Reduced Glycogen Content Research Articles

Resistin Activates p65 Pathway and Reduces Glycogen Content through Keratin 8

Resistin is associated with metabolic syndrome and inflammatory conditions. Many studies have suggested that resistin inhibits the accumulation of glycogen; however, the exact mechanisms of resistin-induced decrease in glycogen content remain unclear. Keratin 8 is a typical epithelial intermediate filament protein, but numerous studies suggest a vital role of K8 in glucose metabolism. However, it is still not known whether K8 participates in the mediation of resistin-induced reduction of cellular glycogen accumulation. In this study, we found that resistin upregulated expression of the p65 subunit of NF-κB, which led to the promotion of K8 transcriptional expression; in turn, the expression of K8 inhibited glycogen accumulation in HepG2 cells.

Overexpression of the constitutive androstane receptor and shaken 3D-culturing increase biotransformation and oxidative phosphorylation and sensitivity to mitochondrial amiodarone toxicity of HepaRG cells

The liver cell line HepaRG is one of the preferred sources of human hepatocytes for in vitro applications. However, mitochondrial energy metabolism is relatively low, which affects hepatic functionality and sensitivity to hepatotoxins. Culturing in a bioartificial liver (BAL) system with high oxygen, medium perfusion, low substrate stiffness, and 3D conformation increases HepaRG functionality and mitochondrial activity compared to conventional monolayer culturing. In addition, drug metabolism has been improved by overexpression of the constitutive androstane receptor (CAR), a regulator of drug and energy metabolism in the new HepaRG-CAR line. Here, we investigated the effect of BAL culturing on the HepaRG-CAR line by applying a simple and downscaled BAL culture procedure based on shaking 3D cultures, named Bal-in-a-dish (BALIAD).We compared monolayer and BALIAD cultures of HepaRG and HepaRG-CAR cells. CAR overexpression and BALIAD culturing synergistically or additively increased transcript levels of CAR and three of the seven tested CAR target genes in biotransformation. Additionally, Cytochrome P450 3A4 activity was 35-fold increased. The mitochondrial energy metabolism was enhanced; lactate production and glucose consumption switched into lactate elimination and glucose production. BALIAD culturing alone reduced glycogen content and increased oxygen consumption and mitochondrial content. Both CAR overexpression and BALIAD culturing decreased mitochondrial superoxide levels. HepaRG-CAR BALIADs were most sensitive to mitochondrial toxicity induced by the hepatotoxin amiodarone, as indicated by oxygen consumption and mitochondrial superoxide accumulation.These data show that BALIAD culturing of HepaRG-CAR cells induces high mitochondrial energy metabolism and xenobiotic metabolism, increasing its potential for drug toxicity studies.

Beneficial effects of polysaccharide-rich extracts from Apocynum venetum leaves on hypoglycemic and gut microbiota in type 2 diabetic mice

Diabetes is one of the most concerned metabolic diseases worldwide and threaten public health. In the present work, two polysaccharide-rich extracts from Apocynum venetum leaves were extracted using distilled water and alkaline solution (0.05 M NaOH), and fully characterized. Hypoglycemic and hypolipidemic effects of two polysaccharide-rich extracts on high-fat diet and streptozocin-induced type 2 diabetic mice were investigated. Treatment of alkaline extracted polysaccharide-rich products significantly decreased the levels of fasting blood glucose, serum insulin, glycated serum protein, as well as serum lipids profiles including total cholesterol, triacylglycerols, low-density lipoprotein cholesterol, and nonesterified fatty acid. Meanwhile, the reduced glycogen contents in liver were prominently improved, and the oxidative damage were markedly ameliorated by alkaline extracted polysaccharide products in diabetic mice. Furthermore, both polysaccharide-rich extracts could reverse the gut microbiota dysbiosis in diabetic mice by increasing the abundance of genera Odoribacter, Anaeroplasma, Parasutterella, and Muribaculum; while by decreasing the abundance of genera Enterococcus, Klebsiella, and Aerococcus. This study provides new sights for exploitation of Apocynum venetum extracts as a promising anti-diabetic nutraceutical for the treatment of type 2 diabetes and metabolic syndrome.

Parental Males of the Plainfin Midshipman Are Physiologically Resilient to the Challenges of the Intertidal Zone.

The decision of where to rear young is influenced by both the needs of offspring and the costs parents incur in certain rearing environments. Plainfin midshipman fish (Porichthys notatus) provide extended paternal care in rocky intertidal zones, where they experience regular bouts of aquatic hypoxia and air exposure during low-tide events. We investigated the physiological responses of plainfin midshipman males to three conditions for 6 h that simulate what these fish naturally experience during tidal cycles while nesting: normoxia, progressive hypoxia, or air exposure. Hypoxia- and air-exposed fish exhibited shifts in energy metabolites, driven largely by elevated lactate and glucose content and reduced glycogen content in several tissues (muscle, heart, liver, and brain), but the magnitude of these changes was relatively modest. Hematocrit increased most in air-exposed fish relative to normoxia-exposed fish, contributing to an increase in whole-blood hemoglobin concentration. Air exposure reduced swim bladder oxygen content, suggesting that internal O2 stores are drawn on during air exposure. In a second experiment, we found that aquatic surface respiration and gill ventilation frequency increased in hypoxia-exposed fish relative to normoxia-exposed fish. Overall, our results suggest that plainfin midshipman overcome the challenges of the intertidal environment through a variety of physiological strategies and exhibit little physiological disturbance in response to the fluctuating and extreme conditions created by regular low tides.

Intermittent Hypoxic Conditioning Alleviates Post-Traumatic Stress Disorder-Induced Damage and Dysfunction of Rat Visceral Organs and Brain.

Posttraumatic stress disorder (PTSD) causes mental and somatic diseases. Intermittent hypoxic conditioning (IHC) has cardio-, vaso-, and neuroprotective effects and alleviates experimental PTSD. IHC’s ability to alleviate harmful PTSD effects on rat heart, liver, and brain was examined. PTSD was induced by 10-day exposure to cat urine scent (PTSD rats). Some rats were then adapted to 14-day IHC (PTSD+IHC rats), while PTSD and untreated control rats were cage rested. PTSD rats had a higher anxiety index (AI, X-maze test), than control or PTSD+IHC rats. This higher AI was associated with reduced glycogen content and histological signs of metabolic and hypoxic damage and of impaired contractility. The livers of PTSD rats had reduced glycogen content. Liver and blood alanine and aspartate aminotransferase activities of PTSD rats were significantly increased. PTSD rats had increased norepinephrine concentration and decreased monoamine oxidase A activity in cerebral cortex. The PTSD-induced elevation of carbonylated proteins and lipid peroxidation products in these organs reflects oxidative stress, a known cause of organ pathology. IHC alleviated PTSD-induced metabolic and structural injury and reduced oxidative stress. Therefore, IHC is a promising preventive treatment for PTSD-related morphological and functional damage to organs, due, in part, to IHC’s reduction of oxidative stress.

Arginine supplementation prevent diabetic mellitus complications on myopathy and visceral organs (liver&pancreas)in experimental model.

The study was designed to investigate the role of arginine on myopathy and some visceral organs like liver and pancreas in diabetic female rats at different period (15,30,45) days post diabetic induction.In this study female rats ( Rattus norvegicus) were used, total number (30) rats were divided into ( non-diabetic and diabetic ) groups, first group with (6) females as control group and diabetic group with (24) rats, this group subdivided into two groups (12) rats on each one, both of them was injected intraperitoneally with single dose about ( 60 mg/kg) B/W from streptozotocin (STZ) with (12) rats at each period (15,30,45) days post (DM) induction one of this two subgroup were given only tap water but the second subgroup (diabetic and treated with arginine)were given L-arginine dissolved in the drinking water as (10mg/L) after (3) days post (STZ) induction.At (15) day post induction the skeletal muscles revealed to atrophied muscle fibers, infarction, irregular, crowded myonuclei, infiltration of inflammatory cells, tapers endings. Moreover at (30) days sever atrophied muscle fibers, myonuclei was detached from their normal location, thick, dark sarcolemma with zigzag shape, while post (45) day sever alterations included filamentous muscle fibers, some completely destructed, wavy fibers, bifurcated and other rounded or circular muscle fibers. The study determined the effect of arginine on diabetic skeletal muscles, post (15) days of induction, the muscle fibers more regular, clear striation, peripheral myonuclei and parallel muscle fibers. post (30) days, normal muscle fibers, number of satellite cells, normal capillaries, regenerated myotubes. At (45) days the muscle fibers with normal diameter, more intense, less inflammation, normal muscle spindles, less congested blood vessels and normal blood walls thickness.Liver sections related to diabetes group showed post (15) days vacuolated hepatocytes with pyknotic nuclei, dilated sinusoids, increased in kupffer cells, mild fatty changes, bile ducts hyperplasia. Post (30) days sever congestion, necrotic foci, hydropic changes, cloudy hepatocytes, swelling with pyknotic nuclei. At (45) days more severity included necrosis, kupffer cells hyperplasia, sever fibrosis, fatty changes. Role of arginine was determined and its effect on liver, after (15) day normal hepatocytes, more regular hepatic plates, mild inflammation, normal periportal area, post (30) days remarkable regeneration, foci of kupffer cells accumulated, proliferation of bile ductules and mild congestion, at (45) days liver structure resemble the control, most hepatocytes was binucleat, arrange in hepatic cords and normal sinusoid.Harmful effect of (DM) on pancreatic tissue which showed after (15) day, shrinkage of Langerhans islets, atrophied pancreatic acini, destruction and necrosis of beta cells, reduced number and size of islets, changes more severity at (30,45) days, revealed to atrophy stroma replaced by fibrous and adipose connective tissue substance, vacuolated and degenerated islets. Whereas pancreas from diabetic rats treated with arginine after (15) day the changes less obvious, more numerous islet of Lankerhanse, regular acini and at (30,45) day normal pancreatic tissue, most islets with normal boundaries, organized pancreatic acini and the protective role on pancreas was noticed.(DM) caused variable changes in glycogen content in both skeletal muscles and liver at each period (15, 30, 45) days. Moreover the results determined the role of arginine on accumulation and stored of glycogen content. The liver from diabetic rats showed the same results and there was mild reduction to moderate and then sever reduction in glycogen content at each period (15,30,45) days respectively whereas restored in glycogen content recorded on rats treated with arginine.The study evaluated changes in cholesterol and Triglycerides( TG) level and the results showed a significant increase at (P<0.05) in their level in all diabetic rats compared to control while significant decrease at (P<0.05) in level of cholesterol and (TG) in rats with (DM) and treated with arginine. Moreover (HDL) showed a significant decrease at (P<0.05) of diabetic rats and there was increase in its concentration in all diabetes rats treated with arginine. Also insulin growth factor like-1 (IGF-1) in all rats related to control and treated group was estimated, the data clarified a significant decrease at (P<0.05) within diabetic group compared to control, while significant increase in rats related to treated group compared to diabetic group.

Oral ethinylestradiol-levonorgestrel normalizes fructose-induced hepatic lipid accumulation and glycogen depletion in female rats.

The present study investigated the effects of oral ethinylestradiol-levonorgestrel (EEL) on hepatic lipid and glycogen contents during high fructose (HF) intake, and determined whether pyruvate dehydrogenase kinase-4 (PDK-4) and glucose-6-phosphate dehydrogenase (G6PD) activity were involved in HF and (or) EEL-induced hepatic dysmetabolism. Female Wistar rats weighing 140-160 g were divided into groups. The control, EEL, HF, and EEL+HF groups received water (vehicle, p.o.), 1.0 μg ethinylestradiol plus 5.0 μg levonorgestrel (p.o.), fructose (10% w/v), and EEL plus HF, respectively, on a daily basis for 8 weeks. Results revealed that treatment with EEL or HF led to insulin resistance, hyperinsulinemia, increased hepatic uric acid production and triglyceride content, reduced glycogen content, and reduced production of plasma or hepatic glutathione- and G6PD-dependent antioxidants. HF but not EEL also increased fasting glucose and hepatic PDK-4. Nonetheless, these alterations were attenuated by EEL in HF-treated rats. Our results demonstrate that hepatic lipid accumulation and glycogen depletion induced by HF is accompanied by increased PDK-4 and defective G6PD activity. The findings also suggest that EEL would attenuate hepatic lipid accumulation and glycogen depletion by suppression of PDK-4 and enhancement of a G6PD-dependent antioxidant barrier.

Metabolic implications of exposure to wastewater effluent in bluegill sunfish

Effluent from wastewater treatment plants (WWTP) contains a complex mixture of contaminants and is a major worldwide source of aquatic pollution. We examined the effects of exposure to treated effluent from a municipal WWTP on the metabolic physiology of bluegill sunfish (Lepomis macrochirus). We studied fish that were wild-caught or experimentally caged (28 d) downstream of the WWTP, and compared them to fish that were caught or caged at clean reference sites. Survival was reduced in fish caged at the effluent-contaminated site compared to those caged at the reference site. Resting rates of O2 consumption (MO2) were higher in fish from the contaminated site, reflecting a metabolic cost of wastewater exposure. The increases in routine MO2 did not reduce aerobic scope (difference or quotient of maximal MO2 and resting MO2), suggesting that physiological compensations accompanied the metabolic costs of wastewater exposure. Fish exposed to wastewater also had larger hearts and livers. The activity of mitochondrial enzymes (cytochrome c oxidase, citrate synthase) per liver mass was unaltered across treatments, so the increased mass of this organ increased its cumulative oxidative capacity in the fish. Wastewater exposure also reduced glycogen content per liver mass. The effects of caging itself, based on comparisons between fish that were wild-caught or caged at clean sites, were generally subtle and not statistically significant. We conclude that exposure to wastewater effluent invokes a metabolic cost that leads to compensatory physiological adjustments that partially offset the detrimental metabolic impacts of exposure.

Hypoglycemic and hypolipidemic effects of a polysaccharide from Fructus Corni in streptozotocin-induced diabetic rats

Type-2 diabetes mellitus and its related complications including dyslipidemia and oxidative stress have been threating the health of a large number of patients all over the world. In this study, FCPC, one polysaccharide fraction separated from the polysaccharides of Chinese medicine Fructus Corni (FCPs), revealed obvious inhibitory effects against α-amylase and α-glucosidase, and marked insulin-sensitizing effect by increasing insulin secretion and promoting pancreatic β cell proliferation. In addition, in streptozotocin (STZ)-induced diabetic rats, the polysaccharide fraction not only significantly restrained the increase of food (p < 0.05) and water (p < 0.01) intake at 800 mg/kg, but also significantly controlled the increase of levels for sugar (p < 0.01), insulin (p < 0.05) and HOMA-IR value (p < 0.05) in blood at 800 mg/kg on 42th day. Meanwhile, the reduced glycogen contents in liver (p < 0.01) and skeletal (p < 0.01) muscle caused by STZ were prominently improved, while the dyslipidemia status and oxidative damage were markedly ameliorated. Therefore, FCPC could be developed to natural medicines and functional foods in the treatment of diabetes and its complications including dyslipidemia status and oxidative stress.

PROTECTIVE EFFECT OF SWIMMING EXERCISE ON ACRYLAMIDE INDUCED DIAPHRAGMATIC MYOPATHY IN MALE ALBINO RATS

Background: Acrylamide (ACR) naturally forms during high-temperature cooking of food. Many studies concluded that ACR has neurological, reproductive toxicities, and can produce carcinogenesis. However, the toxic effect of acrylamide on diaphragmatic muscle is not fully investigated. Objective: To evaluate the effect of acrylamide on diaphragmatic muscle and the effect of swimming exercise on diaphragmatic muscle after exposure to acrylamide. Materials and methods: Thirty white male albino rats classified into three groups, control, acrylamide, and (swimming & acrylamide) groups. Muscle enzymes were assayed. The diaphragm was weighed, and diaphragmatic muscle contractions were recorded and assessed histologically. Results: Acrylamide group significantly increased Creatine kinase-MB (CK-MB) and LDH insignificantly while Troponin I and T decreased. Acrylamide increased Malondialdehyde (MDA) and decreased Superoxide dismutase (SOD). Swimming exercise with acrylamide increased LDH, SOD, decreased Troponin I and T and MDA. Acrylamide increased diaphragmatic muscle weight and decreased muscle contraction immediately and after 30 minutes of activity, swimming exercise returned the weight of the muscle near to normal and increased contractions. Histologically, acrylamide group showed degeneration, splitting, fatty and cellular infiltration, dilatation and hemorrhage of the blood vessel, reduction of glycogen and decrease expression of desmin. Swimming exercise improved the histological architecture of the diaphragmatic muscle, increased glycogen content and the expression of desmin. Conclusion: Acrylamide induced muscle myopathy by oxidative stress, muscle dystrophy, reduction of glycogen content and decreased desmin expression with reduction of diaphragmatic muscle contraction. Swimming exercise ameliorated the effect of acrylamide on diaphragmatic muscle by reversing the previous undesired effects of acrylamide.

Potential Protective Role of Sitagliptin (Januvia) Against Acetaminophen-Induced Hepatotoxicity in Adult Albino Rats

Acetaminophen (APAP) is a commonly used analgesic-antipyretic drug. Overdose of APAP is significant global clinical problem in humans. Sitagliptin (Sitg) an anti-diabetic drug, has shown protective effects against organs toxicities. This work aimed to evaluate the protective effect of Sitg against APAP-induced hepatotoxicity. Forty male rats were divided into four equal groups. Group-I (control; C-GP; distilled water), Group-II (Sitg-GP; 20-mg/kg), Group-III (APAPGP; 500-mg/kg), and Group-IV (Sitg+APAP-GP; 20-mg/kg+500-mg/kg) pretreated with Sitg followed 2-hour later by APAP. The dosages were given once daily by gavage for 15 days and then blood and liver specimens were collected. Liver biomarkers were assayed in sera and included enzymes (aspartate transaminase=AST; alanine transaminase=ALT; alkaline phosphatase=ALP; gamma-glutamyltransferase=GGT; lactate dehydrogenase=LDH), bilirubin (total bilirubin=TB; direct bilirubin=DB; indirect bilirubin=IB), and proteins (total protein=TP; albumin=ALB; globulin=GLB). Oxidative stress biomarkers were estimated in homogenates and included antioxidants (superoxide dismutase=SOD; catalase=CAT; glutathione peroxidase=GPx; glutathione-S-transferase=GST; glutathione=GSH) and oxidative malondialdehyde (MDA) besides tissue total redox status (total oxidative status=TOS; total antioxidant capacity=TAC; oxidative stress index=OSI; OSI=TOS/TAC). The hepatic lesions were semi-quantitatively scored. In APAP-GP, concentrations of all enzymes and bilirubin, MDA, TOS, and OSI were significantly increased, while levels of all proteins, antioxidants, and TAC were significantly decreased. Histopathological changes showed distorted architecture, increased fibrous deposition, and reduced glycogen contents. Pretreatment with Sitg markedly prevented APAP-induced biochemical and histopathological abnormalities. Sitg possess remarkable hepatoprotective effects against APAPinduced hepatotoxicity and may be useful in treatment of APAP-poisoned patients with diabetes mellitus.

A cAMP/CRP-controlled mechanism for the incorporation of extracellular ADP-glucose in Escherichia coli involving NupC and NupG nucleoside transporters

ADP-glucose is the precursor of glycogen biosynthesis in bacteria, and a compound abundant in the starchy plant organs ingested by many mammals. Here we show that the enteric species Escherichia coli is capable of scavenging exogenous ADP-glucose for use as a glycosyl donor in glycogen biosynthesis and feed the adenine nucleotide pool. To unravel the molecular mechanisms involved in this process, we screened the E. coli single-gene deletion mutants of the Keio collection for glycogen content in ADP-glucose-containing culture medium. In comparison to wild-type (WT) cells, individual ∆nupC and ∆nupG mutants lacking the cAMP/CRP responsive inner-membrane nucleoside transporters NupC and NupG displayed reduced glycogen contents and slow ADP-glucose incorporation. In concordance, ∆cya and ∆crp mutants accumulated low levels of glycogen and slowly incorporated ADP-glucose. Two-thirds of the glycogen-excess mutants identified during screening lacked functions that underlie envelope biogenesis and integrity, including the RpoE specific RseA anti-sigma factor. These mutants exhibited higher ADP-glucose uptake than WT cells. The incorporation of either ∆crp, ∆nupG or ∆nupC null alleles sharply reduced the ADP-glucose incorporation and glycogen content initially witnessed in ∆rseA cells. Overall, the data showed that E. coli incorporates extracellular ADP-glucose through a cAMP/CRP-regulated process involving the NupC and NupG nucleoside transporters that is facilitated under envelope stress conditions.

Metabolic effects of reduced growth hormone action in fatty liver disease

BackgroundAdult growth hormone (GH) deficiency is associated with fatty liver disease and shows several features of the metabolic syndrome. Vice versa obesity is characterized as a state of low GH function. Here, we aimed to define the role of hepatic GH signaling and its metabolic consequences in non-alcoholic fatty liver disease.MethodsIn humans, GHR and IGF-1 levels were determined in liver samples of 29 obese patients with non-alcoholic steatohepatitis (NASH) or simple steatosis. Cellular effects of GH on insulin signaling were investigated in GH receptor (GHR) knockdown HepG2 cells.ResultsHepatic IGF-1 expression levels reflecting GH action were significantly lower and fasting glucose concentrations higher in patients with NASH than in patients with simple steatosis. GHR knockdown in hepatocytes resulted in a scenario of high glucose output displayed by reduced glycogen content, increased gluconeogenesis and diminished insulin signaling.ConclusionsOur data suggest that GH signaling in the liver is diminished in patients with NASH and associated with deteriorated hepatic insulin sensitivity and metabolic activity. Reduced hepatic GH action might contribute to insulin resistance in obese patients with NASH.

Elevated seawater temperature, not pCO2, negatively affects post-spawning adult mussels (Mytilus edulis) under food limitation.

Pre-spawning blue mussels (Mytilus edulis) appear sensitive to elevated temperature and robust to elevated pCO2; however, the effects of these stressors soon after investing energy into spawning remain unknown. Furthermore, while studies suggest that elevated pCO2 affects the byssal attachment strength of Mytilus trossulus from southern latitudes, pCO2 and temperature impacts on the byssus strength of other species at higher latitudes remain undocumented. In a 90 day laboratory experiment, we exposed post-spawning adult blue mussels (M. edulis) from Atlantic Canada to three pCO2 levels (pCO2 ~625, 1295 and 2440 μatm) at two different temperatures (16°C and 22°C) and assessed energetic reserves on Day 90, byssal attachment strength on Days 30 and 60, and condition index and mortality on Days 30, 60 and 90. Results indicated that glycogen content was negatively affected under elevated temperature, but protein, lipid, and overall energy content were unaffected. Reduced glycogen content under elevated temperature was associated with reduced condition index, reduced byssal thread attachment strength, and increased mortality; elevated pCO2 had no effects. Overall, these results suggest that the glycogen reserves of post-spawning adult M. edulis are sensitive to elevated temperature, and can result in reduced health and byssal attachment strength, leading to increased mortality. These results are similar to those reported for pre-spawning mussels and suggest that post-spawning blue mussels are tolerant to elevated pCO2 and sensitive to elevated temperature. In contrast to previous studies, however, elevated pCO2 did not affect byssus strength, suggesting that negative effects of elevated pCO2 on byssus strength are not universal.

High Glucose Level Induces Cardiovascular Dysplasia During Early Embryo Development.

The incidence of gestational diabetes mellitus (GDM) has increased dramatically amongst multiethnic population. However, how gestational diabetes mellitus damages the developing embryo is still unknown. In this study, we used yolk sac membrane (YSM) model to investigate angiogenesis in the developing chick embryo. We determined that in the presence of high glucose, it retarded the growth and extension of the embryonic vascular plexus and it also reduced the density of the vasculature in yolk sac membrane model. Using the same strategy, we used the chorioallantoic membrane (CAM) as a model to investigate the influence of high glucose on the vasculature. We established that high glucose inhibited development of the blood vessel plexus and the blood vessels formed had a narrower diameter than control vessels. Concurrent with the abnormal angiogenesis, we also examined how it impacted cardiogenesis. We determined the myocardium in the right ventricle and left atrium were significantly thicker than the control and also there was a reduction in glycogen content in cardiomyocytes. The high glucose also induced excess reactive oxygen species (ROS) production in the cardiomyocytes. We postulated that it was the excess reactive oxygen species that damaged the cardiomyocytes resulting in cardiac hyperplasia.

Effects of stress during pregnancy on hepatic glucogenic capacity in rat dams and their fetuses.

Stress during pregnancy is associated with metabolic dysfunction in the adult offspring in human and other animals. However, little is known about the metabolic effects of pregnancy stress on the mothers and fetuses during pregnancy itself. This study aimed to determine the consequences of the common experimental procedures of injection and single housing in pregnant rats on fetal and maternal hepatic glucogenic capacities. On day (D) 20 of pregnancy, feto‐placental weights and the glycogen content and activities of phosphoenolpyruvate carboxykinase (PEPCK) and glucose‐6‐phosphatase (G6Pase) of fetal and maternal liver were measured in rats pair or single housed from D1 with or without saline injection from D15 to D19. Housing and saline injection both affected hepatic glucogenic capacity. In maternal liver, saline injection but not housing reduced glycogen content and raised G6Pase activity, whereas housing but not treatment increased PEPCK activity. In fetuses, housing and injection interacted in regulating PEPCK activity and reducing hepatic glycogen content and placental weight. Body weight was decreased and hepatic G6Pase increased by injection but not housing in the fetuses. Single‐housed dams ate less than those pair‐housed near term while saline injection elevated maternal plasma corticosterone concentrations. Thus, single housing and saline injection are both stresses during rat pregnancy that alter feto‐placental weight and hepatic glucogenic capacity of the fetuses and dams near term. Routine experimental procedures per se may, therefore, have consequences for offspring hepatic phenotype as well as modifying the outcomes of dietary and other environmental challenges during pregnancy.

Low-Dose Liver-Targeted Gene Therapy for Pompe Disease Enhances Therapeutic Efficacy of ERT via Immune Tolerance Induction

Pompe disease results from acid α-glucosidase (GAA) deficiency, and enzyme replacement therapy (ERT) with recombinant human (rh) GAA has clinical benefits, although its limitations include the short half-life of GAA and the formation of antibody responses. The present study compared the efficacy of ERT against gene transfer with an adeno-associated viral (AAV) vector containing a liver-specific promoter. GAA knockout (KO) mice were administered either a weekly injection of rhGAA (20 mg/kg) or a single injection of AAV2/8-LSPhGAA (8 × 1011 vector genomes [vg]/kg). Both treatments significantly reduced glycogen content of the heart and diaphragm. Although ERT triggered anti-GAA antibody formation, there was no detectable antibody response following AAV vector administration. The efficacy of three lower dosages of AAV2/8-LSPhGAA was evaluated in GAA-KO mice, either alone or in combination with ERT. The minimum effective dose (MED) identified was 8 × 1010 vg/kg to reduce glycogen content in the heart and diaphragm of GAA-KO mice. A 3-fold higher dose was required to suppress antibody responses to ERT. Efficacy from liver gene therapy was slightly greater in male mice than in female mice. Vector dose correlated inversely with anti-GAA antibody formation, whereas higher vector doses suppressed previously formed anti-GAA antibodies as late as 25 weeks after the start of ERT and achieved biochemical correction of glycogen accumulation. In conclusion, we identified the MED for effective AAV2/8-LSPhGAA-mediated tolerogenic gene therapy in Pompe disease mice.

Dexamethasone Alters the Appetite Regulation via Induction of Hypothalamic Insulin Resistance in Rat Brain.

Elevated levels of glucocorticoid, a steroid hormone released in response to stress, have been implicated in the pathophysiology of diabetes, which is now known to extend its effect on brain functions. Hence, we aimed to investigate the status of brain insulin signaling in response to dexamethasone (a synthetic glucocorticoid) treatment in female Charles Foster rat. This model exhibited pronounced hyperinsulinemia and glucose intolerance with loss in appetite and body weight. Immunoblotting of insulin receptor (INSR)-PI3kinase-AKT demonstrated reduced insulin signaling in hypothalamus but no change in hippocampus, cortex, and cerebellum in dexamethasone-treated rats as compared to vehicle-treated rats, signifying the diversity of distribution and function of insulin in different brain regions. These results also correlated with appetite change, a key function governed by hypothalamus. Hence, we further explored the hypothalamic feeding circuit and found altered levels of neuropeptide genes (Agrp, Npy, Pomc) and candidate nutrient sensors (GLUT1, SirT1, and PPARγ). There was also a considerable reduction in glycogen content and appetite-regulating neurotransmitters (GABA, glutamate, dopamine) in dexamethasone-treated rats. Thus, concluding that dexamethasone not only induces peripheral insulin resistance but also impairs hypothalamic function of appetite regulation via the interwoven cascade of insulin signaling, neurotransmitters, and neuropeptides. Graphical Abstract Reduced insulin signaling as well as elevated glucocorticoid levels in hypothalamus modulates the key appetite regulating neuropeptides, neurotransmitters, and nutrient sensors resulting into reduced appetite and bodyweight.

Effect of HFD/STZ on expression of genes involved in lipid, cholesterol and glucose metabolism in rats

Aims: The aim of the study was to evaluate lipid, cholesterol and glucose metabolism in a novel rat model of non-alcoholic fatty liver disease (NAFLD).Main methods: Rats (Wistar) were fed high fat/cholesterol diet (HFD) and a single low dose (35mg/kg) of streptozotocin (STZ). Collagen and glycogen content, oxidative stress and glucokinase activity were measured using biochemical assays. Other metabolic pathways were assessed by qRT-PCR.Key findings: HFD/STZ treated rats, compared to control ones, showed an increase in expression of biomarkers of inflammation (TNFα, IL6), fibrosis (TGFβ), mitochondrial stress (UCP2) and oxidative stress (GSH and carbonylated proteins) but not of ER stress (CHOP, XBP1). Additionally, HFD/STZ treatment caused a reduction in glycogen content, glucokinase activity (a limiting step in glycolysis) and expression of ChREBP gene (a de novo lipogenesis regulator), suggesting a modified glycolytic pathway.The cholesterol biosynthesis in HFD/STZ treated rats was inhibited (reduced expression of SREBP-2-regulated HMGCoA red and LDLr), instead the cholesterol catabolism was increased, as shown by the mRNA induction of the CYP7A1 and CYP8B1 (key genes for BA acid).A reduced gene expression of FXR-dependent SHP (a key gene for feedback inhibition of CYP7A1 and CYP8B1) and of bile acids (NTCP, OATP1A1, BSEP) and cholesterol (ABCA1) transporters was found.Significance: These results widely extend the characterization of HFD/STZ rat model, which might mimic the NAFLD/NASH in diabetic humans.

Effect of sustained training on glycolysis and fatty acids oxidation in swimming muscles and liver in juvenile tinfoil barb Barbonymus schwanenfeldii (Bleeker, 1854)

The present study examines the effect of sustained exercise on glycolysis and fatty acids oxidation in the swimming muscles and liver in juvenile tinfoil barb (Barbonymus schwanenfeldii). The subjects were divided into one control group (water current speed of 0.0bl s-1, body length per second) and two training groups (1.0 and 2.0bls-1), respectively. Results showed that the glycolysis was stimulated by high-speed training in the white muscle, accompanied by significantly increased activities of hexokinase, pyruvate kinase, and reduction in glycogen contents in training groups (P<0.05). On the contrary, the extreme fatty acids oxidation was observed in the red muscle in high-speed training group, showed significant reduction in crude lipid content with a significant increase in the activities of hormone-sensitive lipase, β-hydroxyacyl-CoA dehydrogenase, and cytochrome C oxidase in 2.0 bl s-1 group (P<0.05). In addition, the saturated fatty acids in the red muscle and monounsaturated fatty acids in the white muscle were used preferentially during sustained training, respectively. Furthermore, the glycogen content within the liver was also significantly reduced with increasing training intensities (P<0.05). These results suggested that glycogen and fatty acids were all used as a fuel to support sustained swimming in two functional muscles in B. schwanenfeldii, but higher glycolysis and fatty acids oxidation were seen in white and red muscles during high-speed swimming, respectively. Furthermore, the hepatic glycogen played an important role in the supply of energy in sustained training periods in B. schwanenfeldii.