Discovery of 2-deoxy glucose surfaced mixed layer dendrimer: a smart neuron targeted systemic drug delivery system for brain diseases.

The availability of non-invasive drug delivery systems capable of efficiently transporting bioactive molecules across the blood-brain barrier to specific cells at the injury site in the brain is currently limited. Delivering drugs to neurons presents an even more formidable challenge due to their lower numbers and less phagocytic nature compared to other brain cells. Additionally, the diverse types of neurons, each performing specific functions, necessitate precise targeting of those implicated in the disease. Moreover, the complex synthetic design of drug delivery systems often hinders their clinical translation. The production of nanomaterials at an industrial scale with high reproducibility and purity is particularly challenging. However, overcoming this challenge is possible by designing nanomaterials through a straightforward, facile, and easily reproducible synthetic process. Methods: In this study, we have developed a third-generation 2-deoxy-glucose functionalized mixed layer dendrimer (2DG-D) utilizing biocompatible and cost-effective materials via a highly facile convergent approach, employing copper-catalyzed click chemistry. We further evaluated the systemic neuronal targeting and biodistribution of 2DG-D, and brain delivery of a neuroprotective agent pioglitazone (Pio) in a pediatric traumatic brain injury (TBI) model. Results: The 2DG-D exhibits favorable characteristics including high water solubility, biocompatibility, biological stability, nanoscale size, and a substantial number of end groups suitable for drug conjugation. Upon systemic administration in a pediatric mouse model of traumatic brain injury (TBI), the 2DG-D localizes in neurons at the injured brain site, clears rapidly from off-target locations, effectively delivers Pio, ameliorates neuroinflammation, and improves behavioral outcomes. Conclusions: The promising in vivo results coupled with a convenient synthetic approach for the construction of 2DG-D makes it a potential nanoplatform for addressing brain diseases.

Cellular binding and uptake of fluorescent glucose analogs 2-NBDG and 6-NBDG occurs independent of membrane glucose transporters.

The classical methods for determining glucose uptake rates in living cells involve the use of isotopically labeled 2-deoxy-d-glucose or 3-O-methyl-d-glucose, which enter cells via well-characterized membrane transporters of the SLC2A and SLC5A families, respectively. These classical methods, however, are increasingly being displaced by high-throughput assays that utilize fluorescent analogs of glucose. Among the most commonly used of these analogs are 2-NBDG and 6-NBDG, which contain a bulky 7-nitro-2,1,3-benzoxadiazol-4-yl-amino moiety in place of a hydroxy group on d-glucose. This fluorescent group significantly alters both the size and shape of these molecules compared to glucose, calling into question whether they actually enter cells by the same transport mechanisms. In this study, we took advantage of the well-defined glucose uptake mechanism of L929 murine fibroblasts, which rely exclusively on the Glut1/Slc2a1 membrane transporter. We demonstrate that neither pharmacologic inhibition of Glut1 nor genetic manipulation of its expression has a significant impact on the binding or uptake of 2-NBDG or 6-NBDG by L929 cells, though both approaches significantly impact [3H]-2-deoxyglucose uptake rates. Together these data indicate that 2-NBDG and 6-NBDG can bind and enter mammalian cells by transporter-independent mechanisms, which calls into question their utility as an accurate proxy for glucose transport.

Permeation of Molecules through Astroglial Connexin 43 Hemichannels Is Modulated by Cytokines with Parameters Depending on the Permeant Species.

Recent studies indicate that connexin hemichannels do not act as freely permeable non-selective pores, but they select permeants in an isoform-specific manner with cooperative, competitive and saturable kinetics. The aim of this study was to investigate whether the treatment with a mixture of IL-1ß plus TNF-α, a well-known pro-inflammatory condition that activates astroglial connexin 43 (Cx43) hemichannels, could alter their permeability to molecules. We found that IL-1ß plus TNF-α left-shifted the dye uptake rate vs. dye concentration relationship for Etd and 2-NBDG, but the opposite took place for DAPI or YO-PRO-1, whereas no alterations were observed for Prd. The latter modifications were accompanied of changes in Kd (Etd, DAPI, YO-PRO-1 or 2-NBDG) and Hill coefficients (Etd and YO-PRO-1), but not in alterations of Vmax. We speculate that IL-1ß plus TNF-α may distinctively affect the binding sites to permeants in astroglial Cx43 hemichannels rather than their number in the cell surface. Alternatively, IL-1ß plus TNF-α could induce the production of endogenous permeants that may favor or compete for in the pore-lining residues of Cx43 hemichannels. Future studies shall elucidate whether the differential ionic/molecule permeation of Cx43 hemichannels in astrocytes could impact their communication with neurons in the normal and inflamed nervous system.

The Ability of Quercetin and Ferulic Acid to Lower Stored Fat is Dependent on the Metabolic Background of Human Adipocytes.

SCOPE: Dietary flavonoids and phenolic acids can modulate lipid metabolism, but effects on mature human adipocytes are not well characterized. MATERIALS AND METHODS: Human adipocytes are differentiated, and contain accumulated lipids, mimicking white adipocytes. They are then cultured either under conditions of actively synthesizing and accumulating additional lipids through lipogenesis ("ongoing lipogenic state") or under conditions of maintaining but not increasing stored lipids ("lipid storage state"). Total lipid, lipidomic and transcriptomics analyses are employed to assess changes after treatment with quercetin and/or ferulic acid. RESULTS: In the "lipid storage state," a longer-term treatment (3 doses over 72 h) with low concentrations of quercetin and ferulic acid together significantly lowered stored lipid content, modified lipid composition, and modulated genes related to lipid metabolism with a strong implication of peroxisome proliferator-activated receptor (PPARα)/retinoid X receptor (RXRα) involvement. In the "ongoing lipogenic state," the effect of quercetin and ferulic acid is markedly different, with fewer changes in gene expression and lipid composition, and no detectable involvement of PPARα/RXRα, with a tenfold higher concentration required to attenuate stored lipid content. CONCLUSIONS: Multiple low-dose treatment of quercetin and ferulic acid modulates lipid metabolism in adipocytes, but the effect is dramatically dependent on the metabolic state of the cell.

One-stop radiotherapeutic targeting of primary and distant osteosarcoma to inhibit cancer progression and metastasis using 2DG-grafted graphene quantum dots.

The application of radiotherapy (RT) to treat osteosarcoma (OS) has been limited, but this is starting to change as the ability to target radiation energy to niches improves. Furthermore, lung cancer from highly metastatic OS is a major cause of death, so it is critical to explore new strategies to tackle metastasis. In this study, we designed a nanoscale radiosensitizer by grafting 2-deoxy-d-glucose (2DG) onto graphene quantum dots (GQD) to achieve OS targeting and boost RT efficacy. Combining the use of 2DG-grafted GQDs (2DG-g-GQD) with RT produced a significant increase in oxidative stress response and DNA damage in the 143B OS cell line compared with RT alone. Moreover, 2DG-g-GQDs selectively associated with 143B cells, and demonstrated the inhibition of migration in a scratch assay. We also demonstrated remarkable improvement in their ability to inhibit tumour progression and lung metastasis in an OS xenograft mouse model. Our results show that the use of 2DG-g-GQDs as OS-targeting radiosensitizers improves their therapeutic outcome and exhibits potential for use in low-dose precision RT for OS.

Acacetin enhances glucose uptake through insulin-independent GLUT4 translocation in L6 myotubes.

BACKGROUND: Lowering blood glucose levels by increasing glucose uptake in insulin target tissues, such as skeletal muscle and adipose tissue, is one strategy to discover and develop antidiabetic drugs from natural products used as traditional medicines. PURPOSE: Our goal was to reveal the mechanism and activity of acacetin (5,7-dihydroxy-4'-methoxyflavone), one of the major compounds in Agastache rugose, in stimulating glucose uptake in muscle cells. METHODS: To determine whether acacetin promotes GLUT4-dependent glucose uptake in cultured L6 skeletal muscle cells, we performed a [14C] 2-deoxy-D-glucose (2-DG) uptake assay after treating differentiated L6-GLUT4myc cells with acacetin. RESULTS: Acacetin dose-dependently increased 2-DG uptake by enhancing GLUT4 translocation to the plasma membrane. Our results revealed that acacetin activated the CaMKII-AMPK pathway by increasing intracellular calcium concentrations. We also found that aPKCλ/ζ phosphorylation and intracellular reactive oxygen species (ROS) production were involved in acacetin-induced GLUT4 translocation. Moreover, acacetin-activated AMPK inhibited intracellular lipid accumulation and increased 2-DG uptake in HepG2 cells. CONCLUSION: Taken together, these results suggest that acacetin might be useful as an antidiabetic functional ingredient. Subsequent experiments using disease model animals are needed to verify our results.

Co-delivery of 2-Deoxyglucose and a glutamine metabolism inhibitor V9302 via a prodrug micellar formulation for synergistic targeting of metabolism in cancer.

The unique metabolic demand of cancer cells suggests a new therapeutic strategy targeting the metabolism in cancers. V9302 is a recently reported inhibitor of ASCT2 amino acid transporter which shows promising antitumor activity by blocking glutamine uptake. However, its poor solubility in aqueous solutions and tumor cells' compensatory metabolic shift to glucose metabolism may limit the antitumor efficacy of V9302. 2-Deoxyglucose (2-DG), a derivative of glucose, has been developed as a potential antitumor agent through inhibiting glycolysis in tumor cells. In order to achieve enhanced antitumor effect by inhibiting both metabolic pathways, a 2-DG prodrug-based micellar carrier poly-(oligo ethylene glycol)-co-poly(4-((4-oxo-4-((4-vinylbenzyl)oxy)butyl)disulfaneyl)butanoic acid)-(2-deoxyglucose) (POEG-p-2DG) was developed. POEG-p-2DG well retained the pharmacological activity of 2-DG in vitro and in vivo, More importantly, POEG-p-2DG could self-assemble to form micelles that were capable of loading V9302 to achieve co-delivery of 2-DG and V9302. V9302-loaded POEG-p2DG micelles were small in sizes (~10 nm), showed a slow kinetics of drug release and demonstrated targeted delivery to tumor. In addition, V9302 loaded POEG-p-2DG micelles exhibited improved anti-tumor efficacy both in vitro and in vivo. Interestingly, 2-DG treatment further decreased the glutamine uptake when combined with V9302, likely due to inhibition of ASCT2 glycosylation. These results suggest that POEG-p2DG prodrug micelles may serve as a dual functional carrier for V9302 to achieve synergistic targeting of metabolism in cancers. STATEMENT OF SIGNIFICANCE: Unique cancer cell's metabolism profile denotes a new therapeutic strategy. V9302 is a recently reported glutamine metabolism inhibitor that shows promising antitumor activity. However, its poor waster solubility and tumor cell's compensatory metabolic network may limit its potential clinical application. 2-Deoxyglucose(2-DG) is a widely used glycolysis inhibitor. However, its clinical application is hindered by low efficacy as monotherapy. Thus, in this study, we developed a redox-sensitive, 2-DG-based prodrug polymer, as a dual-functional carrier for co-delivery of V9302 and 2-DG as a combination strategy. V9302 loaded POEG-p-2DG micelle showed significantly improved antitumor activity through synergistic targeting of both glutamine and glycolysis metabolism pathway. More interestingly, POEG-p-2DG itself further facilitates inhibition of glutamine metabolism, likely through inhibition of ASCT2 glycosylation.

An Activatable Cancer-Targeted Hydrogen Peroxide Probe for Photoacoustic and Fluorescence Imaging.

Reactive oxygen species play an important role in cancer, however, their promiscuous reactivity, low abundance, and short-lived nature limit our ability to study them in real time in living subjects with conventional noninvasive imaging methods. Photoacoustic imaging is an emerging modality for in vivo visualization of molecular processes with deep tissue penetration and high spatiotemporal resolution. Here, we describe the design and synthesis of a targeted, activatable probe for photoacoustic imaging, which is responsive to one of the major and abundant reactive oxygen species, hydrogen peroxide (H2O2). This bifunctional probe, which is also detectable with fluorescence imaging, is composed of a heptamethine carbocyanine dye scaffold for signal generation, a 2-deoxyglucose cancer localization moiety, and a boronic ester functionality that specifically detects and reacts to H2O2. The optical properties of the probe were characterized using absorption, fluorescence, and photoacoustic measurements; upon addition of pathophysiologic H2O2 concentrations, a clear increase in fluorescence and red-shift of the absorption and photoacoustic spectra were observed. Studies performed in vitro showed no significant toxicity and specific uptake of the probe into the cytosol in breast cancer cell lines. Importantly, intravenous injection of the probe led to targeted uptake and accumulation in solid tumors, which enabled noninvasive photoacoustic and fluorescence imaging of H2O2. In conclusion, the reported probe shows promise for the in vivo visualization of hydrogen peroxide. SIGNIFICANCE: This study presents the first activatable and cancer-targeted hydrogen peroxide probe for photoacoustic molecular imaging, paving the way for visualization of hydrogen peroxide at high spatiotemporal resolution in living subjects.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/20/5407/F1.large.jpg.

A Warburg effect targeting vector designed to increase the uptake of compounds by cancer cells demonstrates glucose and hypoxia dependent uptake.

Glycoconjugation to target the Warburg effect provides the potential to enhance selective uptake of anticancer or imaging agents by cancer cells. A Warburg effect targeting group, rationally designed to facilitate uptake by glucose transporters and promote cellular accumulation due to phosphorylation by hexokinase (HK), has been synthesised. This targeting group, the C2 modified glucose analogue 2-(2-[2-(2-aminoethoxy)ethoxy]ethoxy)-D-glucose, has been conjugated to the fluorophore nitrobenzoxadiazole to evaluate its effect on uptake and accumulation in cancer cells. The targeting vector has demonstrated inhibition of glucose phosphorylation by HK, indicating its interaction with the enzyme and thereby confirming the potential to facilitate an intracellular trapping mechanism for compounds it is conjugated with. The cellular uptake of the fluorescent analogue is dependent on the glucose concentration and is so to a greater extent than is that of the widely used fluorescent glucose analogue, 2-NBDG. It also demonstrates selective uptake in the hypoxic regions of 3D spheroid tumour models whereas 2-NBDG is distributed primarily through the normoxic regions of the spheroid. The increased selectivity is consistent with the blocking of alternative uptake pathways.

Safety, Biodistribution, and Dosimetry of 123I-6-Deoxy-6-Iodo-D-Glucose, a Tracer of Glucose Transport, in Healthy and Diabetic Volunteers.

PURPOSE: Insulin resistance is a key feature of the metabolic syndrome and type 2 diabetes, in which noninvasive assessment is not currently allowed by any methodology. We previously validated an iodinated tracer of glucose transport (6DIG) and a new methodology for the in vivo quantification of cardiac insulin resistance in rodents. The aim of this study was to investigate the safety, biodistribution, and radiation dosimetry of this method using I-6DIG in 5 healthy and 6 diabetic volunteers. METHODS: The collection of adverse effects (AEs) and medical supervision of vital parameters and biological variables allowed the safety evaluation. Biodistribution was studied by sequentially acquiring whole-body images at 1, 2, 4, 8, and 24 hours postinjection. The total number of disintegrations in each organ normalized to the injected activity was calculated as the area under the time-activity curves. Dosimetry calculations were performed using OLINDA/EXM. RESULTS: No major adverse events were observed. The average dose corresponding to the 2 injections of I-6DIG used in the protocol was 182.1 ± 7.5 MBq. A fast blood clearance of I-6DIG was observed. The main route of elimination was urinary, with greater than 50% of urine activity over 24 hours. No blood or urine metabolite was detected. I-6DIG accumulation mostly occurred in elimination organs such as kidneys and liver. Mean radiation dosimetry calculations indicated an effective whole-body absorbed dose of 3.35 ± 0.57 mSv for the whole procedure. CONCLUSIONS: I-6DIG was well tolerated in human with a dosimetry profile comparable to that of other commonly used iodinated tracers, thereby allowing further clinical development of the tracer.

(all-E)- and (5Z)-Lycopene Display Similar Biological Effects on Adipocytes.

SCOPE: Although about 90% of lycopene in dietary sources occurs in the linear all-trans conformation, a large proportion of the lycopene found in human tissues is of the cis-isomer type, notably (5Z)-lycopene. The biological effects of this (5Z) isomer have been under-researched. The aim of this study is to evaluate some biological functions of (5Z)-lycopene in adipocytes and to compare them with those of (all-E)-lycopene. METHODS AND RESULTS: (all-E)- and (5Z)-Lycopene displayed strong similarities in global gene expression profile and biological pathways impacted. Peroxisome proliferator-activated receptor (PPAR) signaling is identified as a major actor mediating the effects of lycopene isomers. Transactivation assays confirmed the ability of both isomers to transactivate PPARγ. In addition, the TNFα-induced proinflammatory cytokine mRNA expression in 3T3-L1 adipocytes is reduced by both isomers via a reduction in the phosphorylation levels of p65. Finally, lycopene isomers restore the TNF-α-blunted uptake of glucose by adipocytes via a modulation of AKT phosphorylation. CONCLUSION: These results show that lycopene isomers exert similar biological functions in adipocytes, linked to their ability to transactivate PPARγ. These findings add to our knowledge of lycopene effects in adipocyte biology and point to the possible use of lycopene in the prevention of obesity-related disorders.

Exogenous 3-Deoxyglucosone-Induced Carbonyl and Oxidative Stress Causes ß-Cells Dysfunction by Impairing Gut Permeability in Rats.

3-Deoxyglucosone (3DG) is a highly reactive dicarbonyl species, and its accumulation evokes carbonyl and oxidative stress. Our recent data reveal the role of 3DG as an independent factor for the development of prediabetes and suggest that intestine could be its novel target tissue. The present study investigated whether exogenous 3DG increases intestinal permeability by triggering carbonyl and oxidative stress, thus contributing to ß-cell dysfunction. Rats were administered 3DG for two weeks by gastric gavage. Then levels of insulin, ROS, MDA, SOD, NLRP3, TNF-α and IL-1ß in blood plasma as well as the ROS level and content of TNF-α and IL-1ß in pancreas were assessed. Also, the expression of E-cadherin and ZO-1 as well as levels of 3DG, protein carbonylation, ROS, TNF-α and IL-1ß in colon were determined. The 3DG-treated rats showed an elevation in systemic oxidative stress (ROS, MDA and SOD) and in inflammation (TNF-α and IL-1ß), decreased plasma insulin level 15 min after the glucose load, and increased levels of TNF-α, IL-1ß and ROS in pancreatic tissue. In colon tissues of the 3DG-treated rats, decreased E-cadherin expression and increased ROS production as well as an elevation of TNF-α and IL-1ß levels were observed. Interestingly, elevation of colon protein carbonylation was observed in the 3DG-treated rats that displayed 3DG deposition in colon tissues. We revealed for the first time that 3DG deposition in colon triggers carbonyl and oxidative stress and, as a consequence, impairs gut permeability. The enhanced intestinal permeability caused by 3DG deposition in colon results in systemic and pancreatic oxidative stress and inflammatory process, contributing to the development of ß-cell dysfunction.

Chemical exchange-sensitive spin-lock (CESL) MRI of glucose and analogs in brain tumors.

PURPOSE: Glucose uptake and metabolism can be measured by chemical exchange-sensitive spin-lock (CESL) MRI with an administration of glucose or its analogs. This study investigates the sensitivity, the spatiotemporal characteristics, and the signal source of glucoCESL with a 9L rat brain tumor model. METHODS: Dynamic CESL MRI with intravenous injection of D-glucose, 2-deoxy-D-glucose (2DG), and L-glucose were measured and compared with gadolinium-based dynamic contrast-enhanced (DCE) MRI. RESULTS: The CESL signals with an injection of glucose or analogs have faster and larger changes in tumors than normal brain tissue. In tumors, the CESL signal with 2DG injection has larger and slower peak response than that with D-glucose due to the accumulation of 2DG and 2DG-6-phosphate in the intracellular compartment, whereas L-glucose, which cannot be transported intracellularly by glucose transporters, only induces a small change. The initial glucoCESL maps (< 4 minutes) are qualitatively similar to DCE maps, whereas later maps (> 4 minutes) show more widespread responses. The rise times of D-glucose-CESL and 2DG-CESL signals in the tumor are slower than that of DCE. Our data suggest that the initial CESL contrast primarily reflects a passive increase of glucose content in the extracellular space of tumors due to a higher vascular permeability, whereas the later period may have a significant contribution from the uptake/metabolism of glucose in the intracellular compartment. CONCLUSIONS: Our results demonstrate that glucoCESL MRI has both extracellular and intracellular contributions, and can be a useful tool for measurements of both vascular permeability and glucose uptake in tumors.

Limonene promotes osteoblast differentiation and 2-deoxy-d-glucose uptake through p38MAPK and Akt signaling pathways in C2C12 skeletal muscle cells.

BACKGROUND: Limonene is a cyclic monoterpene (CTL) found in citrus fruits and many plant kingdoms. It has attracted attention as potential molecule due to its diverse biological activities. However, molecular mechanism involved in the osteogenic induction of CTL in C2C12 skeletal muscle cells remain unclear. PURPOSE: Skeletal development maintains the bone homeostasis through bone remodeling process. It coordinated between the osteoblast and osteoblast process. Osteoporosis is one of the most common bone diseases caused by a systemic reduction in bone mass. Recent osteoporosis treatment is based on the use of anti-resorptive and bone forming drugs. However, long term use of these drugs is associated with serious side effects and strategies on the discovery of lead compounds from natural products for osteoblast differentiation are urgently needed. Therefore, we planned to find out the role of CTL on osteoblast differentiation and glucose uptake in C2C12 cells and its effect on signaling pathways. METHODS: Cell proliferation, alkaline phosphatase (ALP) activity, calcium deposition, genes, and proteins associated with osteoblast activation and glucose utilization were analysed. RESULTS: CTL did not affect the cell viability. CTL significantly increased ALP activity, calcium depositions and the expression of osteogenic specific genes such as Myogenin, Myogenic differentiation 1 (MyoD), ALP, Run-related transcription factor 2(RUNX2), osteocalcin (OCN). In addition, CTL induced the mRNA expression of bone morphogenetic proteins (BMP-2 BMP-4 BMP-6 BMP-7 BMP-9). CTL treatment enhanced 2-Deoxy-d-glucose (2DG) uptake. Moreover, CTL stimulated the activation of p38 mitogen activated protein kinase (p38MAPK), Protein kinase B (Akt), Extracellular signal related kinase (ERKs) by increasing phosphorylation. CTL treatment abolished p38 inhibitor (SB203580) mediated inhibition of osteoblast differentiation, but no effect was noted by ERKs specific inhibitor (PD98059). CONCLUSION: These results suggest that limonene induces osteoblast differentiation and glucose uptake through activating p38MAPK and Akt signaling pathways, confirming the molecular basis of the osteoblast differentiation by limonene in C2C12 skeletal muscle cells.

The metabolism and transport of 1,5-anhydroglucitol in cells.

AIMS: Our previous studies demonstrated that serum 1,5-anhydroglucitol (1,5-AG) levels increased slightly rather than declined after an acute glucose load. Therefore, the current study aims at exploring the transport and metabolic characteristics of 1,5-AG, as well as the effect of glucose on 1,5-AG transport. METHODS: Km and Vmax were determined to measure the affinity of glucose oxidase (GOD) and hexokinase (HK) for 1,5-AG and glucose. HepG2, C2C12, and primary mouse hepatocytes were incubated for 2 h with 1,5-AG at concentrations of 0, 80, and 160 µg/mL. Then, intracellular and extracellular concentrations of 1,5-AG were measured before and after washing with PBS to evaluate the transport and metabolic rates of 1,5-AG. In addition, the influence of an acute glucose load on the transport of 1,5-AG was studied. RESULTS: The affinity of GOD and HK for 1,5-AG is 5 and 42.5% of that for glucose, respectively. Moreover, there is no de novo synthesis of 1,5-AG, and its metabolic rate is < 3%. After a 2 h incubation with additional 1,5-AG, the intracellular levels of 1,5-AG were 50-80% of extracellular levels. Moreover, intracellular 1,5-AG concentrations decreased rapidly and reached zero following the removal of 1,5-AG from the external medium. In addition, an acute glucose load can affect the dynamic balance of 1,5-AG, causing the intracellular 1,5-AG levels to decline significantly and the extracellular levels to increase slightly in HepG2 cells. CONCLUSIONS: Unlike glucose, 1,5-AG is hard to be metabolized in vivo, and its transport is influenced by an acute glucose load in hepatocytes.

Effects of 1,5-anhydroglucitol on postprandial blood glucose and insulin levels and hydrogen excretion in rats and healthy humans.

The inhibition by 1,5-anhydro-d-glucitol (1,5-AG) was determined on disaccharidases of rats and humans. Then, the metabolism and fate of 1,5-AG was investigated in rats and humans. Although 1,5-AG inhibited about 50 % of sucrase activity in rat small intestine, the inhibition was less than half of d-sorbose. 1,5-AG strongly inhibited trehalase and lactase, whereas d-sorbose inhibited them very weakly. 1,5-AG noncompetitively inhibited sucrase. The inhibition of 1,5-AG on sucrase and maltase was similar between humans and rats. 1,5-AG in serum increased 30 min after oral administration of 1,5-AG (600 mg) in rats, and mostly 100 % of 1,5-AG was excreted into the urine 24 h after administration. 1,5-AG in serum showed a peak 30 min after ingestion of 1,5-AG (20 g) by healthy subjects, and decreased gradually over 180 min. About 60 % of 1,5-AG was excreted into the urine for 9 h following ingestion. Hydrogen was scarcely excreted in both rats and humans 24 h after administration of 1,5-AG. Furthermore, 1,5-AG significantly suppressed the blood glucose elevation, and hydrogen excretion was increased following the simultaneous ingestion of sucrose and 1,5-AG in healthy subjects. 1,5-AG also significantly suppressed the blood glucose elevation following the simultaneous ingestion of glucose and 1,5-AG; however, hydrogen excretion was negligible. The available energy of 1,5-AG, which is absorbed readily from the small intestine and excreted quickly into the urine, is 0 kJ/g (0 kcal/g). Furthermore, 1,5-AG might suppress the blood glucose elevation through the inhibition of sucrase, as well as intestinal glucose absorption.

Resveratrol regulates neuronal glucose uptake and insulin sensitivity via P21-activated kinase 2 (PAK2).

We have recently reported P21-activated kinase 2 (PAK2), a serine/threonine kinase as a negative regulator of neuronal glucose uptake and insulin sensitivity. Resveratrol (RSV), a natural polyphenol with anti-oxidative, anti-inflammatory and anti-diabetic properties, regulates PAK2 activity in HepG2 and ESC-B5 cell apoptosis. However, regulation of PAK2 by RSV in neuronal insulin signaling pathway, if any, is still unknown. In the present study, RSV treatment significantly increased PAK2 activity under insulin-sensitive and insulin-resistant condition, along with a marked decrease in glucose uptake in differentiated N2A cells. Pretreatment with AMPK inhibitor, followed by RSV treatment resulted in reduction in PAK2 activity whereas glucose uptake showed an increase. However, pretreatment with Akt inhibitor and then RSV exposure significantly increased PAK2 activity, with a corresponding decrease in glucose uptake. RSV treatment increased AMPK activity and decreased Akt activity. In conclusion, RSV negatively regulates neuronal glucose uptake and insulin sensitivity via PAK2.

Effect of Three Statins on Glucose Uptake of Cardiomyocytes and its Mechanism.

BACKGROUND The aim of this study was to investigate the effects of different statins on glucose uptake and to confirm its mechanism in primary cultured rat cardiomyocytes after administration of atorvastatin, pravastatin, and rosuvastatin. MATERIAL AND METHODS Primary cultured rat cardiomyocytes were randomly assigned to 5 groups: normal control group (OB), insulin group (S1), statin 1-µM (S2), 5-µM (S3), and 10-µM (S4) groups for 3 different statins. The 2-[3H]-DG uptake of each group was determined and the mRNA and protein expression levels of glucose transporter type 4 (GLUT4), insulin receptor substrate (IRs), and RhoA were assessed. RESULTS After treatment with different concentrations of statins and insulin, the 2-[3H]-DG uptake showed a significant negative correlation with the concentration of atorvastatin (P<0.05), and no significant correlation with pravastatin and rosuvastatin. The mRNA and protein expression levels of GLUT4 and IRs-1 in primary cultured cardiomyocytes were both significantly reduced by atorvastatin treatment (P<0.05). Pravastatin and rosuvastatin showed no significant effects on GLUT4 and IRs-1 expression. The mRNA and protein expression levels of RhoA both showed no significant difference when treated with the 3 statins. CONCLUSIONS These results confirm that atorvastatin can inhibit insulin-induced glucose uptake in primary cultured rat cardiomyocytes by regulating the PI3K/Akt insulin signal transduction pathway.

Neural correlates of the mother-to-infant social transmission of fear.

Although clinical and basic studies show that parental trauma, fear, and anxiety may be transmitted to offspring, the neurobiology of this transmission is still not well understood. We recently demonstrated in an animal model that infant rats acquire threat responses to a distinct cue when a mother expresses fear to this cue in their presence. This ability to acquire maternal fear through social learning is present at birth and, as we previously reported, depends on the pup's amygdala. However, the remaining neural mechanisms underlying social fear learning (SFL) in infancy remain elusive. Here, by using [(14) C]2-deoxyglucose autoradiography, we show that the mother-to-infant transmission of fear in preweaning rats is associated with a significant increase of activity in the subregions of the lateral septum, nucleus accumbens, bed nucleus of stria terminalis, retrosplenial cortex, paraventricular nucleus of the thalamus, mediodorsal and intralaminar thalamic nuclei, medial and the lateral preoptic nuclei of the hypothalamus, and the lateral periaqueductal gray. In contrast to studies of adult SFL demonstrating the role of the anterior cingulate cortex and possibly the insular cortex or research of infant classical fear conditioning showing the role of the posterior piriform cortex, no changes of activation in these areas were observed. Our results indicate that the pup's exposure to maternal fear activates a number of areas involved in processing threat, stress, or pain. This pattern of activation suggests a unique set of neural mechanisms underlying SFL in the developing brain.

Inhibiting Lateral Habenula Improves L-DOPA-Induced Dyskinesia.

BACKGROUND: A systematic search of brain nuclei putatively involved in L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID) in Parkinson's disease shed light, notably, upon the lateral habenula (LHb), which displayed an overexpression of the ∆FosB, ARC, and Zif268 immediate-early genes only in rats experiencing abnormal involuntary movements (AIMs). We thus hypothesized that LHb might play a role in LID. METHODS: ∆FosB immunoreactivity, 2-deoxyglucose uptake, and firing activity of LHb were studied in experimental models of Parkinson's disease and LID. ΔFosB-expressing LHb neurons were then targeted using the Daun02-inactivation method. A total of 18 monkeys and 55 rats were used. RESULTS: LHb was found to be metabolically modified in dyskinetic monkeys and its neuronal firing frequency significantly increased in ON L-DOPA dyskinetic 6-hydroxydopamine-lesioned rats, suggesting that increased LHb neuronal activity in response to L-DOPA is related to AIM manifestation. Therefore, to mechanistically test if LHb neuronal activity might affect AIM severity, following induction of AIMs, 6-hydroxydopamine rats were injected with Daun02 in the LHb previously transfected with ß-galactosidase under control of the FosB promoter. Three days after Daun02 administration, animals were tested daily with L-DOPA to assess LID and L-DOPA-induced rotations. Inactivation of ∆FosB-expressing neurons significantly reduced AIM severity and also increased rotations. Interestingly, the dopaminergic D1 receptor was overexpressed only on the lesioned side of dyskinetic rats in LHb and co-localized with ΔFosB, suggesting a D1 receptor-mediated mechanism supporting the LHb involvement in AIMs. CONCLUSIONS: This study highlights the role of LHb in LID, offering a new target to innovative treatments of LID.