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Guava (Psidium guajava Linn.) leaf extract promotes glucose uptake and glycogen accumulation by modulating the insulin signaling pathway in high-glucose-induced insulin-resistant mouse FL83B cells. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.03.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Scazzocchio B, Varì R, Filesi C, Del Gaudio I, D'Archivio M, Santangelo C, Iacovelli A, Galvano F, Pluchinotta FR, Giovannini C, Masella R. Protocatechuic acid activates key components of insulin signaling pathway mimicking insulin activity. Mol Nutr Food Res 2015; 59:1472-81. [DOI: 10.1002/mnfr.201400816] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/20/2015] [Accepted: 04/09/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Beatrice Scazzocchio
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
| | - Rosaria Varì
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
| | - Carmelina Filesi
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
| | - Ilaria Del Gaudio
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
| | - Massimo D'Archivio
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
| | - Carmela Santangelo
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
| | | | - Fabio Galvano
- Department of Biological Chemistry; Medical Chemistry and Molecular Biology; University of Catania; Catania Italy
| | | | - Claudio Giovannini
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
| | - Roberta Masella
- Department of Veterinary Public Health and Food Safety; Italian National Institute of Health; Rome Italy
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Curcumin Pharmacokinetic and Pharmacodynamic Evidences in Streptozotocin-Diabetic Rats Support the Antidiabetic Activity to Be via Metabolite(s). EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:678218. [PMID: 26064170 PMCID: PMC4433689 DOI: 10.1155/2015/678218] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/16/2015] [Accepted: 03/17/2015] [Indexed: 11/18/2022]
Abstract
This study measures the curcumin concentration in rat plasma by liquid chromatography and investigates the changes in the glucose tolerance and insulin sensitivity of streptozotocin-diabetic rats treated with curcumin-enriched yoghurt. The analytical method for curcumin detection was linear from 10 to 500 ng/mL. The Cmax and the time to reach Cmax (tmax) of curcumin in plasma were 3.14 ± 0.9 μg/mL and 5 minutes (10 mg/kg, i.v.) and 0.06 ± 0.01 μg/mL and 14 minutes (500 mg/kg, p.o.). The elimination half-time was 8.64 ± 2.31 (i.v.) and 32.70 ± 12.92 (p.o.) minutes. The oral bioavailability was about 0.47%. Changes in the glucose tolerance and insulin sensitivity were investigated in four groups: normal and diabetic rats treated with yoghurt (NYOG and DYOG, resp.) and treated with 90 mg/kg/day curcumin incorporated in yoghurt (NC90 and DC90, resp.). After 15 days of treatment, the glucose tolerance and the insulin sensitivity were significantly improved in DC90 rats in comparison with DYOG, which can be associated with an increase in the AKT phosphorylation levels and GLUT4 translocation in skeletal muscles. These findings can explain, at least in part, the benefits of curcumin-enriched yoghurt to diabetes and substantiate evidences for the curcumin metabolite(s) as being responsible for the antidiabetic activity.
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Rosiglitazone, but not epigallocatechin-3-gallate, attenuates the decrease in PGC-1α protein levels in palmitate-induced insulin-resistant C2C12 cells. Lipids 2015; 50:521-8. [PMID: 25893813 DOI: 10.1007/s11745-015-4016-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/27/2015] [Indexed: 01/29/2023]
Abstract
Alteration of lipid metabolism is an important mechanism for the treatment of insulin resistance. PGC-1α, a key regulator of mitochondrial biogenesis and function, plays an important role in the improvement of insulin sensitivity by increasing fatty acids β-oxidation. In the present study, the effects of epigallocatechin-3-gallate (EGCG), an anti-obesity agent and enhancer of lipid catabolism, on PGC-1α protein expression was examined and compared with anti-diabetic drug rosiglitazone (RGZ). After differentiation of C2C12 myoblasts to myotubes, insulin resistance was induced by palmitate treatment. Then the expression of the PGC-1a gene and glucose uptake were evaluated before and after treatment with RGZ and EGCG. Palmitate treatment significantly decreased PGC-1α protein expression in C2C12 cells (P < 0.05). RGZ could restore the expression of PGC-1α in palmitate treated cells (P > 0.05), while EGCG had no significant effect on the expression of this gene (P < 0.05). RGZ and EGCG significantly improved glucose uptake (by 2- and 1.54-fold, respectively) in myotubes treated with palmitate. These data suggest that RGZ and EGCG both exert their anti-diabetic activity by increasing insulin sensitivity, but with different molecular mechanisms. This effect of RGZ, unlike EGCG, is mediated, at least partly, by increasing PGC-1α protein expression.
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Lee J, Jo DG, Park D, Chung HY, Mattson MP. Adaptive cellular stress pathways as therapeutic targets of dietary phytochemicals: focus on the nervous system. Pharmacol Rev 2015; 66:815-68. [PMID: 24958636 DOI: 10.1124/pr.113.007757] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
During the past 5 decades, it has been widely promulgated that the chemicals in plants that are good for health act as direct scavengers of free radicals. Here we review evidence that favors a different hypothesis for the health benefits of plant consumption, namely, that some phytochemicals exert disease-preventive and therapeutic actions by engaging one or more adaptive cellular response pathways in cells. The evolutionary basis for the latter mechanism is grounded in the fact that plants produce natural antifeedant/noxious chemicals that discourage insects and other organisms from eating them. However, in the amounts typically consumed by humans, the phytochemicals activate one or more conserved adaptive cellular stress response pathways and thereby enhance the ability of cells to resist injury and disease. Examplesof such pathways include those involving the transcription factors nuclear factor erythroid 2-related factor 2, nuclear factor-κB, hypoxia-inducible factor 1α, peroxisome proliferator-activated receptor γ, and forkhead box subgroup O, as well as the production and action of trophic factors and hormones. Translational research to develop interventions that target these pathways may lead to new classes of therapeutic agents that act by stimulating adaptive stress response pathways to bolster endogenous defenses against tissue injury and disease. Because neurons are particularly sensitive to potentially noxious phytochemicals, we focus on the nervous system but also include findings from other cell types in which actions of phytochemicals on specific signal transduction pathways have been more thoroughly studied.
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Affiliation(s)
- Jaewon Lee
- Department of Pharmacy, College of Pharmacy, and Molecular Inflammation Research Center for Aging Intervention, Pusan National University, Geumjeong-gu, Busan, Republic of Korea (J.L., D.P., H.Y.C.); School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea (D.-G.J.); Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland (M.P.M.); and Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland (M.P.M.)
| | - Dong-Gyu Jo
- Department of Pharmacy, College of Pharmacy, and Molecular Inflammation Research Center for Aging Intervention, Pusan National University, Geumjeong-gu, Busan, Republic of Korea (J.L., D.P., H.Y.C.); School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea (D.-G.J.); Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland (M.P.M.); and Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland (M.P.M.)
| | - Daeui Park
- Department of Pharmacy, College of Pharmacy, and Molecular Inflammation Research Center for Aging Intervention, Pusan National University, Geumjeong-gu, Busan, Republic of Korea (J.L., D.P., H.Y.C.); School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea (D.-G.J.); Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland (M.P.M.); and Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland (M.P.M.)
| | - Hae Young Chung
- Department of Pharmacy, College of Pharmacy, and Molecular Inflammation Research Center for Aging Intervention, Pusan National University, Geumjeong-gu, Busan, Republic of Korea (J.L., D.P., H.Y.C.); School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea (D.-G.J.); Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland (M.P.M.); and Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland (M.P.M.)
| | - Mark P Mattson
- Department of Pharmacy, College of Pharmacy, and Molecular Inflammation Research Center for Aging Intervention, Pusan National University, Geumjeong-gu, Busan, Republic of Korea (J.L., D.P., H.Y.C.); School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea (D.-G.J.); Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland (M.P.M.); and Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland (M.P.M.)
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Gannon NP, Conn CA, Vaughan RA. Dietary stimulators of GLUT4 expression and translocation in skeletal muscle: a mini-review. Mol Nutr Food Res 2014; 59:48-64. [PMID: 25215442 DOI: 10.1002/mnfr.201400414] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/07/2014] [Accepted: 09/08/2014] [Indexed: 12/23/2022]
Abstract
Chronic insulin resistance can lead to type II diabetes mellitus, which is also directly influenced by an individual's genetics as well as their lifestyle. Under normal circumstances, insulin facilitates glucose uptake in skeletal muscle and adipose tissue by stimulating glucose transporter 4 (GLUT4) translocation and activity. GLUT4 activity is directly correlated with the ability to clear elevated blood glucose and insulin sensitivity. In diabetes, energy excess and prolonged hyperinsulinemia suppress muscle and adipose response to insulin, in part through reduced GLUT4 membrane levels. This work uniquely describes much of the experimental data demonstrating the effects of various dietary components on GLUT4 expression and translocation in skeletal muscle. These observations implicate several individual dietary chemicals as potential adjuvant therapies in the maintenance of diabetes and insulin resistance.
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Affiliation(s)
- Nicholas P Gannon
- Department of Biochemistry and Molecular Biology, University of New Mexico, Health Sciences Center, School of Medicine, Albuquerque, NM, USA
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57
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Yonamine CY, Teixeira SS, Campello RS, Gerlinger-Romero F, Rodrigues CF, Guimarães-Ferreira L, Machado UF, Nunes MT. Beta hydroxy beta methylbutyrate supplementation impairs peripheral insulin sensitivity in healthy sedentary Wistar rats. Acta Physiol (Oxf) 2014; 212:62-74. [PMID: 24962220 DOI: 10.1111/apha.12336] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/28/2014] [Accepted: 06/19/2014] [Indexed: 12/13/2022]
Abstract
AIM Investigate, in healthy sedentary rats, the potential mechanisms involved on the effects of beta hydroxy beta methylbutyrate (HMB) supplementation upon the glycaemic homeostasis, by evaluating the insulin sensitivity in liver, skeletal muscle, and white adipose tissue. METHODS Rats were supplemented with either beta hydroxy beta methylbutyrate (320 mg kg(-1) BW) or saline by gavage for 4 weeks. After the experimental period, the animals were subjected to the glucose tolerance test (GTT) and plasma non-esterified fatty acids (NEFA) concentration measurements. The soleus skeletal muscle, liver and white adipose tissue were removed for molecular (western blotting and RT-PCR) and histological analysis. RESULTS The beta hydroxy beta methylbutyrate supplemented rats presented: (i) higher ratio between the area under the curve (AUC) of insulinaemia and glycaemia during glucose tolerance test; (ii) impairment of insulin sensitivity on liver and soleus skeletal muscle after insulin overload; (iii) reduction of glucose transporter 4 (GLUT 4) total and plasma membrane content on soleus; (iv) increased hormone-sensitive lipase (HSL) mRNA and protein expression on white adipose tissue and plasma NEFA levels and (v) reduction of fibre cross-sectional area of soleus muscle. CONCLUSION The data altogether indicate that beta hydroxy beta methylbutyrate supplementation impairs insulin sensitivity in healthy sedentary rats, which, in the long-term, could lead to an increased risk of developing type 2 diabetes.
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Affiliation(s)
- C. Y. Yonamine
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - S. S. Teixeira
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - R. S. Campello
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - F. Gerlinger-Romero
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - C. F. Rodrigues
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - L. Guimarães-Ferreira
- Department of Sports; Center of Physical Education and Sports; Federal University of Espírito Santo; Vitória Brazil
| | - U. F. Machado
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
| | - M. T. Nunes
- Department of Physiology and Biophysics; Institute of Biomedical Sciences; University of São Paulo; São Paulo Brazil
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Park SY, Kim MH, Ahn JH, Lee SJ, Lee JH, Eum WS, Choi SY, Kwon HY. The Stimulatory Effect of Essential Fatty Acids on Glucose Uptake Involves Both Akt and AMPK Activation in C2C12 Skeletal Muscle Cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2014; 18:255-61. [PMID: 24976766 PMCID: PMC4071179 DOI: 10.4196/kjpp.2014.18.3.255] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/09/2014] [Accepted: 05/20/2014] [Indexed: 12/21/2022]
Abstract
Essential fatty acid (EFA) is known to be required for the body to function normally and healthily. However, the effect of EFA on glucose uptake in skeletal muscle has not yet been fully investigated. In this study, we examined the effect of two EFAs, linoleic acid (LA) and α-linolenic acid (ALA), on glucose uptake of C2C12 skeletal muscle cells and investigated the mechanism underlying the stimulatory effect of polyunsaturated EFAs in comparison with monounsaturated oleic acid (OA). In palmitic acid (PA)-induced insulin resistant cells, the co-treatment of EFAs and OA with PA almost restored the PA-induced decrease in the basal and insulin-stimulated 2-NBDG (fluorescent D-glucose analogue) uptake, respectively. Two EFAs and OA significantly protected PA-induced suppression of insulin signaling, respectively, which was confirmed by the increased levels of Akt phosphorylation and serine/threonine kinases (PKCθ and JNK) dephosphorylation in the western blot analysis. In PA-untreated, control cells, the treatment of 500 µM EFA significantly stimulated 2-NBDG uptake, whereas OA did not. Phosphorylation of AMP-activated protein kinase (AMPK) and one of its downstream molecules, acetyl-CoA carboxylase (ACC) was markedly induced by EFA, but not OA. In addition, EFA-stimulated 2-NBDG uptake was significantly inhibited by the pre-treatment of a specific AMPK inhibitor, adenine 9-β-D-arabinofuranoside (araA). These data suggest that the restoration of suppressed insulin signaling at PA-induced insulin resistant condition and AMPK activation are involved at least in the stimulatory effect of EFA on glucose uptake in C2C12 skeletal muscle cells.
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Affiliation(s)
- So Yeon Park
- Department of Physiology, College of Medicine, Hallym University, Chuncheon 200-702, Korea. ; Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon 200-702, Korea
| | - Min Hye Kim
- Department of Physiology, College of Medicine, Hallym University, Chuncheon 200-702, Korea
| | - Joung Hoon Ahn
- Department of Physiology, College of Medicine, Hallym University, Chuncheon 200-702, Korea
| | - Su Jin Lee
- Department of Physiology, College of Medicine, Hallym University, Chuncheon 200-702, Korea
| | - Jong Ho Lee
- Department of Pharmacology, College of Medicine, Hallym University, Chuncheon 200-702, Korea
| | - Won Sik Eum
- Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon 200-702, Korea
| | - Soo Young Choi
- Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chuncheon 200-702, Korea
| | - Hyeok Yil Kwon
- Department of Physiology, College of Medicine, Hallym University, Chuncheon 200-702, Korea
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Sakiyama S, Usuki T, Sakai H, Sakane F. Regulation of diacylglycerol kinase δ2 expression in C2C12 skeletal muscle cells by free fatty acids. Lipids 2014; 49:633-40. [PMID: 24852321 DOI: 10.1007/s11745-014-3912-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 05/02/2014] [Indexed: 12/14/2022]
Abstract
Decreased expression of diacylglycerol kinase (DGK) δ in skeletal muscles is closely related to the pathogenesis of type 2 diabetes. However, the regulation of DGKδ expression is not well understood. In this study, we found that myristic acid (14:0) significantly increased DGKδ2 protein expression in a dose-dependent manner (EC(50) = 0.16 mM) in mouse C2C12 myotubes. In contrast, oleic [18:1(n-9)], eicosenoic [20:1(n-9)] and erucic [22:1(n-9)] acids markedly decreased DGKδ2 expression. Myristic acid slowly enhanced DGKδ2 expression at the transcription level. Therefore, DGKδ2 expression is positively regulated by the relatively short-chain saturated fatty acid myristic acid but attenuated by n-9 monounsaturated fatty acids.
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Affiliation(s)
- Shizuka Sakiyama
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
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Lin CZ, Xu CG, Feng S, Zhang B, Weng SG. A new biliopancreatic diversion surgery decreases plasma glucose and lipids in Goto-Kakizaki rats. Shijie Huaren Xiaohua Zazhi 2014; 22:1417-1422. [DOI: 10.11569/wcjd.v22.i10.1417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To observe the effects of a new biliopancreatic diversion (NBPD) surgery and duodenal-jejunal bypass (DJB) surgery on plasm glucose and lipids in Goto-Kakizaki (GK) rats and investigate the possibility of surgical treatment of diabetes.
METHODS: Thirty rats were randomly and equally divided into a sham operation group, a NBPD group or a DJB group. The NBPD group and the DJB group underwent NBPD and DJB, respectively, and the sham operation group underwent a sham operation. Body weight, random plasma glucose, OGTT and blood lipids were measured before and after surgery.
RESULTS: One week after surgery, random plasma glucose levels decreased from 17.088 mmol/L ± 3.708 mmol/L to 9.200 mmol/L ± 1.000 mmol/L in the NBPD group and from 17.180 mmol/L ± 3.383 mmol/L to 9.620 mmol/L ± 0.794 mmol/L in the DJB group, respectively, and both were significantly lower than those in the sham operation group. Four weeks postoperatively, fasting cholesterol decreased from 3.220 mmol/L ± 0.185 mmol/L to 3.100 mmol/L ± 0.424 mmol/L in the DJB group and from 3.100 mmol/L ± 0.424 mmol/L to 2.550 mmol/L ± 0.691 mmol/L in the NBPD group.
CONCLUSION: DJB and NBPD decrease plasma glucose and lipids in GK rats possibly via mechanisms associated with diversion of biliopancreatic juice that results in incomplete food digestion and absorption and improves lipid metabolism and plasma glucose.
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Feng S, Tian ZL, Xi HL, Wang XK, Jia GL. Modified billiopancreatic diversion surgery improves glucose levels in Goto-Kakizaki rats. Shijie Huaren Xiaohua Zazhi 2014; 22:766-772. [DOI: 10.11569/wcjd.v22.i6.766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To compare the effect of modified billiopancreatic diversion (MBPD) surgery versus duodenal-jejunal bypass (DJB) surgery in improving glucose levels in Goto-Kakizaki (GK) rats, and to explore the possible mechanisms.
METHODS: Thirty male GK rats were randomized into three groups to undergo sham operation, MBPD surgery and DJB surgery, respectively. Body mass, fasting plasma glucose and random plasma glucose were determined 1 week before and 1, 4, 8 wk after operation. Insulin, oral glucose tolerance test (OGTT), cholesterol, triglyceride and free fatty acid were determined 1 wk before and 4 wk after operation.
RESULTS: One week after the surgery, body mass of MBPD- and DJB-treated rats significantly decreased (304.990 g ± 12.156 g vs 320.568 g ± 10.607 g, P = 0.011; 308.540 g ± 9.637 g vs 320.568 g ± 10.607 g, P = 0.024). MBPD- and DJB-treated rats had better oral glucose tolerance (17.350 mmol/L ± 2.220 mmol/L vs 20.600 mmol/L ± 2.381 mmol/L, P = 0.009; 18.238 mmol/L ± 1.364 mmol/L vs 20.600 mmol/L ± 2.381 mmol/L, P = 0.024) compared with the sham operation group. Random plasma glucose (9.620 mmol/L ± 0.794 mmol/L vs 14.471 mmol/L ± 2.531 mmol/L, P < 0.001; 9.200 mmol/L ± 1.000 mmol/L vs 14.471 mmol/L ± 2.531 mmol/L, P < 0.001), insulin (0.476 ng/mL± 0.068 ng/mL vs 0.724 ng/mL ± 0.192 ng/mL, P < 0.05; 0.542 ng/mL ± 0.055 ng/mL vs 0.724 ng/mL ± 0.192 ng/mL, P < 0.05), cholesterol (2.550 mmol/L ± 0.691 mmol/L vs 3.125 mmol/L ± 0.267 mmol/L, P < 0.05; 2.450 mmol/L ± 0.424 mmol/L vs 3.125 mmol/L ± 0.267 mmol/L, P < 0.05) and free fatty acid (697.667 μEq/L ± 103.77 μEq/L vs 994.667 μEq/L ± 257.817 μEq/L, P < 0.05; 670.333 μEq/L ± 129.421 μEq/L vs 994.667 μEq/L ± 257.817 μEq/L, P < 0.05) of NBPD- and DJB-treated rats were lower than those in the sham operation group after operation, but triglycerides (1.329 mmol/L ± 0.716 mmol/L vs 0.754 mmol/L ± 0.236 mmol/L, P < 0.05; 1.569 mmol/L ± 0.612 mmol/L vs 0.754 mmol/L ± 0.236 mmol/L, P < 0.05) of NBPD- and DJB-treated rats were significantly higher.
CONCLUSION: Modified billiopancreatic diversion surgery is superior to bowel bypass in improving glucose levels in Goto-Kakizaki rats.
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Dietary stimulators of the PGC-1 superfamily and mitochondrial biosynthesis in skeletal muscle. A mini-review. J Physiol Biochem 2013; 70:271-84. [DOI: 10.1007/s13105-013-0301-4] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 11/21/2013] [Indexed: 11/26/2022]
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Curcumin and diabetes: a systematic review. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:636053. [PMID: 24348712 PMCID: PMC3857752 DOI: 10.1155/2013/636053] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 08/30/2013] [Accepted: 09/12/2013] [Indexed: 12/20/2022]
Abstract
Turmeric (Curcuma longa), a rhizomatous herbaceous perennial plant of the ginger family, has been used for the treatment of diabetes in Ayurvedic and traditional Chinese medicine. The active component of turmeric, curcumin, has caught attention as a potential treatment for diabetes and its complications primarily because it is a relatively safe and inexpensive drug that reduces glycemia and hyperlipidemia in rodent models of diabetes. Here, we review the recent literature on the applications of curcumin for glycemia and diabetes-related liver disorders, adipocyte dysfunction, neuropathy, nephropathy, vascular diseases, pancreatic disorders, and other complications, and we also discuss its antioxidant and anti-inflammatory properties. The applications of additional curcuminoid compounds for diabetes prevention and treatment are also included in this paper. Finally, we mention the approaches that are currently being sought to generate a "super curcumin" through improvement of the bioavailability to bring this promising natural product to the forefront of diabetes therapeutics.
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Babu PVA, Liu D, Gilbert ER. Recent advances in understanding the anti-diabetic actions of dietary flavonoids. J Nutr Biochem 2013; 24:1777-89. [PMID: 24029069 DOI: 10.1016/j.jnutbio.2013.06.003] [Citation(s) in RCA: 311] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 04/02/2013] [Accepted: 06/07/2013] [Indexed: 01/06/2023]
Abstract
Flavonoids are polyphenolic compounds that are abundant in fruits and vegetables, and increasing evidence demonstrates a positive relationship between consumption of flavonoid-rich foods and disease prevention. Epidemiological, in vitro and animal studies support the beneficial effects of dietary flavonoids on glucose and lipid homeostasis. It is encouraging that the beneficial effects of some flavonoids are at physiological concentrations and comparable to clinically-used anti-diabetic drugs; however, clinical research in this field and studies on the anti-diabetic effects of flavonoid metabolites are limited. Flavonoids act on various molecular targets and regulate different signaling pathways in pancreatic β-cells, hepatocytes, adipocytes and skeletal myofibers. Flavonoids may exert beneficial effects in diabetes by (i) enhancing insulin secretion and reducing apoptosis and promoting proliferation of pancreatic β-cells; (ii) improving hyperglycemia through regulation of glucose metabolism in hepatocytes; (iii) reducing insulin resistance, inflammation and oxidative stress in muscle and fat and (iv) increasing glucose uptake in skeletal muscle and white adipose tissue. This review highlights recent findings on the anti-diabetic effects of dietary flavonoids, including flavan-3-ols, flavanones, flavonols, anthocyanidins, flavones and isoflavones, with particular emphasis on the studies that investigated the cellular and molecular mechanisms involved in the beneficial effects of the compounds.
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Saturated fatty acid palmitate-induced insulin resistance is accompanied with myotube loss and the impaired expression of health benefit myokine genes in C2C12 myotubes. Lipids Health Dis 2013; 12:104. [PMID: 23866690 PMCID: PMC3723881 DOI: 10.1186/1476-511x-12-104] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 07/02/2013] [Indexed: 02/05/2023] Open
Abstract
Background Excessive circular fatty acid, particlarly saturated fatty acid, can result in insulin resistance in skeletal muscle, but other adverse effects of fatty acid accumulation in myocytes remain unclear. Methods Differentiated C2C12 myotubes were used. The effects of palmitate on cell viability, glucose uptake, gene expression and myotube loss were evaluated by MTT assay, 2NBDG uptake, qRT-PCR, Western Blot and crystal staining-based myotube counting, respectively. In some expreiments, oleate was administrated, or the inhibitors of signaling pathways were applied. Results Palmitate-induced cellular insulin resistance was clarified by the reduced Akt phosphorylation, glucose uptake and Glut4 expression. Palmitate-caused myotube loss was clearly observed under microscope and proved by myotube counting and expression analysis of myotube marker genes. Moreover, palmitate-induced transcriptional suppression of three health benefit myokine genes (FNDC5, CTRP15 and FGF21) was found, and the different involvement of p38 and PI3K in the transcription of these genes was noticed. Conclusions Palmitate-induced insulin resistance accompanys myotube loss and the impaired expression of FNDC5, CTRP15 and FGF21genes in C2C12 myotubes. These results provide novel evidence indicating the negative role of high concentration of palmitate in myotubes.
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Mazibuko SE, Muller CJF, Joubert E, de Beer D, Johnson R, Opoku AR, Louw J. Amelioration of palmitate-induced insulin resistance in C₂C₁₂ muscle cells by rooibos (Aspalathus linearis). PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2013; 20:813-819. [PMID: 23639187 DOI: 10.1016/j.phymed.2013.03.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 03/27/2013] [Indexed: 06/02/2023]
Abstract
Increased levels of free fatty acids (FFAs), specifically saturated free fatty acids such as palmitate are associated with insulin resistance of muscle, fat and liver. Skeletal muscle, responsible for up to 80% of the glucose disposal from the peripheral circulation, is particularly vulnerable to increased levels of saturated FFAs. Rooibos (Aspalathus linearis) and its unique dihydrochalcone C-glucoside, aspalathin, shown to reduce hyperglycemia in diabetic rats, could play a role in preventing or ameliorating the development of insulin resistance. This study aims to establish whether rooibos can ameliorate experimentally-induced insulin-resistance in C₂C₁₂ skeletal muscle cells. Palmitate-induced insulin resistant C₂C₁₂ cells were treated with an aspalathin-enriched green (unfermented) rooibos extract (GRE), previously shown for its blood glucose lowering effect in vitro and in vivo or an aqueous extract of fermented rooibos (FRE). Glucose uptake and mitochondrial activity were measured using 2-deoxy-[³H]-D-glucose, MTT and ATP assays, respectively. Expression of proteins relevant to glucose metabolism was analysed by Western blot. GRE contained higher levels of all compounds, except the enolic phenylpyruvic acid-2-O-glucoside and luteolin-7-O-glucoside. Both rooibos extracts increased glucose uptake, mitochondrial activity and ATP production. Compared to FRE, GRE was more effective at increasing glucose uptake and ATP production. At a mechanistic level both extracts down-regulated PKC θ activation, which is associated with palmitate-induced insulin resistance. Furthermore, the extracts increased activation of key regulatory proteins (AKT and AMPK) involved in insulin-dependent and non-insulin regulated signalling pathways. Protein levels of the glucose transporter (GLUT4) involved in glucose transport via these two pathways were also increased. This in vitro study therefore confirms that rooibos can ameliorate palmitate-induced insulin resistance in C₂C₁₂ skeletal muscle cells. Inhibition of PKC θ activation and increased activation of AMPK and AKT offer a plausible mechanistic explanation for this ameliorative effect.
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Affiliation(s)
- S E Mazibuko
- Diabetes Discovery Platform, South African Medical Research Council, P.O. Box 19070, Tygerberg 7505, South Africa.
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Jia N, Han K, Kong JJ, Zhang XM, Sha S, Ren GR, Cao YP. (-)-Epigallocatechin-3-gallate alleviates spatial memory impairment in APP/PS1 mice by restoring IRS-1 signaling defects in the hippocampus. Mol Cell Biochem 2013; 380:211-8. [PMID: 23660953 DOI: 10.1007/s11010-013-1675-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 05/02/2013] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD) fundamentally represents a metabolic disease associated with brain insulin resistance. TNF-α/c-Jun N-terminal kinase (JNK) signaling plays a central role in serine phosphorylation of insulin receptor substrate-1 (IRS-1). (-)-Epigallocatechin-3-gallate (EGCG), a potent antioxidant, has been verified to attenuate peripheral insulin resistance by reducing IRS-1 signaling blockage. This study aimed to investigate the effects and possible mechanisms of EGCG on central IRS-1 signaling in vivo. APP/PS1 mice were treated with EGCG, and spatial memory was assessed by the Morris water maze test. Levels of soluble and insoluble Aβ42 in the hippocampus were determined by ELISA. The activation of NF-α/JNK and IRS signaling was detected by immunohistochemistry and Western blot analysis. Our results showed that EGCG ameliorated the impaired learning and memory in APP/PS1 mice. Notably, we found a significant reduction of IRS-1pS636 level accompanied with decreased Aβ42 levels in the hippocampus of 13-month-old female APP/PS1 mice after treatment with EGCG (2 or 6 mg/kg/day) for 4 weeks. Furthermore, EGCG treatment inhibited TNF-α/JNK signaling and increased the phosphorylation of Akt and glycogen synthase kinase-3β in the hippocampus of APP/PS1 mice. In conclusion, our study provides evidence that long-term consumption of EGCG may alleviate AD-related cognitive deficits by effectively attenuating central insulin resistance.
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Affiliation(s)
- Ning Jia
- Department of Neurology, First Affiliated Hospital of China Medical University, No. 155 Nanjing North Street, Heping District, Shenyang 110001, Liaoning Province, China
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