fed rats. HFD-fed 8-week-old, male, Wistar rats were subdivided in four groups: HFD, LO (2% of sunflower oil replaced with 2% of LO in the HFD), HIIT (4 days/week for 12 weeks), and HIIT + LO. Wistar rats fed a low-fat diet (LFD) were used as controls. Epididymal and subcutaneous adipose tissue, gastrocnemius muscle, liver, and plasma samples were collected to measure oxidative stress markers (AOPP, oxLDL), antioxidant (SOD, CAT, and GPx activities) and pro-oxidant (NOx and XO) enzyme activities. Compared with the LFD, the HFD altered the pro/antioxidant status in different tissues (increase of AOPP, oxLDL, SOD and catalase activities in plasma, and SOD activity increase in liver and decrease in adipose tissues) but not in gastrocnemius. LO upregulated CAT activity and decreased NOx in liver. HIIT alleviated HFD negative effects in liver by reducing SOD and NOx activities. Moreover, the HIIT + LO combination potentiated SOD activity upregulation in subcutaneous tissue. HIIT and LO supplementation have independent beneficial effects on the pro/antioxidant balance. Their association promotes SOD activity in subcutaneous adipose tissue.

Combination Therapy of Neprilysin Inhibitor with AT2R Agonist C21 Provides Superior Renoprotection Compared to its Combination with AT1R Antagonist Valsartan in High-Sodium Diet-Fed Obese Zucker Rats

Combination Therapy of Neprilysin Inhibitor with AT2R Agonist C21 Provides Superior Renoprotection Compared to its Combination with AT1R Antagonist Valsartan in High-Sodium Diet-Fed Obese Zucker Rats

Necrostatin-1 reduces cardiac and mitochondrial dysfunction in prediabetic rats.

High-fat diet (HFD) consumption induces prediabetes and left ventricular dysfunction through many pathways including cell death pathway like necroptosis. Although the benefit of necroptosis inhibitor (necrostatin-1 or Nec-1) in the brain of prediabetic rats was shown, the effects of Nec-1 on cardiac autonomic function, blood pressure, cardiac function, along with its mechanistic insight have not been investigated. Male Wistar rats were fed with either a normal diet (n = 8) or HFD (n = 24) for 12 weeks to induce prediabetes. Prediabetic rats were randomly assigned into three interventional groups (n = 8/group): (1) vehicle, (2) Nec-1 (1.65 mg/kg, sc injection), and (3) metformin (300 mg/kg, oral gavage feeding). Treatments lasted for 8 weeks. Normal saline was given to normal diet-fed rats and vehicle group. Metabolic parameters, cardiac function and biochemical parameters were assessed. Prediabetic rats exhibited peripheral metabolic impairment as indicated by increased body weight, hyperinsulinemia with euglycemia, and dyslipidemia. Prediabetic rats also had cardiac autonomic imbalance, high blood pressure, and cardiac dysfunction, together with cardiac mitochondrial dysfunction, mitochondrial dynamic imbalance, and increased necroptosis and apoptosis. Treatment with Nec-1 did not affect peripheral metabolic parameters, however, it effectively reduced cardiac autonomic imbalance, blood pressure, and cardiac dysfunction via reducing cardiac inflammation, necroptosis, mitochondrial dysfunction, and increased mitochondrial fusion. Treatment with metformin reduced peripheral metabolic impairment and cardiac dysfunction via decreased cardiac mitochondrial dysfunction, mitochondrial dynamic imbalance, and apoptosis. In summary, Nec-1 directly suppressed necroptosis, cardiac mitochondrial dysfunction, and increased mitochondrial fusion independent of peripheral metabolic function, leading to an improved cardiac function in prediabetic rats.

Vitamin A Deficiency during the Perinatal Period and First Weeks of Life Modifies Vitamin A and Lipid Postprandial Metabolism in Both Female and Male Young Rats.

The effect of vitamin A deficiency on vitamin A and lipid postprandial metabolism in young rats is addressed, considering the effect of sex. Sprague-Dawley rats are fed either 400 UI.kg-1 vitamin A diet (vitamin A-deficient (VAD) diet) or 2300 UI.kg-1 vitamin A (control diet), before being mated. Mothers receive the same VAD or control diet during gestation and lactation. Offspring receive the same diet than mothers until 8 weeks of age. VAD diet-fed female and male offspring display a severe vitamin A deficiency with no body weight or glucose tolerance defects. Fasting plasma triglyceride concentrations are decreased in VAD diet-fed animals compared to controls (p < 0.05). Retinyl ester postprandial responses after vitamin A gavage, expressed as area under the curves, are not different in VAD diet-fed and control animals, although retinyl ester postprandial peak is significantly delayed (p < 0.05) in VAD diet-fed rats. Lipids also accumulate in the distal part of the intestine after gavage and [1-13 C]-oleate postprandial response is decreased in VAD diet-fed males. Vitamin A deficiency modulates both vitamin A absorption rate and lipid postprandial metabolism, which can partly explain the altered fasting lipid status observed in VAD diet-fed offspring.

Supplementation of non-fermented and fermented goji berry (Lycium barbarum) improves hepatic function and corresponding lipid metabolism via their anti-inflammatory and antioxidant properties in high fat-fed rats

Development of obesity is associated with excessive fat accumulation and oxidative stress along with chronic inflammation. Goji berries (Lycium barbarum) are high in polyphenolic compounds and have anti-inflammatory, anti-oxidant, and hypolipidemic properties that may alleviate the pathogenesis of obesity and related metabolic complications. Thus, the aim of this study was to investigate potential metabolic benefits of GB supplementation against high fat (HF) diet-induced obesity and its comorbidities in HF diet-fed rats (male Sprague–Dawley, n = 8/group, 6 weeks old). We also sought to examine the potential metabolic benefits of fermented GB (FGB) with L. plantarum CB3 and possible distinctions in the degree and/or mechanism of action compared to GB. GB and FGB supplementation suppressed the gene expression of inflammation indices at the local (adipose tissues) and systemic (liver) levels. In addition, GB and FGB supplementation upregulated the gene expression of antioxidant enzymes compared to the HF and/or even low fat (LF) group with more remarkable antioxidant effects by GB supplementation. Also, GB and FGB supplementation protected from HF-induced damages of the liver and dyslipidemia. In conclusion, we demonstrated that GB and FGB supplementation protected from HF-induced metabolic complications primarily by improving hepatic function and corresponding lipid metabolism via their anti-inflammatory and antioxidant properties. To our knowledge, this is the first in vivo study confirming metabolic benefits of GB in a fermented form. Thus, these findings support the potential application of both GB and FGB to ameliorate obesity-associated metabolic abnormalities.

Hyperleptinaemia and its Association with Postprandial Hypertriglyceridemia and Glucose Intolerance.

Introduction:Leptin resistance is believed to cause insulin resistance though the exact mechanism is not fully understood. The present study aims to investigate the temporal profile of postprandial triglyceride (PPTG) and leptin levels, and their association with each other as well as with markers of metabolic syndrome.Materials and Methods:Serum leptin and PPTG levels were measured longitudinally till 26 weeks in Wistar rats fed on controlled diet (group 1) and high sucrose diet (HSD) (group 2). Two additional groups fed on HSD were taken and treated with pioglitazone (group 3) and atorvastatin (group 4). Body weight, homeostasis model assessment of insulin resistance (HOMA-IR), and glucose intolerance were also measured during this period. Comparison of the groups were done and Pearson's correlation coefficient was used to ascertain the association.Results:Leptin levels were significantly higher in all three groups receiving HSD compared to controlled diet group from week 2 to week 26 (P < 0.01). The postprandial triglyceride area under the curve (PPTG AUCs) were significantly higher in group 2 than controls during this period (P < 0.001). Body weight, HOMA-IR and glucose AUC were found to be significantly higher in group 2 rats than controls only from week 6, 8, and 12 respectively. In HSD-fed rats, but not in control, mean serum leptin levels from 2-26 weeks as well as peak (10th week) and 26th week were strongly associated with corresponding as well as preceding PPTG levels. Leptin levels significantly predicted HOMA-IR and prediabetes in group 2.Conclusion:This study found significant hyperleptinemia associated with postprandial hypertriglyceridemia that predicted insulin resistance and prediabetes in high sucrose diet–fed rats.

Biochemical and histological investigation on the protective effect of poly-herbal extract in high salt diet-fed male Wistar rats

BackgroundThrough different mechanisms, excessive intake of dietary salt has been documented as a risk factor for the development of elevated blood pressure and organ dysfunction. Therefore, this study evaluated the efficacy of combined extracts of four medicinal plants against high salt diet-induced succinate dehydrogenase depletion and alteration in vital organ (kidney, liver, and cardiac) hemostasis. MethodsThirty-five male Wistar rats with an average weight of 130 g were divided into 5 groups of 7 animals each. Group 1 and 2 rats were fed with normal rat chow (NRC) and 16% high salt diet (HSD) only respectively. Rats in groups 3, 4, and 5 were fed with 16% HSD and 800, 400, and 200 mg/kg poly-herbal extract (PHE), respectively, once daily for 4 weeks. The concentration and activities of creatinine, urea, sodium, magnesium, chloride, potassium, albumin, globulin, total protein, and alkaline phosphate (ALP) were estimated in the serum. Aspartate and alanine aminotransferases (AST and ALT), lactate dehydrogenase (LDH), succinate dehydrogenase (SDH) were estimated in the serum, liver, and aorta. The result revealed that the combined extract significantly (p < 0.05) lowered HSD-induced elevated serum concentration of kidney function markers and electrolytes. More so, a significant (p < 0.05) reduction in serum and tissue activities of liver and cardiac function markers was demonstrated by the poly-herbal extract. No significant changes were observed in serum albumin and globulin level, however total protein and tissue activities of SDH were significantly (p < 0.05) elevated by the PHE. The histopathological examination showed to a large extent, the extract conferred significant protection on the cytoarchitecture of the kidney, liver, and aorta. ConclusionConclusively, combined plants extract protected against high salt diet-induced biochemical and histological derangement in male Wistar rats.

Persistence of cerebellar ataxia during chronic ethanol exposure is associated with epigenetic up-regulation of Fmr1 gene expression in rat cerebellum.

Alcohol intoxication produces ataxia by affecting the cerebellum, which coordinates movements. Fragile X mental retardation (FMR) protein is a complex regulator of RNA and synaptic plasticity implicated in fragile X-associated tremor/ataxia syndrome, which features ataxia and increased Fmr1mRNA expression resulting from epigenetic dysregulation of FMRP. We recently demonstrated that acute ethanol-induced ataxia is associated with increased cerebellar Fmr1gene expression via histone modifications in rats, but it is unknown whether similar behavioral and molecular changes occur following chronic ethanol exposure. Here, we investigated the effects of chronic ethanol exposure on ataxia and epigenetically regulated changes in Fmr1 expression in the cerebellum. Male adult Sprague-Dawley rats were trained on the accelerating rotarod and then fed with chronic ethanol or a control Lieber-DeCarli diet while undergoing periodic behavioral testing for ataxia during ethanol exposure and withdrawal. Cerebellar tissues were analyzed for expression of the Fmr1gene and its targets using a real-time quantitative polymerase chain reaction assay. The epigenetic regulation of Fmr1was also investigated using a chromatin immunoprecipitation assay. Ataxic behavior measured by the accelerating rotarod behavioral test developed during chronic ethanol treatment and persisted at both the 8-h and 24-h withdrawal time points compared to control diet-fed rats. In addition, chronic ethanol treatment resulted in up-regulated expression of Fmr1mRNA and increased activating epigenetic marks H3K27 acetylation and H3K4 trimethylation at 2 sites within the Fmr1 promoter. Finally, measurement of the expression of relevant FMRP mRNA targets in the cerebellum showed that chronic ethanol up-regulated cAMP response element binding (CREB) Creb1, Psd95, Grm5, and Grin2b mRNA expression without altering Grin2a, Eaa1, or histone acetyltransferases CREB binding protein (Cbp) or p300mRNA transcripts. These results suggest that epigenetic regulation of Fmr1 and subsequent FMRP regulation of target mRNA transcripts constitute neuroadaptations in the cerebellum that may underlie the persistence of ataxic behavior during chronic ethanol exposure and withdrawal.

Oleoylethanolamide Reduces Hepatic Oxidative Stress and Endoplasmic Reticulum Stress in High-Fat Diet-Fed Rats.

Long-term high-fat diet (HFD) consumption can cause weight gain and obesity, two conditions often associated with hepatic non-alcoholic fatty liver and oxidative stress. Oleoylethanolamide (OEA), a lipid compound produced by the intestine from oleic acid, has been associated with different beneficial effects in diet-induced obesity and hepatic steatosis. However, the role of OEA on hepatic oxidative stress has not been fully elucidated. In this study, we used a model of diet-induced obesity to study the possible antioxidant effect of OEA in the liver. In this model rats with free access to an HFD for 77 days developed obesity, steatosis, and hepatic oxidative stress, as compared to rats consuming a low-fat diet for the same period. Several parameters associated with oxidative stress were then measured after two weeks of OEA administration to diet-induced obese rats. We showed that OEA reduced, compared to HFD-fed rats, obesity, steatosis, and the plasma level of triacylglycerols and transaminases. Moreover, OEA decreased the amount of malondialdehyde and carbonylated proteins and restored the activity of antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase, which decreased in the liver of HFD-fed rats. OEA had also an improving effect on parameters linked to endoplasmic reticulum stress, thus demonstrating a role in the homeostatic control of protein folding. Finally, we reported that OEA differently regulated the expression of two transcription factors involved in the control of lipid metabolism and antioxidant genes, namely nuclear factor erythroid-derived 2-related factor 1 (Nrf1) and Nrf2, thus suggesting, for the first time, new targets of the protective effect of OEA in the liver.

Metronidazole enhances steatosis-related early-stage hepatocarcinogenesis in high fat diet-fed rats through DNA double-strand breaks and modulation of autophagy.

Nonalcoholic fatty liver disease is a hepatic disorder with deposition of fat droplets and has a high risk of progression to steatosis-related hepatitis and irreversible hepatic cancer. Metronidazole (MNZ) is an antiprotozoal and antimicrobial agent widely used to treat patients infected with anaerobic bacteria and intestinal parasites; however, MNZ has also been shown to induce liver tumors in rodents. To investigate the effects of MNZ on steatosis-related early-stage hepatocarcinogenesis, male rats treated with N-nitrosodiethylamine following 2/3 hepatectomy at week 3 were received a control basal diet, high fat diet (HFD), or HFD containing 0.5% MNZ. The HFD induced obesity and steatosis in the liver, accompanied by altered expression of Pparg and Fasn, genes related to lipid metabolism. MNZ increased nuclear translocation of lipid metabolism-related transcription factor peroxisome proliferator-activated receptor gamma in hepatocytes, together with altered liver expression of lipid metabolism genes (Srebf1, Srebf2, Pnpla2). Furthermore, MNZ significantly increased the number of preneoplastic liver foci, accompanied by DNA double-strand breaks and late-stage autophagy inhibition, as reflected by increased levels of γ-H2AX, LC3, and p62. Therefore, MNZ could induce steatosis-related hepatocarcinogenesis by inducing DNA double-strand breaks and modulating autophagy in HFD-fed rats.

Stimulation of melanocortin-3 receptors accelerates the satiation process and increases the α-MSH expression in high-fat diet-fed rats.

The knowledge about the role of MC3 receptors (MC3r) in the regulation of feeding behavior is limited. The present study was conducted to determine whether MC3r mediates the hypophagic effects of the melanocortins under conditions of positive energy balance. Male Wistar rats were fed with a high-fat diet (HFD) for 15 days and on day 16 the animals received an intracerebroventricular injection of the following treatments: Vehicle, D-Trp8-γ-melanocyte-stimulating hormone (MSH; MC3r agonist), SHU9119 (MC3r/MC4r antagonist), or D-Trp8-γ-MSH+SHU9119. Food intake was measured and the behavioral satiety sequence (BSS) analysis was carried out during the first hour of the dark phase. The c-Fos and α-MSH immunoreactivity in the arcuate nucleus (ARC) was evaluated 60 min later the onset of food intake. The results indicated that D-Trp8-γ-MSH decreased the ingestion of the HFD and this effect is associated with the early development of the satiation process Moreover, the D-Trp8-γ-MSH increased the accumulation of the α-MSH in the ARC and the c-Fos activity in the PVN. The antagonist SHU9119 partially prevented the D-Trp8-γ-MSH-induced hypophagia. Moreover, behavioral analysis suggests that central activation of MC3r accelerated the cessation of feeding in conditions of positive energy balance; the possible role of MC4r is discussed. Present data indicate that central stimulation of MC3r prevented the overconsumption of the HFD without affecting the natural satiation process, suggesting a potential use of MC3r for the treatment of eating disorders that are stimulated by hypercaloric diets. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Slow but Steady-The Responsiveness of Sympathoadrenal System to a Hypoglycemic Challenge in Ketogenic Diet-Fed Rats.

The sympathoadrenal counterregulatory response to hypoglycemia is critical for individuals with type 1 diabetes due to impaired ability to produce glucagon. Ketogenic diets (KD) are an increasingly popular diabetes management tool; however, the effects of KD on the sympathoadrenal response are largely unknown. Here, we determined the effects of KD-induced ketosis on the sympathoadrenal response to a single insulin-induced hypoglycemic challenge. We investigated how a 3 week KD feeding regimen affected the main components of the sympathoadrenal counterregulatory response: adrenal sympathetic nerve activity (ASNA), adrenal gland activity, plasma epinephrine, and brainstem glucose-responsive C1 neuronal activation in anesthetized, nondiabetic male Sprague-Dawley rats. Rats on KD had similar blood glucose (BG) levels and elevated ketone body β-hydroxybutyrate (BHB) levels compared to the control Chow diet group. All KD rats responded to hypoglycemia with a robust increase in ASNA, which was initiated at significantly lower BG levels compared to Chow-fed rats. The delay in hypoglycemia-induced ASNA increase was concurrent with rapid disappearance of BHB from cerebral and peripheral circulation. Adrenal gland activity paralleled epinephrine and ASNA response. Overall, KD-induced ketosis was associated with initiation of the sympathoadrenal response at lower blood glucose levels; however, the magnitude of the response was not diminished.

D-Allose is absorbed via sodium-dependent glucose cotransporter 1 (SGLT1) in the rat small intestine

d-Allose is the C3 epimer of d-glucose and has been reported to have beneficial health effects. The transporter mediating intestinal transport of d-allose is unknown. We examined whether d-allose is absorbed via sodium-dependent glucose cotransporter 1 (SGLT1) as well as via glucose transporter type 5 (GLUT5) using rats. For examination of absorption via SGLT1, KGA-2727, an SGLT1-specific inhibitor, and d-allose were orally administered. KGA-2727 blocked the increase of plasma d-allose levels and suppressed them throughout the experiment (0–180 min), whereas without KGA-2727, the plasma d-allose levels peaked at around 60–90 min. For examination of absorption via GLUT5, rats were fed a high-fructose diet for 3weeks to increase the abundance and activity of GLUT5 in the small intestine. High-fructose diet-fed rats did not exhibit significant changes in the plasma d-allose levels compared to control rats fed a high-glucose diet. These results indicate that SGLT1 but not GLUT5 mediates the intestinal absorption of d-allose.