Fatty acid metabolism, energy expenditure and insulin resistance in muscle

Can caloric restriction improve outcomes of elective surgeries?

Energy restriction (ER) is a nutrition method to reduce the amount of energy intake while maintaining adequate nutrition. In clinical medicine, applications of ER have been implicated in longevity, mortality, metabolic, immune, and psychological health. However, there are limited studies showing the clinical benefit of ER within the immediate surgical setting. A specific, clinically oriented summary of the potential applications of ER is needed to optimize surgery outcomes for patients. The purpose of this article is to examine how ER can be used for perioperative optimization to improve outcomes for the patient and surgeon. It will also explore how these outcomes can feasibly fit in with enhanced recovery after surgery protocols and can be used as a method for nutrition optimization in surgery. Despite evidence of caloric restriction improving outcomes in critically ill surgical patients, there is not enough evidence to conclude that ER, perioperatively across noncritically ill cohorts, improves postoperative morbidity and mortality in elective surgeries. Nevertheless, a contemporary account of how ER techniques may have a significant role in reducing risk factors of adverse surgical outcomes in this cohort, for example, by encouraging preoperative weight loss contributing to decreased operating times, is reviewed.

Postprandial glucose metabolism in children and adolescents with type 1 diabetes mellitus: potential targets for improvement

The main goal of therapeutic management of type 1 Diabetes Mellitus (T1DM) is to maintain optimal glycemic control to prevent acute and long-term diabetes complications and to enable a good quality of life. Postprandial glycemia makes a substantial contribution to overall glycemic control and variability in diabetes and, despite technological advancements in insulin treatments, optimal postprandial glycemia is difficult to achieve. Several factors influence postprandial blood glucose levels in children and adolescents with T1DM, including nutritional habits and adjustment of insulin doses according to meal composition. Additionally, hormone secretion, enteroendocrine axis dysfunction, altered gastrointestinal digestion and absorption, and physical activity play important roles. Meal-time routines, intake of appropriate ratios of macronutrients, and correct adjustment of the insulin dose for the meal composition have positive impacts on postprandial glycemic variability and long-term cardiometabolic health of the individual with T1DM. Further knowledge in the field is necessary for management of all these factors to be part of routine pediatric diabetes education and clinical practice. Thus, the aim of this report is to review the main factors that influence postprandial blood glucose levels and metabolism, focusing on macronutrients and other nutritional and lifestyle factors, to suggest potential targets for improving postprandial glycemia in the management of children and adolescents with T1DM.

Echinacoside stimulates myogenesis and ATP-dependent thermogenesis in the skeletal muscle via the activation of D1-like dopaminergic receptors

Recent studies have shown that some natural compounds from plants prevent obesity and related disorders, including the loss of skeletal muscle mass and strength. In this study, we investigated the effect of echinacoside (ECH), a caffeic acid glycoside from the phenylpropanoid class, on myogenesis and ATP-dependent thermogenesis in the skeletal muscle and its interaction with the dopaminergic receptors 1 and 5 (DRD1 and DRD5). We applied RT-PCR, immunoblot analysis, a staining method, and an assay kit to determine the effects of ECH on diverse target genes and proteins involved in skeletal muscle myogenesis and ATP-consuming futile processes. Our study demonstrated that ECH enhanced myogenic differentiation, glucose, and fatty acid uptake, as well as lipid catabolism, and induced ATP-dependent thermogenesis in vitro and in vivo. Moreover, ECH upregulated mitochondrial biogenesis proteins, mitochondrial oxidative phosphorylation (OXPHOS) complexes, and intracellular Ca2+ signaling as well as thermogenic proteins. These findings were further elucidated by mechanistic studies which showed that ECH mediates myogenesis via the DRD1/5 in C2C12 muscle cells. In addition, ECH stimulates α1-AR-mediated ATP-dependent thermogenesis via the DRD1/5/cAMP/SLN/SERCA1a pathway in C2C12 muscle cells. To the best of our knowledge, this is the first report that demonstrates the myogenic and thermogenic potential of ECH activity through the dopaminergic receptors. Understanding the novel functions of ECH in terms of its ability to prevent skeletal muscle loss and energy expenditure via ATP-consuming futile processes could help to develop potential alternative strategies to address muscle-related diseases, including combating obesity.

Individual bioenergetic capacity as a potential source of resilience to Alzheimer's disease

Impaired glucose uptake in the brain is one of the earliest presymptomatic manifestations of Alzheimer's disease (AD). The absence of symptoms for extended periods of time suggests that compensatory metabolic mechanisms can provide resilience. Here, we introduce the concept of a systemic 'bioenergetic capacity' as the innate ability to maintain energy homeostasis under pathological conditions, potentially serving as such a compensatory mechanism. We argue that fasting blood acylcarnitine profiles provide an approximate peripheral measure for this capacity that mirrors bioenergetic dysregulation in the brain. Using unsupervised subgroup identification, we show that fasting serum acylcarnitine profiles of participants from the AD Neuroimaging Initiative yields bioenergetically distinct subgroups with significant differences in AD biomarker profiles and cognitive function. To assess the potential clinical relevance of this finding, we examined factors that may offer diagnostic and therapeutic opportunities. First, we identified a genotype affecting the bioenergetic capacity which was linked to succinylcarnitine metabolism and significantly modulated the rate of future cognitive decline. Second, a potentially modifiable influence of beta-oxidation efficiency seemed to decelerate bioenergetic aging and disease progression. Our findings, which are supported by data from more than 9,000 individuals, suggest that interventions tailored to enhance energetic health and to slow bioenergetic aging could mitigate the risk of symptomatic AD, especially in individuals with specific mitochondrial genotypes.

Maternal and newborn metabolomic changes associated with urinary polycyclic aromatic hydrocarbon metabolite concentrations at delivery: an untargeted approach

INTRODUCTION

Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with adverse human health outcomes. To explore the plausible associations between maternal PAH exposure and maternal/newborn metabolomic outcomes, we conducted a cross-sectional study among 75 pregnant people from Cincinnati, Ohio.

METHOD

We quantified 8 monohydroxylated PAH metabolites in maternal urine samples collected at delivery. We then used an untargeted high-resolution mass spectrometry approach to examine alterations in the maternal (n = 72) and newborn (n = 63) serum metabolome associated with PAH metabolites. Associations between individual maternal urinary PAH metabolites and maternal/newborn metabolome were assessed using linear regression adjusted for maternal and newborn factors while accounting for multiple testing with the Benjamini-Hochberg method. We then conducted functional analysis to identify potential biological pathways.

RESULTS

Our results from the metabolome-wide associations (MWAS) indicated that an average of 1% newborn metabolome features and 2% maternal metabolome features were associated with maternal urinary PAH metabolites. Individual PAH metabolite concentrations in maternal urine were associated with maternal/newborn metabolome related to metabolism of vitamins, amino acids, fatty acids, lipids, carbohydrates, nucleotides, energy, xenobiotics, glycan, and organic compounds.

CONCLUSION

In this cross-sectional study, we identified associations between urinary PAH concentrations during late pregnancy and metabolic features associated with several metabolic pathways among pregnant women and newborns. Further studies are needed to explore the mediating role of the metabolome in the relationship between PAHs and adverse pregnancy outcomes.

Hemp seed (Cannabis sativa L.) cake as sustainable dietary additive in slow-growing broilers: effects on performance, meat quality, oxidative stability and gut health

Hemp seed cake (HSC) (Cannabis sativa L.) is a rich source of polyunsaturated fatty acids, high-quality proteins and essential amino acids. The aim of this study was to evaluate the effects of dietary inclusion of HSC on growth performance, meat quality traits, fatty acids profile and oxidative status, and intestinal morphology in slow-growing broilers. A total of 180 male slow-growing broilers were randomly assigned to one of three dietary treatments containing different levels of HSC: 0 (HSC0), 5 (HSC5) or 10% (HSC10). Birds were slaughtered at 49 days of age: breast and thigh muscles were analysed and duodenum mucosa histomorphological features were evaluated. Regardless the level of HSC inclusion, no differences among groups were found for performance and meat quality traits. The thigh and breast fatty acid profile were significantly improved in both HSC groups, with an increase of the long chain fatty acids of n-3 series and decrease of n-6/n-3 ratio. The HSC diets lowered the MDA concentration and lipid hydroperoxides in breast meat. Histomorphometrical analysis revealed a significant increase in villus height, surface area and villus/crypt ratio, with a decrease of crypt depth, suggesting that dietary supplementation with HSC may boost intestinal health status in poultry. In conclusion, dietary HSC did not affect performance, carcass traits and meat quality, while it positively influenced the lipid profile of meat, and improved the oxidative status and gut health, thus representing a valuable and sustainable alternative ingredient in broiler diet.

A Narrative Review of Non-Pharmacological Strategies for Managing Sarcopenia in Older Adults with Cardiovascular and Metabolic Diseases

This narrative review examines the mechanisms underlying the development of cardiovascular disease (CVD) and metabolic diseases (MDs), along with their association with sarcopenia. Furthermore, non-pharmacological interventions to address sarcopenia in patients with these conditions are suggested. The significance of combined training in managing metabolic disease and secondary sarcopenia in type II diabetes mellitus is emphasized. Additionally, the potential benefits of resistance and aerobic training are explored. This review emphasises the role of nutrition in addressing sarcopenia in patients with CVD or MDs, focusing on strategies such as optimising protein intake, promoting plant-based protein sources, incorporating antioxidant-rich foods and omega-3 fatty acids and ensuring sufficient vitamin D levels. Moreover, the potential benefits of targeting gut microbiota through probiotics and prebiotic fibres in sarcopenic individuals are considered. Multidisciplinary approaches that integrate behavioural science are explored to enhance the uptake and sustainability of behaviour-based sarcopenia interventions. Future research should prioritise high-quality randomized controlled trials to refine exercise and nutritional interventions and investigate the incorporation of behavioural science into routine practices. Ultimately, a comprehensive and multifaceted approach is essential to improve health outcomes, well-being and quality of life in older adults with sarcopenia and coexisting cardiovascular and metabolic diseases.

Uncovering the Nutritive Profiles of Adult Male Chinese Mitten Crab (E. sinensis) Harvested from the Pond and Natural Water Area of Qin Lake Based on Metabolomics

E. sinensis, normally harvested in October and November, is an economic aquatic product in China. Pond culture has been widely applied for the production of E. sinensis, wherein a stable food supply for crabs is provided. In order to improve the nutritional quality of E. sinensis products, this study evaluated the effect of the local pond culture on the nutritive profiles of E. sinensis and screened out the best harvest time for the nutrient-rich crabs, thereby guiding the local crab industry to improve its aquaculture mode and harvest strategy. The results indicated that pond culture enhanced the levels of protein, amino acids, and specific organic acid derivatives, and reduced the levels of peptides and polyunsaturated fatty acids (PUFAs). Compared with E. sinensis harvested in October, peptide levels were significantly increased, whereas sugar, phenolic acid, and nucleotide levels were decreased in those harvested in November. Overall, the study revealed that the nutritive profile of the pond-reared E. sinensis was significantly modulated by a high-protein diet, thus lacking the diversity of metabolites. Additionally, October could be more appropriate for harvesting E. sinensis than November.

Effects of a Ganoderma lucidum Proteoglycan on Type 2 Diabetic Rats and the Recovery of Rat Pancreatic Islets

Type 2 diabetes (T2D) results from both insulin resistance and pancreatic β-cell dysfunction. A natural proteoglycan extracted from Ganoderma lucidum, namely, FYGL, has been demonstrated to be capable of ameliorating insulin resistance in previous work. In this work, a T2D rat model induced by streptozocin (STZ) and a high-fat diet was used to investigate the effects of FYGL on pancreatic functions, and the transcriptomics of the rat pancreas was used to investigate the biological processes (BP) and signal pathways influenced by FYGL on the gene basis. Furthermore, the results of transcriptomics were verified both by histopathological analyses and protein expression. The studies showed that FYGL positively regulated T2D-related BP and signaling pathways and recovered the pancreatic function, therefore ameliorating hyperglycemia and hyperlipidemia in vivo. Importantly, the recovery of the pancreatic function suggested a crucial strategy to radically treat T2D.

Tcf7l2 in hepatocytes regulates de novo lipogenesis in diet-induced non-alcoholic fatty liver disease in mice

AIMS/HYPOTHESIS

Non-alcoholic fatty liver disease (NAFLD) associated with type 2 diabetes may more easily progress towards severe forms of non-alcoholic steatohepatitis (NASH) and cirrhosis. Although the Wnt effector transcription factor 7-like 2 (TCF7L2) is closely associated with type 2 diabetes risk, the role of TCF7L2 in NAFLD development remains unclear. Here, we investigated how changes in TCF7L2 expression in the liver affects hepatic lipid metabolism based on the major risk factors of NAFLD development.

METHODS

Tcf7l2 was selectively ablated in the liver of C57BL/6N mice by inducing the albumin (Alb) promoter to recombine Tcf7l2 alleles floxed at exon 5 (liver-specific Tcf7l2-knockout [KO] mice: Alb-Cre;Tcf7l2f/f). Alb-Cre;Tcf7l2f/f and their wild-type (Tcf7l2f/f) littermates were fed a high-fat diet (HFD) or a high-carbohydrate diet (HCD) for 22 weeks to reproduce NAFLD/NASH. Mice were refed a standard chow diet or an HCD to stimulate de novo lipogenesis (DNL) or fed an HFD to provide exogenous fatty acids. We analysed glucose and insulin sensitivity, metabolic respiration, mRNA expression profiles, hepatic triglyceride (TG), hepatic DNL, selected hepatic metabolites, selected plasma metabolites and liver histology.

RESULTS

Alb-Cre;Tcf7l2f/f essentially exhibited increased lipogenic genes, but there were no changes in hepatic lipid content in mice fed a normal chow diet. However, following 22 weeks of diet-induced NAFLD/NASH conditions, liver steatosis was exacerbated owing to preferential metabolism of carbohydrate over fat. Indeed, hepatic Tcf7l2 deficiency enhanced liver lipid content in a manner that was dependent on the duration and amount of exposure to carbohydrates, owing to cell-autonomous increases in hepatic DNL. Mechanistically, TCF7L2 regulated the transcriptional activity of Mlxipl (also known as ChREBP) by modulating O-GlcNAcylation and protein content of carbohydrate response element binding protein (ChREBP), and targeted Srebf1 (also called SREBP1) via miRNA (miR)-33-5p in hepatocytes. Eventually, restoring TCF7L2 expression at the physiological level in the liver of Alb-Cre;Tcf7l2f/f mice alleviated liver steatosis without altering body composition under both acute and chronic HCD conditions.

CONCLUSIONS/INTERPRETATION

In mice, loss of hepatic Tcf7l2 contributes to liver steatosis by inducing preferential metabolism of carbohydrates via DNL activation. Therefore, TCF7L2 could be a promising regulator of the NAFLD associated with high-carbohydrate diets and diabetes since TCF7L2 deficiency may lead to development of NAFLD by promoting utilisation of excess glucose pools through activating DNL.

DATA AVAILABILITY

RNA-sequencing data have been deposited into the NCBI GEO under the accession number GSE162449 ( www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE162449 ).

Consumption of Common Bean Suppresses the Obesogenic Increase in Adipose Depot Mass: Impact of Dose and Biological Sex

Obesity prevention is stated as a simple objective in the public health guidelines of most countries: avoid adult weight gain. However, the success of the global population in accomplishing this goal is limited as reflected in the persisting pandemic of overweight and obesity. While many intervention strategies have been proposed, most are directed at mitigating the consequences of obesity. Efforts intended to prevent unintentional weight gain and associated adiposity are termed anti-obesogenic. Herein, evidence is presented that a neglected category of foods, pulses, i.e., grain legumes, have anti-obesogenic activity. Using a preclinical mouse model of obesity, a dose-response study design in animals of both biological sexes, and cooked, freeze-dried, and milled common bean as a representative pulse, data are presented showing that the rate of body weight gain is slowed, and fat accumulation is suppressed when 70% of the dietary protein is provided from common bean. These anti-obesogenic effects are reduced at lower amounts of common bean (17.5% or 35%). The anti-obesogenic responsiveness is greater in female than in male mice. RNA sequence analysis indicates that the sex-related differences extend to gene expression patterns, particularly those related to immune regulation within adipose tissue. In addition, our findings indicate the potential value of a precision nutrition approach for human intervention studies that identify "pulse anti-obesogenic responders". A precision approach may reduce the concentration of pulses required in the diet for benefits, but candidate biomarkers of responsivity to pulse consumption remain to be determined.

Insulin receptor substrate-1 gene polymorphism and lipid panel data in type 2 diabetic patients with comorbid obesity and/or essential hypertension

Objective. The hallmarks of type 2 diabetes mellitus (T2DM) are insulin resistance (IR) and insulin receptor substrate (IRS) proteins essential for the insulin signaling. IRS-1 gene has not only been shown to be associated with T2DM, but also has indicated that it may significantly correlate with diabetic complications, such as coronary heart disease and obesity. The aim of this study was to evaluate changes of the lipid panel data in T2DM patients with comorbid obesity and/or essential hypertension in connection with the IRS-1 (rs2943640) polymorphism. Methods. The study involved 33 T2DM patients and 10 healthy individuals. The IRS-1 (rs2943640) polymorphism was genotyped using a TaqMan real-time polymerase chain reaction method. Blood serum lipid panel data were determined with commercially available kits using a Cobas 6000 analyzer. Results. Analysis of the serum lipid panel data depending on the presence of the C/A alleles of IRS-1 (rs2943640) polymorphism in T2DM patients, regardless of the presence/absence of comorbidities, showed significantly lower level of high-density lipoprotein cholesterol (HDL-C) and significantly higher level of non-HDL-C in the carriers of C allele vs. carriers of A allele. In T2DM patients with comorbid obesity and essential hypertension, proatherogenic lipid changes were found in both C and A alleles carriers. Analysis of the effect of IRS-1 (rs2943640) genotypes on serum lipid panel data in T2DM patients, regardless of the presence/absence of comorbidities, showed that the CC genotype carriers had more pronounced pro-atherogenic changes vs. carriers of СА and АА genotypes. In the comorbid course of T2DM (both in combination with obesity and obesity and essential hypertension), pro-atherogenic changes were found in the carriers of the CA genotype of IRS-1 (rs2943640) polymorphism. Conclusions. The presence of the C allele of IRS-1 (rs2943640) polymorphism in both homo-zygous and heterozygous states indicates increased risk of pro-atherogenic changes in T2DM patients with comorbid obesity and/or essential hypertension.

Glycemic control and its influencing factors in type 2 diabetes patients in Anhui, China

Objective

To investigate the status of glycemic control and analyze its influencing factors in patients with type 2 diabetes (T2D) in Anhui, China.

Methods

1,715 T2D patients aged 18-75 years old were selected from 4 counties or districts in Anhui Province in 2018, using a convenience sampling method. All patients have undergone a questionnaire survey, physical examination, and a glycosylated hemoglobin (HbA1c) test. According to the 2022 American Diabetes Association criteria, HbA1c was used to evaluate the glycemic control status of patients, and HbA1c < 7.0% was defined as good glycemic control. The influencing factors of glycemic control were analyzed by multivariate unconditional logistic regression.

Results

The prevalence of good glycemic control among people with T2D in the Anhui Province was low (22.97%). On univariate analysis, gender, education level, occupation, region, smoking, drinking, waist circumference and disease duration (all P < 0.05) were significantly associated with glycemic control. The factors associated with pool glycemic control were female gender [OR = 0.67, 95%CI (0.52, 0.86), P = 0.001], higher level of education [OR = 0.47, 95%CI (0.27, 0.83), P = 0.001], living in rural areas [OR = 1.77, 95%CI (1.39, 2.26), P < 0.001], central obesity [OR = 1.58, 95%CI (1.19, 2.09), P = 0.001] and longer duration of disease [OR = 2.66, 95%CI (1.91, 3.69), P < 0.001].

Conclusions

The prevalence of good glycemic control in people with T2D in Anhui Province was relatively low, and gender, region, education level, central obesity and course of the disease were influencing factors. The publicity and education on the importance of glycemic control should be further strengthened in T2D patients, and targeted intervention measures should be carried out for risk groups.

Dietary Risk Factors and Eating Behaviors in Peripheral Arterial Disease (PAD)

Dietary risk factors play a fundamental role in the prevention and progression of atherosclerosis and PAD (Peripheral Arterial Disease). The impact of nutrition, however, defined as the process of taking in food and using it for growth, metabolism and repair, remains undefined with regard to PAD. This article describes the interplay between nutrition and the development/progression of PAD. We reviewed 688 articles, including key articles, narrative and systematic reviews, meta-analyses and clinical studies. We analyzed the interaction between nutrition and PAD predictors, and subsequently created four descriptive tables to summarize the relationship between PAD, dietary risk factors and outcomes. We comprehensively reviewed the role of well-studied diets (Mediterranean, vegetarian/vegan, low-carbohydrate ketogenic and intermittent fasting diet) and prevalent eating behaviors (emotional and binge eating, night eating and sleeping disorders, anorexia, bulimia, skipping meals, home cooking and fast/ultra-processed food consumption) on the traditional risk factors of PAD. Moreover, we analyzed the interplay between PAD and nutritional status, nutrients, dietary patterns and eating habits. Dietary patterns and eating disorders affect the development and progression of PAD, as well as its disabling complications including major adverse cardiovascular events (MACE) and major adverse limb events (MALE). Nutrition and dietary risk factor modification are important targets to reduce the risk of PAD as well as the subsequent development of MACE and MALE.

Liver-specific overexpression of lipoprotein lipase improves glucose metabolism in high-fat diet-fed mice

The liver is the main organ that regulates lipid and glucose metabolism. Ectopic lipid accumulation in the liver impairs insulin sensitivity and glucose metabolism. Lipoprotein lipase (LPL), mainly expressed in the adipose tissue and muscle, is a key enzyme that regulates lipid metabolism via the hydrolysis of triglyceride in chylomicrons and very-low-density lipoproteins. Here, we aimed to investigate whether the suppression level of hepatic lipid accumulation via overexpression of LPL in mouse liver leads to improved metabolism. To overexpress LPL in the liver, we generated an LPL-expressing adenovirus (Ad) vector using an improved Ad vector that exhibited considerably lower hepatotoxicity (Ad-LPL). C57BL/6 mice were treated with Ad vectors and simultaneously fed a high-fat diet (HFD). Lipid droplet formation in the liver decreased in Ad-LPL-treated mice relative to that in control Ad vector-treated mice. Glucose tolerance and insulin resistance were remarkably improved in Ad-LPL-treated mice compared to those in control Ad vector-treated mice. The expression levels of fatty acid oxidation-related genes, such as peroxisome proliferator-activated receptor α, carnitine palmitoyltransferase 1, and acyl-CoA oxidase 1, were 1.7–2.0-fold higher in Ad-LPL-treated mouse livers than that in control Ad-vector-treated mouse livers. Furthermore, hepatic LPL overexpression partly maintained mitochondrial content in HFD-fed mice. These results indicate that LPL overexpression in the livers of HFD-fed mice attenuates the accumulation of lipid droplets in the liver and improves glucose metabolism. These findings may enable the development of new drugs to treat metabolic syndromes such as type 2 diabetes mellitus and non-alcoholic fatty liver disease.

A critical role of AMP-activated protein kinase in regulating intestinal nutrient absorption, barrier function, and intestinal diseases

As one of the most important organs in animals, the intestine is responsible for nutrient absorption and acts as a barrier between the body and the environment. Intestinal physiology and function require the participation of energy. 5'-adenosine monophosphate-activated protein kinase (AMPK), a classical and highly expressed energy regulator in intestinal cells, regulates the process of nutrient absorption and barrier function and is also involved in the therapy of intestinal diseases. Studies have yielded findings that AMPK regulates the absorption of glucose, amino acids, and fatty acids in the intestine primarily by regulating transportation systems, as we detailed here. Moreover, AMPK is involved in the regulation of the intestinal mechanical barrier and immune barrier through manipulating the expression of tight junctions, antimicrobial peptides, and secretory immunoglobulins. In addition, AMPK also participates in the regulation of intestinal diseases, which indicates that AMPK is a promising therapeutic target for intestinal diseases and cancer. In this review, we summarized the current understanding regarding how AMPK regulates intestinal nutrient absorption, barrier function, and intestinal diseases.

Metabolomics of Arterial Stiffness

Arterial stiffness (AS) is one of the earliest detectable signs of structural and functional alterations of the vessel wall and an independent predictor of cardiovascular events and death. The emerging field of metabolomics can be utilized to detect a wide spectrum of intermediates and products of metabolism in body fluids that can be involved in the pathogenesis of AS. Research over the past decade has reinforced this idea by linking AS to circulating acylcarnitines, glycerophospholipids, sphingolipids, and amino acids, among other metabolite species. Some of these metabolites influence AS through traditional cardiovascular risk factors (e.g., high blood pressure, high blood cholesterol, diabetes, smoking), while others seem to act independently through both known and unknown pathophysiological mechanisms. We propose the term 'arteriometabolomics' to indicate the research that applies metabolomics methods to study AS. The 'arteriometabolomics' approach has the potential to allow more personalized cardiovascular risk stratification, disease monitoring, and treatment selection. One of its major goals is to uncover the causal metabolic pathways of AS. Such pathways could represent valuable treatment targets in vascular ageing.

UCHL1 Regulates Lipid and Perilipin 2 Level in Skeletal Muscle

Ubiquitin C-terminal hydrolase L1 (UCHL1) is a deubiquitinating enzyme that was originally found in neurons. We found that UCHL1 is highly expressed in slow oxidative skeletal muscles, but its functions remain to be fully understood. In this study, we observed that UCHL1 protein levels in skeletal muscle and C2C12 myotubes were downregulated by fasting or glucose starvation respectively. Skeletal muscle selective knockout (smKO) of UCHL1 resulted in a significant reduction of lipid content in skeletal muscle and improved glucose tolerance. UCHL1 smKO did not significantly change the levels of key proteins involved in oxidative metabolism such as SDHA, Akt, or PDH. Interestingly, while the levels of the major lipases and lipid transporters were unchanged, perilipin 2 was significantly downregulated in UCHL1 smKO muscle. Consistently, in C2C12 myotubes, UCHL1 siRNA knockdown also reduced perilipin 2 protein level. This data suggests that UCHL1 may stabilize perilipin 2 and thus lipid storage in skeletal muscle.

Serum metabolite profiling yields insights into health promoting effect of A. muciniphila in human volunteers with a metabolic syndrome

Reduction of A. muciniphila relative abundance in the gut microbiota is a widely accepted signature associated with obesity-related metabolic disorders. Using untargeted metabolomics profiling of fasting plasma, our study aimed at identifying metabolic signatures associated with beneficial properties of alive and pasteurized A. muciniphila when administrated to a cohort of insulin-resistant individuals with metabolic syndrome. Our data highlighted either shared or specific alterations in the metabolome according to the form of A. muciniphila administered with respect to a control group. Common responses encompassed modulation of amino acid metabolism, characterized by reduced levels of arginine and alanine, alongside several intermediates of tyrosine, phenylalanine, tryptophan, and glutathione metabolism. The global increase in levels of acylcarnitines together with specific modulation of acetoacetate also suggested induction of ketogenesis through enhanced β-oxidation. Moreover, our data pinpointed some metabolites of interest considering their emergence as substantial compounds pertaining to health and diseases in the more recent literature.

Histone Deacetylases as Modulators of the Crosstalk Between Skeletal Muscle and Other Organs

Skeletal muscle plays a major role in controlling body mass and metabolism: it is the most abundant tissue of the body and a major source of humoral factors; in addition, it is primarily responsible for glucose uptake and storage, as well as for protein metabolism. Muscle acts as a metabolic hub, in a crosstalk with other organs and tissues, such as the liver, the brain, and fat tissue. Cytokines, adipokines, and myokines are pivotal mediators of such crosstalk. Many of these circulating factors modulate histone deacetylase (HDAC) expression and/or activity. HDACs form a numerous family of enzymes, divided into four classes based on their homology to their orthologs in yeast. Eleven family members are considered classic HDACs, with a highly conserved deacetylase domain, and fall into Classes I, II, and IV, while class III members are named Sirtuins and are structurally and mechanistically distinct from the members of the other classes. HDACs are key regulators of skeletal muscle metabolism, both in physiological conditions and following metabolic stress, participating in the highly dynamic adaptative responses of the muscle to external stimuli. In turn, HDAC expression and activity are closely regulated by the metabolic demands of the skeletal muscle. For instance, NAD+ levels link Class III (Sirtuin) enzymatic activity to the energy status of the cell, and starvation or exercise affect Class II HDAC stability and intracellular localization. SUMOylation or phosphorylation of Class II HDACs are modulated by circulating factors, thus establishing a bidirectional link between HDAC activity and endocrine, paracrine, and autocrine factors. Indeed, besides being targets of adipo-myokines, HDACs affect the synthesis of myokines by skeletal muscle, altering the composition of the humoral milieu and ultimately contributing to the muscle functioning as an endocrine organ. In this review, we discuss recent findings on the interplay between HDACs and circulating factors, in relation to skeletal muscle metabolism and its adaptative response to energy demand. We believe that enhancing knowledge on the specific functions of HDACs may have clinical implications leading to the use of improved HDAC inhibitors for the treatment of metabolic syndromes or aging.

Emerging Roles of Non-Coding RNAs in the Feed Efficiency of Livestock Species

A global population of already more than seven billion people has led to an increased demand for food and water, and especially the demand for meat. Moreover, the cost of feed used in animal production has also increased dramatically, which requires animal breeders to find alternatives to reduce feed consumption. Understanding the biology underlying feed efficiency (FE) allows for a better selection of feed-efficient animals. Non-coding RNAs (ncRNAs), especially micro RNAs (miRNAs) and long non-coding RNAs (lncRNAs), play important roles in the regulation of bio-logical processes and disease development. The functions of ncRNAs in the biology of FE have emerged as they participate in the regulation of many genes and pathways related to the major FE indicators, such as residual feed intake and feed conversion ratio. This review provides the state of the art studies related to the ncRNAs associated with FE in livestock species. The contribution of ncRNAs to FE in the liver, muscle, and adipose tissues were summarized. The research gap of the function of ncRNAs in key processes for improved FE, such as the nutrition, heat stress, and gut–brain axis, was examined. Finally, the potential uses of ncRNAs for the improvement of FE were discussed.

Recent insights into the molecular regulators and mechanisms of taurine to modulate lipid metabolism: a review

Lipid metabolism disorders such as hypertriglyceridemia and hypercholesterolemia are risk factors for cardiovascular diseases and atherosclerosis that are grave public health issues. Taurine, a sulfur-containing non-essential amino acid exerts a wide range of physiological effects that regulate lipid metabolic disorders. Although the effects of taurine on lipid-lowering have been reported in animals and humans, mechanisms elucidating the lipid-lowering action of taurine remain unclear. A series of molecular regulators associated with lipid metabolism have been identified in the past few decades. These include nuclear receptors, transcription factors, and enzymes that undergo important changes during taurine treatment. In this review, we focus on the role of taurine in lipid metabolism and discuss taurine-related interventions in combating lipid disorders.

Pancreastatin inhibitor PSTi8 prevents free fatty acid-induced oxidative stress and insulin resistance by modulating JNK pathway: In vitro and in vivo findings

AIM

Free fatty acid-mediated obesity plays a crucial role in the pathogenesis of Type 2 Diabetes. FFA induced JNK activation acts as a central regulator in causing hepatic insulin resistance. Similarly, Pancreastatin, a chromogranin A peptide, serves as a crucial link between FFA-induced insulin resistance. Therefore, in the present work, we sought to test Pancreastatin inhibitor PSTi8 to ameliorate FFA-induced hepatic insulin resistance in in vitro and in vivo models.

MATERIAL AND METHODS

To verify our objective, we exposed hepatocytes (HepG2 cells) with palmitate (0.3 mM) or palmitate + PSTi8 (200 nM). Parallelly mice were fed either HFD or HFD + PSTi8 (1 mg/kg). After 21 days animals were scanned for increased fat mass, along with GTT, ITT and PTT experiment to check glucose, and insulin tolerance. Furthermore, ROS generation and hepatic glycogen content was measured in FFA exposed hepatocytes. Gene expression and protein expression studies were further conducted to delineate the action mechanism of PSTi8.

KEY FINDINGS

PSTi8 exposure decreased ROS accumulation, lipid accumulation, and reduced glycogen content in FFA-induced groups. It also enhances glucose uptake and reduces gluconeogenesis to combat the FFA effect. Furthermore, gene expression studies indicate that PSTi8 treatment reduces NADPH oxidase3 (NOX3) expression and inhibits JNK signaling, a predominant source of ROS-induced insulin resistance.

SIGNIFICANCE

To summarize, the protective effect of PSTi8 on FFA-induced insulin resistance is mediated via inhibition of JNK signaling, which leads to decreased ROS generation and enhanced insulin sensitivity. Hence PSTi8 could be a therapeutic molecule to prevent western diet-induced insulin resistance.

CerS1 but Not CerS5 Gene Silencing, Improves Insulin Sensitivity and Glucose Uptake in Skeletal Muscle

Skeletal muscle is perceived as a major tissue in glucose and lipid metabolism. High fat diet (HFD) lead to the accumulation of intramuscular lipids, including: long chain acyl-CoA, diacylglycerols, and ceramides. Ceramides are considered to be one of the most important lipid groups in the generation of skeletal muscle insulin resistance. So far, it has not been clearly established whether all ceramides adversely affect the functioning of the insulin pathway, or whether there are certain ceramide species that play a pivotal role in the induction of insulin resistance. Therefore, we designed a study in which the expression of CerS1 and CerS5 genes responsible for the synthesis of C18:0-Cer and C16:0-Cer, respectively, was locally silenced in the gastrocnemius muscle of HFD-fed mice through in vivo electroporation-mediated shRNA plasmids. Our study indicates that HFD feeding induced both, the systemic and skeletal muscle insulin resistance, which was accompanied by an increase in the intramuscular lipid levels, decreased activation of the insulin pathway and, consequently, a decrease in the skeletal muscle glucose uptake. CerS1 silencing leads to a reduction in C18:0-Cer content, with a subsequent increase in the activity of the insulin pathway, and an improvement in skeletal muscle glucose uptake. Such effects were not visible in case of CerS5 silencing, which indicates that the accumulation of C18:0-Cer plays a decisive role in the induction of skeletal muscle insulin resistance.

Antiobesity therapeutics with complementary dual-agonist activities at glucagon and glucagon-like peptide 1 receptors

AIM

To develop more effective and long-lasting antiobesity and antidiabetic therapeutics by employing novel chemical modifications of glucagon-like peptide-1 receptor (GLP-1R) agonists.

METHODS

We constructed novel unimolecular dual agonists of GLP-1R and glucagon receptor prepared by linking sEx-4 and native glucagon (GCG) via lysine or triazole [sEx4-GCG(K) and sEx4-GCG(T), respectively] and evaluated their antiobesity and antidiabetic efficacy in the diabetic and obese mouse model.

RESULTS

Both sEx4-GCG(K) and sEx4-GCG(T) showed the beneficial metabolic effects of GLP-1 and glucagon: they promoted weight loss and ameliorated insulin resistance and hepatic steatosis. They also increased thermogenesis in brown adipose tissue, and lipolysis and β-oxidation in white adipose tissue, with concomitant suppression of lipogenesis. Furthermore, both dual agonists activated the 5'-AMP-activated protein kinase signalling pathway and prevented palmitate-induced oxidative stress in skeletal muscle cells.

CONCLUSION

Through their complementary dual agonism, sEx4-GCG(T) and sEx4-GCG(K) induce more marked weight loss and metabolic improvements than conventional agonists, and could be developed as novel therapeutic agents for the treatment of obesity and associated metabolic disorders in humans.

Xanthohumol Pyrazole Derivative Improves Diet-Induced Obesity and Induces Energy Expenditure in High-Fat Diet-Fed Mice

The energy intake exceeding energy expenditure (EE) results in a positive energy balance, leading to storage of excess energy and weight gain. Here, we investigate the potential of a newly synthesized compound as an inducer of EE for the management of diet-induced obesity and insulin resistance. Xanthohumol (XN), a prenylated flavonoid from hops, was used as a precursor for the synthesis of a pyrazole derivative tested for its properties on high-fat diet (HFD)-induced metabolic impairments. In a comparative study with XN, we report that 4-(5-(4-hydroxyphenyl)-1-methyl-1H-pyrazol-3-yl)-5-methoxy-2-(3-methylbut-2-en-1-yl)benzene-1,3-diol (XP) uncouples oxidative phosphorylation in C2C12 cells. In HFD-fed mice, XP improved glucose tolerance and decreased weight gain by increasing EE and locomotor activity. Using an untargeted metabolomics approach, we assessed the effects of treatment on metabolites and their corresponding biochemical pathways. We found that XP and XN reduced purine metabolites and other energy metabolites in the plasma of HFD-fed mice. The induction of locomotor activity was associated with an increase in inosine monophosphate in the cortex of XP-treated mice. Together, these results suggest that XP, better than XN, affects mitochondrial respiration and cellular energy metabolism to prevent obesity in HFD-fed mice.

Positive Effects of Exercise Intervention without Weight Loss and Dietary Changes in NAFLD-Related Clinical Parameters: A Systematic Review and Meta-Analysis

One of the focuses of non-alcoholic fatty liver disease (NAFLD) treatment is exercise. Randomized controlled trials investigating the effects of exercise without dietary changes on NAFLD-related clinical parameters (liver parameters, lipid metabolism, glucose metabolism, gut microbiota, and metabolites) were screened using the PubMed, Scopus, Web of Science, and Cochrane databases on 13 February 2020. Meta-analyses were performed on 10 studies with 316 individuals who had NAFLD across three exercise regimens: aerobic exercise, resistance training, and a combination of both. No studies investigating the role of gut microbiota and exercise in NAFLD were found. A quality assessment via the (RoB)2 tool was conducted and potential publication bias, statistical outliers, and influential cases were identified. Overall, exercise without significant weight loss significantly reduced the intrahepatic lipid (IHL) content (SMD: −0.76, 95% CI: −1.04, −0.48) and concentrations of alanine aminotransaminase (ALT) (SMD: −0.52, 95% CI: −0.90, −0.14), aspartate aminotransaminase (AST) (SMD: −0.68, 95% CI: −1.21, −0.15), low-density lipoprotein cholesterol (SMD: −0.34, 95% CI: −0.66, −0.02), and triglycerides (TG) (SMD: −0.59, 95% CI: −1.16, −0.02). The concentrations of high-density lipoprotein cholesterol, total cholesterol (TC), fasting glucose, fasting insulin, and glycated hemoglobin were non-significantly altered. Aerobic exercise alone significantly reduced IHL, ALT, and AST; resistance training alone significantly reduced TC and TG; a combination of both exercise types significantly reduced IHL. To conclude, exercise overall likely had a beneficial effect on alleviating NAFLD without significant weight loss. The study was registered at PROSPERO: CRD42020221168 and funded by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 813781.

Metabolic Remodeling in Skeletal Muscle Atrophy as a Therapeutic Target

Skeletal muscle is a highly responsive tissue, able to remodel its size and metabolism in response to external demand. Muscle fibers can vary from fast glycolytic to slow oxidative, and their frequency in a specific muscle is tightly regulated by fiber maturation, innervation, or external causes. Atrophic conditions, including aging, amyotrophic lateral sclerosis, and cancer-induced cachexia, differ in the causative factors and molecular signaling leading to muscle wasting; nevertheless, all of these conditions are characterized by metabolic remodeling, which contributes to the pathological progression of muscle atrophy. Here, we discuss how changes in muscle metabolism can be used as a therapeutic target and review the evidence in support of nutritional interventions and/or physical exercise as tools for counteracting muscle wasting in atrophic conditions.

Roles of vitamin A in the regulation of fatty acid synthesis

Dietary macronutrients and micronutrients play important roles in human health. On the other hand, the excessive energy derived from food is stored in the form of triacylglycerol. A variety of dietary and hormonal factors affect this process through the regulation of the activities and expression levels of those key player enzymes involved in fatty acid biosynthesis such as acetyl-CoA carboxylase, fatty acid synthase, fatty acid elongases, and desaturases. As a micronutrient, vitamin A is essential for the health of humans. Recently, vitamin A has been shown to play a role in the regulation of glucose and lipid metabolism. This review summarizes recent research progresses about the roles of vitamin A in fatty acid synthesis. It focuses on the effects of vitamin A on the activities and expression levels of mRNA and proteins of key enzymes for fatty acid synthesis in vitro and in vivo. It appears that vitamin A status and its signaling pathway regulate the expression levels of enzymes involved in fatty acid synthesis. Future research directions are also discussed.

Effects of metabolizable protein concentration, amino acid profile, and fiber source on the messenger RNA expression of skeletal muscle in peripartum dairy cows

After parturition, dairy cows mobilize AA from skeletal muscle to meet metabolizable protein (MP) requirements. High mobilization may compromise cow health and longer-term milk production. Postpartum diets with higher MP concentrations, improved AA profiles, or MP increased at the expense of forages rather than nonforage fiber sources may attenuate muscle catabolism; however, the molecular mechanisms responsible need investigation. We evaluated mRNA expression in the longissimus dorsi of cows fed postpartum diets differing in MP concentration, AA profile, and fiber source. From 0 to 25 d after parturition, 40 multiparous cows received the following diets: (1) 13% deficient in MP (D-MP), (2) adequate in MP using primarily soy protein (A-MP), (3) adequate in MP using blends of proteins and individual AA to improve the AA profile (Blend), or (4) similar to Blend except additional protein replaced forage (Blend-fNDF). Biopsies were taken approximately -5, 7, and 25 d relative to parturition. Greater dietary MP concentration (D-MP vs. A-MP and Blend) decreased expression of genes related to protein synthesis (MTOR, RPS6KB1) and degradation (FOXO1), inflammation (IFNG, TLR4), and endoplasmic reticulum (ER) stress (HSPA5, DDIT) and increased genes associated with lipogenesis (PPARG) and glucose oxidation (LDH, MB). In Blend versus A-MP (i.e., effect of AA profile), expression related to apoptosis (CASP8) and inflammation (TNFA) decreased and genes associated with cell cycle progression (E2F1) and fast-twitch glycolytic muscle fiber type (MYH4) increased. Less forage (Blend-fNDF vs. Blend) decreased genes associated with lipogenesis (PPARG, ACACA) and ER stress (BCL2, DDIT3, EIF2AK3, PPP1R15A) and increased genes associated with inflammation (TNF), inhibition of myogenesis (MSTN), and autophagy (PEBP1). In summary and based on mRNA expression, increasing MP supply may attenuate muscle turnover and ER stress. However, an unbalanced AA supply reduced cell cycle progression and protein synthesis. Lower energy supplies may reduce cell growth and cause autophagy.

Effects of Lifestyle Intervention in Tissue-Specific Lipidomic Profile of Formerly Obese Mice

Lipids are highly diverse in their composition, properties and distribution in different biological entities. We aim to establish the lipidomes of several insulin-sensitive tissues and to test their plasticity when divergent feeding regimens and lifestyles are imposed. Here, we report a proton nuclear magnetic resonance (1H-NMR) study of lipid abundance across 4 tissues of C57Bl6J male mice that includes the changes in the lipid profile after every lifestyle intervention. Every tissue analysed presented a specific lipid profile irrespective of interventions. Glycerolipids and fatty acids were most abundant in epididymal white adipose tissue (eWAT) followed by liver, whereas sterol lipids and phosphoglycerolipids were highly enriched in hypothalamus, and gastrocnemius had the lowest content in all lipid species compared to the other tissues. Both when subjected to a high-fat diet (HFD) and after a subsequent lifestyle intervention (INT), the lipidome of hypothalamus showed no changes. Gastrocnemius and liver revealed a pattern of increase in content in many lipid species after HFD followed by a regression to basal levels after INT, while eWAT lipidome was affected mainly by the fat composition of the administered diets and not their caloric density. Thus, the present study demonstrates a unique lipidome for each tissue modulated by caloric intake and dietary composition.

Increased oxidative stress and mitochondrial impairments associated with increased expression of TNF-α and caspase-3 in palmitic acid-induced lipotoxicity in myoblasts

Saturated fatty acids, whose circulating levels are markedly increased in the body, significantly affect the growth and functions of skeletal muscle. These fatty acids may exert a detrimental effect on the undifferentiated skeletal myoblasts that may adversely affect their differentiation. In the present study, the exposure of myoblasts to excess palmitic acid caused an elevation of tumor necrosis factor-α expression and an increase in reactive oxygen species levels consistent with the enhanced inflammation and oxidative stress. Various concentrations of palmitic acid significantly decreased the mitochondrial membrane potential, induced the programmed cell death by an increase in the caspase-3 expression, and DNA fragmentation in the myoblasts. These findings suggest that the increased concentrations of saturated fatty acid in the myoblasts increase lipotoxicity by increasing inflammation and oxidative stress, decreasing the mitochondrial function, and inducing apoptosis.

Energy substrate metabolism in skeletal muscle and liver when consuming diets of different energy levels: comparison between Tibetan and Small-tailed Han sheep

The energy intake of Tibetan sheep on the harsh Qinghai-Tibetan Plateau (QTP) varies greatly with seasonal forage fluctuations and is often below maintenance requirements, especially during the long, cold winter. The liver plays a crucial role in gluconeogenesis and skeletal muscle is the primary tissue of energy expenditure in mammals. Both play important roles in energy substrate metabolism and regulating energy metabolism homeostasis of the body. This study aimed to gain insight into how skeletal muscle and liver of Tibetan sheep regulate energy substrate metabolism to cope with low energy intake under the harsh environment of the QTP. Tibetan sheep (n = 24; 48.5 ± 1.89 kg BW) were compared with Small-tailed Han sheep (n = 24; 49.2 ± 2.21 kg BW), which were allocated randomly into one of four groups that differed in dietary digestible energy densities: 8.21, 9.33, 10.45 and 11.57 MJ /kg DM. The sheep were slaughtered after a 49-d feeding period, skeletal muscle and liver tissues were collected and measurements were made of the activities of the key enzymes of energy substrate metabolism and the expressions of genes related to energy homeostasis regulation. Compared with Small-tailed Han sheep, Tibetan sheep exhibited higher capacities of propionate to glucose conversion and fatty acid oxidation and ketogenesis in the liver, higher glucose utilization efficiency in both skeletal muscle and liver, but lower activities of fatty acid oxidation and protein mobilization in skeletal muscle, especially when in negative energy balance. However, the Small-tailed Han sheep exhibited higher capacities to convert amino acids and lactate to glucose and higher levels of glycolysis and lipogenesis in the liver than Tibetan sheep. These differences in gluconeogenesis and energy substrate metabolism conferred the Tibetan sheep an advantage over Small-tailed Han sheep to cope with low energy intake and regulate whole-body energy homeostasis under the harsh environment of the QTP.

Bringing naturally-occurring saturated fatty acids into biomedical research

This review introduces naturally-occurring saturated fatty acids (NSFAs) and their biomedical applications, including controlled drug release, targeted drug delivery, cancer therapy, antibacterial treatment, and tissue engineering.

Embryonic fatty acid metabolism in diabetic pregnancy: the difference between embryoblasts and trophoblasts

During the first days of development the preimplantation embryo is supplied with nutrients from the surrounding milieu. Maternal diabetes mellitus affects the uterine microenvironment, leading to a metabolic adaptation processes in the embryo. We analysed embryonic fatty acid (FA) profiles and expression of processing genes in rabbit blastocysts, separately in embryoblasts (EBs) and trophoblasts (TBs), to determine the potential consequences of maternal diabetes mellitus on intracellular FA metabolism. Insulin-dependent diabetes was induced by alloxan in female rabbits. On Day 6 post coitum, FA profiles in blastocysts (EB, TB and blastocoel fluid) and maternal blood were analysed by gas chromatography. The expression levels of molecules involved in FA elongation (fatty acid elongases, ELOVLs) and desaturation (fatty acid desaturases, FADSs) were measured in EB and TB. Maternal diabetes mellitus influenced the FA profile in maternal plasma and blastocysts. Independent from metabolic changes, rabbit blastocysts contained a higher level of saturated fatty acids (SFAs) and a lower level of polyunsaturated fatty acids (PUFAs) compared to the FA profile of the maternal plasma. Furthermore, the FA profile was altered in the EB and TB, differently. While SFAs (palmitic and stearic acid) were elevated in EB of diabetic rabbits, PUFAs, such as docosahexaenoic acid, were decreased. In contrast, in the TB, lower levels of SFAs and higher levels of oleic acid were observed. EB and TB specific alterations in gene expression were found for ELOVLs and FADSs, key enzymes for FA elongation and desaturation. In conclusion, maternal diabetes mellitus alters embryonic FA metabolism differently in EB and TB, indicating a lineage-specific metabolic adaptive response.

GPAT Gene Silencing in Muscle Reduces Diacylglycerols Content and Improves Insulin Action in Diet-Induced Insulin Resistance

Skeletal muscle is an important tissue responsible for glucose and lipid metabolism. High-fat diet (HFD) consumption is associated with the accumulation of bioactive lipids: long chain acyl-CoA, diacylglycerols (DAG) and ceramides. This leads to impaired insulin signaling in skeletal muscle. There is little data on the involvement of DAG in the development of these disorders. Therefore, to clarify this enigma, the gene encoding glycerol-3-phosphate acyltransferase enzyme (GPAT, responsible for DAG synthesis) was silenced through shRNA interference in the gastrocnemius muscle of animals with diet-induced insulin resistance. This work shows that HFD induces insulin resistance, which is accompanied by an increase in the concentration of plasma fatty acids and the level of bioactive lipids in muscle. The increase in these lipids inhibits the insulin pathway and reduces muscle glucose uptake. GPAT silencing through electroporation with shRNA plasmid leads to a reduction in DAG and triacylglycerol (TAG) content, an increase in the activity of the insulin pathway and glucose uptake without a significant effect on ceramide content. This work clearly shows that DAG accumulation has a significant effect on the induction of muscle insulin resistance and that inhibition of DAG synthesis through GPAT modulation may be a potential target in the treatment of insulin resistance.

Effects of different rearing systems on intramuscular fat content, fatty acid composition, and lipid metabolism-related genes expression in breast and thigh muscles of Nonghua ducks

Rearing system is a critical nongenetic factor influencing meat quality of ducks. In this study, a total of 360 birds were randomly allocated into floor rearing system (FRS) and net rearing system (NRS) to compare their effects on intramuscular fat (IMF) deposition, fatty acid composition, and related gene expression in muscles of Nonghua ducks. Sawdust bedding and stainless mesh bed were equipped in FRS and NRS, respectively. At the eighth week (8w) and 13th week (13w), the breast and thigh muscles of ducks were collected to determine the profiles of lipids composition and the expressions of lipid metabolism-related genes. The IMF content was higher in 13w-FRS than 8w-FRS and 8w-NRS in breast muscle, whereas it was higher in 13w-NRS than other groups in thigh muscle (P < 0.05). C16:1, C20:5(n-3) of muscles were higher in 8w-NRS than 8w-FRS, whereas C18:1(n-9)c, C18:2(n-6)c, Ʃ monounsaturated fatty acid (MUFA), and ƩMUFA/Ʃsaturated fatty acid (SFA) ratio of muscles were higher in 13w-NRS than 8w-FRS and 8w-NRS (P < 0.05). C22:6(n-3), C20:4(n-6) of breast muscle and C20:3(n-6) of thigh muscle were higher in 13w-NRS than 13w-FRS (P < 0.05). Fatty acids variation was studied by principal component analysis, exhibiting extensive positive loadings on principal components. SREBP1, ACADL, and FABP3 were downregulated in breast muscle, whereas PPARα and ELOVL5 were upregulated in thigh muscle of NRS ducks at 13w. Principal components were extensively correlated with lipids composition parameters, and principal components of breast muscle 1 and principal components of thigh muscle 1 were correlated with SREBP1 and PPARα, respectively (P < 0.05). In conclusion, with increasing age, FRS enhanced IMF deposition in breast muscle, and the same promotion in thigh muscle was because of NRS. The variation of fatty acids in muscles was uniform, and the change of single fatty acid was unable to distinguish NRS and FRS. However, as NRS downregulated SREBP1, ACADL and FABP3 in breast muscle and upregulated PPARα and ELOVL5 in thigh muscle, NRS could improve nutrient value and meat quality by increasing ƩMUFA, ƩMUFA/ƩSFA ratio, and important PUFA levels. Therefore, NRS was more recommended than FRS for Nonghua ducks during week 8 to 13 posthatching.

Altered skeletal muscle glucose-fatty acid flux in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is characterized by the degeneration of upper and lower motor neurons, yet an increasing number of studies in both mouse models and patients with amyotrophic lateral sclerosis suggest that altered metabolic homeostasis is also a feature of disease. Pre-clinical and clinical studies have shown that modulation of energy balance can be beneficial in amyotrophic lateral sclerosis. However, the capacity to target specific metabolic pathways or mechanisms requires detailed understanding of metabolic dysregulation in amyotrophic lateral sclerosis. Here, using the superoxide dismutase 1, glycine to alanine substitution at amino acid 93 (SOD1^G93A) mouse model of amyotrophic lateral sclerosis, we demonstrate that an increase in whole-body metabolism occurs at a time when glycolytic muscle exhibits an increased dependence on fatty acid oxidation. Using myotubes derived from muscle of amyotrophic lateral sclerosis patients, we also show that increased dependence on fatty acid oxidation is associated with increased whole-body energy expenditure. In the present study, increased fatty acid oxidation was associated with slower disease progression. However, within the patient cohort, there was considerable heterogeneity in whole-body metabolism and fuel oxidation profiles. Thus, future studies that decipher specific metabolic changes at an individual patient level are essential for the development of treatments that aim to target metabolic pathways in amyotrophic lateral sclerosis.

Genetic variations (eQTLs) in muscle transcriptome and mitochondrial genes, and trans-eQTL molecular pathways in feed efficiency from Danish breeding pigs

Feed efficiency (FE) is a key trait in pig production, as improvement in FE has positive economic and environmental impact. FE is a complex phenotype and testing animals for FE is costly. Therefore, there has been a desire to find functionally relevant single nucleotide polymorphisms (SNPs) as biomarkers, to improve our biological understanding of FE as well as accuracy of genomic prediction for FE. We have performed a cis- and trans- eQTL (expression quantitative trait loci) analysis, in a population of Danbred Durocs (N = 11) and Danbred Landrace (N = 27) using both a linear and ANOVA model based on muscle tissue RNA-seq. We analyzed a total of 1425x19179 or 2.7x10⁷ Gene-SNP combinations in eQTL detection models for FE. The 1425 genes were from RNA-Seq based differential gene expression analyses using 25880 genes related to FE and additionally combined with mitochondrial genes. The 19179 SNPs were from applying stringent quality control and linkage disequilibrium filtering on genotype data using a GGP Porcine HD 70k SNP array. We applied 1000 fold bootstrapping and enrichment analysis to further validate and analyze our detected eQTLs. We identified 13 eQTLs with FDR < 0.1, affecting several genes found in previous studies of commercial pig breeds. Examples include MYO19, CPT1B, ACSL1, IER5L, CPT1A, SUCLA2, CSRNP1, PARK7 and MFF. The bootstrapping results showed statistically significant enrichment (p-value<2.2x10^-16) of eQTLs with p-value < 0.01 in both cis and trans-eQTLs. Enrichment analysis of top trans-eQTLs revealed high enrichment for gene categories and gene ontologies associated with genomic context and expression regulation. This included transcription factors (p-value = 1.0x10^-13), DNA-binding (GO:0003677, p-value = 8.9x10^-14), DNA-binding transcription factor activity (GO:0003700,) nucleus gene (GO:0005634, p-value<2.2x10^-16), negative regulation of expression (GO:0010629, p-value<2.2x10^-16). These results would be useful for future genome assisted breeding of pigs to improve FE, and in the improved understanding of the functional mechanism of trans eQTLs.

Nutritional and metabolic regulation of the metabolite dimethylguanidino valeric acid: an early marker of cardiometabolic disease

Dimethylguanidino valeric acid (DMGV) is a marker of fatty liver disease, incident coronary artery disease, cardiovascular mortality, and incident diabetes. Recently, it was reported that circulating DMGV levels correlated positively with consumption of sugary beverages and negatively with intake of fruits and vegetables in three Swedish community-based cohorts. Here, we validate these results in the Framingham Heart Study Third Generation Cohort. Furthermore, in mice, diets rich in sucrose or fat significantly increased plasma DMGV concentrations. DMGV is the product of metabolism of asymmetric dimethylarginine (ADMA) by the hepatic enzyme AGXT2. ADMA can also be metabolized to citrulline by the cytoplasmic enzyme DDAH1. We report that a high-sucrose diet induced conversion of ADMA exclusively into DMGV (supporting the relationship with sugary beverage intake in humans), while a high-fat diet promoted conversion of ADMA to both DMGV and citrulline. On the contrary, replacing dietary native starch with high-fiber-resistant starch increased ADMA concentrations and induced its conversion to citrulline, without altering DMGV concentrations. In a cohort of obese nondiabetic adults, circulating DMGV concentrations increased and ADMA levels decreased in those with either liver or muscle insulin resistance. This was similar to changes in DMGV and ADMA concentrations found in mice fed a high-sucrose diet. Sucrose is a disaccharide of glucose and fructose. Compared with glucose, incubation of hepatocytes with fructose significantly increased DMGV production. Overall, we provide a comprehensive picture of the dietary determinants of DMGV levels and association with insulin resistance.

Bioenergetic defects in muscle fibers of RYR1 mutant knock-in mice associated with malignant hyperthermia

Mutations in the skeletal muscle ryanodine receptor gene (RYR1) can cause susceptibility to malignant hyperthermia (MH), a potentially lethal genetic condition triggered by volatile anesthetics. MH is associated with hypermetabolism, which has directed research interest into oxidative phosphorylation and muscle bioenergetics. The most common cause of MH in the United Kingdom is the c.7300G>A RYR1 variant, which is present in ∼16% of MH families. Our study focuses on the MH susceptible G2435R-RYR1 knock-in mouse model, which is the murine equivalent of the human c.7300G>A genotype. Using a combination of transcriptomics, protein expression, and functional analysis, we investigated adult muscle fiber bioenergetics in this mouse model. RNA-Seq data showed reduced expression of genes associated with mitochondria and fatty acid oxidation in RYR1 mutants when compared with WT controls. Mitochondrial function was assessed by measuring oxygen consumption rates in permeabilized muscle fibers. Comparisons between WT and homozygous G2435R-RYR1 mitochondria showed a significant increase in complex I-facilitated oxidative phosphorylation in mutant muscle. Furthermore, we observed a gene-dose-specific increase in reactive oxygen species production in G2435R-RYR1 muscle fibers. Collectively, these findings provide evidence of metabolic defects in G2435R-RYR1 knock-in mouse muscle under basal conditions. Differences in metabolic profile could be the result of differential gene expression in metabolic pathways, in conjunction with mitochondrial damage accumulated from chronic exposure to increased oxidative stress.

The Multifunctionality of CD36 in Diabetes Mellitus and Its Complications-Update in Pathogenesis, Treatment and Monitoring

CD36 is a multiligand receptor contributing to glucose and lipid metabolism, immune response, inflammation, thrombosis, and fibrosis. A wide range of tissue expression includes cells sensitive to metabolic abnormalities associated with metabolic syndrome and diabetes mellitus (DM), such as monocytes and macrophages, epithelial cells, adipocytes, hepatocytes, skeletal and cardiac myocytes, pancreatic β-cells, kidney glomeruli and tubules cells, pericytes and pigment epithelium cells of the retina, and Schwann cells. These features make CD36 an important component of the pathogenesis of DM and its complications, but also a promising target in the treatment of these disorders. The detrimental effects of CD36 signaling are mediated by the uptake of fatty acids and modified lipoproteins, deposition of lipids and their lipotoxicity, alterations in insulin response and the utilization of energy substrates, oxidative stress, inflammation, apoptosis, and fibrosis leading to the progressive, often irreversible organ dysfunction. This review summarizes the extensive knowledge of the contribution of CD36 to DM and its complications, including nephropathy, retinopathy, peripheral neuropathy, and cardiomyopathy.

The Effects of Intermittent Fasting on Glycemic Control and Body Composition in Adults with Obesity and Type 2 Diabetes: A Systematic Review

The purpose of this study was to evaluate the effects of intermittent fasting on glycemic control and body composition in adults with obesity and type 2 diabetes. Although intermittent fasting has shown some promise in improving glucoregulatory indicators and body composition in adults with obesity, there is currently no systematic review evaluating these effects in adults with obesity and type 2 diabetes. A database search of PubMed, CINHAL, and MEDLINE identified five studies that met inclusion criterion. All studies were randomized controlled trials in adult subjects (n = 46-137) with type 2 diabetes and a body mass index of ≥30 kg/m². Four different intermittent fasting regimens were reviewed. All fasting regimens revealed strong evidence to support intermittent fasting as a feasible diet to improve glycemia and body composition measures within 12-24 weeks. Follow-up 12-18 months after intermittent fasting did not show promising results for continued weight loss and improved glycemic control. The majority of the studies demonstrated insignificant differences between intermittent fasting and continuous energy restriction for measures of glycated hemoglobin a1c and body composition. More data on intermittent fasting in adults with obesity and type 2 diabetes are needed to determine its benefits within this patient population. Future research should include consistent fasting regimens and larger sample sizes to improve the reliability and generalizability of the data. Also, consistent follow-up after a fasting intervention may enhance long-term benefits and should be considered in future research.

Exposure to bisphenol analogues interrupts growth, proliferation, and fatty acid compositions of protozoa Tetrahymena thermophila

A number of bisphenol A (BPA) analogues are increasingly used as its industrial alternatives. However, their effects on aquatic organisms at both individual and population levels have not been well understood. In this study, effects of five bisphenol analogues (i.e., BPA, BPAF, BPB, BPE and BPS) were investigated by using the unicellular eukaryote Tetrahymena thermophila as a model organism. All of them inhibited individual growth and population proliferation at a concentration of 2.6 μM or 13.0 μM during the 60-h exposure period, with the population suppression capacify ranked as: BPB > BPA ≈ BPAF > BPE > BPS. These analogues also exhibited chemical-specific disruption of fatty acid profiles in single-cell eukaryotes and the transcriptional levels of enzymes involved in fatty acid metabolism/biosynthesis. For example, exposure to BPA and BPE significantly increased the ratio of saturated fatty acids to unsaturated fatty acids, contrary to the desaturation effects exhibited by BPAF and BPB. Overall, our results clearly indicated that these bisphenol analogues could pose chemical-specific effects on low-trophic level aquatic organisms, particularly disruption of endogenous metabolic balances. Selected analogues (i.e., BPB and BPAF) could result in effects similar to or even greater than that of BPA.

Impact of Acute Pancreatic Injury on Sphingolipid Metabolism in the Salivary Glands

Acute pancreatic injury can be related to both parenchymal (responsible for exocrine functions) and islet (mainly β-cells, responsible for endocrine functions) damage. During embryonic development, both the salivary glands and the pancreas originate from the foregut, which explains many of the observed histological and functional similarities between these two organs. The relationship between several diseases of the pancreas and salivary glands, resulting from morphological and functional similarities, is well established. Sphingolipids constitute a class of biologically active molecules involved in numerous physiological and pathological processes, including acute pancreatitis (AP) and diabetes mellitus. However, the effect of AP on sphingolipid metabolism in the salivary glands remains uncertain. In the presented study, we examined the effect of AP and type 1 diabetes mellitus on sphingolipid metabolism in the salivary glands of rats. We demonstrated that acute pancreatic injury, related to both exocrine and endocrine functions, affects the metabolism of sphingolipids in the parotid, but not submandibular, salivary glands.

Modulation of MicroRNAs as a Potential Molecular Mechanism Involved in the Beneficial Actions of Physical Exercise in Alzheimer Disease

Alzheimer disease (AD) is one of the most common neurodegenerative diseases, affecting middle-aged and elderly individuals worldwide. AD pathophysiology involves the accumulation of beta-amyloid plaques and neurofibrillary tangles in the brain, along with chronic neuroinflammation and neurodegeneration. Physical exercise (PE) is a beneficial non-pharmacological strategy and has been described as an ally to combat cognitive decline in individuals with AD. However, the molecular mechanisms that govern the beneficial adaptations induced by PE in AD are not fully elucidated. MicroRNAs are small non-coding RNAs involved in the post-transcriptional regulation of gene expression, inhibiting or degrading their target mRNAs. MicroRNAs are involved in physiological processes that govern normal brain function and deregulated microRNA profiles are associated with the development and progression of AD. It is also known that PE changes microRNA expression profile in the circulation and in target tissues and organs. Thus, this review aimed to identify the role of deregulated microRNAs in the pathophysiology of AD and explore the possible role of the modulation of microRNAs as a molecular mechanism involved in the beneficial actions of PE in AD.

Genome Regulation and Gene Interaction Networks Inferred From Muscle Transcriptome Underlying Feed Efficiency in Pigs

Improvement of feed efficiency (FE) is key for Sustainability and cost reduction in pig production. Our aim was to characterize the muscle transcriptomic profiles in Danbred Duroc (Duroc; n = 13) and Danbred Landrace (Landrace; n = 28), in relation to FE for identifying potential biomarkers. RNA-seq data on the 41 pigs was analyzed employing differential gene expression methods, gene-gene interaction and network analysis, including pathway and functional analysis. We also compared the results with genome regulation in human exercise data, hypothesizing that increased FE mimics processes triggered in exercised muscle. In the differential expression analysis, 13 genes were differentially expressed, including: MRPS11, MTRF1, TRIM63, MGAT4A, KLH30. Based on a novel gene selection method, the divergent count, we performed pathway enrichment analysis. We found five significantly enriched pathways related to feed conversion ratio (FCR). These pathways were mainly related to mitochondria, and summarized in the mitochondrial translation elongation (MTR) pathway. In the gene interaction analysis, the most interesting genes included the mitochondrial genes: PPIF, MRPL35, NDUFS4 and the fat metabolism and obesity genes: AACS, SMPDL3B, CTNNBL1, NDUFS4, and LIMD2. In the network analysis, we identified two modules significantly correlated with FCR. Pathway enrichment of module genes identified MTR, electron transport chain and DNA repair as enriched pathways. The network analysis revealed the mitochondrial gene group NDUF as key network hub genes, showing their potential as biomarkers. Results show that genes related to human exercise were enriched in identified FCR related genes. We conclude that mitochondrial activity is a key driver for FCR in muscle tissue, and mitochondrial genes could be potential biomarkers for FCR in pigs.

The chemokine CXCL16 can rescue the defects in insulin signaling and sensitivity caused by palmitate in C2C12 myotubes

In obesity, macrophages infiltrate peripheral tissues and secrete pro-inflammatory cytokines that impact local insulin sensitivity. Lipopolysaccharide (LPS) and the saturated fatty acid (FA) palmitate polarise macrophages towards a pro-inflammatory phenotype in vitro and indirectly cause insulin resistance (IR) in myotubes. In contrast, unsaturated FAs confer an anti-inflammatory phenotype and counteract the actions of palmitate. To explore paracrine mechanisms of interest, J774 macrophages were exposed to palmitate ± palmitoleate or control medium and the conditioned media generated were screened using a cytokine array. Of the 62 cytokines examined, 8 were significantly differentially expressed following FA treatments. Notably, CXCL16 secretion was downregulated by palmitate. In follow-up experiments using ELISAs, this downregulation was confirmed and reversed by simultaneous addition of palmitoleate or oleate, while LPS also diminished CXCL16 secretion. To dissect potential effects of CXCL16, C2C12 myotubes were treated with palmitate to induce IR, recombinant soluble CXCL16 (sCXCL16), combined treatment, or control medium. Palmitate caused the expected reduction of insulin-stimulated Akt activation and glycogen synthesis, whereas simultaneous treatment with sCXCL16 attenuated these effects. These data indicate a putative role for CXCL16 in preservation of Akt activation and insulin signaling in the context of chronic low-grade inflammation in skeletal muscle.

Exogenous Oleic Acid and Palmitic Acid Improve Boar Sperm Motility via Enhancing Mitochondrial Β-Oxidation for ATP Generation

Simple Summary

Sperm requires ATP production for maintaining motility. In boar sperm, it is not clear whether the mitochondrial β-oxidation pathway for ATP generation is active or not. We found that boar sperm could utilize oleic acid and palmitic acid during the liquid storage. Addition of oleic acid and palmitic acid to extender improved the sperm quality. Using the incubation model, we found that boar sperm utilized oleic acid and palmitic acid as the energy substrates for ATP generation via mitochondrial β-oxidation pathway. We suggest that addition of fatty acids to the extender would be beneficial to improve boar sperm quality.

Abstract

It takes several hours for mammalian sperm to migrate from the ejaculation or insemination site to the fertilization site in the female reproductive tract in which glucose, amino acids, and fatty acids are regarded as the primary substrates for ATP generation. The present study was designed to investigate whether oleic acid and palmitic acid were beneficial to boar sperm in vitro; and if yes, to elucidate the mechanism that regulates sperm motility. Therefore, the levels of oleic acid and palmitic acid, motility, membrane integrity, acrosome integrity, and apoptosis of sperm were evaluated. Moreover, the enzymes involved in mitochondrial β-oxidation (CPT1: carnitine palmitoyltransferase 1; ACADVL: long-chain acyl-coenzyme A dehydrogenase) were detected with immunofluorescence and Western blotting. Consequently, the ATP content and the activities of CPT1, ACADVL, malate dehydrogenase (MDH), and succinate dehydrogenase (SDH) were also measured. We observed that CPT1 and ACADVL were expressed in boar sperm and localized in the midpiece. The levels of oleic acid and palmitic acid were decreased during storage at 17 °C. The addition of oleic acid and palmitic acid significantly increased sperm motility, progressive motility, straight-line velocity (VSL), membrane integrity, and acrosome integrity with a simultaneous decrease in sperm apoptosis after seven days during storage. When sperm were incubated with oleic acid and palmitic acid at 37 °C for 3 h, the activities of CPT1 and ACADVL, the ATP level, the mitochondrial membrane potential, the activities of MDH and SDH, as well as sperm motility patterns were significantly increased compared to the control (p < 0.05). Moreover, the addition of etomoxir to the diluted medium in the presence of either oleic acid or palmitic acid and the positive effects of oleic acid and palmitic acid were counteracted. Together, these data suggest that boar sperm might utilize oleic acid and palmitic acid as energy substrates for ATP production via β-oxidation. The addition of these acids could improve sperm quality.