GLUT4 Research Articles

Evidence for biexponential glutamate T2 relaxation in human visual cortex at 3T: A functional MRS study.

Functional magnetic resonance spectroscopy (fMRS) measures dynamic changes in metabolite concentration in response to neural stimulation. The biophysical basis of these changes remains unclear. One hypothesis suggests that an increase or decrease in the glutamate signal detected by fMRS could be due to neurotransmitter movements between cellular compartments with different T2 relaxation times. Previous studies reporting glutamate (Glu) T2 values have generally sampled at echo times (TEs) within the range of 30-450 ms, which is not adequate to observe a component with short T2 (<20 ms). Here, we acquire MRS measurements for Glu, (t) total creatine (tCr) and total N-acetylaspartate (tNAA) from the visual cortex in 14 healthy participants at a range of TE values between 9.3-280 ms during short blocks (64 s) of flickering checkerboards and rest to examine both the short- and long-T2 components of the curve. We fit monoexponential and biexponential Glu, tCr and tNAA T2 relaxation curves for rest and stimulation and use Akaike information criterion to assess best model fit. We also include power calculations for detection of a 2% shift of Glu between compartments for each TE. Using pooled data over all participants at rest, we observed a short Glu T2-component with T2 = 10ms and volume fraction of 0.35, a short tCr T2-component with T2 = 26 ms and volume fraction of 0.25 and a short tNAA T2-component around 15 ms with volume fraction of 0.34. No statistically significant change in Glu, tCr and tNAA signal during stimulation was detected at any TE. The volume fractions of short-T2 component between rest and active conditions were not statistically different. This study provides evidence for a short T2-component for Glu, tCr and tNAA but no evidence to support the hypothesis of task-related changes in glutamate distribution between short and long T2 compartments.

Myrothamnus flabellifolius attenuates streptozotocin-high energy diet-induced type 2 diabetes in male sprague dawley rats

Several medicinal plants have anti-diabetic properties and can be considered as an alternative therapy because of their actions which are like those of conventional antidiabetic drugs. In this study, we investigated Myrothamnus flabellifolius (MF) ethanol: water (70:30) extract for its possible anti-diabetic potential in streptozotocin-high energy diet (STZ-HED) induced type 2 diabetes mellitus (T2DM) rats and its possible mechanisms of action. Diabetic rats were divided into MF-50, MF-100, MF200, MF-300, MF-400, and Metformin (MET)-500 groups, where the numbers represent doses in mg.kg.bw that were administered to the groups. Normal (NC) and diabetic (DC) controls were administered distilled water. The animals had their fasting blood glucose levels and body weights determined weekly for 21 days. Blood samples, liver, pancreas, and muscle were collected and used for biochemical and histological examination. Our study showed that MF extract lowered glucose levels, body weight, glycated hemoglobin, thiobarbituric acid reactive substances, serum glutamate pyruvate transaminase, serum glutamate oxaloacetate transaminase, Homeostatic model assessment of insulin resistance, and alkaline phosphatase (p<0.05; p<0.01) in T2DM. While adiponectin, catalase, leptin, lipid profile, insulin Homeostatic model of assessment of β cell function, and superoxide dismutase levels were elevated (p<0.05; p<0.01). Furthermore, MF extract preserved both the liver and the islets structure of T2DM rats and enhanced muscle glucose transporter 4 (GLUT 4) expression. M. flabellifolius extract normalized blood glucose and body weight in T2DM. Further investigations are needed to explore other possible mechanisms of action and clinical potential of MF extracts. Key words: Myrothamnus flabellifolius, T2DM, Lipid profile, blood glucose, oxidative stress, streptozotocin-high energy diet, Sprague dawley rats.

Acteoside-improved streptozotocin-induced learning and memory impairment by upregulating hippocampal insulin, glucose transport, and energy metabolism.

Alzheimer's disease (AD), a neurodegenerative disease, has been, by and large, correlated to insulin pathway, glucose level, and energy metabolism in the brain. Intracerebroventricular administration of streptozotocin (ICV-STZ) leads to glucose and energy metabolism dysfunction, cognitive impairment, and increased oxidative stress in the brain. Acteoside has a myriad of pharmacological effects on the brain, namely, neuroprotection and recuperation of cognitive functions. The primary focus of the current study was to examine the effect of acteoside on insulin, glucose transport, and energy metabolism in the hippocampal area of the brain. The behavioral experiments such as spatial memory, active learning, and passive memory suggested that acetoside ameliorated the ICV-STZ-induced learning and cognitive impairment. The acteoside induced increase in the protein expression of glucose transporters (Glu T1, Glu T3, and Glu T4), glucose, and insulin levels in the hippocampus for maintaining normal learning and memory function were demonstrated by Western blot. In addition, acteoside's long-term oral administration increased the the ratio of ATP content divided by ADP content (ATP/ADP) ratio, which, in turn, reduced the reactiveoxygen species (ROS) level and improved the cellular oxidative stress response. Compared with the model group, the above results show significant differences in different degrees (p < .05 or p < .01). This study suggests that acteoside can ameliorate the ICV-STZ-induced learning and memory impairment caused due to insulin receptor, insulin receptor substrate 1, Glu T1, Glu T3, and Glu T4 pathways by triggering intracerebral metabolism.

Determination of Brain Metabolite T1 Without Interference From Macromolecule Relaxation.

J-coupled metabolites are often measured at a predetermined echo time in the presence of macromolecule signals, which complicates the measurement of metabolite T1 . To evaluate the feasibility and benefits of measuring metabolite T1 relaxation times without changing the overlapping macromolecule baseline signals. Prospective. Five healthy volunteers (three females and two males; age = 27 ± 7 years). 7T scanner using a point resolved spectroscopy (PRESS)-based spectral editing MR spectroscopy (MRS) sequence with inversion recovery (IR). F-tests were performed to evaluate if the new approach, which fitted all the spectra together and used the same baselines for the three different IR settings, significantly reduced the variances of the metabolite T1 values compared to a conventional fitting approach. Cramer-Rao lower bound (CRLB), within-subject coefficient of variation, and F-test. The T1 relaxation times of N-acetylaspartate (NAA), total creatine (tCr), total choline (tCho), myo-inositol (mI), and glutamate (Glu) were determined with CRLB values below 6%. Glutamine (Gln) T1 was determined with a 17% CRLB, and the T1 of γ-aminobutyric acid (GABA) was determined with a 34% CRLB. The new approach significantly reduced the variances (F-test P < 0.05) of NAA, Glu, Gln, tCr, tCho, and mI T1 s compared to the conventional approach. Keeping macromolecule signals intact by using only long IR times allowed the use of a single macromolecule spectral model for different IR settings and significantly reduced the variances of NAA, Glu, Gln, tCr, tCho, and mI T1 s. 1 TECHNICAL EFFICACY STAGE: 1.

Erratum. WASH regulates glucose homeostasis by facilitating GLUT2 receptor recycling in pancreatic B-cells. (Diabetes(2019)68(377–386)Doi: 10.2337/db18-0189)

Erratum. WASH regulates glucose homeostasis by facilitating GLUT2 receptor recycling in pancreatic B-cells. (Diabetes(2019)68(377–386)Doi: 10.2337/db18-0189)

Withaferin A suppresses skin tumor promotion by inhibiting proteasome-dependent isocitrate dehydrogenase 1 degradation

Background: The metabolic enzyme isocitrate dehydrogenase 1 (IDH1) belonging to β-decarboxylase dehydrogenase family has been identified as a tumor suppressor. Withaferin A (WA), a bioactive compound derived from Withania somnifera , has the anti-tumor activity. Based on the data set that WA inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced IDH1 inactivation and mitochondrial dysfunction, we focused on how WA suppressed the skin carcinogenesis mediated by IDH1. Methods: The mRNA levels of IDH1 were measured after treated with TPA and/or WA. The expression of IDH1, lactate dehydrogenase (LDH) involved in glycolysis, hypoxia inducible factor-1α (HIF-1α) and its target gene glucose transporter-1 (Glut1) were detected. The activities of proteasome and the mitochondrial complex I related to mitochondrial functions were determined. The enzymatic activities of LDH, proline hydroxylase (PHD) and vascular endothelial growth factor (VEGF) were analyzed. Results: The qPCR data have shown the mRNA levels of IDH1 were no difference with TPA and/or WA treatment. Next, data demonstrated that WA could stabilize IDH1 by inhibiting the ubiquitin-proteasome pathway (UPP). Followed by illuminating the mechanism of IDH1 inhibiting tumorigenesis, the results mirrored that upregulated IDH1 suppressed LDH activity whereas increased mitochondrial complex I activity. Furthermore, via its product α-KG, upregulated IDH1 activated PHD, and inhibited HIF-1α and its downstream signaling pathway. Conclusions: Our results indicate that WA inhibits tumor promotion partially via stabilizing IDH1, leading to inactivating the HIF-1α signaling.

Aster yomena (Kitam.) Honda Inhibits Adipocyte Differentiation in 3T3-L1 Cells

Background: Obesity has become a global health problem and causes serious complications. In this study, we investigated the effect of ethyl acetate fraction from Aster yomena (Kitam.) Honda (EFAY) on obesity in 3T3-L1 cells. Methods: To examine the effect of EFAY on adipocyte differentiation, we conducted oil red O staining assay in mature adipocytes. 3T3-L1 preadipocytes were differentiated with EFAY (25, 50, and 100 μg/mL) for 4 days. On day 9 of differentiation, the number of lipid droplets was measured by oil red O. The underlying mechanisms of the action of EFAY against differentiation in 3T3-L1 cells were investigated using Western blot analysis. Results: In oil red O staining assay, differentiated adipocytes generated massive lipid droplets compared with preadipocytes. However, treatment with EFAY significantly reduced the generation of lipid droplets compared to EFAY non-treated adipocytes. Western blot analysis revealed that EFAY down-regulated adipogenesis-related protein expressions, such as peroxisome proliferator-activated receptor γ, CCAAT/ enhancer-binding protein (C/EBP) α, and C/EBPβ. Furthermore, EFAY down-regulated levels of lipogenesis- related protein expressions such as fatty acid synthase and acetyl-CoA carboxylase. On the contrary, EFAY promoted lipolysis by activating phospho-hormone-sensitive lipase and adipose triglyceride lipase. Phospho-AMP-activated protein kinase (p-AMPK) and phospho-acetyl-CoA carboxylase were up-regulated by treatment of 3T3-L1 cells with EFAY, subsequently up-regulating GLUT4 levels, indicating that EFAY could regulate glucose uptake as well as lipid metabolism. Conclusions: EFAY reduced adipocyte differentiation by suppressing adipogenesis and lipogenesis, and provoking lipolysis and AMPK pathway. These results imply that EFAY could be employed as a natural agent to ameliorate obesity.

Ketogenic Diet in Patients with GLUT1 Deficiency Syndrome.

Background:The ketogenic diet (KD) is a high fat, low carbohydrate diet considered to be the treatment of choice for GLUT1deficiency syndrome, a metabolic disorder affecting the nervous system. Aim:To present our experience in four patients with GLUT1 deficiency syndrome who were treated with KD. Methods:Retrospective data from case series. Phenotypical features, mainly movement disorder and seizures, are being described for each patient. All four cases are currently following the Modified Atkins Diet. Results:The response to ketogenic diet in our four patients was significant with improvement of movement disorder or seizures control. Conclusion:The ketogenic diet is the treatment of choice for GLUT1deficiency syndrome. Recognition of the disorder is the key for appropriate management among clinicians. Diet compliance is an important issue in school age children.

Construction and effects of functionalized graphene oxide nonparticles-mediated RNA interference of hypoxia-inducible factor-1α gene

Objective To explore the effects of graphene oxide (GO)-polyethylene glycol (PEG)-folic acid (FA)-pyrenemethylamine hydrochloride (PyNH2)-mediated RNA interference (RNAi) of hypoxia-inducible factor-1α (HIF-1α) on the biological behaviors of human pancreatic cancer Patu8988 cells. Methods GO-PEG-FA-PyNH2 and RNAi targeting HIF-1α gene (GO-PEG-FA-PyNH2-HIF-1α-RNAi) was constructed. The expressions of HIF-1α and glucose transporter 1 (Glut-1) in Patu8988 cells were determined after knockdown of HIF-1α by RNAi. The invasive ability, the proliferation and the cell cycle of Patu8988 cells were investigated. The effect of HIF-1α knockdown on the uptake of 18F-fluorodeoxyglucose (FDG) in Patu8988 cells was also detected. Comparison of data was conducted by one-way analysis of variance and least significant difference t test. Results The GO-PEG-FA-PyNH2 was successfully constructed, and no cytotoxicity was found. Under the hypoxia or normoxia state, the mRNA and protein levels of HIF-1α and mRNA level of Glut-1 in cells transfected with GO-PEG-FA-PyNH2-HIF-1α-RNAi (study group) were lower than those in cells transfected with GO-PEG-FA-PyNH2(negative group) and cells transfected with Opti-minimal essential medium (Opti-MEM, control group; F=30.25-32.58, t=3.66-5.81, all P<0.05); the numbers of migrated cells in the study group were much lower than those in the negative group and the control group (F=38.63 and 41.35, t=20.51-35.25, all P<0.01); the cell proliferation in the study group was significantly lower than that in the negative group and the control group (F=35.19 and 38.11, t=15.11-22.19, all P<0.05). The proportions of G0/G1 cells in the study group were higher than those in the negative group and the control group (F=34.60 and 34.83, t=11.55-34.56, all P<0.05); the 18F-FDG uptake in the study group was lower than that in the negative group and control group (F=29.85 and 31.69, t=3.35-4.35, all P<0.05). Conclusion GO-PEG-FA-PyNH2-mediated HIF-1α RNAi inhibits the expression of HIF-1α in pancreatic cancer cells, leading to changes in related biological behaviors. Key words: Pancreatic neoplasms; Tumor cells, cultured; RNA, small interfering; Hypoxia-inducible factor 1, alpha subunit; Graphene oxide; Polyethylene glycols; Folic acid; 1-Pyrenemethylamine

Upregulation of glucose and amino acid transporters in micropapillary carcinoma.

Micropapillary carcinoma (MPC), a relatively rare histologic carcinoma observed in various organs, is associated with vascular invasion, nodal metastasis, and poor prognosis. MPC is different from papillary carcinoma as it has no fibrovascular core and is thus considered essentially hypovascular. MPCs are known to upregulate glucose transporter 1 (GLUT1) via the activation of a transcription factor, hypoxia-inducible factor (HIF)-1. Here we evaluated the expression of nutrient transporters in MPCs to gain a better understanding of the system used by MPCs to compensate for their intrinsic poor vascularity. We immunohistochemically evaluated 29 MPCs including breast (n=14), lung (n=8), gastrointestinal tract (n=5), and urinary tract cancers (n=2), and compared them with non-micropapillary control cancers (n=32) regarding the expression of amino acid (ASCT1, ASCT2, LAT1, and SNAT1) and glucose (GLUT1, GLUT2) transporters. Each section was scored by the staining intensity (0-3) multiplied by the occupying area (0-10), with a possible range 0-30. The average scores of the MPC and control groups were compared by Student's or Welch's t-test according to the homoscedasticity. The MPC group showed significantly higher scores for ASCT1 (p=0.007), ASCT2 (p=0.001), GLUT1 (p<0.001), and GLUT2 (p<0.001), whereas no significant scores were noted for LAT1 and SNAT1. In conclusion, MPC could be associated with the upregulation of several nutrient transporters, which may contribute to the malignant potential by supporting the survival of cancer cells.

Role of glucose transporter 2 and 4 in insulin resistance in spontaneous hyperuricemia mice

Objective To investigate the role of glucose transporter (GLUT) 2 and 4 in hyperuricemia-induced insulin resistance. Methods Male uric acid oxidase gene knock-out spontaneous hyperuricemia mice (KO) and wild-type mice (WT) were fed with high-fat diet to establish an insulin resistance model. Then, some of KO mice were treated with allopurinol for lowering uric acid. Uric acid, fasting plasma glucose (FPG), and fasting insulin (FINS) were detected. Intraperitoneal glucose tolerance test (IPGTT) and insulin tolerance test (ITT) were performed. Finally, the expression levels of Slc2a4 and Slc2a2 mRNA in tissues were determined by real-time PCR, while those of GLUT2 and GLUT4 proteins in tissues were analyzed by Western blot. Results There was no significant difference in FPG among various groups. The level of FINS in KO group was significantly higher than that in WT group [(0.636±0.07) vs (0.456±0.03) ng/ml, P<0.01], with decreased insulin sensitivity and impaired glucose tolerance. The uric acid level in the KO group remained at a high level [(549.68±48.7) vs (216.61±27.5)μmol/L]. After uric acid level in KO mice was reduced by allopurinol, insulin sensitivity and glucose metabolism were improved. Compared with WT group, the expression levels of Slc2a4 and GLUT4 in the gastrocnemius muscle were decreased while the expression levels of Slc2a2 and GLTU2 in liver were increased in KO group, which were reversed by allopurinol-mediated uric acid reduction. Conclusion Uric acid may induce insulin resistance via decreasing Slc2a4/GLUT4 expressions in skeletal muscle, and increasing Slc2a2/GLTU2 expressions in liver. (Chin J Endocrinol Metab, 2018, 34: 862-866) Key words: Hyperuricemia; Insulin resistance; Glucose transporter 2; Glucose transporter 4

Correlation of Glut-1, Glut-3 and HK-II expression with 18F-FDG uptake in non-small cell lung cancer and pulmonary inflammatory lesions

Objective To analyze the expression of glucose transport protein (Glut)-1, Glut-3 and hexokinase (HK)-Ⅱ in non-small-cell lung cancer (NSCLC) lesions and pulmonary inflammatory lesions and discuss the correlation of them with 18F-fluorodeoxyglucose (FDG) uptake. Methods Twenty-four patients with NSCLC and 22 patients with pulmonary inflammatory lesions (25 males, 21 females; age range: 37-81 years) who underwent PET/CT from November 2012 to May 2016 were retrospectively analyzed. All patients had surgery and were confirmed by pathology. The expression of Glut-1, Glut-3 and HK-Ⅱ in the lesions was detected by immunohistochemistry. Immunohistochemical staining scores and maximum standardized uptake value (SUVmax) were calculated. One-way analysis of variance, the least significant difference t test, two-sample t test and Spearman correlation analysis were used. Results The SUVmax of NSCLC lesions was 8.71±7.62, higher than that of pulmonary inflammatory lesions (3.29±2.16; t=3.220, P 0.05), but the expression of Glut-3 was higher than that of Glut-1 and HK-Ⅱ (F=4.123, t values: 0.970, 0.150, all P<0.05) in pulmonary inflammatory lesions. Conclusions The expression of Glut-1, Glut-3 and HK-Ⅱ is higher in NSCLC lesions than that in pulmonary inflammatory lesions. Glut-1 and HK-Ⅱ are the important factors for 18F-FDG uptake in NSCLC. Glut-3 may play an important role in 18F-FDG uptake in pulmonary inflammatory lesions. Key words: Carcinoma, non-small-cell lung; Glucose transport proteins, facilitative; Hexokinase; Positron-emission tomography; Tomography, X-ray computed; Deoxyglucose

Regulation of microRNA-22 on glycometabolism of hematopoietic stem cell TF-1 and its molecular mechanism

Objective To study the regulation of microRNA-22(miR-22) on glycometabolism of hematopoietic stem cell TF-1 and its molecular mechanism. Methods TF-1 cells were cultured for 2 h under hypoxic conditions.The expression levels of Glut4 and miR-22 was detected by quantitative real-time PCR(qRT-PCR). The sgRNA vector of the miR-22 gene was constructed and miR-22 gene of TK-1 cells was knocked out by the CRISPR/Cas9 technique.Overexpression vectors were constructed, and miR-22 knocked-out cells were introduced to overexpress miR-22, the expression of miR-22 was detected by qRT-PCR and the expression levels of Glut4 and PPAR-γ were detected by qRT-PCR and Western blot. Results Compared with the control group, the expression of miR-22 in TF-1 cells decreased (0.015±0.000 vs. 0.056±0.001) and the expression of Glut4 (0.351±0.038 vs. 0.152±0.005) and PPAR-γ (0.421±0.017 vs. 0.248±0.008) increased, when TF-1 cells were cultured for 2 h under hypoxic conditions, and the differences were statistically significant (all P<0.05). Compared with the control group, the expression levels of Glut4 (0.019±0.00 vs. 0.008±0.000) and PPAR-γ (0.038±0.001 vs. 0.019±0.000) were significantly increased after miR-22 gene silencing, and they were significantly decreased (Glut4: 0.005±0.000 vs. 0.008±0.000; PPAR-γ: 0.137±0.000 vs. 0.019±0.000) after overexpression of miR-22, and the differences were statistically significant (all P<0.05). Conclusions It suggests that miR-22 exerts a negative regulation on glycometabolism of hematopoietic stem cell TF-1 by downregulating the expression of PPAR-γ.A new regulatory factor of TF-1 glycometabolism and the mechanisms are identified, which has provided new ideas for the targeted medication of diseases induced by hematopoietic stem cell dysfunction. Key words: Hematopoietic stem cells; Glycometabolism; MicroRNA; Peroxisome proliferators-activated receptor-γ

Study on Mechanisms Underlying the Preventive Effects of Canarium album L. ethanol Extract on Modulation of Hyperglycemia and Hypercholesterolemia in Diabetic Rats

Canarium album L. has attracted attention for its high polyphenol content and various potential pharmacological activities, exhibiting potential to reduce the risk of metabolic disorders. We hypothesized that Canarium album L. may regulate glucose and lipid metabolic pathways. To examine the application potential of Canarium album L. on metabolism, we designed the present study to investigate the effect of Canarium album L. ethanol extract (CO-EtOH) on high-fat diet (HFD) and streptozotocin (STZ)-induced diabetic rats. Our data showed CO-EtOH significantly reduced elevated fasting blood glucose, TC, TNF-α, and bile acid. Administration of CO-EtOH increased hepatic mRNA levels of GLUT2 and GK but decreased those of PEPCK and G6Pase. Furthermore, CO-EtOH remarkably reduced hepatic levels of cholesterol; lowered the expression of genes involved in cholesterol biosynthesis, transportation, and degradation, including SREBP-2, HMG-CoAR, SR-B1, CYP7A1, BSEP, MRP3, MRP4, and NTCP; and decreased the expression of LDLR, ABCG8, FXR, and SHP that govern cholesterol transportation and bile acid synthesis. The protein expressions of LDLR, ABCA1, FXR, and SHP were also significantly increased upon CO-EtOH treatment. Finally, CO-EtOH could increase glucose uptake in rat skeletal muscle cells in both normal and palmitic acid-challenged conditions. These findings suggest that Canarium album L. may have great potential for treating hyperglycemia and hypercholesterolemia.

Is Propranolol as Safe as Reported in Managing All Pediatric Hemangiomas

Introduction: Hemangiomas are the most common benign vascular tumors of infancy. Infantile (IHs) and congenital (CHs) hemangiomas are similar in appearance, but differ in their presentation and behavior. Definitive diagnosis of IHs reflects presence of the GLUT1 marker; CHs have different markers. Despite the hypoglycemia seen in beta-blocker overdose, propranolol has a long-standing record of safety in various pediatric indications. With this history, and its effectiveness in IHs, it has become the drug of choice in IHs, and initial therapy in CHs. Case Report: A 4-year-old previously healthy African-American girl …

GLUT-1: An important adjunct in predicting prognosis of VC &amp; OSCC

GLUT-1: An important adjunct in predicting prognosis of VC &amp; OSCC

Mechanism study of glucose transport by recombinant human brain natriuretic peptide pretreating myocardial cells in rats with hypoxia/reoxygenation

Objective To investigate the mechanism of glucose transport by recombinant human brain natriuretic peptide(rh-BNP) pretreating myocardial cells in rats with hypoxia/reoxygenation. Methods Left ventricular cardiomyocytes were obtained from SD rats aged 6~8 weeks and were cultured in vitro.They were divided randomly into 5 groups including the control group, hypoxia group, hypoxia/reoxygenation group, rh-BNP pretreating hypoxia group and rh-BNP pretreating hypoxia/reoxygenation group.MTT assay was used to detect the changes of cells viability.The levels of lactate dehydrogenase(LDH), glutathione, superoxide dismutase(SOD) and BNP were measured by ELISA.The expression of iNOS, eNOS, GLUT1 and GLUT4 were detected by RT-PCR. Results The rh-BNP intervention significantly increased the viability of hypoxia and hypoxia/reoxygenation treated cardiomyocytes(P<0.05), reduced the levels of LDH, glutathione, SOD and BNP induced by hypoxia and hypoxia/reoxygenation(P<0.05), and increased the mRNA expression of iNOS, eNOS, GLUT1 and GLUT4 in cardiomyocytes(P<0.05). Conclusion The rh-BNP alleviates hypoxia/reoxygenation-induced cardiomyocytes injury by affecting oxidative stress and the expression of GLUT1 and GLUT4. Key words: Recombinant human brain natriuretic peptide; Hypoxia/Reoxygenation; Glucose transporter; Oxidative stress

Establishment of an acquired tamoxifen-resistant human breast cancer cell line and its mechanism of 18F-FDG uptake reduction

Objective To establish the acquired tamoxifen (TAM)-resistant human breast cancer cell line T47D-TamR, compare the 18F-FDG uptake rate between T47D-TamR and its parental cell line T47D, and study the mechanism. Methods Long-term step-wise drug stimulation was used for cell line T47D-TamR establishment and then the cell proliferation and resistance index (RI) were determined by MTT assay. The 18F-FDG uptake rates of T47D-TamR and T47D cells were measured in the setting of different cell counts, reaction time, 18F-FDG dosages and glucose concentrations. The LDH activity, cellular ATP level and lactic acid concentration in cell supernatant of T47D-TamR and T47D cells were detected. Western blot was used to examine the expression of ERα, Glut-1, phosphorylated AMPK (p-AMPK) and phosphorylated mTOR (p-mTOR). Two-sample t test and two-way analysis of variance were used to analyze the data. Results T47D-TamR cell line was successfully established and its drug RI was 1.97±0.08, with a significantly decreased cell proliferation efficacy (F=230.10, P<0.05). Significant differences of 18F-FDG uptake rates were found between T47D-TamR cell and T47D cell when changing the cell count, reaction time, and 18F-FDG dosage (F values: 419.00-1 116.00, all P<0.05). The LDH activities of T47D cell and T47D-TamR cell were (0.42±0.04) and (0.32±0.02) U/mg protein, cellular ATP levels were (19.99±0.32) and (14.01±0.70) nmol/mg protein, lactic acid concentrations in cell supernatant were (2.95±0.05) and (2.02±0.07) mmol/L, respectively. The differences of above parameters between the two groups were significant (t values: 4.39-18.80, all P<0.05). The relative expressions of ERα, p-AMPK, p-mTOR, Glut-1 were 0.26±0.03, 0.36±0.06, 0.75±0.11, 0.35±0.07 in T47D cell, and 0.17±0.02, 0.61±0.09, 0.52±0.08, 0.21±0.04 in T47D-TamR cell, and there were significant differences (t values: 12.20-16.45, all P<0.05) between the two groups. Conclusions Compared with parental cells, T47D-TamR cells have lower 18F-FDG uptake rate, LDH activity, cellular ATP level and lactic acid concentration, increased p-AMPK expression and decreased ERα, p-mTOR, Glut-1 expression, indicating the decreased glycolysis ability in TAM-resistant breast cancer cells. Key words: Breast neoplasms; Tumor cells, cultured; Tamoxifen; Fluorine radioisotopes; Deoxyglucose

Role of nitric oxide synthase inhibitor in the skeletal muscle contractile dysfunction of type 2 diabetic rats

Objective To investigate the role of endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) in the contractile dysfunction of skeletal muscle in diabetic rats and on which the therapeutic effects of L-Arginine. Methods Type 2 diabetic rats were induced by high fat diet and a single intraperitoneal injection of streptozotocin (STZ, 30 mg/kg), followed by high fat diet for 8 weeks. Specific twicth tension and specific tetanic tension of soleus (SOL) and extensor digitorum longus (EDL) isolated from control and diabetic rats were detected by electric stimulation to reflect contractile function of skeletal muscle. ADMA content of skeletal muscle was analyzed by enzyme linked immunosorbent assay (ELISA), and activities of dimethylarginie dimethylaminohydrolase (DDAH) and NOS, NO content were measured by colorimetry. The protein expression of ADMA synthetase protein arginine methyl transferase 1 (PRMT1) and ADMA hydrolase DDAH and NOS were determined detected by Western blott-ing. Oral glucose tolerance test and protein expressions of phosphorylated insulin receptor substrate 1(p-IRS-1) and protein kinase B (p-Akt) as well as the membrane transportation of glucose transporter 4 (Glut4) were measured to reflect insulin resistance. Results In comparison with control rats, specific twicth tension and tetanic tension of SOL and EDL in diabetic rats were significantly decreased (P<0.01), indicating the contractile dysfunction. Increased ADMA content (P<0.05), decreased DDAH and NOS activities as well as NO content (P<0.01) in comparison with up-regulated protein expression of PRMT1 and down-regulated protein expression of DDAH, endothelial NOS (eNOS) and neuronal NOS (nNOS)(P<0.05) were observed in the skeletal muscle of diabetic rats compared to control rats, indicating that the pathway of PRMT1/ADMA/DDAH/ NOS/NO was disordered in the skeletal muscle of diabetic rats. Furthermore, the glucose tolerance, both IRS-1 and Akt protein phosphorylation as well as the membrane translocation of Glut4 were decreased (P<0.05), indicating the insulin resistance in diabetic rats. Treatment with L-Arginine for 8 weeks not only significantly improved the contractile dysfunction but also reversed the disorder of ADMA signaling pathway and insulin resistance in skeletal muscle of diabetic rats compared to untreated diabetic rats. Conclusions The accumulation of endogenous NOS inhibitor ADMA contributes to the contractile dysfunction of skeletal muscle in diabetic rats, the underlying mechanism may be related to insulin resistance. Key words: Asymmetric dimethylarginine; Type 2 diabetes mellitus; Contractile dysfunction; Insulin resistance; L-arginine

Eugenia polyantha enhances adipogenesis via CEBP-α and adiponectin overexpression in 3T3-L1

Fat cells or adipocytes are important sites in glucose metabolism where triglycerides are synthesised from the excessive glucose in blood. These cells are produced from a complex process called adipogenesis where preadipocytes are differentiated by chemical inducer into mature adipocytes. Herbs and plants have shown tremendous effects on adipogenesis. Eugenia polyantha is a tropical plant that has been used in Asian culinary preparations as well as traditional medicine in treating diabetes, arthritis and cardiovascular diseases. In this study, we examined the effect of water extract of Eugenia polyantha on 3T3-L1 cells differentiation in the presence and absence of insulin. Result shows that water extract of Eugenia polyantha alone failed to enhance differentiation, but addition of 1 μg/mL of insulin significantly increased the formation of adipocytes. Ten days treatment with Eugenia polyantha significantly increased the triglyceride content as measured by Oil Red O assay and glucose utilisation in medium by dose dependent manner. Intracellular CEBP-α, adiponectin and GLUT4 proteins were also expressed significantly during the treatment of low concentration of Eugenia polyantha. This study provides the first evidence of Eugenia polyantha sensitising effect on 3T3-L1 adipogenesis process by enhancing the expression of CEBP-α, adiponectin and GLUT4 proteins.