Β-oxidation Of Long-chain Fatty Acids Research Articles

Responses of lipid metabolism and lipidomics in the hepatopancreas of Pacific white shrimp Litopenaeus vannamei to microcystin-LR exposure

Microcystin-LR (MC-LR) is a toxic substance that threatens the health of aquatic animals. Hepatopancreas is the target organ of MC-LR toxicity. In this study, we investigated the effects of MC-LR on hepatopancreas lipid metabolism and lipidomic responses in Litopenaeus vannamei. After MC-LR exposure for 72 h, the hepatopancreas showed obvious tissue damage, and the activities of several lipase isoenzymes were decreased. Furthermore, the relative gene expression levels of lipolysis (CPT1, AMPKα), lipogenesis (SREBP, FAS, ACC, 6PGD), and long-chain fatty acid β-oxidation (ACDL, ACDVL, ACBP) were increased. MC-LR exposure also affected lipidomics homeostasis. Specifically, the levels of glycerophospholipids (phosphatidylcholine, phosphatidic acid, lyso-phosphatidylcholine, lyso-phosphatidylethanolamine, lyso-phosphatidylglycerol), sphingolipids (sphingomyelin and ceramides) and cholesteryl ester were increased, and those of phosphatidylinositol and triglyceride were decreased. The significantly altered lipid molecules were mainly associated with the pathways of lipid and fatty acid metabolism and autophagy. These results reveal that MC-LR exposure influences lipid metabolism and lipidomic homeostasis in the shrimp hepatopancreas.

Metabolomic profiling of plasma from middle-aged and advanced-age male mice reveals the metabolic abnormalities of carnitine biosynthesis in metallothionein gene knockout mice.

Metallothionein (MT) is a family of low molecular weight, cysteine-rich proteins that regulate zinc homeostasis and have potential protective effects against oxidative stress and toxic metals. MT1 and MT2 gene knockout (MTKO) mice show shorter lifespans than wild-type (WT) mice. In this study, we aimed to investigate how MT gene deficiency accelerates aging. We performed comparative metabolomic analyses of plasma between MTKO and WT male mice at middle age (50-week-old) and advanced age (100-week-old) using liquid chromatography with time-of-flight mass spectrometry (LC-TOF-MS). The concentration of N6,N6,N6-trimethyl-L-lysine (TML), which is a metabolic intermediate in carnitine biosynthesis, was consistently higher in the plasma of MTKO mice compared to that of WT mice at middle and advanced age. Quantitative reverse transcription PCR (RT-PCR) analysis revealed remarkably lower mRNA levels of Tmlhe, which encodes TML dioxygenase, in the liver and kidney of male MTKO mice compared to that of WT mice. L-carnitine is essential for β-oxidation of long-chain fatty acids in mitochondria, the activity of which is closely related to aging. Our results suggest that reduced carnitine biosynthesis capacity in MTKO mice compared to WT mice led to metabolic disorders of fatty acids in mitochondria in MTKO mice, which may have caused shortened lifespans.

Hepatic CPT1A Facilitates Liver-Adipose Cross-Talk via Induction of FGF21 in Mice.

Hepatosteatosis, defined as excessive intrahepatic lipid accumulation, represents the first step of NAFLD. When combined with additional cellular stress, this benign status progresses to local and systemic pathological conditions such as NASH and insulin resistance. However, the molecular events directly caused by hepatic lipid build-up, in terms of its impact on liver biology and peripheral organs, remain unclear. Carnitine palmitoyltransferase 1A (CPT1A) is the rate limiting enzyme for long chain fatty acid beta-oxidation in the liver. Here we utilise hepatocyte-specific Cpt1a knockout (LKO) mice to investigate the physiological consequences of abolishing hepatic long chain fatty acid metabolism. Compared to the wild-type (WT) littermates, high fat diet (HFD)-fed LKO mice displayed more severe hepatosteatosis but were otherwise protected against diet-induced weight gain, insulin resistance, hepatic ER stress, inflammation and damage. Interestingly, increased energy expenditure was observed in LKO mice, accompanied by enhanced adipose tissue browning. RNAseq analysis revealed that the peroxisome proliferator activator alpha (PPARα)- fibroblast growth factor 21 (FGF21) axis was activated in liver of LKO mice. Importantly, antibody-mediated neutralization of FGF21 abolished the healthier metabolic phenotype and adipose browning in LKO mice, indicating that the elevation of FGF21 contributes to the improved liver pathology and adipose browning in HFD-treated LKO mice. Liver with deficient CPT1A expression adopts a healthy steatotic status that protects against HFD-evoked liver damage and potentiates adipose browning in an FGF21-dependent manner. Inhibition of hepatic CPT1A may serve as a viable strategy for the treatment of obesity and NAFLD.

PHDs/CPT1B/VDAC1 axis regulates long-chain fatty acid oxidation in cardiomyocytes.

SUMMARYCardiac metabolism is a high-oxygen-consuming process, showing a preference for long-chain fatty acid (LCFA) as the fuel source under physiological conditions. However, a metabolic switch (favoring glucose instead of LCFA) is commonly reported in ischemic or late-stage failing hearts. The mechanism regulating this metabolic switch remains poorly understood. Here, we report that loss of PHD2/3, the cellular oxygen sensors, blocks LCFA mitochondria uptake and β-oxidation in cardiomyocytes. In high-fat-fed mice, PHD2/3 deficiency improves glucose metabolism but exacerbates the cardiac defects. Mechanistically, we find that PHD2/3 bind to CPT1B, a key enzyme of mitochondrial LCFA uptake, promoting CPT1B-P295 hydroxylation. Further, we show that CPT1B-P295 hydroxylation is indispensable for its interaction with VDAC1 and LCFA β-oxidation. Finally, we demonstrate that a CPT1B-P295A mutant constitutively binds to VDAC1 and rescues LCFA metabolism in PHD2/3-deficient cardiomyocytes. Together, our data identify an oxygen-sensitive regulatory axis involved in cardiac metabolism.

Пероксисомні біогенні порушення в спектрі синдрому Цельвегера: діагностика, моніторинг і лікування відповідно до рекомендацій глобальної фундації пероксисомних захворювань

Стаття присвячена сучасним принципам діагностики та лікування пероксисомних біогенних порушень у спектрі синдрому Цельвегера відповідно до рекомендацій глобальної фундації пероксисомних захворювань 2016 р. Автори представили клінічні особливості захворювань даного спектра. Ураження нервової, кісткової, сечовидільної, ендокринної, сенсорної систем і зубної емалі є характерною ознакою захворювання. Окремо виділено власне клінічне спостереження, пов’язане з порушенням окислення жирних кислот із дуже довгими ланцюгами в дитини раннього віку. Розділ діагностики захворювань спектра синдрому Цельвегера заснований на світових стандартах і включає маркери β-окислення дуже довголанцюжкових жирних кислот, а також α-окислення пристанової і фітанової кислот, метаболізму піпеколінової кислоти й інших пероксисомних дисфункцій. Остаточний діагноз пероксисомних біогенних порушень у спектрі синдрому Цельвегера на сучасному етапі встановлюється методом генетичного тестування, за допомогою методів секвенування нового покоління для генів PEX. Тяжкість неврологічних розладів і прогредієнтний перебіг захворювання, а також можливість лікування Х-зчепленої адренолейкодистрофії відкрили перспективи скринінгу для Х-зчепленої адренолейкодистрофії (X-ALD), заснованого на комбінації рідинної хроматографії і тандемної мас-спектрометрії (LC-MS/MS), для виявлення підвищених рівнів VLCFA у новонароджених у плямах крові. Клінічний моніторинг із моменту встановлення діагнозу включає корекцію стартових порушень і виявлення симптомів захворювання, що з’являються пізніше.

Controlled lipid β-oxidation and carnitine biosynthesis by a vitamin D metabolite

Lactone-vitamin D3 is a major metabolite of vitamin D3, a lipophilic vitamin biosynthesized in numerous life forms by sunlight exposure. Although lactone-vitamin D3 was discovered 40 years ago, its biological role remains largely unknown. Chemical biological analysis of its photoaffinity probe identified the hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit alpha (HADHA), a mitochondrial enzyme that catalyzes β-oxidation of long-chain fatty acids, as its selective binding protein. Intriguingly, the interaction of lactone-vitamin D3 with HADHA does not affect the HADHA enzymatic activity but instead limits biosynthesis of carnitine, an endogenous metabolite required for the transport of fatty acids into the mitochondria for β-oxidation. Lactone-vitamin D3 dissociates the protein-protein interaction of HADHA with trimethyllysine dioxygenase (TMLD), thereby impairing the TMLD enzyme activity essential in carnitine biosynthesis. These findings suggest a heretofore undescribed role of lactone-vitamin D3 in lipid β-oxidation and carnitine biosynthesis, and possibly in sunlight-dependent shifts of lipid metabolism in animals.

The role of electrical voltage application in enhancing anaerobic digestion of long chain fatty acids: Connection Matters!

Although electrical voltage (EV) application is widely used for direct interspecies electron transfer stimulation (DIET-S) in anaerobic digestion (AD), three relevant questions are yet to answer, i.e., i) can EV stimulate AD of recalcitrant/toxic wastes, e.g., long chain fatty acid (LCFA)?, ii) is it beneficial to combine EV with other DIET-S strategy?, and iii) after microbial community enrichment, if EV is disconnected, will the enhanced AD performance be affected?. For answering these questions, we operated four reactors: CR, EVR, MR, and (EV-M)R, referring to control, EV-applied, magnetite-supplemented, and “EV-applied with magnetite-supplemented” reactors, respectively, using oleate as substrate. Maximal treatable organic loading rate in CR and DIET-S reactors was 0.75, and 2.00 g COD/L/d. CH4 production yields from EVR, MR, and (EV-M)R were 0.19, 0.16, and 0.22 L CH4/g CODadded, respectively. DIET-S enriched DIET-implicated species, and thermodynamically enhanced LCFA β-oxidation. Genes involved in CH4 generation via CO2 reduction in EVR, MR, and (EV-M)R, were 2.4, 2.6, and 4.0 times higher than CR, respectively. Considering its CO2 reduction capability, Methanothrix sp. is claimed to establish DIET network with Syntrophomonas sp. in DIET-S reactors. For answering the third question, we further operated EVR and (EV-M)R. EV disconnection sharply lessened CH4 production, however, EV reconnection caused performance recovery, without significant change in microbial community structure. Relative abundances of pilA, ATPase, and hydrogenotrophic methanogenesis-related genes were increased by EV reconnection, and vice versa. This study provides engineering tool for enhancing LCFAs degradation, and scientific clues for the importance of continuous EV application, as DIET-S warranty.

Dietary restriction in the long-chain acyl-CoA dehydrogenase knockout mouse

Patients with a disorder of mitochondrial long-chain fatty acid β-oxidation (FAO) have reduced fasting tolerance and may present with hypoketotic hypoglycemia, hepatomegaly, (cardio)myopathy and rhabdomyolysis. Patients should avoid a catabolic state because it increases reliance on FAO as energy source. It is currently unclear whether weight loss through a reduction of caloric intake is safe in patients with a FAO disorder. We used the long-chain acyl-CoA dehydrogenase knockout (LCAD KO) mouse model to study the impact of dietary restriction (DR) on the plasma metabolite profile and cardiac function. For this, LCAD KO and wild type (WT) mice were subjected to DR (70% of ad libitum chow intake) for 4 weeks and compared to ad libitum chow fed mice. We found that DR had a relatively small impact on the plasma metabolite profile of WT and LCAD KO mice. Echocardiography revealed a small decrease in left ventricular systolic function of LCAD KO mice, which was most noticeable after DR, but there was no evidence of DR-induced cardiac remodeling. Our results suggest that weight loss through DR does not have acute and detrimental consequences in a mouse model for FAO disorders.

Exploring the metabolic fate of medium-chain triglycerides in healthy individuals using a stable isotope tracer

Medium chain triglyceride (MCT) supplementation is often recommended as treatment for patients with long-chain fatty acid β-oxidation (lcFAO) disorders, since they can be utilized as an energy source without the use of the defective enzyme. However, studies in mice and preterm infants suggest that not all medium-chain fatty acids (MCFA) are oxidized and may undergo elongation to long-chain fatty acids (LCFA). In this single blinded study, we explored the metabolic fates of MCT in healthy individuals using a 13C-labeled MCT tracer. Three healthy males in rest received on two test days a primed continuous infusion of glyceryl tri[1,2,3,4-13C4]-octanoate with either an isocaloric supplementation of 1) exclusively MCT (MCT-only) or 2) a mixture of MCT, proteins and carbohydrates (MCT-mix). Gas chromatography - combustion - isotope ratio mass spectrometry (GC-C-IRMS) was used to determine 13C-enrichment of long-chain fatty acids in plasma and of 13CO2 in exhaled air. When provided as single energy source, an estimated 42% of administered MCT was converted to CO2. In combination with carbohydrates and proteins in the diet, oxidation of MCT was higher (62%). In both diets <1% of 13C-label was incorporated in LCFA in plasma, indicating that administered MCT underwent chain-elongation to LCT. Although the relative MCT oxidation rate was higher when combined with carbohydrates and protein, quantitatively more MCT was oxidized when given an isocaloric meal with solely MCT. As these results were obtained in the resting state opposed to during exercise, it is too early to give a recommendation concerning the use of MCT in lcFAO disorders. The data show that in resting healthy individuals only a very small part of the MCT is traced back as LCFA in plasma, suggesting that MCT treatment does not result in a large LCFA burden, however further research on storage of MCT in tissues is warranted. The study was registered in the Nederlands Trialregister. Protocol ID: Trial NL7417 (NTR7650).

Subclinical effects of long-chain fatty acid β-oxidation deficiency on the adult heart: A case-control magnetic resonance study.

Cardiomyopathy can be a severe complication in patients with long‐chain fatty acid β‐oxidation disorders (LCFAOD), particularly during episodes of metabolic derangement. It is unknown whether latent cardiac abnormalities exist in adult patients. To investigate cardiac involvement in LCFAOD, we used proton magnetic resonance imaging (MRI) and spectroscopy (1H‐MRS) to quantify heart function, myocardial tissue characteristics, and myocardial lipid content in 14 adult patients (two with long‐chain 3‐hydroxyacyl‐CoA dehydrogenase deficiency (LCHADD); four with carnitine palmitoyltransferase II deficiency (CPT2D); and eight with very long‐chain acyl‐CoA dehydrogenase deficiency (VLCADD)) and 14 gender‐, age‐, and BMI‐matched control subjects. Examinations included cine MRI, MR tagging, native myocardial T1 and T2 mapping, and localized 1H‐MRS at 3 Tesla. Left ventricular (LV) myocardial mass (P = .011) and the LV myocardial mass‐to‐volume ratio (P = .008) were higher in patients, while ejection fraction (EF) was normal (P = .397). LV torsion was higher in patients (P = .026), whereas circumferential shortening was similar compared with controls (P = .875). LV hypertrophy was accompanied by high myocardial T1 values (indicative of diffuse fibrosis) in two patients, and additionally a low EF in one case. Myocardial lipid content was similar in patients and controls. We identified subclinical morphological and functional differences between the hearts of LCFAOD patients and matched control subjects using state‐of‐the‐art MR methods. Our results suggest a chronic cardiac disease phenotype and hypertrophic LV remodeling of the heart in LCFAOD, potentially triggered by a mild, but chronic, energy deficiency, rather than by lipotoxic effects of accumulating lipid metabolites.

Reprogramming of Lipid Metabolism as a New Driving Force Behind Tauroursodeoxycholic Acid-Induced Neural Stem Cell Proliferation.

Recent evidence suggests that neural stem cell (NSC) fate is highly dependent on mitochondrial bioenergetics. Tauroursodeoxycholic acid (TUDCA), an endogenous neuroprotective bile acid and a metabolic regulator, stimulates NSC proliferation and enhances adult NSC pool in vitro and in vivo. In this study, we dissected the mechanism triggered by this proliferation-inducing molecule, namely in mediating metabolic reprogramming. Liquid chromatography coupled with mass spectrometry (LC-MS) based detection of differential proteomics revealed that TUDCA reduces the mitochondrial levels of the long-chain acyl-CoA dehydrogenase (LCAD), an enzyme crucial for β-oxidation of long-chain fatty acids (FA). TUDCA impact on NSC mitochondrial proteome was further confirmed, including in neurogenic regions of adult rats. We show that LCAD raises throughout NSC differentiation, while its silencing promotes NSC proliferation. In contrast, nuclear levels of sterol regulatory element-binding protein (SREBP-1), a major transcription factor of lipid biosynthesis, changes in the opposite manner of LCAD, being upregulated by TUDCA. In addition, alterations in some metabolic intermediates, such as palmitic acid, also supported the TUDCA-induced de novo lipogenesis. More interestingly, a metabolic shift from FA to glucose catabolism appears to occur in TUDCA-treated NSCs, since mitochondrial levels of pyruvate dehydrogenase E1-α (PDHE1-α) were significant enhanced by TUDCA. At last, the mitochondria-nucleus translocation of PDHE1-α was potentiated by TUDCA, associated with an increase of H3-histones and acetylated forms. In conclusion, TUDCA-induced proliferation of NSCs involves metabolic plasticity and mitochondria-nucleus crosstalk, in which nuclear PDHE1-α might be required to assure pyruvate-derived acetyl-CoA for histone acetylation and NSC cycle progression.

Mitoregulin Controls β-Oxidation in Human and Mouse Adipocytes.

SummaryWe previously discovered in mouse adipocytes an lncRNA (the homolog of human LINC00116) regulating adipogenesis that contains a highly conserved coding region. Here, we show human protein expression of a peptide within LINC00116, and demonstrate that this peptide modulates triglyceride clearance in human adipocytes by regulating lipolysis and mitochondrial β-oxidation. This gene has previously been identified as mitoregulin (MTLN). We conclude that MTLN has a regulatory role in adipocyte metabolism as demonstrated by systemic lipid phenotypes in knockout mice. We also assert its adipocyte-autonomous phenotypes in both isolated murine adipocytes as well as human stem cell-derived adipocytes. MTLN directly interacts with the β subunit of the mitochondrial trifunctional protein, an enzyme critical in the β-oxidation of long-chain fatty acids. Our human and murine models contend that MTLN could be an avenue for further therapeutic research, albeit not without caveats, for example, by promoting white adipocyte triglyceride clearance in obese subjects.

Sex-specific perturbation of complex lipids in response to medium-chain fatty acids in very long-chain acyl-CoA dehydrogenase deficiency.

Very-long-chain acyl-CoA dehydrogenase deficiency (VLCAD) is the most common defect of long-chain fatty acid β-oxidation. The recommended treatment includes the application of medium-chain triacylglycerols (MCTs). However, long-term treatment of VLCAD-/- mice resulted in the development of a sex-specific metabolic syndrome due to the selective activation of the ERK/mTORc1 signalling in females and ERK/peroxisome proliferator-activated receptor gamma pathway in males. In order to investigate a subsequent sex-specific effect of MCT on the lipid composition of the cellular membranes, we performed lipidomic analysis, SILAC-based quantitative proteomics and gene expression in fibroblasts from WT and VLCAD-/- mice of both sexes. Treatment with octanoate (C8) affected the composition of complex lipids resulting in a sex-specific signature of the molecular profile. The content of ceramides and sphingomyelins in particular differed significantly under control conditions and increased markedly in cells from mutant female mice but remained unchanged in cells from mutant males. Moreover, we observed a specific upregulation of biosynthesis of plasmalogens only in male mice, whereas in females C8 led to the accumulation of higher concentration of phosphatidylcholines and lysophosphatidylcholines. Our data on membrane lipids in VLCAD after supplementation with C8 provide evidence of a sex-specific lipid perturbation. We hypothesize a likely C8-induced pro-inflammatory response contributing to the development of a severe metabolic syndrome in female VLCAD-/- mice on long-term MCT supplementation.

L-Carnitine counteracts in vitro fructose-induced hepatic steatosis through targeting oxidative stress markers

PurposeNonalcoholic fatty liver disease (NAFLD) is defined by excessive lipid accumulation in the liver and involves an ample spectrum of liver diseases, ranging from simple uncomplicated steatosis to cirrhosis and hepatocellular carcinoma. Accumulating evidence demonstrates that high fructose intake enhances NAFLD development and progression promoting inhibition of mitochondrial β-oxidation of long-chain fatty acids and oxidative damages. l-Carnitine (LC), involved in β-oxidation, has been used to reduce obesity caused by high-fat diet, which is beneficial to ameliorating fatty liver diseases. Moreover, in the recent years, various studies have established LC anti-oxidative proprieties. The objective of this study was to elucidate primarily the underlying anti-oxidative mechanisms of LC in an in vitro model of fructose-induced liver steatosis.MethodsHuman hepatoma HepG2 cells were maintained in medium supplemented with LC (5 mM LC) with or without 5 mM fructose (F) for 48 h and 72 h. In control cells, LC or F was not added to medium. Fat deposition, anti-oxidative, and mitochondrial homeostasis were investigated.ResultsLC supplementation decreased the intracellular lipid deposition enhancing AMPK activation. However, compound C (AMPK inhibitor-10 μM), significantly abolished LC benefits in F condition. Moreover, LC, increasing PGC1 α expression, ameliorates mitochondrial damage-F induced. Above all, LC reduced ROS production and simultaneously increased protein content of antioxidant factors, SOD2 and Nrf2.ConclusionOur data seemed to show that LC attenuate fructose-mediated lipid accumulation through AMPK activation. Moreover, LC counteracts mitochondrial damages and reactive oxygen species production restoring antioxidant cellular machine. These findings provide new insights into LC role as an AMPK activator and anti-oxidative molecule in NAFLD.

Role of membrane curvature on the activation/deactivation of Carnitine Palmitoyltransferase 1A: A coarse grain molecular dynamic study

Carnitine Palmitoyltransferase 1A (CPT 1A) is an enzyme anchored to the outer mitochondrial membrane (OMM), where it regulates the passage of fatty acids into the mitochondria and intervenes in the process of β-oxidation of long-chain fatty acids. Although CPT 1A is inhibited by malonyl-CoA, its activity is also modulated by the curvature of OMM. This modulation depends on the behavior of the N-terminal domain (NTD), which can be adsorbed onto the OMM (nonactive CPT 1A) or interacting with the C-terminal domain (active CPT 1A). Aimed to provide mechanistic insights on the regulatory mechanism of CPT 1A, we studied the influence of the bilayer curvature on the NTD behavior through a series of coarse-grained (CG) molecular dynamics simulations using curved and planar membranes. Comparative analysis suggests that the main determinant for the activation/deactivation of the enzyme is the tilt angle orientation of the transmembrane (TM) domains. Planar membranes induce a wide variation on the tilt angle orientation of TM helices, while curved geometries promote small angles with the membrane normal. Our results identify the first TM domain as an important component of the membrane sensing mechanism.

Metabolomics meets machine learning: Longitudinal metabolite profiling in serum of normal versus overconditioned cows and pathway analysis

This study aimed to investigate the differences in the metabolic profiles in serum of dairy cows that were normal or overconditioned when dried off for elucidating the pathophysiological reasons for the increased health disturbances commonly associated with overconditioning. Fifteen weeks antepartum, 38 multiparous Holstein cows were allocated to either a high body condition (HBCS; n = 19) group or a normal body condition (NBCS; n = 19) group and were fed different diets until dry-off to amplify the difference. The groups were also stratified for comparable milk yields (NBCS: 10,361 ± 302 kg; HBCS: 10,315 ± 437 kg; mean ± standard deviation). At dry-off, the cows in the NBCS group (parity: 2.42 ± 1.84; body weight: 665 ± 64 kg) had a body condition score (BCS) <3.5 and backfat thickness (BFT) <1.2 cm, whereas the HBCS cows (parity: 3.37 ± 1.67; body weight: 720 ± 57 kg) had BCS >3.75 and BFT >1.4 cm. During the dry period and the subsequent lactation, both groups were fed identical diets but maintained the BCS and BFT differences. A targeted metabolomics (AbsoluteIDQ p180 kit, Biocrates Life Sciences AG, Innsbruck, Austria) approach was performed in serum samples collected on d -49, +3, +21, and +84 relative to calving for identifying and quantifying up to 188 metabolites from 6 different compound classes (acylcarnitines, AA, biogenic amines, glycerophospholipids, sphingolipids, and hexoses). The concentrations of 170 metabolites were above the limit of detection and could thus be used in this study. We used various machine learning (ML) algorithms (e.g., sequential minimal optimization, random forest, alternating decision tree, and naïve Bayes-updatable) to analyze the metabolome data sets. The performance of each algorithm was evaluated by a leave-one-out cross-validation method. The accuracy of classification by the ML algorithms was lowest on d 3 compared with the other time points. Various ML methods (partial least squares discriminant analysis, random forest, information gain ranking) were then performed to identify those metabolites that were contributing most significantly to discriminating the groups. On d 21 after parturition, 12 metabolites (acetylcarnitine, hexadecanoyl-carnitine, hydroxyhexadecenoyl-carnitine, octadecanoyl-carnitine, octadecenoyl-carnitine, hydroxybutyryl-carnitine, glycine, leucine, phosphatidylcholine-diacyl-C40:3, trans-4-hydroxyproline, carnosine, and creatinine) were identified in this way. Pathway enrichment analysis showed that branched-chain AA degradation (before calving) and mitochondrial β-oxidation of long-chain fatty acids along with fatty acid metabolism, purine metabolism, and alanine metabolism (after calving) were significantly enriched in HBCS compared with NBCS cows. Our results deepen the insights into the phenotype related to overconditioning from the preceding lactation and the pathophysiological sequelae such as increased lipolysis and ketogenesis and decreased feed intake.

Addition of l-carnitine to formulated feed improved growth performance, antioxidant status and lipid metabolism of juvenile largemouth bass, Micropterus salmoides

l-carnitine is essential for fatty acids transportation from cytosol into the mitochondrial matrix, and promotes the β-oxidation of long-chain fatty acids to provide energy for fish. The aim of this study was to research the effect of dietary l-carnitine on the growth performance, antioxidant capacity and lipid metabolism in juvenile largemouth bass, Micropterus salmoides. Four formulated diets (Diet 1, Diet 2, Diet 3 and Diet 4) were supplemented with graded levels (0, 0.1, 0.2 and 0.3 g/kg) of l-carnitine. The results showed dietary supplementation of 0.1 g/kg l-carnitine significantly increased weight gain, while 0.3 g/kg l-carnitine supplementation decreased viscerasomatic index and intraperitoneal ratio of largemouth bass. The Plasma high density lipoprotein cholesterol (HDL-C) content of the fish which fed Diet 2 and Diet 4 were significantly higher than the fish fed Diet 1. Fish fed Diet 1 had significantly lower hepatic glutathione peroxidase (GSH-Px) activity and mRNA expression than fish fed Diet 2, Diet 3 and Diet 4. Contrary, fish fed Diet 1 had significantly higher hepatic fatty acid synthetase (FAS) activity and the mRNA expression than fish fed Diet 2, Diet 3 and Diet 4. Fish fed Diet 2, Diet 3 and Diet 4 had significantly increased the activity of hepatic carnitine palmitoyltransferase (CPT1), but no significant effect on the expression of hepatic CPT1 gene than fish fed Diet 1. In conclusion, these results confirmed that dietary supplemented of l-carnitine was beneficial for promoting growth in largemouth bass and could improve the antioxidant capacity. Furthermore, l-carnitine could play an important role in fatty acids metabolism.

Analysis of Direct Effects of the CB1 Receptor Antagonist Rimonabant on Fatty Acid Oxidation and Glycogenolysis in Liver and Muscle Cells in vitro.

Recent pharmacological findings regarding rimonabant, an anorectic and cannabinoid type 1 receptor (CB1R) antagonist, strongly suggest that some of its effects on the metabolic parameters and energy balance in rats are not related to the centrally mediated reduction in caloric intake. Instead, they may be associated with acute induction of glycogenolysis in the liver, in combination with transient increase in glucose oxidation and persistent increase in fat oxidation. It is possible that rimonabant produced direct short- or long-term stimulatory effect on these processes in primary and cultured rat cells. Rimonabant slightly stimulated β-oxidation of long-chain fatty acids in cultured rat myocytes overexpressing glucose transporter isoform 4, as well as activated phosphorylation of adenosine monophosphate-dependent protein kinase (AMPK) in primary rat hepatocytes upon long-term incubation. However, short-term action of rimonabant failed to stimulate β-oxidation in myocytes, myotubes, and hepatocytes, as well as to upregulate AMPK phosphorylation, glycogenolysis, and cAMP levels in hepatocytes. As a consequence, the acute effects of rimonabant on hepatic glycogen content (reduction) and total energy expenditure (increase) in rats fed with a standard diet cannot be explained by direct stimulation of glycogenolysis and fatty acid oxidation in muscles and liver. Rather, these effects seem to be centrally mediated.

Role of SNPs of CPTIA and CROT genes in the carnitine-shuttle in coronary artery disease: a case-control study

Abstract Objective Fatty acid β-oxidation defects can lead to difficulties at covering energy requirement of heart. The carnitine-shuttle is responsible for the transfering of long-chain fatty acids from the internal mitochondrial membrane. The role of genetic variants of the enzymes in the carnitine shuttle in coronary artery disease (CAD) has not been studied. Therefore, we performed a case-control study investigating the possible relation between the CPTIA-rs3019613 and CROT-rs2214930 gene variations located carnitine shuttle and CAD risk. Materials and methods Study groups were comprised of 96 CAD patients and 85 controls. CPTIA-rs3019613 G &gt; A and CROT-rs2214930 T &gt; C polymorphisms were determined by real-time-PCR. Results The CROT-rs2214930-CC genotype was found to be associated with decreased HDL-cholesterol (HDL-C) in controls (p = 0.029). In patients with CPTIA-rs3019613-A allele, body mass index (BMI) (p = 0.016) and BMI threshold-value (p = 0.030) were found be higher compared to those with GG-genotype, while HDL-C threshold-value (HDL-C ≤ 0.90 mmol/L) was found to be lower (p = 0.015). Regression analysis confirmed CPTIA-rs3019613-A allele has a significant relationship with decreased HDL-C (p = 0.009) in patients. Conclusion Our study indicated that the polymorphisms of the CROT and CPTIA genes related to β-oxidation of long-chain fatty acids had an important effect on serum HDL-C levels and may be a potential risk for CAD.

The combined effects of graphene oxide and bisphenol A on oxidative damage in early development of zebrafish

Bisphenol A (BPA) is widely present in natural surface water, and was found to be at the high level of μg/L in the surface water around a BPA manufacturing plant. Mass production and application make BPA ubiquitous in the environment, biota and humans. As a two-dimensional carbon based nanomaterial, graphene oxide (GO) is used in many fields, and there is a great potential for GO to discharge to aquatic environment via various pathways. Thus GO has the potential to interact with organic pollutants, such as BPA, copresent in water system. GO could adsorb organic pollutants in water, and adhere on the surface of organisms, displaying different effects on the behaviors and toxicities of organic pollutants in organisms at different developmental stages. But the intrinsic mechanisms for the different effects remain unclear. To fill this gap, zebrafish ( Danio rerio ) was selected as a vertebrate model to investigate the toxicities of a variety of pollutants and nanomaterials in this study. Embryogenesis is an important growth phase in the zebrafish life cycle. Pollutants can induce excessive reactive oxygen species (ROS) and generate a large number of oxidative intermediate products by destroying the balance between oxidation and antioxidation, thus causing oxidative damage. Superoxide dismutase (SOD) can catalyze the oxidation of superoxide anion (O2−) to O2 and H2O, in an attempt to maintain ROS at a physiological level and protect the body from damage. Catalase (CAT) exists primarily within peroxisomes and removes the H2O2 generated by the long-chain fatty acid β-oxidation pathway. Excessive ROS can attack the polyunsaturated fatty acids in the biomembrane system, resulting in lipid peroxidation. Malondialdehyde (MDA) is the product of irreversible lipid peroxidation, and the change of MDA can reflect the level and damage degree of lipid peroxidation in organisms. Glutathione (GSH), as an important non-enzymatic antioxidant in organism, can be induced and effectively scavenged by external stimulation to regulate oxidative stress. Toxic effects occur in organisms when GSH is gradually reduced. This study focused on the joint effects of GO and BPA on the oxidative responses in zebrafish at early development stage. Zebrafish embryos were individually exposed to BPA (0, 50, 500 µg/L), GO (0, 0.1, 1 mg/L), BPA+GO (50 µg/L+ 0.1 mg/L, 500 µg/L+ 0.1 mg/L, and 50 µg/L +1 mg/L, 500 µg/L +1 mg/L) solutions for 7 d. The levels of SOD, MDA, GSH, CAT, and ROS in the exposed zebrafish larvae were determined. The results indicated that BPA displayed strong oxidative damage effects on zebrafish larvae. However, the presence of GO distinctly alleviated the various indicators of oxidative damages caused by BPA. Based on analyses using the Bliss independence model, GO and BPA exhibited antagonistic effects on the oxidative damage of zebrafish in the early development stage, which indicated that GO could reduce the oxidative damage toxicities of BPA on zebrafish embryos under the experimental conditions. These could be due to the formation of a GO layer on the zebrafish embryos, which depressed the absorption of BPA by zebrafish, leading to reduced BPA accumulation in zebrafish in early developmental stage.