Phosphoenolpyruvate Carboxykinase mRNA Expression Research Articles

Metabolic remodeling caused by heat hardening in the Mediterranean mussel Mytilus galloprovincialis.

Organisms can modify and increase their thermal tolerance faster and more efficiently after a brief exposure to sublethal thermal stress. This response is called 'heat hardening' as it leads to the generation of phenotypes with increased heat tolerance. The aim of this study was to investigate the impact of heat hardening on the metabolomic profile of Mytilus galloprovincialis in order to identify the associated adjustments of biochemical pathways that might benefit the mussels' thermal tolerance. Thus, mussels were exposed sequentially to two different phases (heat hardening and acclimation phases). To gain further insight into the possible mechanisms underlying the metabolic response of the heat-hardened M. galloprovincialis, metabolomics analysis was complemented by the estimation of mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK) and alternative oxidase (AOX) implicated in the metabolic pathways of gluconeogenesis, glycolysis and redox homeostasis, respectively. Heat-hardened mussels showed evidence of higher activity of the tricarboxylic acid (TCA) cycle and diversification of upregulated metabolic pathways, possibly as a mechanism to increase ATP production and extend survival under heat stress. Moreover, formate and taurine accumulation provide an antioxidant and cytoprotective role in mussels during hypoxia and thermal stress. Overall, the metabolic responses in non-heat-hardened and heat-hardened mussels underline the upper thermal limits of M. galloprovincialis, set at 26°C, and are in accordance with the OCLTT concept. The ability of heat-hardened mussels to undergo a rapid gain and slow loss of heat tolerance may be an advantageous strategy for coping with intermittent and often extreme temperatures.

Deacetylated nimbin analog N2 fortifies alloxan-induced pancreatic β-cell damage in insulin-resistant zebrafish larvae by upregulating phosphoenolpyruvate carboxykinase (PEPCK) and insulin levels

This study aims to evaluate the protective behaviour of N2, a semi-natural analog of nimbin, for its anti-diabetic efficacy against alloxan-induced oxidative damage and β-cell dysfunction in in-vivo zebrafish larvae. A 500 μM of alloxan was exposed to zebrafish larvae for 24 h to induce oxidative stress in the pancreatic β-cells and co-exposed with N2 to study the protection of N2 by inhibiting ROS by DCFH-DA, DHE and NDA staining along with Cellular damage, apoptosis and lipid peroxidation. The zebrafish was further exposed to 500 μM alloxan for 72 h to induce β-cell destruction along with depleted glucose uptake and co-exposed to N2 to study the protective mechanism. Glucose levels were estimated, and PCR was used to verify the mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK) and insulin. Alloxan induced (24 h) oxidative stress in the pancreatic β-cells in which N2's co-exposure inhibited ROS by eliminating O−₂ radicals and restoring the glutathione levels, thus preventing cellular damage and lipid peroxidation. The zebrafish exposed to 500 μM alloxan for 72 h was observed with β-cell destruction along with depleted glucose uptake when stained with 2NBDG, wherein N2 was able to protect the pancreatic β-cells from oxidative damage, promoted high glucose uptake and reduced glucose levels. N2 stimulated insulin production and downregulated PEPCK by inhibiting gluconeogenesis, attenuating post-prandial hyperglycemia. N2 may contribute to anti-oxidant protection against alloxan-induced β-cell damage and anti-hyperglycemic activity, restoring insulin function and suppressing PEPCK expression.

Cyclocarya paliurus triterpenoids suppress hepatic gluconeogenesis via AMPK-mediated cAMP/PKA/CREB pathway

BackgroundAbnormal enhancement of hepatic gluconeogenesis is a vital mechanism of the pathogenesis of Type 2 diabetes mellitus (T2DM); thus, its suppression may present an efficient therapeutic strategy for T2DM. Cyclocarya paliurus (CP), a plant species native to China, has been reported to have anti-hyperglycemia activity. Our previous studies have revealed that Cyclocarya paliurus triterpenic acids (CPT) exert the favorable glucose-lowering activity, but the regulatory effect of CPT on hepatic gluconeogenesis is still unclarified. PurposeThis study aimed to investigate the potential role and mechanism of CPT in gluconeogenesis. Study designIn this study, the ameliorative effect and underlying mechanism of CPT on gluconeogenesis were investigated: high-fat diet and streptozotocin-induced T2DM mice and glucagon-challenged mouse primary hepatocytes. MethodsT2DM model mice with or without oral administration of CPT for 4 weeks were monitored for body weight, glucose and lipid metabolism. Hematoxylin and eosin staining was used to observe liver lipid deposition. Real-time PCR assays were performed to examine the mRNA expression of glucose-6-phosphate (G6Pase), and phosphoenolpyruvate carboxykinase (PEPCK), two key enzymes involved in liver gluconeogenesis. Western blotting was used to determine AMP-dependent protein kinase (AMPK) expression and induction of the glucagon signaling pathway. The possible mechanism of CPT on liver gluconeogenesis was further explored in glucagon-induced mouse primary hepatocytes. ResultsIn vivo and in vitro experiments revealed that CPT treatment significantly reduced fasting blood glucose, total cholesterol and triglyceride levels, and improved insulin resistance. Furthermore, CPT could obviously decreased the mRNA and protein expression of G6Pase and PEPCK, the cyclic AMP content, the phosphorylation level of protein kinase A and cyclic AMP response element-binding protein. But CPT promoted the phosphorylation of AMP-dependent protein kinase (AMPK) and activation of phosphodiesterase 4B. Mechanistically, intervention with Compound C (an AMPK inhibitor) partially blocked the suppressive effect of CPT on hepatic gluconeogenesis. ConclusionThese findings suggested that CPT may inhibit hepatic gluconeogenesis against T2DM by activating AMPK.

The role of apelin in regulating glucose metabolism in common carp ( Cyprinus carpio L.)

Apelin plays pivotal roles in fluid homeostasis, food intake and energy metabolism in mammals. However, the regulatory role of apelin in glucose metabolism in teleosts is still unclear. In this study, we investigated the regulatory role of Pyr-apelin-13 in glucose metabolism of common carp (Cyprinus carpio L.). The results showed that apelin mRNA abundance was significantly increased in the foregut and hepatopancreas after glucose injection. Insulin and glucagon also up-regulated apelin mRNA levels in the foregut, hepatopancreas and hepatocytes. In vivo, intraperitoneal injection of Pyr-apelin-13 induced hypoglycaemia through the up-regulation of mRNA expression and activity of hexokinase (HK) coupled with the down-regulation of mRNA expression and activity of glucose-6-phosphatase (G6Pase) in the hepatopancreas. In vitro, upon incubation of the primary hepatocytes with Pyr-apelin-13 (0, 10, 100 and 1000 nM), the mRNA expression of glucokinase (GK) was increased, whereas the mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK) and G6Pase was reduced. For glucose transport, the glucose transporter 2 (GLUT2) mRNA expression increased in the hepatopancreas, intestine, primary enterocytes and hepatocytes after Pyr-apelin-13 treatment. Collectively, our data may provide a basis for further studies on elucidation of the role and mechanism of apelin in glucose metabolism of teleosts.

Effects of microRNA-106b on hepatic gluconeogenesis and its underlying mechanism

Objective: To investigate the potential effects of microRNA-106b (miR-106b) on gluconeogenesis in normal human liver cell line L02 and its underlying mechanisms. Methods: Normal human liver L02 cells were cultured in DMEM containing 10% FBS and transfected with 20 nmol/L of miR-106b mimic or antagomiR-106b, respectively. Twenty-four hours later after transfection, Western blot was performed to detect the levels of proteins or phosphorylated proteins. Quantitative RT-PCR was carried out to measure the mRNA expressions of gluconeogenesis-related genes. Glucose Assay Kit was used to detect the glucose contents in the medium. Results: MiR-106b mimic significantly increased the protein abundances of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase)(P＜0.01,P＜0.01, respectively), enhanced the mRNA expression of phosphoenolpyruvate carboxykinase 1 (PCK1) (P＜0.01), and decreased the mRNA level of glucokinase (GCK) (P＜0.01). AntagomiR-106b dramatically reduced the protein levels of PEPCK and G6Pase (P＜0.01,P＜0.01, respectively), suppressed the mRNA level of PCK1 (P＜0.01), and increased the mRNA level of GCK(P＜0.01). In addition,miR-106b mimic or antagomiR-106b significantly reduced or enhanced the protein levels of signal transducer and activator of transcription 3 (STAT3)(P＜0.01,P＜0.01, respectively).The inhibition of STAT3 by its specific inhibitor abolished the inhibitory effects of antagomiR-106b on hepatic gluconeogenesis. Conclusion: miR-106b increases hepatic gluconeogenesis by inhibiting the STAT3 signaling pathway.

Regulation of glucose and lipid metabolism by insulin and glucagon in vivo and in vitro in common carp Cyprinus carpio L.

Our objective is to study the low metabolic utilization of dietary carbohydrates in fish. The regulation of key enzymes involved in glucose and lipid metabolism in the common carp (Cyprinus carpio L.), known to be relatively tolerant to dietary carbohydrates, were assessed. We performed intraperitoneal (i.p.) administration of insulin and glucagon to common carp and also subjected common carp primary hepatocytes to insulin or glucagon. The results showed that insulin administration induced hypoglycaemia through up-regulation of the expression of the glycolysis genes glucokinase (GK) and hexose kinase (HK), coupled with increased gene expression of fatty acid synthase (FAS), acetyl-CoA carboxylase-1 (ACC-1), sterol-regulator element-binding protein-1 (SREBP-1). Insulin also limited the expression of the gluconeogenesis genes phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), coupled with decreased gene expression of lipoprotein lipase (LPL) and carnitine palmitoyl transferase I (CPT-1). However, glucagon had the opposite effect. The results showed that glucagon induced hyperglycemia with increased expression of PEPCK and G6Pase and increased lipolytic capacity as indicated by lower mRNA levels of SREBP-1. Glucagon (i.p.) significantly increased the activity of PEPCK and LPL in hepatopancreas. In addition, the mRNA expression of HK showed an up-regulated trend and the mRNA expression of PEPCK and G6Pase showed a down-regulated trend in the group of glucose (i.p.). This study demonstrates that insulin and glucagon possess the intrinsic ability to regulate hepatic energy metabolism in common carp, the regulation of which seems to be similar to that of the mammals at least at the molecular level.

1720-P: The Modulation in Glucose Metabolism by B1 Kinin Receptor Does Not Depend in Hepatic Insulin Signaling

Background: The kinin B1 receptor (B1R), an inducible effector of Kallikrein-Kinin System during inflammation, has been blamed also to influence glucose metabolism and leptin sensitivity. Aim: To investigate the effects of cafeteria diet (CAF) on hepatic glucose metabolism in B1R knockout mice (B1RKO). Methods: Two months old male C57Bl/6 wild type and B1RKO mice were fed with standard chow (SC) or CAF ad libitumfor 14 weeks (WT-SC n=7; B1RKO-SC n=8; WT-CAF n=7; B1RKO-CAF n =10). We performed glucose tolerance test (GTT) and insulin tolerance test (ITT) at the last week before organs collection. HOMA IR index was calculated. Quantitative PCR was used to determine hepatic expression of glucose-6-phospatase (G6Pase), glucokinase (GK), phosphoenolpyruvate carboxykinase (PEPCK), fructose 1,6-bisphosphatase (FBPase1) and hepatocyte nuclear factor 4 alpha (HNF4A). We also performed western blot to analyze AKT phosphorylation in liver. Two-way ANOVA was used to analyze differences between groups. Values were expressed as mean ± SEM and p ≤0.05 was considered statistically significant. Results: Although the increment of glucose area under the curve during GTT was lower in B1RKO-CAF than WT-CAF (WT-SC 46.246 ± 4.302 vs. B1RKO-SC 35.699 ± 3.383; p=0.03; and B1RKO-CAF 28.521 ± 5.338 vs. WT-CAF 56.564 ± 3.477; AUC p=0.0001), B1RKO mice presented a similar decay in glucose levels during ITT as well as HOMA-IR values . While there was a decrease in liver mRNA expression of G6Pase and PEPCK, GK expression increased in mice fed with CAF diet, without differences between genotypes. FBPase1 and HNF4A mRNA expression were not different between groups. Liver AKT phosphorylation increased with CAF in both C57Bl/6 wild type and B1RKO mice. Conclusion: The increased glucose uptake of B1RKO mice during GTT might not be related to insulin signaling in the liver, since no changes were observed in insulin resistance or in the hepatic expression of gluconeogenesis regulatory enzymes. Disclosure P. Espíndola Correia: None. C.B. Gomes: None. P.N. Merello: None. G.R. Natividade: None. C.C. Barros: None. F. Gerchman: None. Funding Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (16-0397)

Maternal nicotinamide supplementation during late gestation and early lactation alters hepatic glucose and lipid metabolism in kids

The objective of this study was to determine whether maternal nicotinamide (NAM) supplementation in does during the late pregnancy and early lactation results in differences in intestinal glucose transporters and hepatic genes and enzymes regulating glucose and fatty acid metabolism of kids. Fifteen multiparous does were paired into 5 blocks based on similarities in BW, previous milking yield, and the number of fetuses then randomly assigned within block to 1 of 3 treatments: control (C, no supplementation), postpartum (P, supplemented post-kidding), and entire-perinatal (EP, supplemented from d -21 to 28 around kidding). The NAM at 5 g/d were drenched to does in P and EP daily at 0700 h. After kidding, the kids were separated from their dams, named LC, LP, and LEP, respectively, and fed equal amounts of milk from their mothers until 28 days of age. The DMI and milk of the does were measured weekly, and the blood and tissue samples of the kids were taken at d 28. Data were analyzed using the MIXED procedure of SAS. For the does, the DMI and lactation performance of does were not affected (P > 0.10). For the kids, the plasma triglyceride (TG) concentration was greater in LEP than in LC and LP (P < 0.01). The enzyme activity of alanine transaminase was decreased and lipase was increased in both LP and LEP (P < 0.01). The Glucose transporter 2 (GLUT2) relative mRNA expression in the jejunum was increased in LP (P < 0.01), and the sodium-dependent glucose transporters 1 relative mRNA expression was greater in both LP and LEP than in LC (P < 0.01). The hepatic free fatty acid was increased in LP and LEP, and glycogen tended to decrease (P = 0.05 and 0.06, respectively). Liver TG and cholesterol were not affected (P> 0.10). The hepatic enzyme activity of 1- acylglycerol-3-phosphate acyltransferases 6 was decreased in LEP (P = 0.04), and hormone-sensitive lipase activity was increased in LP compared that in LC (P = 0.04). Furthermore, the hepatic relative mRNA expression of phosphoenolpyruvate carboxykinase, glycogen synthase and GLUT2 were reduced in LP and LEP, (P < 0.05). The fatty acid synthase relative mRNA expression was downregulated in LEP (P = 0.05) and microsomal triglyceride transfer protein was upregulated in LEP (P < 0.01). The relative mRNA expression of peroxisome proliferator- activated receptor-γ coactivator α and forkhead box protein O1 were also reduced by maternal NAM supplementation in both LP and LEP (P ⩽ 0.05). These findings suggested that NAM supplementation during late gestation and early lactation inhibited hepatic fat synthesis and promoted lipolysis of kids. Further research on glucose metabolism is needed.

Myricitrin Ameliorates Hyperglycemia, Glucose Intolerance, Hepatic Steatosis, and Inflammation in High-Fat Diet/Streptozotocin-Induced Diabetic Mice.

To test the hypothesis that myricitrin (MYR) improves type 2 diabetes, we examined the effect of MYR on hyperglycemia, glucose intolerance, hepatic steatosis, and inflammation in high-fat diet (HFD) and streptozotocin (STZ)-induced type 2 diabetic mice. Male C57BL/6J mice were randomly divided into three groups: non-diabetic, diabetic control, and MYR (0.005%, w/w)-supplemented diabetic groups. Diabetes was induced by HFD and STZ, and MYR was administered orally for 5 weeks. Myricitrin exerted no significant effects on food intake, body weight, fat weight, or plasma lipids levels. However, MYR significantly decreased fasting blood glucose levels, improved glucose intolerance, and increased pancreatic β-cell mass compared to the diabetic control group. Myricitrin administration also markedly increased glucokinase mRNA expression and activity as well as lowered glucose-6-phosphatase and phosphoenolpyruvate carboxykinase mRNA expression and activity in the liver. In addition, liver weight, hepatic triglyceride content, and lipid droplet accumulation were markedly decreased following MYR administration. These changes were seemingly attributable to the suppression of the hepatic lipogenic enzymes—fatty acid synthase and phosphatidate phosphohydrolase. Myricitrin also significantly lowered plasma MCP-1 and TNF-α levels and the mRNA expression of hepatic pro-inflammatory genes. These results suggest that MYR has anti-diabetic potential.

Protocatechuic acid exhibits hepatoprotective, vasculoprotective, antioxidant and insulin-like effects in dexamethasone-induced insulin-resistant rats

Protocatechuic acid (PCA), the natural phenolic antioxidant, reportedly exhibited hypoglycemic and insulin-like effects. Recent studies have reported its cardioprotective effect in glucocorticoid (GC)-induced hypertensive rats. Nevertheless, its beneficial role has not been investigated in the setting of GCs excess-induced insulin resistance. This study aimed to investigate the possible protective potential and the plausible mechanisms of pretreatment with PCA against GCs-induced insulin resistance, liver steatosis and vascular dysfunction. Insulin resistance was induced in male Wistar rats by a 7-day treatment with dexamethasone (DEX) (1 mg/kg/day, i.p.). PCA (50, 100 mg/kg/day, orally) was started 7 days before DEX administration and continued during the test period. PCA significantly and dose-dependently attenuated DEX-induced a) glucose intolerance (↓ AUCOGTT), b) hyperglycemia (↓ fasting blood glucose), c) impaired insulin sensitivity [↓fasting plasma insulin and homeostasis model assessment of insulin resistance (HOMA-IR) index)] and d) dyslipidemia (↓total cholesterol, triglycerides, low-density lipoprotein-cholesterol and very low-density lipoprotein-cholesterol). PCA mitigated DEX-induced liver steatosis with associated reduction in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Moreover, PCA ameliorated DEX-induced vascular dysfunction and enhanced ACh-induced relaxation in aortic rings. The metabolic ameliorating effects of PCA might be attributed to the enhanced insulin signaling in soleus muscles (↑AKT phosphorylation) and mitigating gluconeogenesis (↓ hepatic mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). The vasculoprotective effect of PCA might be related to its ability to restore normal mRNA expression of [endothelial nitric oxide synthase (eNOS) and NADPH Oxidase 4 (NOX4)]. PCA restored normal oxidative balance [↓ oxidant species, malondialdehyde (MDA) and (↑ antioxidant superoxide dismutase (SOD)]. The findings herein reveal for the first time that PCA may be taken as a supplement with GCs to limit their metabolic and vascular side effects through its hypoglycemic, insulin-sensitizing, hypolipidemic and antioxidant effects.

Adlay Bran Oil Suppresses Hepatic Gluconeogenesis and Attenuates Hyperlipidemia in Type 2 Diabetes Rats.

This study aimed to examine the antidiabetic effects of various concentrations of adlay bran oil (ABO) in high fat diet and streptozotocin-induced diabetic rats. Dietary supplementation with 10% ABO for 4 weeks effectively decreased the blood triacylglycerol, glucose, and total cholesterol levels in diabetic rats, although body weight remained the same. The mRNA and protein expressions of hepatic glucose transporter 2 (GLUT-2) and phosphoenolpyruvate carboxykinase (PEPCK) were increased and that of glucokinase (GCK) were decreased in diabetic rats. However, 10% ABO treatment reduced the mRNA and protein expressions of GLUT-2 and PEPCK and elevated the expression of hepatic GCK in diabetic rats. Thus, ABO enhanced hepatic glucose metabolism to decrease blood glucose in diabetic rats. In addition, 10% ABO supplementation increased the expression of phosphorylated protein kinase B (Akt) relative to the total Akt levels in the muscles of diabetic rats, indicating enhanced insulin sensitivity. The results indicate that ABO displays a potential for improving hyperlipidemia and hyperglycemia in diabetes by enhancing insulin sensitivity and hepatic glucose metabolism.

Effects of Ginsenoside Rg3 on fatigue resistance and SIRT1 in aged rats

BackgroundGinsenoside Rg3 (Rg3) is one of the key components of a frequently used herbal tonic panax ginseng for fatigue treatment. However, the molecular mechanisms of Rg3 on anti-fatigue effects have not been completely understood yet. Methods and materialsWe built a postoperative fatigue syndrome (POFS) model and tried to elucidate the molecular mechanisms responsible for anti-fatigue effects of Rg3. 160 aged male rats were randomly divided into four groups (n = 40/group): normal group, Rg3-treated normal group (Rg3 group), postoperative fatigue syndrome model group (POFS group) and Rg3-treated postoperative fatigue syndrome model group (POFS + Rg3 group). The open field test (OFT) was used to assess general activity and exploratory behavior of rats in different groups. We then analyzed total cholesterol (TC), serum triglyceride (TG) and lactate dehydrogenase (LDH) in the blood, as well as superoxide dismutase (SOD), malondialdehyde (MDA), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression in skeletal muscles of rats. We also detected the influence of Rg3 on silent information regulator of transcription 1 (sirtuin1, SIRT1) activity and protein 53 (p53) transcriptional activity in vitro. ResultsRg3 significantly increased the journey distance and rearing frequency, while slowed down the rest time. The serum concentrations of TC, TG and LDH were all up-regulated by Rg3. Meanwhile, Rg3 increased concentrations of SOD, but also decreased MDA release out of skeletal muscles. The mRNA expressions of PGC-1α and PEPCK were also enhanced by Rg3. Besides, Rg3 could activate SIRT1 and suppress p53 transcriptional activity in the biological process. Discussion and ConclusionRg3 could improve exercise performance and resist fatigue possibly through elevating SIRT1 deacetylase activity.

Dietary incorporation of whey protein isolate and galactooligosaccharides exhibits improvement in glucose homeostasis and insulin resistance in high fat diet fed mice.

This study was planned to investigate the effectiveness of the whey protein isolate (WPI) of high purity and a galactooligosaccharides (GOS) preparation on glucose homeostasis and insulin resistance in high fat diet (HFD) (45.47% energy from fat) fed conditions in C57BL/6J mice. Fasting blood glucose level, serum insulin, and glucagon-like peptide-1 (enzyme-linked immunosorbent assay) were measured; also, homeostasis model assessment of insulin resistance (HOMA-IR) was determined in different treatment groups. mRNA expression of gluconeogenesis genes in liver and small intestine tissues was analyzed by quantitative real time-polymerase chain reaction. Dietary incorporation of WPI and GOS was observed to significantly resist (P < 0.001) the HFD-induced increase in blood glucose levels indicating a mitigating effect on glycemic load. It is important to note that no additive effects of administration of WPI and GOS could be observed. The administration of WPI and GOS exhibited maximum resistance (37.8%) to the rise in insulin level. Thus, the resistance to the increase in HOMA-IR was also noticed on the dietary incorporation of two functional ingredients . The positive effects on mRNA expression of phosphoenolpyruvate carboxykinase and glucose 6-phosphatase could be detected in liver only. Both types of functional components exhibit potential to improve glucose homeostasis under HFD fed conditions. Resistance to HFD-induced hyperinsulinemia and HOMA-IR is also recorded .

Hypoglycemic and Hypolipidemic Effects of Lycium barbarum Polysaccharide in Diabetic Rats

ObjectiveTo study the antidiabetic effects and the underlying molecular mechanisms of Lycium barbarum polysaccharide (LBP) and its DEAE cellulose elution fraction LBP-IV in diabetic rats induced by high fat diet (HFD) and streptozotocin (STZ). MethodsAfter ig administration of LBP-IV [50, 100, and 200 mg/(kg·d)] and LBP [100 mg/(kg·d)] once daily for consecutive 4 weeks to diabetic rats, the glucose and lipids in blood, mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK), sterol regulatory element binding-protein-1c (SREBP-1c), and fatty acid synthase (FAS) in liver were determined. ResultsIg administration of LBP and LBP-IV significantly decreased the levels of blood glucose, HbA1c, TC, TG, and LDL-C, as well as the hepatic mRNA expression of PEPCK, SREBP-1c, and FAS, whereas significantly increased the oral glucose tolerance of diabetic rats. ConclusionThe findings suggest that the antidiabetic effects of LBP and LBP-IV are associated with the decreased hepatic mRNA expression of PEPCK, SREBP-1c, and FAS in HFD-STZ induced diabetic rats.

Insulin sensitivity improvement of fermented Korean Red Ginseng (Panax ginseng) mediated by insulin resistance hallmarks in old-aged ob/ob mice

BackgroundThe biological actions of various ginseng extracts have been studied for treating obesity and diabetes mellitus. However, few studies have evaluated the effects of fermented Korean Red Ginseng (Panax ginseng Meyer) on metabolic syndrome. The present study evaluated the antiobesity and antidiabetic effects of fermented red ginseng (FRG) on old-aged, obese, leptin-deficient (B6.V-Lepob, “ob/ob”) mice. MethodsThe animals were divided into three groups and given water containing 0%, 0.5%, and 1.0% FRG for 16 wk. The effect of FRG on ob/ob mice was determined by measuring changes in body weight, levels of blood glucose, serum contents of triglycerides, total cholesterol and free fatty acids, messenger RNA (mRNA) expressions of key factors associated with insulin action, such as insulin receptor (IR), lipoprotein lipase (LPL), glucose transporter 1 and 4 (GLUT1 and GLUT4), peroxisome proliferators-activated receptor gamma (PPAR-γ), and phosphoenolpyruvate carboxykinase (PEPCK) in the liver and in muscle, and histology of the liver and pancreas. ResultsFRG-treated mice had decreased body weight and blood glucose levels compared with control ob/ob mice. However, anti-obesity effect of FRG was not evident rather than hypoglycemic effect in old aged ob/ob mice. The hyperlipidemia in control group was attenuated in FRG-treated ob/ob mice. The mRNA expressions of IR, LPL, GLUT1, GLUT4, PPAR-γ, and PEPCK in the liver and in muscle were increased in the FRG-treated groups compared with the control group. ConclusionThese results suggest that FRG may play a vital role in improving insulin sensitivity relative to reducing body weight in old-aged ob/ob mice.

Liver inflammation and metabolic signaling in ApcMin/+ mice: the role of cachexia progression.

The ApcMin/+ mouse exhibits an intestinal tumor associated loss of muscle and fat that is accompanied by chronic inflammation, insulin resistance and hyperlipidemia. Since the liver governs systemic energy demands through regulation of glucose and lipid metabolism, it is likely that the liver is a pathological target of cachexia progression in the ApcMin/+ mouse. The purpose of this study was to determine if cancer and the progression of cachexia affected liver endoplasmic reticulum (ER)-stress, inflammation, metabolism, and protein synthesis signaling. The effect of cancer (without cachexia) was examined in wild-type and weight-stable ApcMin/+ mice. Cachexia progression was examined in weight-stable, pre-cachectic, and severely-cachectic ApcMin/+ mice. Livers were analyzed for morphology, glycogen content, ER-stress, inflammation, and metabolic changes. Cancer induced hepatic expression of ER-stress markers BiP (binding immunoglobulin protein), IRE-1α (endoplasmic reticulum to nucleus signaling 1), and inflammatory intermediate STAT-3 (signal transducer and activator of transcription 3). While gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression was suppressed by cancer, glycogen content or protein synthesis signaling remained unaffected. Cachexia progression depleted liver glycogen content and increased mRNA expression of glycolytic enzyme PFK (phosphofrucktokinase) and gluconeogenic enzyme PEPCK. Cachexia progression further increased pSTAT-3 but suppressed p-65 and JNK (c-Jun NH2-terminal kinase) activation. Interestingly, progression of cachexia suppressed upstream ER-stress markers BiP and IRE-1α, while inducing its downstream target CHOP (DNA-damage inducible transcript 3). Cachectic mice exhibited a dysregulation of protein synthesis signaling, with an induction of p-mTOR (mechanistic target of rapamycin), despite a suppression of Akt (thymoma viral proto-oncogene 1) and S6 (ribosomal protein S6) phosphorylation. Thus, cancer induced ER-stress markers in the liver, however cachexia progression further deteriorated liver ER-stress, disrupted protein synthesis regulation and caused a differential inflammatory response related to STAT-3 and NF-κB (Nuclear factor—κB) signaling.

Hepatic phosphoenolpyruvate carboxykinase expression after gastric bypass surgery in rats with type 2 diabetes mellitus.

The objective of this study was to investigate the mRNA expression of hepatic phosphoenolpyruvate carboxykinase (PEPCK) after gastric bypass surgery (GBS) in rats with type 2 diabetic mellitus (T2DM). Thirty-six male Goto-Kakizaki rats, aged 12 weeks, were randomly divided into the GBS, sham operation with diet restriction (SO), and sham operation alone (control) groups (N = 12 per group). Liver specimens from all rats were obtained during the operation and 8 weeks after operation. Blood lipid levels were measured before and 8 weeks after operation. Fasting blood glucose (FBG), food intake, and body weight were recorded at weekly time points after operation. The blood glucose area under the curve (AUC) was calculated, and insulin sensitivity indices (ISI) were assessed. The expression PEPCK mRNA and protein were measured by real-time polymerase chain reaction and western blot. Compared with those of the SO and control groups, the blood lipid levels and the FBG in the GBS group was significantly decreased (P < 0.05), as was the AUC (P < 0.05), whereas the ISI was significantly increased (P < 0.05). PEPCK mRNA and protein levels in the GBS group were lower than those in the control group, whereas those in the SO group were significantly higher than those in controls (P < 0.05). In conclusion, GBS can reduce blood glucose in T2DM rats while improving glucose tolerance and hyperglycemia, and the mechanism appears to be associated with a decrease of hepatic PEPCK mRNA and protein expression.

Discovery of a phosphodiesterase 9A inhibitor as a potential hypoglycemic agent.

Phosphodiesterase 9 (PDE9) inhibitors have been studied as potential therapeutics for treatment of diabetes and Alzheimer’s disease. Here we report a potent PDE9 inhibitor 3r that has an IC50 of 0.6 nM and >150-fold selectivity over other PDEs. The HepG2 cell-based assay shows that 3r inhibits the mRNA expression of phosphoenolpyruvate carboxykinase and glucose 6-phosphatase. These activities of 3r, together with the reasonable pharmacokinetic properties and no acute toxicity at 1200 mg/kg dosage, suggest its potential as a hypoglycemic agent. The crystal structure of PDE9-3r reveals significantly different conformation and hydrogen bonding pattern of 3r from those of previously published 28s. Both 3r and 28s form a hydrogen bond with Tyr424, a unique PDE9 residue (except for PDE8), but 3r shows an additional hydrogen bond with Ala452. This structure information might be useful for design of PDE9 inhibitors.

Long-acting hypoglycemic effects of PEGylated FGF21 and insulin glargine in mice with type 1 diabetes

ObjectiveIn this study, we compared the long-acting hypoglycemic effect of PEGylated FGF21 (PEG-FGF21) with insulin glargine in mice with STZ-induced type 1 diabetes. MethodsPEG-FGF21 and insulin glargine were administered once daily for two months, and blood glucose was measured prior to the next administration. Real-time PCR was used to measure mRNA expression of glucokinase (GK), glucose 6-phosphatase (G6pase), phosphoenolpyruvate carboxykinase (PEPCK), glucose transporter 1 (GLUT1) and glucose transporter 4 (GLUT4). ResultsDuring long-term treatment, the blood glucose of untreated mice remained at 25.0 to 28.0mmol/L for the whole experiment, and the blood glucose of mice treated with insulin glargine remained at 16.5 to 18.0mmol/L. However, mice treated with PEG-FGF21 had lower blood glucose levels of 8.0 to 9.0mmol/L on day 10 and maintained this level until the end of the experiment. qRT-PCR showed that PEG-FGF21 up-regulated mRNA expression of GK and GLUT1, and down-regulated mRNA expression of G6Pase and PEPCK. Insulin glargine up-regulated mRNA expression of GLUT4, but had no effect on GK, G6Pase, PEPCK or GLUT1. ConclusionsPEG-FGF21 has a better long-acting efficacy than insulin glargine. PEG-FGF21 achieves glucose clearance by accelerating glycolysis by up-regulating expression of GK and GLUT1 and inhibiting gluconeogenesis via down-regulation of G6Pase and PEPCK expression.

The role of phosphoenolpyruvate carboxykinase in neuronal steroidogenesis under acute inflammation

Phosphoenolpyruvate carboxykinase (PEPCK) is a key gluconeogenic enzyme found in many tissues throughout the body including brain. In the present study, we have investigated the effect of bacterial lipopolysaccharide (LPS) on PEPCK and its role in neuronal steroidogenesis. Adult female albino rats were administered LPS (5mg/kg body weight) to induce acute inflammation. LPS administration resulted in a significant increase of PEPCK mRNA expression with concomitant increase in mRNA levels of steroidogenic acute regulatory (StAR) protein and other steroidogenic enzymes including 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) and aromatase in brain tissue. Further, the inhibition of PEPCK expression by glipizide significantly decreased the mRNA expression of steroidogenic proteins and concurrently increased the mRNA levels of proinflammatory cytokines under LPS administration. The results of this study suggest a novel finding that PEPCK may have an important role in neuronal steroidogenesis; which serves as an adaptive response under inflammation.