Glucose Transporter mRNA Levels Research Articles

Effects of UBE3A on the insulin resistance in polycystic ovary syndrome through the ubiquitination of AMPK

BackgroundPolycystic ovary syndrome (PCOS) is a reproductive hormonal abnormality and a metabolic disorder, which is frequently associated with insulin resistance (IR). We aim to investigate the potential therapeutic effects of Ubiquitin-protein ligase E3A (UBE3A) on IR in the PCOS rats via Adenosine 5‘-monophosphate (AMP)-activated protein kinase (AMPK) activation.MethodsThe PCOS and IR rats model was established by dehydroepiandrosterone (DHEA) and high fat diet (HFD) treatment, and the fat rate, glucose tolerance and insulin tolerance were measured. The IR rats numbers were calculated. Besides, the mRNA levels of glucose transporter 4 (GLUT4) and UBE3A were detected by RT-qPCR. Furthermore, the relationship between was demonstrated by co-IP assay. The phosphorylation and ubiquitination of AMPK were analyzed by western blot.ResultsUBE3A was up-regulated in the PCOS rats. UBE3A knockdown significantly decreased the fat rate, glucose tolerance and insulin tolerance in the PCOS and IR rats. Additionally, the GLUT4 levels were significantly increased in PCOS + IR rats. Besides, after UBE3A knockdown, the IR rats were decreased, the p-IRS1 and p-AKT levels were significantly up-regulated. Furthermore, UBE3A knockdown enhanced phosphorylation of AMPK through decreasing the ubiquitination of AMPK. AMPK knockdown reversed the role of UBE3A knockdown in the PCOS + IR rats.ConclusionsUBE3A knockdown inhibited the IR in PCOS rats through targeting AMPK. Our study indicated that UBE3A might become a potential biological target for the clinical treatment of PCOS.

Perturbated glucose metabolism augments epithelial cell proinflammatory function in chronic rhinosinusitis

Glucose concentrations are increased in nasal secretions in chronic rhinosinusitis (CRS). However, the glucose metabolism and its contribution to disease pathogenesis in CRS remain unexplored. We sought to explore the glucose metabolism and its effect on the function of nasal epithelial cells in CRS with and without nasal polyps (CRSwNP and CRSsNP). Glucose metabolites were detected with mass spectrometry. The mRNA levels of glucose transporters (GLUTs), metabolic enzymes, and inflammatory mediators were detected by quantitative RT-PCR. The protein expression of GLUTs was studied by immunofluorescence staining, Western blotting, and flow cytometry. Glucose uptake was measured by using fluorescent glucose analog. Human nasal epithelial cells (HNECs) were cultured. Bioenergetic analysis was performed with Seahorse XF analyzer. Gene expression in HNECs was profiled by RNA sequencing. Increased glucose concentrations in nasal secretions was confirmed in both CRSsNP and CRSwNP. GLUT4, GLUT10, and GLUT11 were abundantly expressed in HNECs, whose expression was upregulated by inflammatory cytokines and D-glucose and was increased in CRS. Glucose uptake, glycolysis and tricarboxylic acid cycle metabolites, metabolic enzymes, and extracellular acidification rate and oxygen consumption rates were increased in HNECs in CRSsNP and CRSwNP, with a predominant shift to glycolysis. HNECs treated with high-level apical D-glucose showed enhanced glucose uptake, predominant glycolysis, and upregulated production of IL-1α, IL-1β, TNF-α, CCL20, and CXCL8, which was suppressed by 2-deoxy-D-glucose, an inhibitor of glycolysis. Increased glucose in nasal secretions promotes glucose uptake and predominant glycolysis in epithelial cells, augmenting the proinflammatory function of epithelial cells in CRS.

Effect of dietary soybean saponin Bb on the growth performance, intestinal nutrient absorption, morphology, microbiota, and immune response in juvenile Chinese soft-shelled turtle (Pelodiscus sinensis).

Soybean meal is widely applied in the aquafeeds due to the limitation of fish meal resources. Numerous studies have manifested that dietary soybean saponin, an anti-nutrient factor in soybean meal, may slow growth and induce intestinal inflammation in aquatic animals, but the possible causes are unclear. The juvenile Pelodiscus sinensis (mean initial body weight: 6.92 ± 0.03g) were fed basal diet (CON group) and 2.46% soybean saponin Bb-supplemented diet (SAP group) for 35 days to further explore the effects of dietary soybean saponin Bb on the growth performance, apparent digestibility coefficients, intestinal morphology, the gut microbiota, intestinal transporters/channels, and immune-related gene expression. The results indicated that dietary soybean saponin Bb significantly decreased final body weight, specific growth rate, protein deposition ratio, and apparent digestibility coefficients (dry matter, crude protein, and crude lipid) of nutrients in Pelodiscus sinensis, which may be closely correlated with markedly atrophic villus height and increased lamina propria width in the small intestine. In addition, plasma contents of cholesterol, calcium, phosphorus, potassium, lysozyme, and C3 were significantly decreased in the SAP group compared with the control group. Soybean saponin Bb significantly downregulated the mRNA levels of glucose transporter 2, fatty acid binding protein 1 and fatty acid binding protein 2, amino acid transporter 2, b0,+-type amino acid transporter 1, and sodium-dependent phosphate transport protein 2b in the small intestine. At the same time, the expressions of key transcription factors (STAT1, TBX21, FOS), chemokines (CCL3), cytokines (TNF-α, IL-8), and aquaporins (AQP3, AQP6) in the inflammatory response were increased by soybean saponin Bb in the large intestine of a turtle. Additionally, dietary supplementation of SAP significantly reduced the generic abundance of beneficial bacteria (Lactobacillus, Bifidobacterium, and Bacillus) and harmful bacteria (Helicobacter and Bacteroides). In a nutshell, dietary supplementation of 2.46% soybean saponin not only hindered the growth performance by negatively affecting the macronutrients absorption in the small intestine but also induced an inflammatory response in the large intestine possibly by damaging the intestinal morphology, disturbing the intestinal microbiota and decreasing intestinal epithelial cell membrane permeability.

A comparison between high carbohydrate and high lipid diets reception on the growth, feed utilization and glucose homeostasis of genetically improved farmed tilapia Oreochromis niloticus

This study was performed to compare the effects of high carbohydrate and high lipid diets reception on the growth, feed utilization and glucose homeostasis of genetically improved farmed tilapia Oreochromis niloticus. Three isonitrogenous (ca 30.2% protein) diets were formulated with different levels of starch and lipid: the control (CON, 24.2% starch and 6.57% lipid), high carbohydrate diet (HCD, 33.8% starch and 6.91% lipid), and high lipid diet (HLD, 24.0% starch and 16.5% lipid). Tilapia juveniles (initial mean body weight: 32.2 ± 0.2 g/fish) were randomly divided into 12 rectangular tanks (250 L) with 20 fish per tank, and fed the diets to apparent satiation for 8 weeks. The results showed that mean body weight was lower in the HLD fish (183 g/fish) than in the CON (212 g/fish) and HCD fish (206 g/fish). Feeding ratio and feed efficiency ratio were not affected by different treatments. Both dietary starch and lipid provision in excess exhibited poor protein-sparing effect, as protein efficiency ratio and protein productive value were not affected while whole-body protein percentages were lower in the HCD and HLD fish than in the CON fish. High lipid diets reception exerted a greater impact on proximate composition of the whole fish and intraperitoneal fat deposition, while high carbohydrate diets reception exerted a greater impact on liver size through promoting glycogen deposition. Plasma glucose level sharply increased in the HLD fish (7.17 mmol/L) as compared with the CON fish (4.66 mmol/L). Evidences from the molecular level revealed that hyperglycemia of the HLD fish was probably resulted from hepatic glucose output (represented by mRNA levels of glucose transporter 2 and glucose-6-phosphatase catalytic subunit a2) through stimulating gluconeogenesis (the expression of phosphoenolpyruvate carboxykinase 2) rather than glycogenolysis. In addition, high lipid diets reception suppressed hepatic de novo lipogenesis (mRNA level of fatty acid synthase (fas)) along with muscular glucose transport (mRNA level of glucose transporter 4) and glycogenesis (the expression of glycogen synthase 1), which aggravated the hyperglycemia of the HLD fish. In contrast, high carbohydrate diets reception did not affect the expression of representative genes involved with glycolysis and gluconeogenesis, but sharply upregulated the mRNA abundances of lipogenic acetyl-CoA carboxylase α and fas in the liver of tilapia. Except lipid, glycogen concentration also increased in the liver of the HCD fish as compared with the CON fish. Thus, plasma glucose slightly increased in the HCD fish (5.58 mmol/L) as compared with the CON fish. The overall results of this study suggested that tilapia possessed a better capability to tolerate high carbohydrate diets (33.8%) than high lipid diets (16.5%) based on growth performance and the maintenance of glucose homeostasis. This conclusion might have limitations, because the energy density of diets HCD and HLD was different. Further studies are still warranted to compare the glucose homeostasis of tilapia in response to high carbohydrate and high lipid diets reception on an isoenergetic basis.

Effect of Cinnamomum cassia Stem-Bark Extracts on the Synthesis and Secretion of Insulin in RIN-m5F Cells

Cinnamomum cassia (C. cassia) crude stem-bark extracts possess some hypoglycemic properties through inhibiting the uptake of glucose by the intestines and/or enhancing insulin sensitivity. To further investigate the mechanism through which the hypoglycemic effect is exerted, this research explored the influence of the extracts of the crude stem-bark of C. cassia, with various polarities, on particular aspects of glucose consumption as well as glucose-stimulated insulin synthesis and secretion by RIN-m5F cells. All C. cassia extracts did not enhance glucose consumption when compared to the untreated cells (p˂0.001). However, lower concentrations of the extracts significantly increased mRNA levels of Glucose Transporter 2 (GLUT2) and glucokinase genes. Furthermore, all C. cassia extracts significantly stimulated/increased total insulin synthesis (intracellular and secreted) when compared with the control cells, though the effect was not dose-dependent except for water extracts at higher concentration (p<0.001). The results of this investigation revealed that generally, the extracts upregulated the expression of Musculoaponeurotic fibrosarcoma homolog A (MafA), the transcription factor involved in insulin gene expression, while that of the Pancreatic Duodenal Homeobox-1 (PDX-1) gene was mostly suppressed. In concluding, the results of this study proposes that C. cassia stem-bark extracts may exert hypoglycemic effects through stimulating insulin synthesis and secretion in the RIN-m5F pancreatic beta cells.

Dysregulated GLUT1 may be involved in the pathogenesis of preeclampsia by impairing decidualization

Preeclampsia (PE), a hypertensive complication in pregnancy, is a major contributor to maternal and fetal morbidity and mortality. PE has long been regarded a heterogeneous disorder with a pathogenesis that involves multiple genes and factors. Glucose transporter 1 (GLUT1) is a central rate-limiting pump that is involved in glucose uptake and subsequent utilization. Our previous RNA-seq results demonstrated GLUT1 was significantly downregulated in deciduas from patients with severe PE. Therefore, in this study, we aimed to explore the role of GLUT1 in the occurrence of PE. Our data showed that mRNA and protein levels of GLUT1 were significantly downregulated in the deciduas from patients with severe PE. Additionally, GLUT1 levels were substantially upregulated in human endometrial stromal cells (HESCs) during in vitro decidualization. Moreover, GLUT1 knockdown significantly reduced the mRNA levels of decidualization markers (IGFBP1 and PRL) and aerobic glycolysis-related genes (LDHA and MCT4), as well as decreased glucose uptake and lactate production. Furthermore, upon GLUT1 knockdown, the levels of apoptotic genes P53, P21, and BAX increased whereas the level of BCL2 decreased. Target prediction results and luciferase analysis showed that GLUT1 is one of the targets of miR-140-5p, which is partly responsible for downregulated GLUT1 levels. Collectively, these results demonstrate that GLUT1 exerts a pivotal role in human decidualization by participating in glycolysis, and that GLUT1 deficiency may trigger aberrant glycolysis, thereby leading to destructive decidualization that may impede blastocyst implantation, trophoblast invasion, and subsequent placental development, which are associated with PE. Taken together, these data suggest that GLUT1 might be a promising target for PE therapy.

Glucose and insulin regulate cell proliferation and glucose transporter (GLUT) synthesis in the liver of overfed geese

Abstract In order to detect the role of glucose and insulin in cell proliferation of primary goose hepatocytes, Tianfu Meat Geese were overfed and the primary goose hepatocytes were treated with single insulin (50 nmol/l), single glucose (5 mmol/l), glucose (5 mmol/l) and insulin (50 nmol/l), respectively. The related parameters of cell proliferation and glucose transporter expression were measured. The results showed that after overfeeding, the serum concentration of insulin and glucose increased ( P<Â 0.05), the mRNA level of Cyclin D1 ( CCND1), Glucose transporter 1 ( GLUT1) and Glucose transporter 2 ( GLUT2) increased and the mRNA level of P21 decreased ( P<Â 0.05). Compared with the control group and the single treatment groups of glucose or insulin, the co-treatment of glucose and insulin had more dyed green bromodeoxyuridine (BrdU)-positive cells, higher G2/M phase and proliferative index (PI), indicating that the cell proliferation of primary hepatocytes was more evident. Secondly, compared with the control group, the co-treatment of glucose and insulin significantly increased the mRNA expression levels of CCND1, Cyclin D2 ( CCND2) and Cyclin D3 ( CCND3) ( P<Â 0.05). Compared with the control group, single treatments of glucose or insulin, and the co-treatment with glucose and insulin significantly increased the Cyclin D1 protein content ( P<Â 0.05). Also, compared with the control group, the co-treatment of glucose and insulin increased significantly ( P<Â 0.05) the mRNA levels of GLUT1 and GLUT2. In conclusion, the combined treatment of glucose and insulin had a stronger effect on cell proliferation, and GLUT1 and GLUT2 could indirectly induce cell proliferation of goose hepatocytes by regulating glucose uptake and insulin secretion of hepatocytes.

Treatment with broad-spectrum antibiotics upregulates Sglt1 and induces small intestinal villous hyperplasia in mice.

Although extensive evidence indicates that the gut microbiota plays a crucial role in regulating glucose homeostasis, the exact regulatory mechanism remains unclear. This study aimed to investigate the effect of broad-spectrum antibiotics on the expression of glucose transporters, histomorphology of the small intestine, and glucose metabolism in mice. C57BL/6 mice were administered drinking water with or without a broad-spectrum antibiotic combination for 4 weeks. Thereafter, an oral glucose tolerance test was performed. Body weight, small intestine histopathology, mRNA levels of glucose transporters (SGLT1 and GLUT2) and intestinal transcription factors (CDX1 and CDX2) were evaluated. SGLT1 and CDX1 were upregulated in the small intestine upon antibiotic administration compared with that in the control group. The height and surface area of the jejunal villi were significantly higher upon antibiotic administration than in the control group. Fasting glucose levels were significantly higher upon antibiotic administration than in the control group. The present results indicate that treatment with broad-spectrum antibiotics upregulates SGLT1 and CDX1 and induces hyperplasia in the small intestine, thus increasing fasting blood glucose levels. Our results further the current understanding of the effects of broad-spectrum antibiotics on the gut microbiota and glucose homeostasis that may have future clinical implications.

Dysregulated GLUT1 is Involved in the Pathogenesis of Preeclampsia by Impairing Decidualization

Background: Preeclampsia (PE), a hypertensive complication in pregnancy, is a major contributor to maternal and fetal morbidity and mortality. Thus far, the molecular mechanism underlying PE has not been investigated thoroughly. Glucose transporter 1 (GLUT1) is a central rate-limiting pump for glucose uptake and subsequent utilization. Our previous RNA-seq results demonstrated it was significantly downregulated in the decidua of severe preeclampsia (sPE) patients. Therefore, we aimed to explore the role of GLUT1 in the occurrence of PE. Methods: GLUT1 levels were evaluated by quantitative PCR, Western blotting and immunohistochemical staining in severe preeclamptic decidua. The regulatory role of GLUT1 in decidualization was further studied in human endometrial stromal cells (hESCs). We also explored the regulatory role of miRNA in GLUT1 expression. Findings: We observed a significant downregulation of GLUT1 mRNA and protein levels in the decidual tissues of women with sPE. Additionally, the expression of GLUT1 was substantially induced during in vitro decidualization. Moreover, GLUT1 knockdown in human endometrial stromal cells resulted in significant reduction in the mRNA levels of decidualization markers (IGFBP1 and PRL) and aerobic glycolysis-related genes (LDHA and MCT4), and decreased glucose uptake and lactate production. Furthermore, the expression of apoptotic signaling genes P53, P21 and BAX increased whereas the expression of BCL2 decreased after GLUT1 knockdown. Target prediction results and luciferase analysis showed that GLUT1 is one of the targets of miR-140-5p, which is partly responsible for the impaired GLUT1 level. Interpretation: Collectively, these results demonstrate that GLUT1 exerts pivotal role in human decidualization by participating in glycolysis, and its deficiency may trigger aberrant glycolysis and thus leads to destructive decidualization, which may be a pathogenetic mechanism of PE. These data suggest GLUT1 might be a promising target for PE therapy. Funding: This study was supported by grants from the National Key R&D Program of China (2019YFA0802600 and 2017YFC1001403), and National Natural Science Foundation of China (NSFC: 31871512 and 31671199) to C. Zhang. Support was also obtained by the Shanghai Commission of Science and Technology (17DZ2271100). Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: This study was approved by the Ethics Committee of Ji’nan Maternity and Child Care Hospital and informed written consent forms were obtained from all pregnant women.

MiR-150 regulates glucose utilization through targeting GLUT4 in insulin-resistant cardiomyocytes.

MicroRNAs (miRNAs) play an important role in cardiac function and metabolism. However, whether they regulate insulin resistance (IR) of cardiomyocytes remains unclear. The aim of the present study was to shed light on this issue with a focus on miR-150. We found here that miR-150 level was elevated in myocardium of type 2 diabetes mellitus (T2DM) rat model and in insulin-resistant cardiomyocytes induced by high glucose (25 mM) and high insulin (1 μM). Deregulation of miR-150 downregulated the protein and mRNA levels of glucose transporter 4 (GLUT4) as assessed by western blot, real-time polymerase chain reaction (qPCR), and immunofluorescence assays. Overexpression of miR-150 inhibited glucose utilization in cardiomyocytes as detected by 2-deoxyglucose transport and glucose consumption assays. In contrast, knockdown of miR-150 significantly increased glucose uptake in cardiomyocytes. Moreover, GLUT4 translocation was increased after transfection of miR-150 inhibitor (AMO-150). Collectively, miR-150 reduced glucose utilization by directly decreasing the expression and translocation of GLUT4 in the cardiomyocytes with IR and therefore might be a new therapeutic target for metabolic diseases such as T2DM.

Protective effects of bee bread on testicular oxidative stress, NF-κB-mediated inflammation, apoptosis and lactate transport decline in obese male rats

Oxidative stress, chronic inflammation and apoptosis are associated with obesity. Herein, we investigated the potential protective effect of bee bread, a natural bee product, on testicular oxidative stress, inflammation and apoptosis, as well as lactate transport in the testis of high-fat diet (HFD)-induced obese rats. Adult male Sprague-Dawley rats were either fed with normal chow (NC), HFD, HFD + bee bread (0.5 g/kg b.w./day) or HFD + orlistat (10 mg/kg b.w./day) for 12 weeks. Our results show significant decreases in the activities and mRNA expression of antioxidant genes (Nrf2, Sod, Cat and Gpx), with significant increase in pro-inflammatory (Nf-κb, Tnf-α, iNos, Il-1β) and pro-apoptotic (p53, Bax, Bax/Bcl2, Caspase-8, Caspase-9 and Caspase-3) genes in the testis of HFD group relative to the NC group. Furthermore, proliferating cell nuclear antigen (PCNA) was poorly expressed in the testis of the HFD group relative to the NC group. Similarly, the mRNA levels of glucose transporters (Glut1 and Glut3), monocarboxylate transporters (Mct2 and Mct4) and lactate dehydrogenase type C (Ldhc) decreased significantly, with decrease in lactate utilisation. Treatment with bee bread upregulated testicular antioxidant enzymes, downregulated inflammation and apoptosis, and increased PCNA immunoexpression, in addition to improving lactate transport. Taken together, our results suggest that bee bread is a promising natural product with the potential to improve male fertility.

Orlistat reverses intratesticular lactate transport decline and infertility in male obese rats.

Obesity and its accompanying complications predispose to abnormal testicular glucose metabolism, penile erectile dysfunction and subfertility. This study examined the potentials of orlistat in attenuating erectile dysfunction and fertility decline in high-fat diet (HFD)-induced obesity in male rats. Eighteen adult male Sprague-Dawley rats whose weights were between 250 and 300 g were divided into three groups (n = 6/group) namely: normal control (NC), HFD and HFD + orlistat (10 mg/kg body weight/day co-administered for 12 weeks) (HFD+O). During the 11th and 12th week, mating behaviour and fertility parameters were evaluated, and parameters of glucose metabolism were assessed at the end of the 12th week. Orlistat increased testicular mRNA levels of glucose transporters (Glut1 and Glut3), monocarboxylate transporters (Mct2 and Mct4) and lactate dehydrogenase type C (Ldhc), decreased intratesticular lactate and glucose levels, and LDH activity in obese rats. Furthermore, orlistat increased superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) activities, and total antioxidant capacity (TAC), but decreased malondialdehyde level in the penis of obese rats. Similarly, orlistat improved penile cGMP level, sexual behaviour and fertility outcome in obese rats. Penile cGMP level correlated positively with total mounts and intromissions but correlated negatively with mount/intromission ratio. Orlistat improves fertility potential in obese state by targeting testicular lactate metabolism, penile oxidative stress and sexual behaviour in rats. Therefore, orlistat shows a promising protective effect and may preserve the fertility potential of obese men.

LncRNA-SNHG16 Silencing Inhibits Prostate Carcinoma Cell Growth, Downregulate GLUT1 Expression and Reduce Glucose Uptake.

BackgroundlncRNA-SNHG16 was identified as an oncogene in many cancers, but its involvement in prostate carcinoma is unknown.Material and MethodExpression of lncRNA-SNHG16 and glucose transporter 1 (GLUT-1) in 52 prostate carcinoma tissues and 36 normal prostate tissues was analyzed by RT-qPCR. Transfections were performed to analyze gene interactions. Cell proliferation was analyzed by cell proliferation assay.ResultsOverexpression of lncRNA-SNHG16 effectively distinguished prostate carcinoma patients from normal ones. Expression levels of lncRNA-SNHG16 and GLUT-1 mRNA were significantly and positively correlated across prostate carcinoma tissues. In vitro cancer cell experiments revealed that lncRNA-SNHG16 siRNA silencing downregulated the expressions of GLUT-1 and reduced glucose uptake. lncRNA-SNHG16 siRNA silencing also significantly inhibited prostate carcinoma cell proliferation. However, lncRNA-SNHG16 siRNA silencing did not affect the normal prostate.ConclusionIn conclusion, lncRNA-SNHG16 might be a possible treatment target for prostate cancer.

Effects of dietary starch levels on the growth, plasma metabolites and expression of genes involved in glucose transport and metabolism inPelodiscus sinensisjuveniles

A 10-week feeding trial was conducted to evaluate the growth performance, glucose transport and metabolism of Chinese soft-shelled turtles (Pelodiscus sinensis) exposure to graded levels of dietary starch (0.52%, 7.43%, 14.74%, 22.99% and 31.38%). The 360 turtles (initial body weight, 12.94 ± 0.50 g) with 12 replicates were randomly assigned to five experimental diets. The highest weight gain and specific growth rate (SGR) were observed in 7.43% group and the lowest in 31.38% group. The protein efficiency ratio, whole-body lipid contents, hepatic glycogen contents and the 4-hr postprandial plasma glucose levels were significantly increased with the increment of starch levels (p < .05). In contrast, the daily feed intake and feed conversion ration were significantly declined (p < .05). The mRNA levels of glucose transporter 2, glucokinase, pyruvate kinase, malic enzyme and acetyl-CoA carboxylase alpha genes in the liver significantly increased as the increase in starch levels at 4-hr and 24-hr post feeding (p < .05). No significant differences were observed in the expression of gluconeogenesis genes at each time point (p > .05). These results suggested that dietary addition of starch up-regulated hepatic glycolysis, glycogenesis and lipogenesis genes expression, but the deficient response of gluconeogenesis to dietary starch might be part of the causes limited the starch utilization. Based on the secondary polynomial regression of SGR, y = −0.0011x2 + 0.028x + 1.63 (R2 = 0.9292), the 12.73% inclusion level of dietary starch was recommended in juvenile turtles.

Hyperpolarized [1-13C]lactate flux increased in the hippocampal region in diabetic mice

Increasing evidence suggests there is a relationship between cognitive impairment and metabolic dysfunction. Diabetes is a chronic disease, and metabolic factors affecting brain metabolisms, such as serum glucose, insulin, and glucagon, are altered according to disease progression. In our previous study, we applied hyperpolarized [1-13C] pyruvate magnetic resonance spectroscopy in prediabetic mice after feeding them a 60% high-fat diet (HFD) for 6 months. Ultimately, we detected significantly increased [1-13C]lactate conversion in the whole brain and an almost five-fold increased [1-13C]lactate/pyruvate ratio in the hippocampal region. In the present study, we induced diabetes in mice by injecting streptozotocin and feeding them an HFD for 6 months. Unlike in prediabetic mice, [1-13C]lactate conversion in the diabetic mice did not differ from that in the control group, but [1-13C]lactate/total 13C ratio showed an almost 1.4-fold increase in the hippocampal region. We measured the amount of the lactate and mRNA levels of glucose transporters from isolated hippocampus and cortex samples. In the hippocampus, significantly decreased GLUT1 mRNA levels and increased lactate were detected, suggesting an inconsistency between glucose and pyruvate metabolism. Pyruvate can be produced from oxaloacetate as well as glucose. We investigated ATP citrate lyase (ACLY) because it cleaves citrate into oxaloacetate and acetyl CoA. Phosphorylated ACLY (Ser455), the active form, was increased in both hippocampus and cortex samples of mice injected with streptozotocin and fed an HFD. Also, phosphorylated ACLY/total ACLY showed a positive correlation with lactate amount in the hippocampus. Our results suggest that the brain has different responses to diabetic progression, but, in the hippocampus, maintains metabolic alteration toward increasing lactate production from the prediabetic to the diabetic stage. We suggest that ACLY-mediated pyruvate be used to support lactate levels in the hippocampus in cases of limited glucose availability.

Transplantation of neuregulin 4-overexpressing adipose-derived mesenchymal stem cells ameliorates insulin resistance by attenuating hepatic steatosis

Due to high-fat and high-sugar diets accompanied by sedentary lifestyles, diabetes has become a global epidemic. Literature findings suggest a potential therapeutic effect of Nrg4 on treating obesity-related metabolic disorders including type 2 diabetes (T2D). Adipose tissue-derived MSCs (ADSCs) were used in our study as they are abundant and can be harvested with minimally invasive procedures. In the end, our study reveals that ADSC transplantation improves glucose tolerance and metabolic balance in HFD-fed mice by multiple mechanisms, including upregulating GLUT4 expression and suppressing inflammation. More importantly, our study shows that Nrg4 overexpression could improve the efficacy of ADSCs in ameliorating insulin resistance (IR) and other obesity-related metabolic disorders, given the function of Nrg4 in attenuating hepatic lipogenesis. It would provide a new therapeutic strategy for the treatment of obesity, IR, and T2D.

Effects of dietary supplementation with epidermal growth factor on nutrient digestibility, intestinal development and expression of nutrient transporters in early‐weaned piglets

The abnormalities in intestinal morphology and digestive function during weaning are associated with the loss of milk-borne growth factors. Epidermal growth factor (EGF) has been shown to stimulate the growth of animals. This study was to determine the effect of dietary EGF on nutrient digestibility, intestinal development and the expression of genes encoding nutrient transporters in weaned piglets. Forty-two piglets were weaned at 21days and assigned to one of three treatment groups: (1) basal diet (control), (2) basal diet+200µg/kg EGF or (3) basal diet+400µg/kg EGF. Each treatment consisted of 14 replicates, and seven piglets from each treatment were sampled on day 7 and 14. The EGF supplementation significantly elevated (p<0.05) the coefficients of total tract apparent digestibility of crude protein, calcium and phosphorus, but tended to decrease sucrase activity (p<0.10) than the control group. At day 7 post-weaning, animals receiving EGF diets showed a tendency (p<0.10) towards greater ileal villus height (VH), jejunal crypt depth (CD) and duodenal VH:CD when compared with the control group. Moreover, the mRNA levels of glucose transporter 2 (Slc2a2), neutral amino acid transporter (Slc6a19) and calbindin D9k (S100G) tended to be higher (p<0.10) for EGF groups than the control group. By day 14, EGF supplementation markedly enhanced (p<0.05) the VH, CD and VH:CD in the jejunum compared to the control group. This addition also up-regulated (p<0.05) the mRNA level and the protein abundance of peptide transporter 1 than the control group. These findings demonstrated that dietary EGF beneficially enhanced nutrient digestibility, improved intestinal development and increased the mRNA expression of nutrient transporters in weaned piglets.

Molecular mechanistic insight into the anti-hyperuricemic effect of Eucommia ulmoides in mice and rats

Context: Eucommia ulmoides Oliver (Eucommiaceae) has various medicinal properties. Our previous studies revealed that Eucommia ulmoides has a protective effect on hyperuricaemia.Objective: This study investigates the effect of Eucommia ulmoides cortex ethanol extract (EU) on hyperuricaemia and explores the underlying mechanism in Kunming mice and Sprague–Dawley rats.Material and methods: Sixty mice and sixty rats were divided into normal control, hyperuricaemia, allopurinol (10 mg/kg) and three EU groups. The EU groups received intragastric EU at 80, 160, 320 mg/kg in mice and 100, 200, 400 mg/kg in rats for 7 days. Serum uric acid (SUA) was measured using a kit. mRNA and proteins were quantified by RT-qPCR and immunohistochemical assays (IHC), respectively.Results: The Maximal Tolerable Dose (MTD) of EU administered intragastrically was 18 g/kg in mice. The intermediate (160 mg/kg) and high (320 mg/kg) EU treatment significantly reduced (p < 0.05) SUA levels to 130.16 μmol/L and 109.29 μmol/L, respectively, and markedly elevated the mRNA expression of organic anion transporters 1 (OAT1) and organic anion transporters 3 (OAT3), while significantly deceasing the mRNA levels of glucose transporter 9 (GLUT9) and uric acid transporter 1 (URAT1) in the mouse kidney (p < 0.05). In hyperuricemic rats, high EU (400 mg/kg) significantly reduced SUA levels to 253.85 μmol/L, and increased OAT1 and OAT3 levels, but decreased URAT1 and GLUT9, compared to the hyperuricaemia group (p < 0.05).Discussion and conclusions: This study demonstrated the potential hyperuricaemia ameliorating effect of EU. Specific active ingredients in EU should be evaluated. These results are valuable for the development of antihyperuritic agents from EU.

Decabromodiphenyl ether exacerbates hyperglycemia in diet-induced obese mice

Decabromodiphenyl ether (decaBDE) is a brominated flame retardant used in plastic and textile articles. It has become a ubiquitous environmental contaminant, however; the relationship between decaBDE and obesity remains to be elucidated. We aimed to clarify if oral decaBDE exposure can be a factor in obesity and its related metabolic dysfuctions. Male C57BL/6 J mice were fed a normal (ND, 9.0 kcal% fat) or high-fat (HFD, 62.2 kcal% fat) diet and treated with decaBDE (the equivalent of three doses of 0, 0.5 (L-DecaBDE), and 10 (H-DecaBDE) μg/kg body weight/day) ad libitum in drinking water from 5 to 20 weeks of age. In HFD-fed mice, decaBDE exposure markedly increased both fasting blood glucose levels compared with vehicle exposure, which was more prominent in H-DecaBDE-exposed mice. DecaBDE exposure significantly reduced mRNA levels of glucose transporter 4 and thyroid hormone receptor alpha in skeletal muscle and mechanistic target of rapamycin complex 2 in brown adipose tissue compared with vehicle exposure under HFD-feeding. The tendency for hyperglycemia and the remarkable activation of insulin signaling pathway-related genes were observed in ND + DecaBDE mice compared to the ND + Vehicle mice. These results demonstrate that decaBDE can contribute to the enhancement of diet-induced hyperglycemia through disruption of glucose homeostasis.

185 - Short-term hyperoxic exposure causes dysregulation of pyruvate oxidation

Due to the advances in perinatal and neonatal care, preterm infants can survive from 22 weeks of gestation. Following extreme prematurity, mechanical ventilation and supplemental oxygen are employed to sustain life. Though supplemental oxygen therapy is clinically necessary it can cause impaired lung growth and repair due to perturbed energy metabolism. To better understand this, we investigated the role of hyperoxia on bioenergetics in mouse lung epithelial cells (MLE-12) exposed to hyperoxia (95% O2, 5% CO2). As short as 4 hours of hyperoxic exposure caused a reduction in the basal respiration, ATP production, and pyruvate utilization compared to air exposed controls as measured by the seahorse bioanalyzer. In addition, the decreased pyruvate utilization was not associated with altered mRNA levels of glucose transporters and mitochondrial pyruvate carriers, nor changes in glycolysis as measured by the glycolytic rate assay. Interestingly, MLE-12 cells exposed to hyperoxia had significantly increased mRNA and protein levels of UCP-1, a transport and uncoupling protein found in the inner mitochondrial membrane which can export monocarboxylate anions such as pyruvate. Despite this increase in UCP-1 we did not see an expected increase in proton leak. These data suggest that hyperoxia may enhance UCP-1 mediated export of pyruvate outside of the mitochondrial matrix rendering it unavailable for oxidative phosphorylation.