Metabolism In Rat Liver Research Articles

Eucommia Leaf Extract Induces BDNF Production in Rat Hypothalamus and Enhances Lipid Metabolism and Aerobic Glycolysis in Rat Liver.

Mutations in the brain-derived neurotrophic factor (BDNF) gene and its receptor, tyrosine receptor kinase B (TrkB), have been reported to cause severe obesity in rodents. Our previous study demonstrated that the oral administration of 5% Eucommia leaf extract (ELE) or ELE aroma treatment (ELE aroma) produced anti-obesity effects. In this study, we investigated the effects of ELE on glycolysis and lipid metabolism in male Sprague-Dawley rats, as well as the effects of ELE on BDNF in rat hypothalamus. A significant reduction and a reduction tendency in the respiratory quotient were observed in association with 5% ELE and ELE aroma treatment, respectively. Furthermore, RT-qPCR results showed significant increases in Cpt2, Acad, Complex II, and Complex V mRNA levels in the liver with both treatments. In addition, in rat hypothalamus, significant elevations in BDNF, Akt, PLCγ proteins and CREB phosphorylation were observed in the 5% ELE group and the ELE aroma group. Furthermore, the Ras protein was significantly increased in the ELE aroma group. On the other hand, significant dephosphorylation of ERK1/2 was observed by the western blotting in the 5% ELE group and the ELE aroma group. These findings suggest that the ELE treatment enhances the lipid metabolism and increases the aerobic glycolytic pathway, while ELE-induced BDNF may affect such energy regulation. Therefore, ELE has the possibility to control metabolic syndrome.

Different training intensities induced autophagy and histopathology appearances potentially associated with lipid metabolism in wistar rat liver

IntroductionAerobic training has a beneficial effect on enhancing liver functions. Autophagy might potentially play a role in preventing excessive lipid accumulation, regulating oxidative stress, and inflammation in the liver. ObjectiveTo investigate the potential linking role of autophagy-related gene expressions and protein levels with histopathology changes in Wistar rat livers after treadmill training under different intensities. Methods20 rats were divided into 4 groups (control, low intensity, moderate intensity, and high intensity). 8 weeks of treadmill training was conducted with a frequency of 5 days per week, for a duration of 30 min per day. Liver histopathology was studied using hematoxylin-eosin, and oil red O staining. RNA and protein from the liver tissues were extracted to examine the autophagy-related gene (LC3, p62) and protein levels (Beclin, ATG5, LC3, p62). The gene expressions of CPT1a, CD36, FATP 2,3,5, GLUT2, and FGF21 were also studied. ResultsDifferent intensities of training might potentially modulate autophagy-related gene expressions in rat livers. LC3 and p62 mRNA expressions in moderate and high intensities decreased compared to control. Beclin, ATG5, and LC3 protein level increased compared to control, while p62 protein level decreased compared to control. Whereas for the other genes, we found an increase in CPT1a, but we did not observed any changes in the expression of the other genes. Interestingly, autophagy-related gene expressions might be correlated with the changes of sinusoidal dilatation, cloudy swelling, inflammation, and lipid droplets of the liver tissues. ConclusionModerate and high intensities of training induce autophagy activity, combined with a shift in metabolic zonation in liver that might be potentially correlated with lipophagy. Our results showed the potential interplay role between autophagy and liver histopathology appearances as a part of the adaptation process to training.

Indexes of citrulline metabolism in rat liver under the toxic injury against the background of alimentary protein deficiency

Indexes of citrulline metabolism in rat liver under the toxic injury against the background of alimentary protein deficiency

Widespread Dysregulation of Long Noncoding Genes Associated With Fatty Acid Metabolism, Cell Division, and Immune Response Gene Networks in Xenobiotic-exposed Rat Liver.

Xenobiotic exposure dysregulates hundreds of protein-coding genes in mammalian liver, impacting many physiological processes and inducing diverse toxicological responses. Little is known about xenobiotic effects on long noncoding RNAs (lncRNAs), many of which have important regulatory functions. Here, we present a computational framework to discover liver-expressed, xenobiotic-responsive lncRNAs (xeno-lncs) with strong functional, gene regulatory potential and elucidate the impact of xenobiotic exposure on their gene regulatory networks. We assembled the long noncoding transcriptome of xenobiotic-exposed rat liver using RNA-seq datasets from male rats treated with 27 individual chemicals, representing 7 mechanisms of action (MOAs). Ortholog analysis was combined with coexpression data and causal inference methods to infer lncRNA function and deduce gene regulatory networks, including causal effects of lncRNAs on protein-coding gene expression and biological pathways. We discovered > 1400 liver-expressed xeno-lncs, many with human and/or mouse orthologs. Xenobiotics representing different MOAs often regulated common xeno-lnc targets: 123 xeno-lncs were dysregulated by ≥ 10 chemicals, and 5 xeno-lncs responded to ≥ 20 of the 27 chemicals investigated; 81 other xeno-lncs served as MOA-selective markers of xenobiotic exposure. Xeno-lnc-protein-coding gene coexpression regulatory network analysis identified xeno-lncs closely associated with exposure-induced perturbations of hepatic fatty acid metabolism, cell division, or immune response pathways, and with apoptosis or cirrhosis. We also identified hub and bottleneck lncRNAs, which are expected to be key regulators of gene expression. This work elucidates extensive networks of xeno-lnc-protein-coding gene interactions and provides a framework for understanding the widespread transcriptome-altering actions of foreign chemicals in a key-responsive mammalian tissue.

Deciphering the particle specific effects on metabolism in rat liver and plasma from ZnO nanoparticles versus ionic Zn exposure

Toxicity of ZnO nanoparticles (NPs) are often related to the release of Zn2+ ions due to their dissolution. Studies also suggest that the toxicity of ZnO NPs cannot be solely explained by the release of Zn2+ ions; however, there is a lack of direct evidence of ZnO particulate effects. This study compared the acute toxicity of ZnO NPs and ZnSO4 following intranasal exposure using a combination of metallomics and metabolomics approaches. Significant accumulation of Zn in the liver was only found in the ZnO NP treatment, with 29% of the newly accumulated Zn in the form of ZnO as revealed by X-ray fine structure spectroscopy (XAFS). This is the first direct evidence suggesting the persistence of ZnO NPs in liver upon intranasal exposure. Although both ZnO NPs and ZnSO4 altered the metabolite profiles, with some overlaps and considerable specificity, of both liver and plasma samples, more and distinct metabolites in the liver and opposite effects in the plasma were altered by ZnO NPs compared with ZnSO4, consistent with no accumulation of Zn detected in liver from ZnSO4. Specifically, a large number of antioxidant-related compounds and energetic substrates were exclusively elevated in the liver of ZnO NP-treated animals. These findings provided direct evidence that persistence of ZnO NPs induced particle-specific effects on the antioxidant systems and energy metabolism pathways.

Evaluation of antioxidant and hepatoprotective property of ethanolic extract of curculigoorchioides in albino rats

Background: Liver, the largest organ invertebrate body, it the major site of intense metabolic activities. Being the largest chemical factory of the body, the liver performs innumerable functions. The functional units of liver are called either hepatic or classic lobules or acini. The hepatic lobules consist largely of parenchymal or epithelial glandular cells called hepatocytes, which are arranged as interconnected plates or laminae.Methods: All the animal experiments were conducted according to the ethical norms approved by Ministry of Social Justices and Empowerment, Government of India, and Institutional Animal Ethical Committee guidelines. Fifteen rats were selected for this study and randomly divided into three groups of five each. Group I include control rats that received isocarolic quantity of sucrose in the same volume as experimental rats that received ethanol. Group II includes ethanol treated rats. Ethanol was administered daily at regular intervals by gastric intubation at a dose of as 20% aqueous solution 1 ml for 60 days. Group III includes ethanol (1ml of 25%) + Curculigoorchioides rhizome (80mg/kg b.wt) treated rats for 60 days, daily at regular intervals by gastric intubation.Results: The effect of ethanol alone and ethanol+curculigoorchioides rhizome extract (combined) on adult male rat liver metabolism were assessed in the present study and compared with the control rate. The mean body weight of ethanol treated rats was lesser than control and ethanol+curculigoorchioides rhizome extract treated rats. (Table 1, Figure 1) Data on liver weight from control, ethanol alone and ethanol+curculigoorchioides extract (combined) treated rats did not show much variation (Table 1, Figure 2).Conclusions: The effect of curculigo orchioides rizhomes extract+ethanol (combined) on adult male rat liver metabolism was assessed in the present study and compared with control and ethanol alone treated rats. The administration of ethanol accelerates the glycogenolysis and drastically reduced the hepatic glycogen content. The hepatic transaminase activity was swayed by ethanol treatment and reverted to normalcy by combined treatment. Elevated levels of serum enzyme are indicative of cellular leakage and loss of functional integrity of cell membrane in liver. The reversal of altered transaminase activities to normal by plant extract supplementation suggest its hepatoprotective action.

Short-chain chlorinated paraffins (SCCPs) disrupt hepatic fatty acid metabolism in liver of male rat via interacting with peroxisome proliferator-activated receptor α (PPARα)

Short-chain chlorinated paraffins (SCCPs) are frequently detected in environmental matrices and human tissues. It was hypothesized that SCCPs might interact with the peroxisome proliferator-activated receptor α (PPARα). In the present study, an in vitro, dual-luciferase reporter gene assay and in silico molecular docking analysis were employed together to study the interactions between SCCPs congeners and PPARα. Expressions of genes downstream in pathways activated by PPARα in liver of rats exposed to 1, 10, or 100 mg/kg bm/d of C10−13-CPs (56.5% Cl) for 28 days were examined to confirm activation potencies of SCCPs toward PPARα signaling. Effects of exposure to C10−13-CPs (56.5% Cl) on fatty acid metabolism in rat liver were also explored via a pseudo-targeted metabolomics strategy. Our results showed that C10−13-CPs (56.5% Cl) caused a dose-dependent greater expression of luciferase activity of rat PPARα. Molecular docking modeling revealed that SCCPs had a strong capacity to bind with PPARα only through hydrophobic interactions and the binding affinity was dependent on the degree of chlorination in SCCPs congeners. In livers of male rats, exposure to 100 mg/kg bm/d of C10−13-CPs (56.5% Cl) resulted in up-regulated expressions of 11 genes that are downstream in the PPARα-activated pathway and regulate catabolism of fatty acid. Consistently, accelerated fatty acid oxidation was observed mainly characterized by lesser concentrations of ∑fatty acids in livers of rats. Overall, these results demonstrated, for the first time, that SCCPs could activate rat PPARα signaling and thereby disrupt metabolism of fatty acid in livers of male rats.

Network Modeling of Liver Metabolism to Predict Plasma Metabolite Changes During Short-Term Fasting in the Laboratory Rat.

The liver—a central metabolic organ that integrates whole-body metabolism to maintain glucose and fatty-acid regulation, and detoxify ammonia—is susceptible to injuries induced by drugs and toxic substances. Although plasma metabolite profiles are increasingly investigated for their potential to detect liver injury earlier than current clinical markers, their utility may be compromised because such profiles are affected by the nutritional state and the physiological state of the animal, and by contributions from extrahepatic sources. To tease apart the contributions of liver and non-liver sources to alterations in plasma metabolite profiles, here we sought to computationally isolate the plasma metabolite changes originating in the liver during short-term fasting. We used a constraint-based metabolic modeling approach to integrate central carbon fluxes measured in our study, and physiological flux boundary conditions gathered from the literature, into a genome-scale model of rat liver metabolism. We then measured plasma metabolite profiles in rats fasted for 5–7 or 10–13 h to test our model predictions. Our computational model accounted for two-thirds of the observed directions of change (an increase or decrease) in plasma metabolites, indicating their origin in the liver. Specifically, our work suggests that changes in plasma lipid metabolites, which are reliably predicted by our liver metabolism model, are key features of short-term fasting. Our approach provides a mechanistic model for identifying plasma metabolite changes originating in the liver.

<b>Analytical methods for evaluation of the fatty acid metabolism in rat liver

The liver is an essential organ for body energy homeostasis, controlling the biosynthesis, uptake and the disposal of carbohydrates and lipids. The hepatic steatosis is a common condition frequently associated with metabolic diseases and is characterized by the excessive accumulation of triglycerides in the liver. In recent years, many efforts have been devoted to prevent and treat the hepatic steatosis, but it remains being pointed out as the major cause for chronic hepatic diseases in Western countries. A considerable part of the knowledge about the physiopathology of hepatic steatosis, the effects of diets and drugs on the metabolic capacity of the liver to metabolize fatty acids, as well as the potential therapeutic approaches for hepatic steatosis derived from experimental animal models using rodents. Here, in this article, we present the details of some of the most common techniques used to evaluate fatty acid metabolism in liver of rats, including quantification of total lipid content, measurement of fatty acid oxidation in isolated subcellular fractions and procedures to measure the activities of important lipogenic enzymes. Classical protocols previously described to be performed using samples from other tissues were adapted to liver samples and different techniques with equivalent aims were compared. The principles and the advantages in terms of reliability and costs were discussed and the procedures here described can be applied for a low-cost broad evaluation of the fatty acid metabolism in liver of rats submitted to different experimental conditions.

Exogenous putrescine affects polyamine and arginine metabolism in rat liver following bile ductus ligation.

Rat bile duct ligation (BDL) represents a useful method that mimics obstructive extrahepatic cholestasis, which is known to be a frequent disorder in humans. Polyamines (putrescine, spermidine, and spermine) are one of the key molecules regulating cell proliferation and differentiation. This work aimed to evaluate the potential beneficial properties of putrescine in rat BDL model by studying several biochemical parameters reflecting liver function and polyamine metabolism. Rats that were subjected to BDL were injected with putrescine (150 mg/kg) for 9 days, while in parallel another group with BDL remained untreated. Two control groups were included as well, sham-opened and putrescine-treated group. The following plasma parameters: ALT, AST, γ-GT, ALP, bilirubin, bile acids, as well as liver malondialdehyde and polyamine concentration and the activity of enzymes involved in polyamine metabolism were studied. After BDL, significant alterations in plasma biochemical parameters occurred, where a 9-day putrescine treatment significantly alleviated liver function deterioration. Putrescine also increased liver polyamines' concentrations and polyamine and diamine oxidase activities in rats submitted to BDL. Our results demonstrated, for the first time, that putrescine plays an important role in preserving liver tissue function in rats with experimentally induced cholestasis.

Metabolic network-based predictions of toxicant-induced metabolite changes in the laboratory rat

In order to provide timely treatment for organ damage initiated by therapeutic drugs or exposure to environmental toxicants, we first need to identify markers that provide an early diagnosis of potential adverse effects before permanent damage occurs. Specifically, the liver, as a primary organ prone to toxicants-induced injuries, lacks diagnostic markers that are specific and sensitive to the early onset of injury. Here, to identify plasma metabolites as markers of early toxicant-induced injury, we used a constraint-based modeling approach with a genome-scale network reconstruction of rat liver metabolism to incorporate perturbations of gene expression induced by acetaminophen, a known hepatotoxicant. A comparison of the model results against the global metabolic profiling data revealed that our approach satisfactorily predicted altered plasma metabolite levels as early as 5 h after exposure to 2 g/kg of acetaminophen, and that 10 h after treatment the predictions significantly improved when we integrated measured central carbon fluxes. Our approach is solely driven by gene expression and physiological boundary conditions, and does not rely on any toxicant-specific model component. As such, it provides a mechanistic model that serves as a first step in identifying a list of putative plasma metabolites that could change due to toxicant-induced perturbations.

Early Effects of a Low Fat, Fructose-Rich Diet on Liver Metabolism, Insulin Signaling, and Oxidative Stress in Young and Adult Rats.

The increase in the use of refined food, which is rich in fructose, is of particular concern in children and adolescents, since the total caloric intake and the prevalence of metabolic syndrome are increasing continuously in these populations. Nevertheless, the effects of high fructose diet have been mostly investigated in adults, by focusing on the effect of a long-term fructose intake. Notably, some reports evidenced that even short-term fructose intake exerts detrimental effects on metabolism. Therefore, the aim of this study was to compare the metabolic changes induced by the fructose-rich diet in rats of different age, i.e., young (30 days old) and adult (90 days old) rats. The fructose-rich diet increased whole body lipid content in adult, but not in young rats. The analysis of liver markers of inflammation suggests that different mechanisms depending on the age might be activated after the fructose-rich diet. In fact, a pro-inflammatory gene-expression analysis showed just a minor activation of macrophages in young rats compared to adult rats, while other markers of low-grade metabolic inflammation (TNF-alpha, myeloperoxidase, lipocalin, haptoglobin) significantly increased. Inflammation was associated with oxidative damage to hepatic lipids in young and adult rats, while increased levels of hepatic nitrotyrosine and ceramides were detected only in young rats. Interestingly, fructose-induced hepatic insulin resistance was evident in young but not in adult rats, while whole body insulin sensitivity decreased both in fructose-fed young and adult rats. Taken together, the present data indicate that young rats do not increase their body lipids but are exposed to metabolic perturbations, such as hepatic insulin resistance and hepatic oxidative stress, in line with the finding that increased fructose intake may be an important predictor of metabolic risk in young people, independently of weight status. These results indicate the need of corrective nutritional interventions for young people and adults as well for the prevention of fructose-induced metabolic alterations.

Effect of high chronic intake of sucrose on liver metabolism in aging rats. Modulation by rutin and micronutrients.

High-sugar intake and senescence share common deleterious effects, in particular in liver, but combination of these two factors was little studied. Our aims were to examine the effect of a high-sucrose diet in liver of old rats and also the potential benefices of a polyphenol/micronutrient supplementation. Four groups of 22-month-old male rats fed during 5months with a diet containing either 13 or 62% sucrose, supplemented or not with rutin, vitamin E, A, D, selenium, and zinc were compared. We measured liver macronutrient composition, glycation/oxidative stress, enzyme activities (lipogenesis, β-oxidation, fructokinase), gene expression (enzymes and transcription factors), in vivo protein synthesis rates and plasma parameters. Sucrose induced an increase in plasma and liver lipid content, and a stimulation of liver protein synthesis rates. Gene expression was little changed by sucrose, with lower levels for LXR-α and LXR-β. Polyphenol/micronutrient supplementation tended to limit liver triglyceride infiltration through variations in fatty acid synthase, acyl coA oxidase, and possibly ATP-citrate lyase activities. In conclusion, despite differences in enzymatic regulations, and blunted responses of gene expression, high-sucrose diet was still able to induce a marked increase in liver lipid content in old animals. However, it probably attenuated the positive impact of polyphenol/micronutrients.

Short-chain chlorinated paraffins (SCCPs) induced thyroid disruption by enhancement of hepatic thyroid hormone influx and degradation in male Sprague Dawley rats

Short-chain chlorinated paraffins (SCCPs) are known to disturb thyroid hormone (TH) homeostasis in rodents. However, the mechanism remains to be fully characterized. In this study, male Sprague Dawley rats received SCCPs (0, 1, 10, or 100mg/kg/day) via gavage once a day for consecutive 28days. Plasma and hepatic TH concentrations, thyrocyte structure, as well as thyroid and hepatic mRNA and protein levels of genes associated with TH homeostasis were examined. Moreover, we performed molecular docking to predict interactions between constitutive androstane receptor (CAR), a key regulator in xenobiotic-induced TH metabolism, with different SCCP molecules. Exposure to SCCPs significantly decreased the circulating free thyroxine (T4) and triiodothyronine (T3) levels, but increased thyroid-stimulating hormone (TSH) levels by a feedback mechanism. Decreased hepatic T4 and increased hepatic T3 levels were also seen after 100mg/kg/day SCCPs exposure. SCCPs didn't show any significant effects on the expression of thyroid TH synthesis genes or thyrocyte structure. However, stimulation effects were observed for mRNA and protein levels of hepatic uridine diphosphoglucuronosyl transferase (UGT) 1A1 and organic anion transporter 2, suggesting an accelerated TH metabolism in rat liver. The increased cytochrome P450 2B1 but not 1A1 mRNA and protein levels indicated that the CAR signaling was activated by SCCPs exposure. According to docking analysis, SCCPs form hydrophobic interactions with CAR and the binding affinity shows dependency on chlorine content. Overall, our data showed that CAR implicated enhancement of hepatic TH influx and degradation could be the main cause for SCCPs induced TH deficiency in male rats.

In vivo effects of hemin and nitric oxide donors on parameters of heme metabolism in rat liver and serum

In vivo effects of hemin chloride (15 mg/kg body weight) and donors of nitrogen monoxide (NO) – sodium nitroprusside (SNP, 1 mg/kg) and substrate of NO-synthase L-arginine (L-Arg, 600 mg/kg) on the activity of key enzymes of heme synthesis (5-aminolevulinate synthase, ALAS) and heme degradation (heme oxygenase, HO), on the free heme level in liver and on the content of heme in blood serum of rats were studied. NO donors were administered alone or 30 min before hemin chloride injection. The level of free heme in liver was estimated by the ratio of holoenzyme and total tryptophan 2,3-dioxygenase (TDO) activities. Two hours after hemin chloride administration a significant increase in the level of heme-containing products and lipid peroxidation products (TBARS) was found in blood serum. These changes were accompanied by decrease in ALAS activity and by increase in holoenzyme activity and heme saturation of TDO, which was the result of free heme accumulation in liver. 24 hrs after administration of hemin chloride the content of heme in serum returned to normal level, while level of TBARS remained elevated. 24 hrs after hemin action a significant increase in the activities of HO and ALAS was observed in liver, while the degree of TDO heme saturation decreased, indicating the prevalence of heme degradation over its synthesis. Both NO donors did not affect the accumulation of heme in serum and liver first hours after hemin action. However, the specific features of SNP and L-Arg effects on the key enzyme of heme synthesis in liver and the TBARS level in serum were revealed. L-Arg, unlike SNP, prevented the accumulation of TBARS in serum, but did not prevent a decrease in ALAS activity 2 hrs after hemin chloride injection. The treatment by SNP itself caused an increase in TBARS level in serum, an increase in TDO activity and a decrease in ALAS activity in liver 2 hrs after action. Heme content in serum positively correlated with holoenzyme activity and heme saturation of TDO in liver. The pretreatment with NO donors did not affect the increase in HO activity, however, it blocked the induction of ALAS, a decrease in holoenzyme activity and heme saturation of TDO 24 hrs after the administration of hemin chloride. Thus, both SNP and Arg prevented a decrease in free heme level in liver, which might be due to heme nitrosylation in the presence of NO donors and, as a result, its slower degradation in the heme oxygenase reaction.

MUCOSA-ADHESIVE GELS WITH QUERCETIN – EFFECTIVE MEDICINAL FORM FOR CORRECTION OF METABOLIC DISTURBANCES

Introduction Mucosa­adhesive gels are applied to mucous membranes. Advantages: 1) presence of the active substance on the mucosal surface is prolonged; 2) it is possible to increase the concentration of active ingredient and implement local therapeutic effect with reduced probability of side effects; 3) the consumption of pharmaceuticals is reduced. Purpose To study the effectiveness of oral injection of quercetin­containing gels on the parameters of the functional state of the liver and fat metabolism in rats against the background of the experimental metabolic syndrome. Methods. Studies were carried out on male Wistar rats, with metabolic syndrome simulated by means of addition to mixed fodder of 15% unrefied sunflwer oil, lincomycin (60 mg/kg) in drinking water for the first 5 days of intraperitoneal administration of cyclophosphane (25 mg/kg) a day later. Every day, 0.5 ml of mucosal gels with quercetin and inulin, with quercetin and imidone or with quercetin and hyaluronic acid were applied onto the mucous membrane of the mouth. Duration constituted 35 days. The content of triglycerides was determined in the liver homogenates, in the serum – the activity of alanine aminotransaminase and alkaline phosphatase, the content of triglycerides, total cholesterol and bilirubin. Results Modeling of metabolic syndrome in rats caused an increase in triglycerides, cholesterol, and “liver” markers. Prophylaxis by daily application of mucosal quercetin­containing gels, with some advantage of “Quertulin” (quercetin + inulin), had a expressed therapeutic and prophylactic effect, preventing metabolic disturbances. Conclusion Local (oral) application of quercetin­containing gels can effectively prevent disorders of fat metabolism and liver function. It is proposed to introduce a dosage form “mucosa­adhesive gels” with the introduction of various drugs into medical practice for prevention and treatment of the most common diseases

Effect of methapyrilene hydrochloride on hepatic intracellular iron metabolism in vivo and in vitro

The liver, a central detoxification organ and main regulator of systemic iron homeostasis, is prone to damage by xenobiotics. In the present study, we investigated the effect of the hepatotoxicant and hepatocarcinogen methapyrilene hydrochloride on iron metabolism in rat liver in a repeat-dose in vivo toxicity study and in human HepaRG cells in vitro. Treatment of male Fischer 344 (F344) rats with methapyrilene at doses 40 and 80mg/kg body weight (bw)/day by gavage for 6 weeks resulted in changes in the expression of classic hepatotoxicity-related marker genes and iron homeostasis-related genes, especially a prominent, dose-dependent down-regulation of the transferrin (Tf) gene and an up-regulation of the ferritin, light chain (Ftl) gene. A decrease in the level of TF and an increase in the level of FTL also occurred in methapyrilene-treated differentiated HepaRG cells, indicating the existence of interspecies and in vitro-in vivo similarities in the disturbance of cellular iron homeostasis upon liver injury. In contrast, there was minimal overlap in the expression of liver toxicity-marker genes in the livers of rats and in HepaRG cells treated with methapyrilene. Importantly, the decrease of transferrin at mRNA and protein levels occurred after the treatment with a low dose of methapyrilene that exhibited minimal cytotoxicity. These results demonstrate the significance of the dysregulation of hepatic iron metabolism in the pathogenesis and mechanism of chemical-induced liver toxicity and suggest that these changes may be sensitive and useful indicators of potentially hepatotoxic chemicals.

Multi-omic network-based interrogation of rat liver metabolism following gastric bypass surgery featuring SWATH proteomics.

Morbidly obese patients often elect for Roux-en-Y gastric bypass (RYGB), a form of bariatric surgery that triggers a remarkable 30% reduction in excess body weight and reversal of insulin resistance for those who are type II diabetic. A more complete understanding of the underlying molecular mechanisms that drive the complex metabolic reprogramming post-RYGB could lead to innovative non-invasive therapeutics that mimic the beneficial effects of the surgery, namely weight loss, achievement of glycemic control, or reversal of non-alcoholic steatohepatitis (NASH). To facilitate these discoveries, we hereby demonstrate the first multi-omic interrogation of a rodent RYGB model to reveal tissue-specific pathway modules implicated in the control of body weight regulation and energy homeostasis. In this study, we focus on and evaluate liver metabolism three months following RYGB in rats using both SWATH proteomics, a burgeoning label free approach using high resolution mass spectrometry to quantify protein levels in biological samples, as well as MRM metabolomics. The SWATH analysis enabled the quantification of 1378 proteins in liver tissue extracts, of which we report the significant down-regulation of Thrsp and Acot13 in RYGB as putative targets of lipid metabolism for weight loss. Furthermore, we develop a computational graph-based metabolic network module detection algorithm for the discovery of non-canonical pathways, or sub-networks, enriched with significantly elevated or depleted metabolites and proteins in RYGB-treated rat livers. The analysis revealed a network connection between the depleted protein Baat and the depleted metabolite taurine, corroborating the clinical observation that taurine-conjugated bile acid levels are perturbed post-RYGB.

Inter-relations between 3-hydroxypropionate and propionate metabolism in rat liver: relevance to disorders of propionyl-CoA metabolism.

Propionate, 3-hydroxypropionate (3HP), methylcitrate, related compounds, and ammonium accumulate in body fluids of patients with disorders of propionyl-CoA metabolism, such as propionic acidemia. Although liver transplantation alleviates hyperammonemia, high concentrations of propionate, 3HP, and methylcitrate persist in body fluids. We hypothesized that conserved metabolic perturbations occurring in transplanted patients result from the simultaneous presence of propionate and 3HP in body fluids. We investigated the inter-relations of propionate and 3HP metabolism in perfused livers from normal rats using metabolomic and stable isotopic technologies. In the presence of propionate, 3HP, or both, we observed the following metabolic perturbations. First, the citric acid cycle (CAC) is overloaded but does not provide sufficient reducing equivalents to the respiratory chain to maintain the homeostasis of adenine nucleotides. Second, there is major CoA trapping in the propionyl-CoA pathway and a tripling of liver total CoA within 1 h. Third, liver proteolysis is stimulated. Fourth, propionate inhibits the conversion of 3HP to acetyl-CoA and its oxidation in the CAC. Fifth, some propionate and some 3HP are converted to nephrotoxic maleate by different processes. Our data have implications for the clinical management of propionic acidemia. They also emphasize the perturbations of the liver intermediary metabolism induced by supraphysiological, i.e., millimolar, concentrations of labeled propionate used to trace the intermediary metabolism, in particular, inhibition of CAC flux and major decreases in the [ATP]/[ADP] and [ATP]/[AMP] ratios.

Effects of hydrophilic compounds in purple rice husk on AFB1-induced mutagenesis

Rice husk has been shown to possess cancer chemopreventive activity. This study focused on mutagenicity and antimutagenicity of the crude acidified methanolic extract of purple rice husk and its solvent- partitioned fractions using a Salmonella mutation assay and rat liver micronucleus test. The purple rice husk extracts were not mutagenic in S. typhimurium strain TA98, but were mutagenic in TA100 (crude extract and its hydrophilic fractions). There was no significant mutagenicity of purple rice husk extracts in rat liver. The rice husks possessed antimutagenicity against AFB1-induced mutagenesis in both bacterial and animal models. The dichloromethane-partitioned fraction (DPF) showed the highest antimutagenicity. Vanillic acid, a major phenolic compound found in DPF, exhibited antimutagenicity against AFB1 in both bacterial and rat models. The inhibitory mechanism was associated with the induction of detoxifying enzymes in AFB1 metabolism of rat liver. These findings suggested that vanillic acid may be a principal antimutagenic compound in purple rice husk.