Glycogen Reduction Research Articles

First-in-Human Evaluation of Safety, Pharmacokinetics and Muscle Glycogen Lowering of a Novel Glycogen Synthase 1 Inhibitor for the Treatment of Pompe Disease.

Pompe disease is a rare glycogen storage disease caused by mutations in the enzyme acid α-glucosidase (GAA) resulting in pathological accumulation of glycogen in muscle tissues leading to progressive weakness and respiratory dysfunction. Enzyme replacement therapy (ERT) with GAA is currently the sole treatment option for patients with Pompe disease. ERT burdens patients with frequent intravenous infusions while insufficiently halting disease progression due to incomplete ERT skeletal muscle distribution. Glycogen synthase 1 (GYS1) has been proposed as a substrate reduction therapy (SRT) target for Pompe disease. Here, we report results from the first-in-human study of the orally available GYS1 inhibitor MZE001 in healthy subjects. In 88 participants, MZE001 was well-tolerated up to a single dose of 480 mg BID and multiple doses of 720 mg BID for 10 days. Noncompartmental analysis determined that the half-life and Ctrough concentrations of MZE001 could provide efficacious exposures with once or twice daily oral dosing. Change from baseline of peripheral blood mononuclear cell (PBMC) glycogen, which correlated with muscle glycogen levels in preclinical models, was significantly reduced dose-dependently following 10 days of MZE001 treatment in healthy subjects. A muscle biopsy sub-study demonstrated that 10 days of MZE001 (480 mg BID) dosing safely and substantially lowered muscle glycogen stores in healthy adults. This correlated with the PBMC exposure response and supports the use of PBMC glycogen reduction as a surrogate for muscle response, and MZE001 potential for development as the first oral substrate reduction therapy for patients with Pompe disease.

Influence of Starvation on Biochemical, Physiological, Morphological, and Transcriptional Responses Associated with Glucose and Lipid Metabolism in the Liver of Javelin Goby (Synechogobius hasta).

In this study, the influence of fasting on hepatic glucose and lipid metabolism was explored by examining biochemical, antioxidative, and morphological indicators and transcriptional expression in the liver of javelin goby (Synechogobius hasta) after 0, 3, 7, or 14 days of starvation. Marked reductions in hepatic glycogen and triglycerides occurred from the seventh day of starvation until the end of the trial (p < 0.05). However, no alterations in hepatic cholesterol or protein were detected throughout the entire experiment (p > 0.05). During fasting, the activities of pyruvate kinase, lactate dehydrogenase, and glycogen phosphorylase a all rose firstly and then fell (p < 0.05). The activities of hepatic fatty acid synthase and acetyl-CoA carboxylase were minimized to their lowest levels at the end of food deprivation (p < 0.05), while lipase was elevated after 7-14 days of fasting (p < 0.05). Catalase, glutathione, and the total antioxidative capacity were increased and maintained their higher values in the later stage of fasting (p < 0.05), whereas malondialdehyde was not significantly changed (p > 0.05). Hepatic vein congestion, remarkable cytoplasmic vacuoles, and irregular cell shape were present in S. hasta which endured 3-7 days of fasting and were less pronounced when food shortage was prolonged. In terms of genes associated with glucose and lipid metabolism, the hepatic phosphofructokinase gene was constantly up-regulated during fasting (p < 0.05). However, the mRNA levels of glycogen synthase and glucose-6-phosphatase were obviously lower when the food scarcity extended to 7 days or more (p < 0.05). Fatty acid synthase, stearoyl-CoA desaturase 1, and peroxisome proliferator-activated receptor γ were substantially down-regulated in S. hasta livers after 7-14 days of food deprivation (p < 0.05). However, genes involved in lipolysis and fatty acid transport were transcriptionally enhanced to varying extents and peaked at the end of fasting (p < 0.05). Overall, starvation lasting 7 days or more could concurrently mobilize hepatic carbohydrates and fat as energy resources and diminished their hepatic accumulation by suppressing biosynthesis and enhancing catabolism and transport, ultimately metabolically and structurally perturbing the liver in S. hasta. This work presents preliminary data on the dynamic characteristics of hepatic glucose and lipid metabolism in S. hasta in response to starvation, which may shed light on the sophisticated mechanisms of energetic homeostasis in fish facing nutrient unavailability and may benefit the utilization/conservation of S. hasta.

T-Allele Carriers of Mono Carboxylate Transporter One Gene Polymorphism rs1049434 Demonstrate Altered Substrate Metabolization during Exhaustive Exercise.

Polymorphism rs1049434 characterizes the nonsynonymous exchange of adenosine (A) by thymidine (T) in the gene for monocarboxylate transporter 1 (MCT1). We tested whether T-allele carriers of rs1049434 demonstrate increased accumulation of markers of metabolic strain. Physically active, healthy, young male subjects (n = 22) conducted a power-matched one-legged cycling exercise to exhaustion. Metabolic substrates in capillary blood, selected metabolic compounds, and indices for the slow oxidative phenotype of vastus lateralis muscle were quantified in samples collected before and after exercise. The genotypes of the rs1049434 polymorphism were determined with polymerase chain reactions. One-legged exercise affected the concentration of muscle metabolites entering the tricarboxylic acid cycle, such as acetyl-co-enzyme A (+448%) and acetyl-L-carnitine (+548%), muscle glycogen (-59%), and adenosine monophosphate (-39%), 30 min post-exercise. Exercise-related variability in the muscular concentration of glycogen, long-chain acyl co-enzyme As and a triglyceride, nicotinamide adenine dinucleotide (NADH), and adenosine monophosphate (AMP) interacted with rs1049434. T-allele carriers demonstrated a 39% lesser reduction in glycogen after exercise than non-carriers when NADH increased only in the non-carriers. Muscle lactate concentration was 150% higher, blood triacyl-glyceride concentration was 53% lower, and slow fiber percentage was 20% lower in T-allele carriers. The observations suggest a higher anaerobic glycolytic strain during exhaustive exercise and a lowered lipid handling in T-allele non-carriers.

EFFECTS OF PETROL CONTAMINATED DIET AND WATER ONGLUCOSE, LIVER GLYCOGEN, PLASMA LACTATE AND LIPID PROFILE IN MALE WISTAR RATS

Exposure to petrol have been shown to cause detrimental health effects. Literature is sparse on whether exposure to petrol causes metabolic disorders. This study investigated the effects of petrol contaminated diet andwater on blood glucose, liver glycogen, plasma lactate, triglycerides and lipid profile in male Wistar rats. The study was divided into two phases. Phase one study consisted of 15 male Wistar rats divided into three groups (n = 5/group). Groups 1-3 were given distilled water, petrol-contaminated diet (20 mL petrol/200 g rodent chow PCD), and petrol-contaminated water (0.5 mL/kg PCW) orally and respectively for .two weeks. In the phase two study, 15 male Wistar rats were divided into three groups (n = 5/group), animals in groups 1-3 received distilled water, petrol contaminated diet, and petrol-contaminated water orally and respectively for four weeks.At the end of the experiment, fasting blood glucose, liver glycogen, plasma lactate, triglycerides and lipid profie were measured.The results of this study showed that the administration of petrol contaminated diet and water caused significant increase in plasma lactate levels, triglycerides (TG),total cholesterol (TC), low density lipoprotein (LDL), very low density lipoprotein (VLDL)and a significant reduction in liver glycogen and high density lipoprotein( HDL) in male Wistar rats. In conclusion, the study revealed that, exposure of rats to petrol contaminated diet and water caused changes in lipid profile, altered glucose and lipid metabolism in male Wistar rats. Exposure to petrol should therefore be restricted or avoided.

Nanoparticle targeting of neutrophil glycolysis prevents lung ischemia-reperfusion injury

Neutrophils exacerbate pulmonary ischemia-reperfusion injury (IRI) resulting in poor short and long-term outcomes for lung transplant recipients. Glycolysis powers neutrophil activation, but it remains unclear if neutrophil-specific targeting of this pathway will inhibit IRI. Lipid nanoparticles containing the glycolysis flux inhibitor 2-deoxyglucose (2-DG) were conjugated to neutrophil-specific Ly6G antibodies (NP-Ly6G[2-DG]). Intravenously administered NP-Ly6G(2-DG) to mice exhibited high specificity for circulating neutrophils. NP-Ly6G(2-DG)–treated neutrophils were unable to adapt to hypoglycemic conditions of the lung airspace environment as evident by the loss of demand-induced glycolysis, reductions in glycogen and ATP content, and an increased vulnerability to apoptosis. NP-Ly6G(2-DG) treatment inhibited pulmonary IRI following hilar occlusion and orthotopic lung transplantation. IRI protection was associated with less airspace neutrophil extracellular trap generation, reduced intragraft neutrophilia, and enhanced alveolar macrophage efferocytotic clearance of neutrophils. Collectively, our data show that pharmacologically targeting glycolysis in neutrophils inhibits their activation and survival leading to reduced pulmonary IRI.

M021 (rhGAA) has a unique glycosylation profile which enables more efficient glycogen reduction and may allow for alternative Pompe ERT dosing strategies

M021 (rhGAA) has a unique glycosylation profile which enables more efficient glycogen reduction and may allow for alternative Pompe ERT dosing strategies

Cotadutide promotes glycogenolysis in people with overweight or obesity diagnosed with type 2 diabetes

Cotadutide is a dual glucagon-like peptide 1 and glucagon receptor agonist under development for the treatment of non-alcoholic steatohepatitis and type 2 diabetes mellitus (T2DM) and chronic kidney disease. Non-alcoholic steatohepatitis is a complex disease with no approved pharmacotherapies, arising from an underlying state of systemic metabolic dysfunction in association with T2DM and obesity. Cotadutide has been shown to improve glycaemic control, body weight, lipids, liver fat, inflammation and fibrosis. We conducted a two-part, randomized phase 2a trial in men and women with overweight or obesity diagnosed with T2DM to evaluate the efficacy and safety of cotadutide compared with placebo and liraglutide. The primary endpoints were change from baseline to day 28 of treatment in postprandial hepatic glycogen (part A) and to day 35 of treatment in fasting hepatic glycogen (part B) with cotadutide versus placebo. Secondary endpoints in part B were changes in fasting hepatic glycogen with cotadutide versus the mono glucagon-like peptide 1 receptor agonist, liraglutide, and change in hepatic fat fraction. The trial met its primary endpoint. We showed that cotadutide promotes greater reductions in liver glycogen and fat compared with placebo and liraglutide. Safety and tolerability findings with cotadutide were comparable to those of previous reports. Thus, this work provides evidence of additional benefits of cotadutide that could be attributed to glucagon receptor engagement. Our results suggest that cotadutide acts on the glucagon receptor in the human liver to promote glycogenolysis and improve the metabolic health of the liver. ClinicalTrials.gov registration: NCT03555994.

Muscle of dark and normal beef differs metabolically

Reduction in muscle glycogen triggered by adverse antemortem handling events alters postmortem energy metabolism and results in a high ultimate pH and dark, firm and dry beef, often referred to as ‘dark-cutting’. However, the relationship between atypical dark (AT) beef, postmortem energy metabolism and underlying tissue characteristics remains somewhat unclear. Cattle harvested in the US and Canada representing normal (pH < 5.6), AT dark (pH 5.6–5.8) and dark cutting (DC; pH > 5.8) beef were analyzed for tissue characteristics related to energy metabolism. Results show AT dark beef is more oxidative but similar to normal beef in glycolytic potential and nucleotide abundance. Mitochondria DNA content (P < 0.05, Canada; P < 0.005, US) and oxidative enzymes for DC and AT dark beef were greater (P < 0.01; Canada and US) compared to normal beef. Myoglobin tracked (P < 0.01) with color classification. These findings show both DC and AT beef are inherently more oxidative and raise the possibility that more oxidative muscle may be more prone to develop dark beef.

Effect of melatonin on the liver histophysiology of adolescent rats exposed to alcohol

The present study evaluated whether melatonin administered during adolescence can prevent the deleterious effects produced by alcohol on the liver. Thirty albino female rats (Rattus norvegicus albinus), 40 days old, virgins, weighing approximately 150±10g, from the Wistar lineage and were divided into the following groups: I – Adolescent rats that did not receive alcohol and euthanized at 60 days of life; II – Adolescent rats subjected to chronic alcohol consumption and euthanized at 60 days of life; III – Adolescent rats subjected to chronic alcohol consumption and simultaneously treated with melatonin, and euthanized at 60 days of life. The collected organs underwent histological processing and to obtain the results, morphometric, histopathological and histochemical analyzes were performed. Alcohol was administered by gavage. intragastric injection at a dosage of 3 g/Kg of ethyl alcohol in the rats of groups II and III for 20 days. Melatonin was administered in daily injections of 0.8 mg/Kg, always at the beginning of the night, intraperitoneally for 20 days. When analyzing the weight of the animals, no significant difference was observed between the groups. The animals in group II presented alterations in the livers such as congestion of the centrilobular vein, hepatocellular ballooning, microgoticular steatosis, leukocyte infiltrate, several pyknotic nuclei in the livers, increase in lobular parenchyma and reduction in non-lobular parenchyma, greater deposition of collagen and reduction of glycogen. Melatonin treatment prevented all these changes. With this, we can conclude that melatonin has great therapeutic potential in the prevention of liver damage in adolescent rats subjected to moderate alcohol consumption, in addition to positive effects on the deposition of collagen and glycogen in the liver.

Clinical and Functional Characterization of Novel AGL Variants in Two Families with Glycogen Storage Disease Type III.

Glycogen storage disease type III (GSDIII) is a uncommon autosomal recessive inherited metabolic disorder, which is caused by variants in the AGL gene. The purpose of this study was to elucidate the clinical and functional features of two novel variants in two families with GSDIIIa. We collected the clinical and laboratory data of the two patients. Genetic testing was performed using GSDs gene panel sequencing, and the identified variants were classified according to the American College of Medical Genetics (ACMG) criteria. The pathogenicity of the novel variants was furthermore assessed through bioinformatics analysis and cellular functional validation experiments. The two patients were hospitalized with abnormal liver function or hepatomegaly, which was characterized by remarkably elevated liver enzyme and muscle enzyme levels, as well as hepatomegaly, and were eventually diagnosed with GSDIIIa. Genetic analysis detected two novel variants of AGL gene in the two patients: c.1484A > G (p.Y495C), c.1981G > T (p.D661Y). Bioinformatics analysis indicated that the two novel missense mutations most likely altered the protein's conformation and therefore made the enzyme it encodes less active. Based on the ACMG criteria, both variants were considered likely pathogenic, in accordance with the functional analysis results, which demonstrated that the mutated protein was still localized in the cytoplasm and that the glycogen content of cells transfected with the mutated AGL was increased compared to cells transfected with the wild-type one. These findings indicated that the two newly identified variants in the AGL gene (c.1484A > G; c.1981G > T) were undoubtedly pathogenic mutations, inducing a slight reduction in glycogen debranching enzyme activity and a mild increase in intracellular glycogen content. Two patients who visited us with abnormal liver function, or hepatomegaly, improved dramatically after treatment with oral uncooked cornstarch, but the effects on skeletal muscle and myocardium required further observation.

Inhibition of GSK3B phosphorylation improves glucose and lipid metabolism disorder

Hepatic glycolipid metabolism disorder is considered as one of the key pathogenic factors for many chronic diseases. Revealing the molecular mechanism of metabolic disorder and exploring drug targets are crucial for the treatment of glucose and lipid metabolic diseases. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been reported to be associated with the pathogenesis of various metabolic diseases. Herein, GAPDH-knockdown ZFL cells and GAPDH-downregulation zebrafish exhibited significant lipid deposition increase and glycogen reduction, thus inducing glucose and lipid metabolism disorders. Using high-sensitivity mass spectrometry-based proteomic and phosphoproteomic analysis, we identified 6838 proteins and 3738 phosphorylated proteins in GAPDH-knockdown ZFL cells. The protein-protein interaction network and DEPPs analyses showed that gsk3baY216 were involved in lipid and glucose metabolism, which was verified by In vitro study. The enzyme activity analysis and cell staining results showed that HepG2 and NCTC-1469 cells transfected with GSK3BY216F plasmid had significantly lower glucose and insulin levels, the decreased lipid deposition, and the increased glycogen synthesis than those transfected with GSK3BY216E plasmid, suggesting that inhibition of GSK3B phosphorylation could significantly improve GSK3B hyperphosphorylation-induced glucose tolerance impairment and insulin sensitivity reduction. To our knowledge, this is the first multi-omic study of GAPDH-knockdown ZFL cells. This study provides insights into the molecular mechanism of glucose and lipid metabolic disorder, and provides potential targets (kinases) for the treatments of human glucose and lipid metabolic diseases.

THE ROLE OF ADRENERGIC RECEPTORS IN THE ACTION OF ADRENALINE ON PLASMA LACTATE, GLUCOSE, LIVER, AND SKELETAL MUSCLE GLYCOGEN IN THE COMMON AFRICAN TOAD BUFO REGULARIS

In mammals, the roles of liver and skeletal muscle glycogen in adrenaline-induced hyperglycaemia are well known. However, in amphibians, there is limited information on the relative contribution of liver and skeletal muscle glycogen in adrenaline-induced hyperglycaemia. This study investigated the effects of adrenaline on blood glucose, plasma lactate, liverand skeletal muscle glycogen and the role of adrenergic receptors in the common African toad, bufo regularis. One hundred and twenty-five adult common African toads (70-100g) of both sexes were randomly collected and used in the study.Blood samples were collected from truncus arteriosus to estimate glucose and lactate levels. Blood glucose was determined immediately by modified glucose oxidase method. Plasma lactate was determined by modification of the Barker-Summerson method. Liver and gastrocnemius muscle glycogen were determined using anthrone reagents method. Adrenaline caused significant increase in blood glucose, lactate levels and significant reduction in liver and muscle glycogen. When toads were pre-treated with propranolol or prazosin, adrenalines reduction in liver and muscle glycogen was significantly reduced while the increase in blood glucose and lactate levels was prevented. Combination of both blockers abolished the increase in blood glucose, lactate levels and blocked reduction in liver and muscle glycogen produced by adrenaline. The results of this study showed that adrenalinecaused liver and skeletal muscle glycogen breakdown, increase in plasma lactate levels which resulted in hyperglycaemia in the common African toad bufo regularis. The study also showed that both alpha- and beta-adrenergic receptors are involved in mediating the effects of adrenaline on blood glucose, plasma lactate, liver, and muscle glycogenolysis and gluconeogenesis.

Rationed and satiated growth hormone transgenic Coho Salmon (Oncorhynchus kisutch) show tissue specific differences in energy stores.

Growth hormone transgenic coho salmon experience increased growth rates, driven primarily through elevated feed intake and feed conversion. However, neuropeptides that signal appetite stimulation have been shown to exhibit variable responses across fed states, suggesting a more complex system mediating growth in these fish. Studies have proposed that growth hormone may have a modulatory role on the energy reserves of fish, possibly through AMP-activated protein kinase (AMPK) activation. AMPK, an energy sensor in cells, has previously been shown to be upregulated in growth hormone transgenic salmon when compared to wild type, however, whether this effect is seen across fed states is unknown. Here, we tested the hypothesis that growth hormone induces an energetic deficit in metabolic tissues, leading to constitutive AMPK activation in growth hormone transgenic salmon. This study compared AMPK activity, ATP, and glycogen, of the liver, heart, and muscle of wild-type, and growth hormone transgenic salmon either fed to satiation or a wild-type ration. The results suggest that white muscle ATP levels in growth hormone salmon are elevated in satiation and rationed conditions. In the liver, growth hormone transgenic salmon fed a rationed wild-type diet experience reductions in ATP level and glycogen. In none of the tissues examined, did AMPK activity change. Taken together, these results indicate that growth hormone transgenic salmon experience metabolic duress when not fed to satiation.

Effect of Requisite Nutrition for Athletes of Endurance Training: A Non-Empirical Review

Weakness during endurance exercise is associated with a reduction in muscle glycogen beyond the physiological basal level, the response to compensate for this effect has been through the increase in carbohydrate uptake. Also, other dietary combinations have shown effectiveness in the required carbohydrate supply in improving the performance of athletes before and during endurance workouts. The search was made in Green Science Hub, PubMed, Free Full PDF, and World Wide Web for randomized trials published from 1995 to 2022 with a basic interest in performance in endurance exercise. All citations amounted to 22 which were examined based on the inclusion criteria of randomization or crossover allocation to diet and the basic result was endurance performance. Four full-text articles qualified for inclusion and were added to the current review. In the days to weeks before testing, one trial with an increased fat diet versus carbohydrate enhanced performance, others proved infinitesimal in effect. There was no advantage in changing protein for carbohydrates during this period, but hazelnut consumption improved performance. In the pre-event meal, fat improved performance in combination with carbohydrate intake. During endurance events, interchanging carbohydrates with protein had different results on performance and should be studied more. Conclusively, carbohydrate provides the highest energy before and during activities for all endurance performance compared to other ones needed in high amount, including water.

Polyethylene microplastics increases the tissue damage caused by 4-nonylphenol in the common carp (Cyprinus carpio) juvenile

Plastic particles have the ability to transfer harmful chemical pollutants due to their high adsorption capacity. Therefore, this study aimed to investigate the effects of combined exposure to polyethylene microplastics (PE-MPs) and 4-nonylphenol (4-NP) on juvenile common carp (Cyprinus carpio) using histopathological and histochemical biomarkers. Fish were separated into a control group and three treatment groups (10 mg/L PE-MPs; 10 mg/L PE-MPs + 200 µg/L 4-NP; 200 µg/L 4-NP) for a two-week continuous exposure experiment followed by two weeks of recovery. The three treatment groups showed histopathological changes compared to the control. These alterations included severe edema, lifting of the outer epithelium, interlamellar fusion and vacuolation, secondary lamellar shortening and complete fusion, increased mucous cell numbers in the gill tissue, enlargement of inner layer stratum periventricular, cell degeneration with pyknotic nuclei, increased blood capillaries, spongiosis in the brain tissue (optic tectum), central vein hemorrhage, shrunken and fatty degeneration of hepatocytes, rosette shapes around small congested blood sinusoids, vacuoles, necrosis, and severe glycogen reduction in the liver tissue. Some tissue changes improved during the two-week recovery period but did not return to normal. In conclusion, the mixture exposure of the PE-MPs and 4-NP on fish carp induced some histological alterations in most studied tissues and post-exposure made improvement in cellular and tissue structure.

Screening chimeric GAA variants in preclinical study results in hematopoietic stem cell gene therapy candidate vectors for Pompe disease

Pompe disease is a rare genetic neuromuscular disorder caused by acid α-glucosidase (GAA) deficiency resulting in lysosomal glycogen accumulation and progressive myopathy. Enzyme replacement therapy, the current standard of care, penetrates poorly into the skeletal muscles and the peripheral and central nervous system (CNS), risks recombinant enzyme immunogenicity, and requires high doses and frequent infusions. Lentiviral vector-mediated hematopoietic stem and progenitor cell (HSPC) gene therapy was investigated in a Pompe mouse model using a clinically relevant promoter driving nine engineered GAA coding sequences incorporating distinct peptide tags and codon optimizations. Vectors solely including glycosylation-independent lysosomal targeting tags enhanced secretion and improved reduction of glycogen, myofiber, and CNS vacuolation in key tissues, although GAA enzyme activity and protein was consistently lower compared with native GAA. Genetically modified microglial cells in brains were detected at low levels but provided robust phenotypic correction. Furthermore, an amino acid substitution introduced in the tag reduced insulin receptor-mediated signaling with no evidence of an effect on blood glucose levels in Pompe mice. This study demonstrated the therapeutic potential of lentiviral HSPC gene therapy exploiting optimized GAA tagged coding sequences to reverse Pompe disease pathology in a preclinical mouse model, providing promising vector candidates for further investigation.

IGF2-tagging of GAA promotes full correction of murine Pompe disease at a clinically relevant dosage of lentiviral gene therapy

Pompe disease is caused by deficiency of acid α-glucosidase (GAA), resulting in glycogen accumulation in various tissues, including cardiac and skeletal muscles and the central nervous system (CNS). Enzyme replacement therapy (ERT) improves cardiac, motor, and respiratory functions but is limited by poor cellular uptake and its inability to cross the blood-brain barrier. Previously, we showed that hematopoietic stem cell (HSPC)-mediated lentiviral gene therapy (LVGT) with codon-optimized GAA (LV-GAAco) caused glycogen reduction in heart, skeletal muscles, and partially in the brain at high vector copy number (VCN). Here, we fused insulin-like growth factor 2 (IGF2) to a codon-optimized version of GAA (LV-IGF2.GAAco) to improve cellular uptake by the cation-independent mannose 6-phosphate/IGF2 (CI-M6P/IGF2) receptor. In contrast to LV-GAAco, LV-IGF2.GAAco was able to completely normalize glycogen levels, pathology, and impaired autophagy at a clinically relevant VCN of 3 in heart and skeletal muscles. LV-IGF2.GAAco was particularly effective in treating the CNS, as normalization of glycogen levels and neuroinflammation was achieved at a VCN between 0.5 and 3, doses at which LV-GAAco was largely ineffective. These results identify IGF2.GAA as a candidate transgene for future clinical development of HSPC-LVGT for Pompe disease.

Fibre type- and localisation-specific muscle glycogen utilisation during repeated high-intensity intermittent exercise.

Glycogen particles are situated in key areas of the muscle cell in the vicinity of the main energy-consumption sites and may be utilised heterogeneously dependent on the nature of the metabolic demands. The present study aimed to investigate the time course of fibre type-specific utilisation of muscle glycogen in three distinct subcellular fractions (intermyofibrillar, IMF; intramyofibrillar, Intra; and subsarcolemmal, SS) during repeated high-intensity intermittent exercise. Eighteen moderately to well-trained male participants performed three periods of 10×45s cycling at ∼105% watt max (EX1-EX3) coupled with 5×6s maximal sprints at baseline and after each period. Muscle biopsies were sampled at baseline and after EX1 and EX3. A higher glycogen breakdown rate in type 2 compared to type 1 fibres was found during EX1 for the Intra (-72 vs. -45%) and IMF (-59 vs. -35%) glycogen fractions (P<0.001) but with no differences for SS glycogen (-52 vs. -40%). In contrast, no fibre type differences were observed during EX2-EX3, where the utilisation of Intra and IMF glycogen in type 2 fibres was reduced, resulting in depletion of all three subcellular fractions to very low levels post-exercise within both fibre types. Importantly, large heterogeneity in single-fibre glycogen utilisation was present with an early depletion of especially Intra glycogen in individual type 2 fibres. In conclusion, there is a clear fibre type- and localisation-specific glycogen utilisation during high-intensity intermittent exercise, which varies with time course of exercise and is characterised by exacerbated pool-specific glycogen depletion at the single-fibre level. KEY POINTS: Muscle glycogen is the major fuel during high-intensity exercise and is stored in distinct subcellular areas of the muscle cell in close vicinity to the main energy consumption sites. In the present study quantitative electron microscopy imaging was used to investigate the utilisation pattern of three distinct subcellular muscle glycogen fractions during repeated high-intensity intermittent exercise. It is shown that the utilisation differs dependent on fibre type, subcellular localisation and time course of exercise and with large single-fibre heterogeneity. These findings expand on our understanding of subcellular muscle glycogen metabolism during exercise and may help us explain how reductions in muscle glycogen can attenuate muscle function even at only moderately lowered whole-muscle glycogen concentrations.

Genetic reduction of muscle glycogen is well tolerated in UK Biobank participants

Genetic reduction of muscle glycogen is well tolerated in UK Biobank participants

Perfluorooctanoic acid-induced lipid metabolism disorder in SD rat liver and its effect on the expression of fatty acid metabolism-related proteins.

Perfluorooctanoic acid (PFOA) can cause lipid metabolism disorders in animal body and affect the lipolysis and synthesis of fatty acids. Peroxisome proliferators-activated receptor (PPAR) plays an extremely important role in this process. This study aims to explore the effects of PFOA on liver lipid metabolism disorders in Sprague Dewley (SD) rats and the expression of PPAR. A total of 40 male SD rats were randomly divided into 4 groups (n=10 in each group): a control group (ddH2O), a low-dose PFOA group [PFOA 1.25 mg/(kg·d)], a middle-dose PFOA group [PFOA 5.00 mg/(kg·d)], and a high-dose PFOA group [PFOA 20.00 mg/(kg·d)]. The rats were fed with normal diet, and PFOA exposure were performed by oral gavage for 14 days, and the rats were observed, weighted and recorded every day during the exposure. After the exposure, the blood was collected, and the livers were quickly stripped after the rats were killed. Part of the liver tissues were fixed in 4% paraformaldehyde for periodic acid-schiff (PAS) staining; the contents of HDLC, LDLC, TG, TC in serum and liver tissues, as well as the activities of their related enzymes were assayed; The expression levels of cyclic adenosine monophosphate-response element binding protein (Cbp), general control of amino acid synthesis 5-like 2 (Gcn5L2), peroxidation peroxisome proliferation factor activated receptor γ (PPAR), silent information regulator 1 (Sirt1) and human retinoid X receptor alpha 2 (Rxrα2) ) were detected by Western blotting. After 14 days of PFOA exposure, the PAS staining positive particles in the cytoplasm and nucleus of SD rats in the medium and high dose groups were significantly reduced compared with the control group. The serum levels of LDLC and TC in the low-dose and middle-dose groups were significantly reduced compared with the control group (all P<0.05), while the high-dose group showed an increasing tendency, without siginificant difference (P>0.05), there was no significant difference in HDLC and TG (both P>0.05). The activities of alkaline phosphatase (AKP) and alanine aminotransferase (ALT) were increased significantly (both P<0.05) compared with control group; the ratio of ALT/aspartate aminotransferase (AST) in the high-dose group was increased significantly (P<0.05), there was no significant difference in LDH and TG (both P>0.05); the HDLC content in the liver tissues in the high-dose group was significantly reduced, compared with the control group (P<0.05); the TC contents in the liver tissues in the low, medium and high-dose groups were significantly increased (all P<0.05), there was no significant difference in LDLC and TG (both P>0.05); the AKP activity in the livers in the medium and high-dose groups was significantly increased (both P<0.05), there was no siginificant difference in LDH, ALT, and the ratio of ALT/AST (all P>0.05); the protein expression levels of Ppar γ, Cbp and Rxrα2 in the liver in the high dose groups were significantly down-regulated compared with the control group (all P<0.05), while the protein expression levels of Sirt1 were significantly up-regulated (all P<0.05). PFOA exposure can cause lipid metabolism disorder and glycogen reduction in SD rat livers, which may be related to the activation of Sirt1 and inhibition of Ppar γ expression, leading to affecting the normal metabolism of fatty acids and promoting glycolysis.