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Steviol Glycoside, L-Arginine, and Chromium(III) Supplementation Attenuates Abnormalities in Glucose Metabolism in Streptozotocin-Induced Mildly Diabetic Rats Fed a High-Fat Diet. Pharmaceuticals (Basel) 2022; 15:ph15101200. [PMID: 36297315 PMCID: PMC9607630 DOI: 10.3390/ph15101200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/16/2022] [Accepted: 09/23/2022] [Indexed: 11/24/2022] Open
Abstract
Stevia rebaudiana Bertoni and its glycosides are believed to exhibit several health-promoting properties. Recently, the mechanisms of the anti-diabetic effects of steviol glycosides (SG) have been the subject of intense research. The following study aims to evaluate the results of SG (stevioside (ST) and rebaudioside A (RA)) combined with L-arginine (L-Arg) and chromium(III) (CrIII) supplementation in streptozotocin- (STZ) induced mild type 2 diabetic rats fed a high-fat diet (HFD), with particular emphasis on carbohydrate and lipid metabolisms. The experiment was carried out on 110 male Wistar rats, 100 of which were fed an HFD to induce insulin resistance, followed by an intraperitoneal injection of streptozotocin to induce mild type 2 diabetes. After confirmation of hyperglycemia, the rats were divided into groups. Three groups served as controls: diabetic untreated, diabetic treated with metformin (300 mg/kg BW), and healthy group. Eight groups were fed an HFD enriched with stevioside or rebaudioside A (2500 mg/kg BW) combined with L-arginine (2000 or 4000 mg/kg BW) and Cr(III) (1 or 5 mg/kg BW) for six weeks. The results showed that supplementation with SG (ST and RA) combined with L-arg and Cr(III) could improve blood glucose levels in rats with mild type 2 diabetes. Furthermore, ST was more effective in improving blood glucose levels, insulin resistance indices, and very low-density lipoprotein cholesterol (VLDL-C) concentrations than RA. Although L-arg and Cr(III) supplementation did not independently affect most blood carbohydrate and lipid indices, it further improved some biomarkers when combined, particularly with ST. Notably, the beneficial impact of ST on the homeostatic model assessment–insulin resistance (HOMA-IR) and on the quantitative insulin-sensitivity check index (QUICKI) was strengthened when mixed with a high dose of L-arg, while its impact on antioxidant status was improved when combined with a high dose of Cr(III) in rats with mild type 2 diabetes. In conclusion, these results suggest that supplementary stevioside combined with L-arginine and Cr(III) has therapeutic potential for mild type 2 diabetes. However, further studies are warranted to confirm these effects in other experimental models and humans.
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Kurek JM, Zielińska-Wasielica J, Kowalska K, Krejpcio Z, Olejnik A. Modulating effects of steviol and steviol glycosides on adipogenesis, lipogenesis, glucose uptake and insulin resistance in 3T3-L1 adipocyte model. J Funct Foods 2022. [DOI: 10.1016/j.jff.2022.105141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Bugliani M, Tavarini S, Grano F, Tondi S, Lacerenza S, Giusti L, Ronci M, Maidecchi A, Marchetti P, Tesi M, Angelini LG. Protective effects of Stevia rebaudiana extracts on beta cells in lipotoxic conditions. Acta Diabetol 2022; 59:113-126. [PMID: 34499239 PMCID: PMC8758658 DOI: 10.1007/s00592-021-01793-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 08/23/2021] [Indexed: 12/16/2022]
Abstract
AIMS Stevia rebaudiana Bertoni leaf extracts have gained increasing attention for their potential protection against type 2 diabetes. In this study, we have evaluated the possible beneficial effects of Stevia rebaudiana leaf extracts on beta-cells exposed to lipotoxicity and explored some of the possible mechanisms involved. METHODS Extracts, deriving from six different chemotypes (ST1 to ST6), were characterized in terms of steviol glycosides, total phenols, flavonoids, and antioxidant activity. INS-1E beta cells and human pancreatic islets were incubated 24 h with 0.5 mM palmitate with or without varying concentrations of extracts. Beta-cell/islet cell features were analyzed by MTT assay, activated caspase 3/7 measurement, and/or nucleosome quantification. In addition, the proteome of INS-1E cells was assessed by bi-dimensional electrophoresis (2-DE). RESULTS The extracts differed in terms of antioxidant activity and stevioside content. As expected, 24 h exposure to palmitate resulted in a significant decrease of INS-1E cell metabolic activity, which was counteracted by all the Stevia extracts at 200 μg/ml. However, varying stevioside only concentrations were not able to protect palmitate-exposed cells. ST3 extract was also tested with human islets, showing an anti-apoptotic effect. Proteome analysis showed several changes in INS-1E beta-cells exposed to ST3, mainly at the endoplasmic reticulum and mitochondrial levels. CONCLUSIONS Stevia rebaudiana leaf extracts have beneficial effects on beta cells exposed to lipotoxicity; this effect does not seem to be mediated by stevioside alone (suggesting a major role of the leaf phytocomplex as a whole) and might be due to actions on the endoplasmic reticulum and the mitochondrion.
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Affiliation(s)
- Marco Bugliani
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Silvia Tavarini
- Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy
| | - Francesca Grano
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Silvia Tondi
- Aboca SpA Società Agricola, Sansepolcro, Tuscany, Italy
| | | | - Laura Giusti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
- School of Pharmacy, University of Camerino, Camerino, Italy
| | - Maurizio Ronci
- Department of Pharmacy and Centre for Advanced Studies and Technologies (CAST), University "G. D'Annunzio" of Chieti-Pescara, Chieti, Italy
| | | | - Piero Marchetti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
- Department of Pharmacy and Centre for Advanced Studies and Technologies (CAST), University "G. D'Annunzio" of Chieti-Pescara, Chieti, Italy.
| | - Marta Tesi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Luciana G Angelini
- Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy
- Centro Interdipartimentale NUTRAFOOD, University of Pisa, Pisa, Italy
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Sharma N, Kumar P, Giri R. Polysaccharides like pentagalloylglucose, parishin a and stevioside inhibits the viral entry by binding the Zika virus envelope protein. J Biomol Struct Dyn 2020; 39:6008-6020. [PMID: 32705969 DOI: 10.1080/07391102.2020.1797538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ZIKV belongs to a flavivirus family in which class II fusion proteins involve a low pH-dependent membrane fusion leading to infection of host cells. Envelope (E) protein is primarily responsible for the viral host membrane fusion and is the major target for inhibiting viral entry. Our findings reveal that compounds like PGG, Parishin A, and Stevioside have shown a high affinity for E protein and found to be active against various other viral infections. The binding of these molecules to E protein was found to decrease the RMSD and RMSF values of the ligand protein complex and restricted the Radius of Gyration in molecular dynamics simulation analysis. Further, the binding free energy calculations suggested the stability of complexes throughout simulations trajectory that could reduce the flexibility of the linker so as to block the folding back event of membrane fusion. A recent study has shown that PGG inhibits the early stages of viral entry in HCV and ZIKV. Therefore, we propose that PGG inhibits the entry of virion via binding the E protein and restricting the conformational rearrangement during membrane fusion.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Nitin Sharma
- Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh, India
| | - Prateek Kumar
- Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh, India
| | - Rajanish Giri
- Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh, India
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Bhattacharya S, Oksbjerg N, Young JF, Jeppesen PB. Caffeic acid, naringenin and quercetin enhance glucose-stimulated insulin secretion and glucose sensitivity in INS-1E cells. Diabetes Obes Metab 2014; 16:602-12. [PMID: 24205999 DOI: 10.1111/dom.12236] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/21/2013] [Accepted: 11/06/2013] [Indexed: 02/06/2023]
Abstract
AIMS Caffeic acid, naringenin and quercetin are naturally occurring phenolic compounds (PCs) present in many plants as secondary metabolites. The aim of this study was to investigate their effect on glucose-stimulated insulin secretion (GSIS) in INS-1E cells and to explore their effect on expression of genes involved in β-cell survival and function under normoglycaemic and glucotoxic conditions. METHODS For acute studies, INS-1E cells were grown in 11 mM glucose (72 h) and then incubated with the PCs (1 h) with 3.3/16.7 mM glucose; whereas, for chronic studies, the cells were grown in 11 mM glucose (72 h) with/without the PCs, and then incubated with 3.3/16.7 mM glucose (1 h); thereafter, GSIS was measured. For GSIS and gene expression studies (GES) under glucotoxic conditions, two sets of cells were grown in 11/25 mM glucose with/without the PCs (72 h): one was used for GES, using real time RT-PCR, and the other was exposed to 3.3/16.7 mM glucose, followed by measurement of GSIS. RESULTS The study demonstrated that the PCs can enhance GSIS under hyperglycaemic and glucotoxic conditions in INS-1E cells. Moreover, these compounds can differentially, yet distinctly change the expression profile of genes [Glut2 (glucose transporter 2), Gck (glucokinase), Ins1 (insulin 1), Ins2, Beta2 (neurogenic differentiation protein 1), Pdx1 (pancreatic and duodenal homeobox protein 1), Akt1 (RAC-α serine/threonine-protein kinase encoding gene), Akt2 (RAC-β serine/threonine-protein kinase encoding gene), Irs1 (insulin receptor substrate 1), Acc1 (acetyl CoA carboxylase 1), Bcl2 (β-cell lymphoma 2 protein), Bax (Bcl-2 associated X protein), Casp3 (Caspase 3), Hsp70 (heat shock protein 70), and Hsp90] involved in β-cell stress, survival and function. CONCLUSION The results indicate that the PCs tested enhance GSIS and glucose sensitivity in INS-1E cells. They also modulate gene expression profiles to improve β-cell survival and function during glucotoxicity.
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Affiliation(s)
- S Bhattacharya
- Department of Food Science, Aarhus University, Tjele, Denmark
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Akbarzadeh S, Eskandari F, Tangestani H, Bagherinejad ST, Bargahi A, Bazzi P, Daneshi A, Sahrapoor A, O'Connor WJ, Rahbar AR. The Effect of Stevia Rebaudiana on Serum Omentin and Visfatin Level in STZ-Induced Diabetic Rats. J Diet Suppl 2014; 12:11-22. [DOI: 10.3109/19390211.2014.901999] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Moons N, Goyens D, Jacobs J, Meervelt LV, De Borggraeve WM, Dehaen W. Fused derivatives of (iso)steviol via pericyclic reactions. Tetrahedron Lett 2012. [DOI: 10.1016/j.tetlet.2012.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Yeo RWY, Yang K, Li G, Lim SK. High glucose predisposes gene expression and ERK phosphorylation to apoptosis and impaired glucose-stimulated insulin secretion via the cytoskeleton. PLoS One 2012; 7:e44988. [PMID: 23024780 PMCID: PMC3443235 DOI: 10.1371/journal.pone.0044988] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 08/11/2012] [Indexed: 01/09/2023] Open
Abstract
Chronic high glucose (HG) inflicts glucotoxicity on vulnerable cell types such as pancreatic β cells and contributes to insulin resistance and impaired insulin secretion in diabetic patients. To identify HG-induced cellular aberrations that are candidate mediators of glucotoxicity in pancreatic β cells, we analyzed gene expression in ERoSHK6, a mouse insulin-secreting cell line after chronic HG exposure (six-day exposure to 33.3 mM glucose). Chronic HG exposure which reduced glucose-stimulated insulin secretion (GSIS) increased transcript levels of 185 genes that clustered primarily in 5 processes namely cellular growth and proliferation; cell death; cellular assembly and organization; cell morphology; and cell-to-cell signaling and interaction. The former two were validated by increased apoptosis of ERoSHK6 cells after chronic HG exposure and reaffirmed the vulnerability of β cells to glucotoxicity. The three remaining processes were partially substantiated by changes in cellular morphology and structure, and instigated an investigation of the cytoskeleton and cell-cell adhesion. These studies revealed a depolymerized actin cytoskeleton that lacked actin stress fibers anchored at vinculin-containing focal adhesion sites as well as loss of E-cadherin-mediated cell-cell adherence after exposure to chronic HG, and were concomitant with constitutive ERK1/2 phosphorylation that was refractory to serum and glucose deprivation. Although inhibition of ERK phosphorylation by PD98059 promoted actin polymerization, it increased apoptosis and GSIS impairment. These findings suggest that ERK phosphorylation is a proximate regulator of cellular processes targeted by chronic HG-induced gene expression and that dynamic actin polymerization and depolymerization is important in β cell survival and function. Therefore, chronic HG alters gene expression and signal transduction to predispose the cytoskeleton towards apoptosis and GSIS impairment.
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Affiliation(s)
- Ronne Wee Yeh Yeo
- Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | | | - GuoDong Li
- Department of Clinical Research, Singapore General Hospital, Singapore, Singapore
| | - Sai Kiang Lim
- Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- * E-mail:
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Luo DX, Peng XH, Xiong Y, Liao DF, Cao D, Li L. Dual role of insulin-like growth factor-1 in acetyl-CoA carboxylase-alpha activity in human colon cancer cells HCT-8: downregulating its expression and phosphorylation. Mol Cell Biochem 2011; 357:255-62. [PMID: 21638027 DOI: 10.1007/s11010-011-0896-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 05/18/2011] [Indexed: 02/03/2023]
Abstract
Insulin-like growth factor-1 (IGF-1) plays the role in cellular lipid synthesis and cell proliferation. However, the role of IGF-1 on the growth of colon cancer cell line HCT-8 is not clear. In this study, HCT-8 cells were exposed to IGF-1 at 0, 10, 50, or 100 ng/ml in serum-free medium. Fatty acid/lipid synthesis in HCT-8 cells was examined by 2-14C-acetate incorporation. HCT-8 cell growth and proliferation were determined by MTT assay and Trypan blue exclusive viable cell counting. We found that in serum starvation conditions, IGF-1 at 10-100 ng/ml induced dose-dependent down regulation of both the ACCα expression and the phosphorylation in HCT-8 cells, maintaining a balance in ACCα activity and lipid synthesis. IGF-1 reduced p-ATM, p-AMPK, and then p-ACCα protein levels in HCT-8 cells. IGF-1 increased p-Akt levels, but decreased p-ERK1/2 levels, leading to the decrease in ACCα protein and mRNA levels. Similarly, ERK1/2 inhibitor PD98059 reduced ACCα expression. IGF-1 influences neither HCT-8 cell growth nor their p53 protein levels and PARP cleavage. In a word, IGF-1 reduced ACCα phosphorylation via an ATM/AMPK signaling pathway and suppressed ACCα expression through an ERK1/2 transduction, playing a dual role in regulating ACCα activity and lipogenesis. This may render a cell with survival advantages under a serum starvation crisis, representing a novel mitogenic role of IGF-1.
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Affiliation(s)
- Di-Xian Luo
- School of Pharmaceutics, Central South University, Changsha, 410083, China
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Kujur RS, Singh V, Ram M, Yadava HN, Singh KK, Kumari S, Roy BK. Antidiabetic activity and phytochemical screening of crude extract of Stevia rebaudiana in alloxan-induced diabetic rats. Pharmacognosy Res 2010; 2:258-63. [PMID: 21808578 PMCID: PMC3141138 DOI: 10.4103/0974-8490.69128] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 08/02/2010] [Accepted: 09/07/2010] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Stevia rebaudiana regulates blood sugar, prevents hypertension and tooth decay. Other studies have shown that it has antibacterial as well as antiviral property. METHODS Preliminary phytochemical screening of aqueous, ether and methanolic extracts of S. rebaudiana was done. Acute and sub-acute toxicity were conducted on twenty four Albino rats, divided into one control (Group I) and three treatment groups viz. aqueous extract (Group II), ether extract (Group III) and methanolic extract (Group IV). For the study of antidiabetic effect of S. rebaudiana rats were divided into seven groups (n=6). Diabetes was induced by a single dose of 5% alloxan monohydrate (125 mg/kg, i.p.) after 24 hour fasting.Blood samples were analysed on day 0, 1, 5, 7, 14 and 28. RESULTS Phytochemical tests showed presence of different kinds of phyto-constituents in aqueous, ether and methanol extract of Stevia rebaudiana leaves. Daily single dose (2.0 g/kg) administration of aqueous extract (A.E.) , ether extract (E.E.) and methanol extract (M.E.) for 28 days of S. rebaudiana could not show any significant change in ALT and AST levels in rats. Blood sugar level was found to be decreased on day 28 in groups of rats treated with A.E., E.E. and M.E. of S. rebaudiana. CONCLUSION The extracts of Stevioside rebaudiana could decrease the blood glucose level in diabetic rats in time dependent manner.
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Affiliation(s)
- R. S. Kujur
- Department of Pharmacology and Toxicology, College of Veterinary Science and A.H., Birsa Agricultural University, Ranchi - 834 006, India
| | - Vishakha Singh
- Department of Pharmacology and Toxicology, College of Veterinary Science and A.H., Birsa Agricultural University, Ranchi - 834 006, India
| | - Mahendra Ram
- Department of Pharmacology and Toxicology, College of Veterinary Science and A.H., Birsa Agricultural University, Ranchi - 834 006, India
| | | | - K. K. Singh
- Department of Veterinary Pathology, College of Veterinary Science and A.H., Birsa Agricultural University, Ranchi - 834 006, India
| | - Suruchi Kumari
- Department of Pharmacology and Toxicology, College of Veterinary Science and A.H., Birsa Agricultural University, Ranchi - 834 006, India
| | - B. K. Roy
- Department of Pharmacology and Toxicology, College of Veterinary Science and A.H., Birsa Agricultural University, Ranchi - 834 006, India
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El-Assaad W, Joly E, Barbeau A, Sladek R, Buteau J, Maestre I, Pepin E, Zhao S, Iglesias J, Roche E, Prentki M. Glucolipotoxicity alters lipid partitioning and causes mitochondrial dysfunction, cholesterol, and ceramide deposition and reactive oxygen species production in INS832/13 ss-cells. Endocrinology 2010; 151:3061-73. [PMID: 20444946 DOI: 10.1210/en.2009-1238] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Elevated glucose and saturated fatty acids synergize in inducing apoptosis in INS832/13 cells and in human islet cells. In order to gain insight into the molecular mechanism(s) of glucolipotoxicity (Gltox), gene profiling and metabolic analyses were performed in INS832/13 cells cultured at 5 or 20 mm glucose in the absence or presence of palmitate. Expression changes were observed for transcripts involved in mitochondrial, lipid, and glucose metabolism. At 24 h after Gltox, increased expression of lipid partitioning genes suggested a promotion of fatty acid esterification and reduced lipid oxidation/detoxification, whereas changes in the expression of energy metabolism genes suggested mitochondrial dysfunction. These changes were associated with decreased glucose-induced insulin secretion, total insulin content, ATP levels, AMP-kinase activity, mitochondrial membrane potential and fat oxidation, unchanged de novo fatty acid synthesis, and increased reactive oxygen species, cholesterol, ceramide, and triglyceride levels. However, the synergy between elevated glucose and palmitate to cause ss-cell toxicity in term of apoptosis and reduced glucose-induced insulin secretion only correlated with triglyceride and ceramide depositions. Overexpression of endoplasmic reticulum glycerol-3-phosphate acyl transferase to enhance lipid esterification amplified Gltox at intermediate glucose (11 mm), whereas reducing acetyl-coenzyme A carboxylase 1 expression by small interfering RNA to shift lipid partitioning to fat oxidation reduced Gltox. The results suggest that Gltox entails alterations in lipid partitioning, sterol and ceramide accumulation, mitochondrial dysfunction, and reactive oxygen species production, all contributing to altering ss-cell function. The data also suggest that the early promotion of lipid esterification processes is instrumental in the Gltox process.
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Affiliation(s)
- Wissal El-Assaad
- Molecular Nutrition Unit and the Montreal Diabetes Research Center, the Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada H1W 4A4
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Scientific Opinion on the safety of steviol glycosides for the proposed uses as a food additive. EFSA J 2010. [DOI: 10.2903/j.efsa.2010.1537] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Chatsudthipong V, Muanprasat C. Rebuttal to the comments of Ashley Roberts and Ian Munro “Stevioside and related compounds: Therapeutic benefits beyond sweetness”. Pharmacol Ther 2009. [DOI: 10.1016/j.pharmthera.2009.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ronnebaum SM, Joseph JW, Ilkayeva O, Burgess SC, Lu D, Becker TC, Sherry AD, Newgard CB. Chronic suppression of acetyl-CoA carboxylase 1 in beta-cells impairs insulin secretion via inhibition of glucose rather than lipid metabolism. J Biol Chem 2008; 283:14248-56. [PMID: 18381287 DOI: 10.1074/jbc.m800119200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetyl-CoA carboxylase 1 (ACC1) currently is being investigated as a target for treatment of obesity-associated dyslipidemia and insulin resistance. To investigate the effects of ACC1 inhibition on insulin secretion, three small interfering RNA (siRNA) duplexes targeting ACC1 (siACC1) were transfected into the INS-1-derived cell line, 832/13; the most efficacious duplex was also cloned into an adenovirus and used to transduce isolated rat islets. Delivery of the siACC1 duplexes decreased ACC1 mRNA by 60-80% in 832/13 cells and islets and enzyme activity by 46% compared with cells treated with a non-targeted siRNA. Delivery of siACC1 decreased glucose-stimulated insulin secretion (GSIS) by 70% in 832/13 cells and by 33% in islets. Surprisingly, siACC1 treatment decreased glucose oxidation by 49%, and the ATP:ADP ratio by 52%, accompanied by clear decreases in pyruvate cycling activity and tricarboxylic acid cycle intermediates. Exposure of siACC1-treated cells to the pyruvate cycling substrate dimethylmalate restored GSIS to normal without recovery of the depressed ATP:ADP ratio. In siACC1-treated cells, glucokinase protein levels were decreased by 25%, which correlated with a 36% decrease in glycogen synthesis and a 33% decrease in glycolytic flux. Furthermore, acute addition of the ACC1 inhibitor 5-(tetradecyloxy)-2-furoic acid (TOFA) to beta-cells suppressed [(14)C]glucose incorporation into lipids but had no effect on GSIS, whereas chronic TOFA administration suppressed GSIS and glucose metabolism. In sum, chronic, but not acute, suppression of ACC1 activity impairs GSIS via inhibition of glucose rather than lipid metabolism. These findings raise concerns about the use of ACC inhibitors for diabetes therapy.
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Affiliation(s)
- Sarah M Ronnebaum
- Sarah W Stedman Nutrition and Metabolism Center and Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27704, USA
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