2-deoxyglucose Research Articles

Retrospective evaluation of focal hypermetabolic thyroid nodules incidentally identified by 18 F-FDG PET/CT in a large population

Objective To investigate the prevalence of focal hypermetabolic thyroid nodules incidentally detected by 18 F-FDG PET/CT in a relatively large population and explore its value in differentiating malignancy from benign thyroid nodules.Methods During August 2007 to March 2010,8463 patients with no history of thyroid cancer or thyroidectomy underwent 18F-FDG PET/CT.Among them,145 patients were found to have abnormal hypermetabolic thyroid nodules.Sixty-eight patients were conformed with histopathological or clinical follow-up,including 37 with malignancy and 31 with benign nodules ( male 21,female 47,average age (53.66 ± 10.85)y).The SUVmax,nodule size,single or multiple nodules,with or without calcification and patient's age were chosen as the parameters for predicting malignancy in hypermetabolic thyroid nodules.Univariate analysis was performed using t test,x2 test and Fisher exact test.Binary logistic regression was performed for multi-variate analysis.The AUCs of SUVmax and logistic regression analysis were compared.Results The incidence of focal hypermetabolic thyroid nodules was 1.71％ ( 145/8463 ),with malignancy rate 54.41％ ( 37/68 ).The SUVmax of benign and malignant nodules were 5.13 ±4.02 and 7.61 ± 4.78,respectively ( t =2.235,P =0.029 ).Logistic regression indicated that SUVmax,with or without calcification,single or multiple nodules,nodule size and patient's age were all the predictors for malignancy in hypermetabolic thyroid nodules.The AUC of logistic regressive model( AUCL ) and SUVmax (AUCs )were 0.878 ±0.043 (95％ CI:0.793-0.962,P＜0.05) and 0.694 ±0.067 (95％ CI:0.562-0.825,P＜0.05),respectively (P ＜ 0.05).Conclusions Focal hypermetabolic thyroid nodules incidentally identified by 18F-FDG PET/CT come with high rate of thyroid malignancy.Differential diagnosis could be improved significantly using SUVmax and logistic regressive model aided by other parameters from 18F-FDG PET/CT as well as patient's age. Key words: Thyroid nodule; Tomography, emission-computed; Tomography, X-ray computed; Diagnosis, differential; Deoxyglucose

The correlation between FDG uptake and the expressions of Ki67, MMP-2 and microvessel density in esophageal carcinoma

Objective To investigate the correlation between 18 F-FDG SUVmax and the expressions of Ki67,matrix metalloproteinase-2 (MMP-2) and microvessel density (MVD) in esophageal carcinoma as to determine if SUVmax might reflect cancer cell proliferation,invasiveness and angiogenesis.Methods From Jan.2007 to Jan.2009,47 patients underwent18F-FDG PET/CT one week before surgical resection of esophageal carcinoma.The tumor specimens were analyzed by immunohistochemical staining for Ki67 proliferation index,MMP-2 marker index and MVD.The correlation between SUVmax over tumor foci on 18F-FDG PET/CT and Ki67 index,MMP-2 index and MVD was analyzed respectively using Pearson linear correlation.Results The mean 18F-FDG SUVmax,Ki67 index,MMP-2 index and MVD were (12.504 ± 6.805)( range:1.9 to 24.0),( 67.837 ± 29.798 ) ％,( 71.551 ± 27.126 ) ％ and 18.429 ± 9.603 respectively.SUVmax was positively correlated with Ki67 ( r =0.581,P ＜ 0.05 ) and MMP-2 indices ( r =0.594,P ＜0.05),but not correlated with MVD ( r =0.167,P ＞ 0.05).Conclusion 18 F-FDG SUVmax may semiquantitatively reflect the proliferation and invasiveness of esophageal carcinoma,but not tumor angiogenesis. Key words: Esophageal neoplasms; Tomography, emission-computed; Tomography,X-ray computed; Deoxyglucose

Resistin Exacerbates Insulin Resistance under the Condition of Low Adiponectin in 3T3-L1 Adipocytes

Adipocytokines such as resistin, TNF-α, and adiponectin, which are adipocyte-derived peptides, play important roles in glucose metabolism. Resistin and TNF-α have been implicated as factors associated with the development of insulin resistance in obesity. In contrast, adiponectin has been shown to improve insulin sensitivity in insulin resistance. However, the interaction among these adipocytokines is still unknown. In this study, we investigated the mechanism of the effects of these 3 adipocytokines (resistin, adiponectin, and TNF-α) on glucose transport in 3T3-L1 adipocytes. Glucose uptake was evaluated by 2-[3H] deoxy-glucose (DOG) uptake assay in 3T3-L1 adipocytes. Resistin and adiponectin secretion were analyzed by western blotting. Adenovirus-mediated overexpression of resistin inhibited insulin-stimulated 2-DOG uptake by only 15% compared with control cells. In contrast, pretreatment of cells with 10 ng/mL TNF-α for 3 hrs did not inhibit insulin stimulated 2-DOG uptake compared with control cells, whereas overexpression of resistin led to a ~ 40% decrease in insulin stimulated 2-DOG uptake following pretreatment with TNF-α. TNF-α has been shown to suppress the expression and secretion of adiponectin from adipocytes. Therefore, we speculated that this potentiating effect of resistin might be caused by the reduction in adiponectin secretion. We confirmed that the secretion of adiponectin was decreased by ~ 50% in TNF-α treated cells compared to control cells. Furthermore, overexpression of adiponectin prevented this additive effect of resistin and TNF-α. In conclusion, these results suggest that: (1) TNF-α enhances the action of resistin via the reduction of adiponectin, 2) Resistin may cause severe insulin resistance under low adiponectin levels.

Utility of Pretreatment Mean Apparent Diffusion Coefficient and Apparent Diffusion Coefficient Histograms in Prediction of Outcome to Chemoradiation in Head and Neck Squamous Cell Carcinoma

This study aimed to evaluate pretreatment whole-tumor mean apparent diffusion coefficient (ADC) and ADC histogram as predictors of outcome to chemoradiation in patients with head and neck squamous cell carcinoma (HNSCC). Patients with HNSCC underwent pretreatment 3-T diffusion-weighted magnetic resonance imaging with calculation of mean ADC and ADC histograms. Outcomes were determined 2 years after chemoradiation. Positive outcome was defined as no abnormal 18-fluoro deoxy glucose uptake on posttherapy computed tomography-positron emission tomography (or abnormal uptake that was proven benign), no locoregional recurrence or metastatic disease, and no requirement for salvage surgery. Negative outcome was defined as residual abnormal 18-fluoro deoxy glucose avidity that was proven malignant, salvage surgery requirement, locoregional recurrence or metastatic disease, death, or a combination of these. A 2-sample t test was used to compare the mean ADC between patients with positive and negative outcomes. The ADC cut point for dividing the groups was determined by looking at its distribution. A Kaplan-Meier plot was produced, and a log-rank test was conducted with calculation of sensitivity, specificity, and positive and negative predictive values. Nine patients showed positive and 8 showed negative outcomes. Significant difference (P = 0.03) was seen in mean ADC (in 10 mm/s) between patients showing positive and negative outcomes (1.18 and 1.43, respectively). According to the log-rank test, tumors with greater than 45% of their volume below the ADC threshold of 1.15 × 10 mm/s were more likely to have a positive outcome (accuracy, 77%). Patients with HNSCC demonstrating lower pretreatment ADC and with greater than 45% of volume below ADC threshold of 1.15 × 10 mm/s may have better outcome to chemoradiation at 2 years.

Anaerobic xylose fermentation by Spathaspora passalidarum

A cost-effective conversion of lignocellulosic biomass into bioethanol requires that the xylose released from the hemicellulose fraction (20-40% of biomass) can be fermented. Baker's yeast, Saccharomyces cerevisiae, efficiently ferments glucose but it lacks the ability to ferment xylose. Xylose-fermenting yeast such as Pichia stipitis requires accurately controlled microaerophilic conditions during the xylose fermentation, rendering the process technically difficult and expensive. In this study, it is demonstrated that under anaerobic conditions Spathaspora passalidarum showed high ethanol production yield, fast cell growth, and rapid sugar consumption with xylose being consumed after glucose depletion, while P. stipitis was almost unable to utilize xylose under these conditions. It is further demonstrated that for S. passalidarum, the xylose conversion takes place by means of NADH-preferred xylose reductase (XR) and NAD(+)-dependent xylitol dehydrogenase (XDH). Thus, the capacity of S. passalidarum to utilize xylose under anaerobic conditions is possibly due to the balance between the cofactor's supply and demand through this XR-XDH pathway. Only few XRs with NADH preference have been reported so far. 2-Deoxy glucose completely inhibited the conversion of xylose by S. passalidarum under anaerobic conditions, but only partially did that under aerobic conditions. Thus, xylose uptake by S. passalidarum may be carried out by different xylose transport systems under anaerobic and aerobic conditions. The presence of glucose also repressed the enzymatic activity of XR and XDH from S. passalidarum as well as the activities of those enzymes from P. stipitis.

Effects of adult catch-up growth on insulin sensitivity and stress in rats

Objective To investigate the effects of adult catch-up growth on insulin sensitivity and stress in rats, as well as the probable mechanism of insulin resistance. Methods Male Sprague-Dawley rats were divided into 6 groups:caloric restriction group ( R4, caloric restriction for 4 weeks) and normal controls for 4 weeks ( NC4 ) ; catchup growth group refed with normal chow( RN4, refeeding for 4 weeks after caloric restriction for 4 weeks), catch-up growth group refed with high-fat diet( RH4, refeeding for 4 weeks after caloric restriction for 4 weeks ), normal chow (NC8) or high-fat diet( HF8 ) controls for 8 weeks. The animal model of catch-up growth was devoloped by way of refeeding after caloric restriction as scheduled. The glucose infusion rate( GIR ), 2-deoxyglucose uptake and insulinsitmulated insulin signaling in skeletal muscle during hyperinsulinemic-euglycemic clamp, plasma corticosterone, and 11β-hydroxysteroid dehydrogenase type 1 ( 11β-HSD1 ) mRNA expression level in skeletal muscle were determined.Results After caloric restriction for 4 weeks, plasma corticosterone and 1 1 β-HSD1 mRNA expression in skeletal muscle were significantly higher in R4 group compared with NC4 group( both P＜0. 05 ), but there were no differences in 2-deoxyglucose uptake and Ser473 phosphorylation of Akt in skeletal muscle between two groups. The plasma corticosterone and 11β-HSD1 mRNA expression in skeletal muscle in RN4 group were significantly higher than those in NC8 group, and were higher in RH4 group than those in NC8 and HF8 groups; while the 2-deoxyglucose uptake and insulin-stimulated Ser473 phosphorylation of Akt in skeletal muscle during the clamp in RN4 were remarkably lower than those in NC8 group, and were lower in RH4 than those in NC8, HF8, and RN4 groups (all P ＜ 0. 05 ).Conctusions Catch-up growth rats refed with normal chow or high-fat diet are characterized by significant insulin resistance and stress in the whole body and skeletal muscle. These changes are more evident in catch-up growth rats refed with high-fat diet. The interaction of increased stress and diet might be of utmost importance in the etiology of insulin resistance in catch-up growth animals. Key words: Catch-up growth; Insulin resistance; Stress; Rats

Selective cytotoxicity of Carthamus tinctorius against glucose-deprived HT-29 human colon carcinoma cells

Glucose deprivation, a feature of poorly vascularized solid tumors, activates the unfolded protein response (UPR) which is a stress-signaling pathway in tumor cells that is associated with the molecular chaperone, glucose-regulated protein 78 (GRP78). Induction of GRP78 protects cells against programmed cell death. Methanolic extract of Carthamus tinctorius(CTE) induced selective cytotoxicity in glucose-deprived HT-29 human colon carcinoma cells; this effect was not seen under normal growth conditions. CTE also suppressed the accumulation of the GRP78 protein and was highly toxic in HT-29 cells, with IC50 values for colony formation of < 50 mg/ml under 2-deoxyglucose (2DG) supplemented and glucose-deprived conditions. Interestingly, apoptotic activity of CTE was also detected by Hoechst staining and flow cytometric analysis. Therefore, these results suggest that CTE prevent the up-regulation of GRP78 and exhibit selective cytotoxicity in glucose-deprived HT-29 cells. Key words: Glucose deprivation, unfolded protein response, (glucose-regulated protein 78) GRP78, Carthamus tinctorius, HT-29 cells.

Influence of the expression of parathyroid hormone 1 receptor to INS-1 cell function under high glucose condition

Objective To observe insulin synthesis and secretion in INS-1 under high glucose, and to clarify the effect of PTH1R. Methods After successful construction of recombinant PTH1R-siRNA vectors in INS-1 cell, insulin secretion and intracellular insulin content of control group, siPTH1R-Negative control group, PTHrP group, and siPTH1R group under 25 mmol/L glucose were measured by radioimmunoassay in INS-1 cell. Intracellular calcium were detected by Fluo-3/AM and the capability of glucose transport was calculated by assaying the uptake of [3H]-2-deoxy-D-glucose in cells.Results Compared with control group, and siPTH1R-NC group, PTHrP group showed increased capability of insulin secretion; PTHrP group had higher intracellular insulin levels than others; PTHrP group showed increased intracellular calcium; the uptake of [3H]-2-deoxy-D-glucose under high glucose after 48h of PTHrP group was increased(all P＜0.01). Conclusion There is a close relationship between PTH1R activation and insulin secretion and synthesis, PTH1R activation may be one of the protective mechanisms in maintaining function of β-cell under high glucose. Key words: Parathyroid hormone receptor 1; INS-1 cells; Insulin synthesis; Insulin secretion; High concentration of glucose

Effect of Tinospora crispa on glucose uptake in skeletal muscle: role of glucose transporter 1 expression and extracellular signal-regulated kinase1/2 activation

Background: Tinospora crispa (TC) has been used for years as diabetic remedy in Thai-traditional medicine. It has recently been reported that the aqueous extract from TC’s dried stem enhances glucose transport of L6 myotubes. Objective: Investigate the effects of the water-ethanol extract of T. crispa (WETC) on glucose transport in a rat muscle cell-line L6 myotubes, and explore the mechanism of action of T. crispa in muscle cells. Materials and methods: Glucose uptake rate was determined with the [3H] 2-deoxyglucose uptake method and the cell viability was assessed by sulforhodamine B (SRB) assay. Expressions of glucose transporter 1 (GLUT1), GLUT4, extracellular signal regulated kinase 1/2 (ERK1/2), and AMP-activated protein kinase (AMPK) were measured by quantitative Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. Results: At 400 μg/mL, WETC significantly stimulated glucose uptake into L6 myotubes after 24 hours incubation (246.10.1% above basal; p <0.05). The enhancement of glucose transport by WETC was blocked by cycloheximide, a protein synthesis inhibitor. The up-regulation of GLUT1 protein was accompanied by a significant increased in GLUT1 mRNA expression. ERK1/2 was significantly activated in WETC-treated L6 myotubes. In addition, WETC treatment increased AMPK activity in L6 myotubes. Conclusion: T. crispa increased glucose transport activity of L6 myotubes by enhancing GLUT1 expression, a result of AMPK stimulation. Keywords: AMPK, ERK1/2, Glucose uptake, GLUT1, GLUT4, Tinospora crispa

2-Deoxyglucose and inflammation.

2-Deoxyglucose and inflammation.

Neuroprotective effects of Angelicae Acutilobae Radix water extract against ischemia·reperfusion-induced apoptosis in SK-N-SH neuronal cells

Objectives : The purpose of the study is to determine the neuroprotective effects of the water extract of Angelicae Acutilobae Radix(AA) on ischemia reperfusion-induced apoptosis in SK-N-SH human brain neuronal cells. Methods: SK-N-SH cells were treated with different concentrations of AA water extract (0.1, 0.2, 0.5 and 1.0 mg/ml) for 2 hr and then stimulated with Dulbecco's phosphate-buffered saline containing CI-DPBS: 3mM sodium azide and 10 mM 2-deoxy-D-glucose for 45 min, reperfused with growth medium, and incubated for 24 h. Cell viability was determined by WST-1 assay, and ATP/ADP levels were measured by ADP/ATP ratio assay kit. The levels of caspase-3 protein were determined by Western blot and apoptotic body was observed by Hoechst 33258 staining. Results : AA extract significantly inhibited decreasing the cell viability in ischemia-induced SK-N-SH cells. AA also increased the ratio of ADP/ATP in ischemia-induced neuronal cells and decreased the expression levels of apoptotic protein, caspase-3 and apoptotic DNA damage. Conclusions : Our results suggest that AA extract has a neuroprotective property via suppressing the apoptosis and increasing the energy levels in neuronal cells, suggesting that AA extract may has a therapeutic potential in the treatment of ischemic brain injury.

Role of positron emission tomography computed tomography in carcinoma lung evaluation

Lung cancer has graduated from merely a reportable disease of 1912 to being the most common cause of cancer death in developed countries in recent years. The annual number of lung cancer deaths is greater than the combined cancer deaths from breast, colon and prostate. Its association with tobacco has been proved and is related to the type, amount of tobacco used, the age at initiation and duration of use. Significant advances have been made in the diagnosis and management of lung cancer over the past decade. The primary treatment of lung cancer is surgery and the best chance for a complete cure comes from the total resection of localized disease. Once nodal or distant metastases have developed, primary surgical intervention is ruled out and patient is considered for adjuvant chemotherapy with or without radiation therapy. Accurate staging and delineation of disease extent is therefore critical in the treatment planning of lung carcinoma patients. 18 F fluoro deoxy glucose (FDG) positron emission tomography (PET) has been proven to be a valuable noninvasive imaging modality in the evaluation of patients with known or suspected lung cancer and its integration with computed tomography (CT) has changed the face of PET imaging in many ways. This article will review the current role of FDG PET CT in the evaluation of pulmonary nodules, diagnosis, staging and restaging of non-small-cell lung carcinoma (NSCLC), role of PET in small cell lung Carcinoma (Ca), pleural disease and will also discuss its potential future applications.

Inhibitors of myosin, but not actin, alter transport through Tradescantia plasmodesmata

Actin and myosin are components of plasmodesmata, the cytoplasmic channels between plant cells, but their role in regulating these channels is unclear. Here, we investigated the role of myosin in regulating plasmodesmata in a well-studied, simple system comprising single filaments of cells which form stamen hairs in Tradescantia virginiana flowers. Effects of myosin inhibitors were assessed by analysing cell-to-cell movement of fluorescent tracers microinjected into treated cells. Incubation in the myosin inhibitor, 2,3-butanedione monoxime (BDM) or injection of anti-myosin antibodies increased cell-cell transport of fluorescent dextrans, while treatment with the myosin inhibitor N-ethylmaleimide (NEM) decreased cell-cell transport. Pretreatment with the callose synthesis inhibitor, deoxy-D: -glucose (DDG), enhanced transport induced by BDM treatment or injection of myosin antibodies but did not relieve NEM-induced reduction in transport. In contrast to the myosin inhibitors, cell-to-cell transport was unaffected by treatment with the actin polymerisation inhibitor, latrunculin B, after controlling for callose synthesis with DDG. Transport was increased following azide treatment, and reduced after injection of ATP, as in previous studies. We propose that myosin detachment from actin, induced by BDM, opens T. virginiana plasmodesmata whereas the firm attachment of myosin to actin, promoted by NEM, closes them.

Basolateral potassium (IKCa) channel inhibition prevents increased colonic permeability induced by chemical hypoxia

Major liver resection is associated with impaired intestinal perfusion and intestinal ischemia, resulting in decreased mucosal integrity, increased bacterial translocation, and an increased risk of postoperative sepsis. However, the mechanism by which ischemia impairs intestinal mucosal integrity is unclear. We therefore evaluated the role of Ca(2+)-sensitive, intermediate-conductance (IK(Ca)) basolateral potassium channels in enhanced intestinal permeability secondary to chemical hypoxia. The effects of chemical hypoxia induced by 100 μM dinitrophenol (DNP) and 5 mM deoxyglucose (DG) on basolateral IK(Ca) channel activity and whole cell conductance in intact human colonic crypts, and paracellular permeability (G(S)) in isolated colonic sheets, were determined by patch-clamp recording and transepithelial electrical measurements, respectively. DNP and DG rapidly stimulated IK(Ca) channels in cell-attached basolateral membrane patches and elicited a twofold increase (P = 0.004) in whole cell conductance in amphotericin B-permeabilized membrane patches, changes that were inhibited by the specific IK(Ca) channel blockers TRAM-34 (100 nM) and clotrimazole (CLT; 10 μM). In colonic sheets apically permeabilized with nystatin, DNP elicited a twofold increase (P = 0.005) in G(S), which was largely inhibited by the serosal addition of 50 μM CLT. We conclude that, in intestinal epithelia, chemical hypoxia increases G(S) through a mechanism involving basolateral IK(Ca) channel activation. Basolateral IK(Ca) channel inhibition may prevent or limit increased intestinal permeability during liver surgery.

FDG PET or PET-CT versus MRI in detecting local residue or recurrence of nasopharyngeal carcinoma after radiotherapy: a meta-analysis

Objective To compare the value of 18 F-labeled deoxyglucose (FDG) PET or PET-CT with MRI in detecting local residue or recurrence of nasopharyngeal carcinoma after radiotherapy, by performing a meta-analysis of relevant trials.Methods A literature search was performed to English original articles about FDG PET or PET-CT and MRI in Medline, Embase and the Cochrane database from January 1995 to August 2009.The reference standard was histopathologic analysis and/or close clinical and imaging follow-up.Two reviewers searched articles and extracted data independently.Sensitivity, specificity,summary receiver operating characteristic curves (SROC), and the Q index for FDG PET or PET-CT and MRI were pooled, respectively.Results Seventeen studies about FDG PET or PET-CT and 10 studies about MRI were included in this meta-analysis.The pooled sensitivity of FDG PET or PET-CT and MRI were 0.935(95% CI= 0.901 -0.964) and 0.792 (95% CI= 0.731 -0.844), separately.The pooled specificity were 0.924 (95 % CI= 0.898 - 0.945) and 0.787 (95 % GI= 0.746 - 0.825), separately.Area under SROC curves of PET-CT or PET (0.966) was significantly larger than that of MRI (0.852) (z =2.29, P < 0.05).The Q * index estimates for PET-CT or PET (0.914) were significantly higher than for MRI (0.783)(z=2.94,P<0.05).Conclusions FDG-PET/PET-CT has higher accuracy than MRI in diagnosing local residue or recurrence of nasopharyngeal carcinoma after radiotherapy. Key words: Neoplasm residue or recurrence, nasopharyngeal; Tomography, positron emissions,18F-labeled deoxyglucose; Magnetic resonance imaging

Why is the developing brain more susceptible to status epilepticus?

Why is the developing brain more susceptible to status epilepticus?

Validation of a new metabolic marker to assess the vascular viability of vitrified whole ewe ovaries

OBJECTIVE: To explore the pedicle metabolism of VS4 (cryoprotector avoiding ice formation in isolated ovarian pedicles but not in cortex) vitrified whole ovaries, by developing a drip of Thiazodyl Blue Tetrazolium (MTT) as metabolic marker. DESIGN: In-vitro study. MATERIALS AND METHODS: Pairs of ewe ovaries were perfused with MTT (1g/l) for 2 hours at 39°C. Group A: tissue lesions were induced by immersing ovaries into 53° or 65°C heated mediums or into liquid nitrogen, prior to MTT drip. Group B: different metabolic substrates (D-glucose, L-glucose) and inhibitor (2-deoxy D-glucose) were added to the MTT drip. Group C: ovaries were exposed to VS4 ± vitrified-thawed prior to MTT perfusion. Pedicle's MTT staining was either qualitatively analyzed on frozen sections (histological assessment) or solubilized in alcohol and quantified by optical density at 564 nm. Statistics: ANOVA, p<0.05 considered significant. Each experiment compared the MTT staining of 10 treated ovaries with their paired controls. RESULTS: MTT stained strongly and reproductively vessel's smooth muscle. Liquid nitrogen, 53°C or 65°C tissue lesions significantly reduce MTT staining by 93.9%, 48.0% and 94.3%, respectively. MTT could thus be considered as a viability marker. MTT staining partially depended on D-glucose metabolism: its inhibition by 2-deoxy D-glucose, privation of D-glucose or its replacement by unmetabolised L-glucose significantly reduce MTT staining by 23.6%, 40.9% and 31.6% respectively. While thawing, ice seeding from ovarian cortex, constantly invaded the fully VS4 vitrified pedicles (recrystallisation): they significantly stained 29.9% less than control, with histological focal unstained areas, whereas unvitrified VS4 exposed pedicles stained like controls. CONCLUSIONS: Thawing is critical for incompletely vitrified whole ovary. Thus MTT appears to be a proper marker to evaluate whole organ cryoprotection protocols.

Curcumin activates AMPK and suppresses gluconeogenic gene expression in hepatoma cells

Curcumin, the bioactive component of curry spice turmeric, and its related structures possess potent anti-oxidant and anti-inflammatory properties. Several lines of evidence suggest that curcumin may play a beneficial role in animal models of diabetes, both by lowering blood glucose levels and by ameliorating the long-term complications of diabetes. However, current understanding of the mechanism of curcumin action is rudimentary and is limited to its anti-oxidant and anti-inflammatory effects. In this study we examine potential anti-diabetic mechanisms of curcumin, curcumin C3 complex ®, and tetrahydrocurcuminoids (THC). Curcuminoids did not exert a direct effect on receptor tyrosine kinase activity, 2-deoxy glucose uptake in L6-GLUT4myc cells, or intestinal glucose metabolism measured by DPP4/α-glucosidase inhibitory activity. We demonstrate that curcuminoids effectively suppressed dexamethasone-induced phosphoenol pyruvate carboxy kinase (PEPCK) and glucose6-phosphatase (G6Pase) in H4IIE rat hepatoma and Hep3B human hepatoma cells. Furthermore, curcuminoids increased the phosphorylation of AMP-activated protein kinase (AMPK) and its downstream target acetyl-CoA carboxylase (ACC) in H4IIE and Hep3B cells with 400 times (curcumin) to 100,000 times (THC) the potency of metformin. These results suggest that AMPK mediated suppression of hepatic gluconeogenesis may be a potential mechanism mediating glucose-lowering effects of curcuminoids.

Effects of a high-salt diet on adipocyte glucocorticoid receptor and 11-β hydroxysteroid dehydrogenase 1 in salt-sensitive hypertensive rats

High-salt diets decrease insulin sensitivity in salt-sensitive hypertensive rats, and glucocorticoids promote adipocyte growth and may have pathophysiological roles in the metabolic syndrome. The aim of this study was to clarify the relationship between high-salt diet and the adipocyte glucocorticoid hormones in salt-sensitive hypertensive rats. Six-week-old Dahl salt-sensitive (DS) hypertensive rats and salt-resistant (DR) rats were fed a high-salt diet or a normal-salt diet for 4 weeks. Fasting blood glucose (FBG), serum adiponectin, plasma insulin, and corticosterone in plasma and in visceral adipose tissues, 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) activities in adipose tissues and glucose uptake in isolated muscle were measured. Animals underwent an oral glucose tolerance test (OGTT). The expression of mRNA for glucocorticoid receptor (GR), 11β-HSD1 and tumor necrosis factor-α (TNF-α) in adipose tissues were measured using a real-time PCR. A high-salt diet did not influence FBG; however, decreased 2-deoxy glucose uptake and plasma insulin during OGTT in DS rats. The high-salt diet increased significantly adipose tissue corticosterone concentration and 11β-HSD1 activities, gene expression for GR, 11β-HSD1 and TNF-α in adipose tissues in DS rats compared with DR rats ( p < 0.05). The high-salt diet did not influence plasma corticosterone and serum adiponectin concentration in DS and DR rats. These results suggest that changes in GR and 11β-HSD1 in adipose tissue may contribute to insulin sensitivity in salt-sensitive hypertensive rats.

Selective astrocytic gap junctional trafficking of molecules involved in the glycolytic pathway: impact on cellular brain imaging

To assess the specificity of metabolite trafficking among gap junction-coupled astrocytes, we developed novel, real-time, single-cell enzymatic fluorescence assays to assay cell-to-cell transfer of unlabeled glycolytic intermediates and report (i) highly restricted transfer of glucose-6-phosphate (P) and two analogs, deoxyglucose (DG)-6-P, and 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-DG-6-P, compared with DG and 2- and 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-DG, (ii) extensive junctional diffusion of glyceraldehyde-3-P, NADH, and NADPH plus three anionic fluorescent dyes used as internal standards for transfer assays, and (iii) stimulation of gap junctional communication by increased intracellular Na(+) that also evokes metabolic responses in nearby coupled astrocytes. Thus, dye transfer does not predict gap junctional permeability of endogenous metabolites. Intracellular retention of flux-regulating compounds (e.g. glucose-6-P) may be necessary for local metabolic control, whereas 'syncytial sharing' may dissipate the work load on peri-synaptic astrocytes. Imaging of brain functional activity depends on local accumulation of exogenous or endogenous signals, and DG-6-P is trapped in the cell where it is phosphorylated, whereas rapid dispersal of cytoplasmic NAD(P)H and labeled glucose metabolites throughout the astrocytic syncytium can interfere with cellular assessment of neuron-astrocyte relationships in autoradiographic, fluorescence microscopic, and magnetic resonance spectroscopic studies.