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Moharram FA, Nagy MM, El Dib RA, El-Tantawy MM, El Hossary GG, El-Hosari DG. Pharmacological activity and flavonoids constituents of Artemisia judaica L aerial parts. JOURNAL OF ETHNOPHARMACOLOGY 2021; 270:113777. [PMID: 33412247 DOI: 10.1016/j.jep.2021.113777] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 12/22/2020] [Accepted: 12/30/2020] [Indexed: 06/12/2023]
Abstract
ETHNO-PHARMACOLOGICAL RELEVANCE Artemisia judaica L is an aromatic medicinal plant growing widely in Saint Katherine, Sinai, Egypt, and used in traditional medicine as a herbal remedy for antibacterial, anthelmintic, antidiabetic, analgesic and anti-inflammatory activities. Additionally, other Arabic regions commonly used it in their folk medicines for the treatment of fungal infections, atherosclerosis, cancer, diabetes, arthritis, and inflammatory-related diseases. AIM OF THE STUDY Based on the traditional medicinal uses of A. judaica, the present study was designed to validate some of the traditional uses as the analgesic, anti-inflammatory, antipyretic, hepatoprotective, antidiabetic, and antioxidant activities of 80% aqueous methanol extract (AME) of A. judaica aerial parts as well as isolation and identification of its flavonoid content. MATERIALS AND METHODS AME of A. judaica aerial parts was fractionated using column chromatography and the structures of the isolated compounds were established using different spectroscopic data. Analgesic activity was evaluated using acetic acid-induced writhing in mice; antipyretic activity was assessed using yeast suspension-induced hyperthermia in rats; anti-inflammatory activity was evaluated using carrageenan-induced paw edema; the hepatoprotective effect was studied by measuring liver enzymes in carbon tetrachloride(CCl4)-induced hepatotoxicity rats while antidiabetic activity was estimated in alloxan hyperglycemia. RESULTS Eight flavone compounds namely luteolin 4' methyl ether 7-O-β-D-4C1-glucopyranoside (1), 8-methoxyapigenin 7-O-β-D-4C1-galactopyranoside (2), isovitexin (3), 8-methoxyluteolin 7-O-β-D-4C1-glucopyranoside (4), diosmetin (5), cirsimaritin (6), luteolin (7), and apigenin (8) were identified from AME of A. judaica. The AME was found to be non-toxic to mice up to 5 g/kg b.w. Moreover, it exhibits significant analgesic antipyretic, anti-inflammatory, antidiabetic, hepatoprotective, and antioxidant activities in a dose-dependent manner. CONCLUSION The AME was nontoxic; it exhibits significant analgesic, antipyretic, anti-inflammatory, antidiabetic, hepatoprotective, and antioxidant activities. Moreover, the isolated flavone was identified from AME for the first time.
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Affiliation(s)
- Fatma A Moharram
- Department of Pharmacognosy, Faculty of Pharmacy, Helwan University, Cairo, Egypt.
| | - Maii M Nagy
- Department of Phytochemistry, National Organization for Drug Control and Research, Giza, Egypt
| | - Rabab A El Dib
- Department of Pharmacognosy, Faculty of Pharmacy, Helwan University, Cairo, Egypt
| | - Mona M El-Tantawy
- Department of Phytochemistry, National Organization for Drug Control and Research, Giza, Egypt
| | - Ghada G El Hossary
- Department of Pharmacology, Research Institute of Ophthalmology, Giza, Egypt
| | - Doaa G El-Hosari
- Department of Pharmacognosy, Faculty of Pharmacy, Helwan University, Cairo, Egypt
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Uwazie JN, Yakubu MT, Ashafa AOT, Ajiboye TO. Identification and characterization of anti-diabetic principle in Senna alata (Linn.) flower using alloxan-induced diabetic male Wistar rats. JOURNAL OF ETHNOPHARMACOLOGY 2020; 261:112997. [PMID: 32534114 DOI: 10.1016/j.jep.2020.112997] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 06/11/2023]
Abstract
ETHNO-PHARMACOLOGICAL RELEVANCE The age-long folkloric use of Senna alata flower (SAF) was recently substantiated with scientific evidence. However, the study did not account for the anti-diabetic principle(s) in SAF. AIM OF THE STUDY The study aimed to identify and characterize the bioactive principle(s) responsible for the anti-diabetic activity in SAF. MATERIALS AND METHODS Ninety-one male Wistar rats were used for the two phases of this study. In phase 1, forty-two of these were allotted into six groups (A-F) of seven rats each. Animals in group A received distilled water while those in groups B-F were made diabetic by treatment with 150 mg/kg body weight (b.w.) of alloxan. Group B received 0.5 mL of distilled water; C, D and E were treated each with 75 mg/kg b.w. of ethyl acetate, n-butanol and aqueous residual fractions of SAF, while F received 2.5 mg/kg b.w. of glibenclamide. In the second phase, forty-nine rats were assigned into seven groups (A-G) of seven rats each. Group A received distilled water. Animals in Groups B-G were also made diabetic by alloxan treatment. B received 0.5 mL of distilled water; C, D, E and F were treated with 5.77, 25.96, 15.40, 27.87 mg/kg b.w (equivalent dose of 75 mg/kg b.w.) of sub-fractions obtained from the ethyl acetate fraction of SAF respectively whereas G received 2.5 mg/kg b.w. of glibenclamide. Fasting blood glucose (FBG), serum lipids, albumin, globulin, liver glycogen, urine ketone, hexokinase and glucose-6-phosphate dehydrogenase activities, α-glucosidase and α-amylase inhibitory activities and cardiac function indices were evaluated using standard methods. Compounds D, E and F isolated from ethyl acetate sub-fraction B were evaluated for in vitro anti-diabetic activity. The structure of the anti-diabetic compound was identified using FTIR, 1H-NMR, 1³C-NMR, HCOSY, HSQC and HMBC. Data were subjected to Analysis of Variance and Duncan Multiple Range Test at p < 0.05. RESULTS Alloxan treatment increased the levels of FBG, total cholesterol, LDL-cholesterol, VLDL-cholesterol, urine ketone and cardiac function indices and reduced the levels of globulin, albumin, HDL-cholesterol, globulin, liver glycogen, hexokinase and glucose-6-phosphate dehydrogenase activities. Ethyl acetate fraction and sub-fraction B reversed the level and/or activities of these biochemical indices to levels and/or activities that compared favourably with the distilled water treated non-diabetic animals. Of the three compounds (D, E and F) that were obtained from the sub-fraction B, compound E which was Emodin (1, 3, 8-trihydroxy-6-methylanthraquinone) produced the highest α-glucosidase and α-amylase inhibitory activities. CONCLUSION Emodin is one of the bioactive constituents present in Senna alata flower.
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Affiliation(s)
- Judith Nkechiyere Uwazie
- Department of Biochemistry, Faculty of Natural and Applied Sciences, Nile University of Nigeria, Abuja, Nigeria; Phytomedicine and Phytopharmacology Research Group, Department of Plant Sciences, University of the Free State, Qwaqwa Campus, South Africa.
| | - Musa Toyin Yakubu
- Phytomedicine, Toxicology, Reproductive and Developmental Biochemistry Research Laboratory, Department of Biochemistry, University of Ilorin, Nigeria
| | - Anofi Omotayo Tom Ashafa
- Phytomedicine and Phytopharmacology Research Group, Department of Plant Sciences, University of the Free State, Qwaqwa Campus, South Africa
| | - Taofeek Olakunle Ajiboye
- Antioxidant, Redox Biology and Toxicology Research Laboratory, Department of Medical Biochemistry, College of Health Sciences, Nile University of Nigeria, Abuja, Nigeria
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Santos JLD, Araújo SSD, Silva AMDOE, Lima CA, Vieira Souza LM, Costa RA, Aidar Martins FJ, Voltarelli FA, Estevam CDS, Marçal AC. Ethanolic extract and ethyl acetate fraction of Coutoubea spicata attenuate hyperglycemia, oxidative stress, and muscle damage in alloxan-induced diabetic rats subjected to resistance exercise training program. Appl Physiol Nutr Metab 2019; 45:401-410. [PMID: 31539486 DOI: 10.1139/apnm-2019-0331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Gentianaceae family (such as Coutoubea spicata) contains iridoids and flavonoids with antidiabetic properties. However, there is no information available about the antidiabetic effects of C. spicata when combined with resistance exercise training (RET). This study evaluated the effects of the ethanolic extract (EE) and ethyl acetate fraction (EAF) of C. spicata on biochemical markers, muscle damage, and oxidative stress in diabetic rats submitted to RET. Alloxan-induced diabetic rats were distributed into 4 groups (each group, n = 8) treated with distilled water (TD), EE, EAF, or metformin and submitted to RET. Two groups without the disease (each group, n = 8) (sedentary control and trained control), as well as a sedentary diabetic group (n = 8) were included. Body weight and glycemia were evaluated weekly. After 30 days, lipid/lipoprotein profile, aspartate aminotransferase, alanine aminotransferase, muscle damage ((creatine kinase (CK) and lactate dehydrogenase (LDH)), and oxidative stress (malondialdehyde (MDA), sulfhydryl groups (SH), and ferric reducing antioxidant power) were evaluated. MDA and SH for pancreas, liver, heart, and muscle were evaluated. C. spicata extract and fraction combined with RET recovered body weight and reduced glycemia, muscle damage (CK: 36.83% and 21.45%; LDH: 49.83% and 68.55%), and low-density lipoprotein cholesterol (70.63%; 59.18%) and improved redox status (MDA: 50.33%, 39.74%; and SH: 53.97%; 76.41%), respectively, when compared with the TD group. C. spicata plus RET promoted anti-hyperglycemic, lipid-reducing, and antioxidant effects in diabetic rats. Novelty C. spicata presents anti-hyperglycemic and lipid-lowering effects potentiated by RET. C. spicata reduces muscle injury and increases antioxidant defense.
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Affiliation(s)
- Jymmys Lopes Dos Santos
- Laboratory of Natural Product Chemistry and Biochemistry, Department of Physiology, Federal University of Sergipe, São Cristóvão, SE 49100-000, Brazil
| | - Silvan Silva de Araújo
- Laboratory of Natural Product Chemistry and Biochemistry, Department of Physiology, Federal University of Sergipe, São Cristóvão, SE 49100-000, Brazil
| | | | - Clésio Andrade Lima
- Laboratory of Natural Product Chemistry and Biochemistry, Department of Physiology, Federal University of Sergipe, São Cristóvão, SE 49100-000, Brazil
| | - Lúcio Marques Vieira Souza
- Laboratory of Natural Product Chemistry and Biochemistry, Department of Physiology, Federal University of Sergipe, São Cristóvão, SE 49100-000, Brazil
| | - Rôas Araújo Costa
- Laboratory of Natural Product Chemistry and Biochemistry, Department of Physiology, Federal University of Sergipe, São Cristóvão, SE 49100-000, Brazil
| | | | - Fabrício Azevedo Voltarelli
- Graduate Program of Health Sciences, Faculty of Medicine, Federal University of Mato Grosso, Cuiabá, MT 78060-900, Brazil
| | - Charles Dos Santos Estevam
- Laboratory of Natural Product Chemistry and Biochemistry, Department of Physiology, Federal University of Sergipe, São Cristóvão, SE 49100-000, Brazil
| | - Anderson Carlos Marçal
- Department of Morphology, Federal University of Sergipe, São Cristóvão, SE 49100-000, Brazil
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Liu J, Yang K, Yang J, Xiao W, Le Y, Yu F, Gu L, Lang S, Tian Q, Jin T, Wei R, Hong T. Liver-derived fibroblast growth factor 21 mediates effects of glucagon-like peptide-1 in attenuating hepatic glucose output. EBioMedicine 2019; 41:73-84. [PMID: 30827929 PMCID: PMC6443026 DOI: 10.1016/j.ebiom.2019.02.037] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 01/30/2019] [Accepted: 02/18/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Glucagon-like peptide-1 (GLP-1) and its based agents improve glycemic control. Although their attenuating effect on hepatic glucose output has drawn our attention for decades, the potential mechanisms remain unclear. METHODS Cytokine array kit was used to assess cytokine profiles in db/db mice and mouse primary hepatocytes treated with exenatide (exendin-4). Two diabetic mouse models (db/db and Pax6m/+) were treated with a GLP-1 analog exenatide or liraglutide. The expression and secretion of fibroblast growth factor 21 (FGF21) in the livers of diabetic mice, primary mouse and human hepatocytes, and the human hepatic cell line HepG2 treated with or without GLP-1 analog were measured. Blockage of FGF21 with neutralizing antibody or siRNA, or hepatocytes isolated from Fgf21 knockout mice were used, and the expression and activity of key enzymes in gluconeogenesis were analyzed. Serum FGF21 level was evaluated in patients with type 2 diabetes (T2D) receiving exenatide treatment. FINDINGS Utilizing the cytokine array, we identified that FGF21 secretion was upregulated by exenatide (exendin-4). Similarly, FGF21 production in hepatocytes was stimulated by exenatide or liraglutide. FGF21 blockage attenuated the inhibitory effects of the GLP-1 analogs on hepatic glucose output. Similar results were also observed in primary hepatocytes from Fgf21 knockout mice. Furthermore, exenatide treatment increased serum FGF21 level in patients with T2D, particularly in those with better glucose control. INTERPRETATION We identify that function of GLP-1 in inhibiting hepatic glucose output is mediated via the liver hormone FGF21. Thus, we provide a new extra-pancreatic mechanism by which GLP-1 regulates glucose homeostasis. FUND: National Key Research and Development Program of China, the National Natural Science Foundation of China, the Natural Science Foundation of Beijing and Peking University Medicine Seed Fund for Interdisciplinary Research.
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Affiliation(s)
- Junling Liu
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Kun Yang
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Jin Yang
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Wenhua Xiao
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Yunyi Le
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Fei Yu
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Liangbiao Gu
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Shan Lang
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Qing Tian
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Tianru Jin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Banting and Best Diabetes Center, University of Toronto, Toronto, Ontario, Canada
| | - Rui Wei
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China.
| | - Tianpei Hong
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China.
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Seckinger KM, Rao VP, Snell NE, Mancini AE, Markwardt ML, Rizzo MA. Nitric Oxide Activates β-Cell Glucokinase by Promoting Formation of the "Glucose-Activated" State. Biochemistry 2018; 57:5136-5144. [PMID: 30053375 PMCID: PMC6338087 DOI: 10.1021/acs.biochem.8b00333] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The release of insulin from the pancreas is tightly controlled by glucokinase (GCK) activity that couples β-cell metabolism to changes in blood sugar. Despite having only a single glucose-binding site, GCK displays positive glucose cooperativity. Ex vivo structural studies have identified several potential protein conformations with varying levels of enzymatic activity, yet it is unclear how living cells regulate GCK cooperativity. To better understand the cellular regulation of GCK activation, we developed a homotransfer Förster resonance energy transfer (FRET) GCK biosensor and used polarization microscopy to eliminate fluorescence crosstalk from FRET quantification and improve the signal-to-noise ratio. This approach enhanced sensor contrast compared to that seen with the heterotransfer FRET GCK reporter and allowed observation of individual GCK states using an automated method to analyze FRET data at the pixel level. Mutations known to activate and inhibit GCK activity produced distinct anisotropy distributions, suggesting that at least two conformational states exist in living cells. A high glucose level activated the biosensor in a manner consistent with GCK's enzymology. Interestingly, glucose-free conditions did not affect GCK biosensor FRET, indicating that there is a single low-activity state, which is counter to proposed structural models of GCK cooperativity. Under low-glucose conditions, application of chemical NO donors efficiently shifted GCK to the more active conformation. Notably, GCK activation by mutation, a high glucose level, a pharmacological GCK activator, or S-nitrosylation all shared the same FRET distribution. These data suggest a simplified model for GCK activation in living cells, where post-translational modification of GCK by S-nitrosylation facilitates a single conformational transition that enhances GCK enzymatic activity.
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Affiliation(s)
- Kendra M. Seckinger
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Vishnu P. Rao
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Nicole E. Snell
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Allison E. Mancini
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Michele L. Markwardt
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - M. A. Rizzo
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
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Ali ES, Hua J, Wilson CH, Tallis GA, Zhou FH, Rychkov GY, Barritt GJ. The glucagon-like peptide-1 analogue exendin-4 reverses impaired intracellular Ca(2+) signalling in steatotic hepatocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2135-46. [PMID: 27178543 DOI: 10.1016/j.bbamcr.2016.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/20/2016] [Accepted: 05/04/2016] [Indexed: 02/07/2023]
Abstract
The release of Ca(2+) from the endoplasmic reticulum (ER) and subsequent replenishment of ER Ca(2+) by Ca(2+) entry through store-operated Ca(2+) channels (SOCE) play critical roles in the regulation of liver metabolism by adrenaline, glucagon and other hormones. Both ER Ca(2+) release and Ca(2+) entry are severely inhibited in steatotic hepatocytes. Exendin-4, a slowly-metabolised glucagon-like peptide-1 (GLP-1) analogue, is known to reduce liver glucose output and liver lipid, but the mechanisms involved are not well understood. The aim of this study was to determine whether exendin-4 alters intracellular Ca(2+) homeostasis in steatotic hepatocytes, and to evaluate the mechanisms involved. Exendin-4 completely reversed lipid-induced inhibition of SOCE in steatotic liver cells, but did not reverse lipid-induced inhibition of ER Ca(2+) release. The action of exendin-4 on Ca(2+) entry was rapid in onset and was mimicked by GLP-1 or dibutyryl cyclic AMP. In steatotic liver cells, exendin-4 caused a rapid decrease in lipid (half time 6.5min), inhibited the accumulation of lipid in liver cells incubated in the presence of palmitate plus the SOCE inhibitor BTP-2, and enhanced the formation of cyclic AMP. Hormone-stimulated accumulation of extracellular glucose in glycogen replete steatotic liver cells was inhibited compared to that in non-steatotic cells, and this effect of lipid was reversed by exendin-4. It is concluded that, in steatotic hepatocytes, exendin-4 reverses the lipid-induced inhibition of SOCE leading to restoration of hormone-regulated cytoplasmic Ca(2+) signalling. The mechanism may involve GLP-1 receptors, cyclic AMP, lipolysis, decreased diacylglycerol and decreased activity of protein kinase C.
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Affiliation(s)
- Eunüs S Ali
- Department of Medical Biochemistry and Centre for Neuroscience, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia
| | - Jin Hua
- Department of Medical Biochemistry and Centre for Neuroscience, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia
| | - Claire H Wilson
- Molecular Regulation Laboratory, Centre for Cancer Biology, Division of Health Sciences, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - George A Tallis
- Medical Biochemistry, SA Pathology, Finders Medical Centre, Bedford Park, South Australia 5042, Australia
| | - Fiona H Zhou
- School of Medicine, The University of Adelaide, and South Australian Health and Medical Research Institute, Adelaide, South Australia 5005, Australia
| | - Grigori Y Rychkov
- School of Medicine, The University of Adelaide, and South Australian Health and Medical Research Institute, Adelaide, South Australia 5005, Australia
| | - Greg J Barritt
- Department of Medical Biochemistry and Centre for Neuroscience, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia.
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Francini F, Massa ML, Polo MP, Villagarcía H, Castro MC, Gagliardino JJ. Control of liver glucokinase activity: A potential new target for incretin hormones? Peptides 2015; 74:57-63. [PMID: 26524624 DOI: 10.1016/j.peptides.2015.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 10/13/2015] [Accepted: 10/26/2015] [Indexed: 12/27/2022]
Abstract
We tested the exendin-4 and des-fluoro-sitagliptin effects on fructose-induced increase in liver glucokinase activity in rats with impaired glucose tolerance and the exendin-4 effect on glucokinase activity in HepG2 cells incubated with fructose in the presence/absence of exendin-9-39. After 3 weeks of in vivo fructose administration we measured: (1) serum glucose, insulin and triglyceride levels; (2) liver and HepG2 cells glucokinase activity and (3) liver glucokinase and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase mRNA and protein levels. Fructose fed rats had: hypertriglyceridemia, hyperinsulinemia and high liver glucokinase activity (mainly located in the cytosolic fraction) together with higher glucokinase and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase mRNA and protein concentrations compared to control rats. Co-administration of either exendin-4 or des-fluoro-sitagliptin prevented serum and liver changes except glucokinase protein expression. Exendin-4 also prevented fructose-induced increase in glucokinase activity in cultured HepG2 cells, effect blunted by co-incubation with exendin-9-36. In conclusion exendin-4/des-fluro-sitagliptin prevented fructose-induced effect on glucokinase activity, mainly affecting enzyme activity modulators. Exendin 9-39 blunted in vitro protective exendin-4 effect on glucokinase activity, thus suggesting a direct effect of the later on hepatocytes through GLP-1 receptor. Alterations of glucokinase activity modulators could play a role in the pathogenesis of liver dysfunction, becoming a potential new treatment target for GLP-1 receptor agonists.
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Affiliation(s)
- Flavio Francini
- CENEXA (UNLP-CONICET CCT LA PLATA), PAHO/WHO Collaborating Centre for Diabetes, National University of La Plata School of Medicine, La Plata, Argentina.
| | - María Laura Massa
- CENEXA (UNLP-CONICET CCT LA PLATA), PAHO/WHO Collaborating Centre for Diabetes, National University of La Plata School of Medicine, La Plata, Argentina
| | | | - Hernán Villagarcía
- CENEXA (UNLP-CONICET CCT LA PLATA), PAHO/WHO Collaborating Centre for Diabetes, National University of La Plata School of Medicine, La Plata, Argentina
| | - María Cecilia Castro
- CENEXA (UNLP-CONICET CCT LA PLATA), PAHO/WHO Collaborating Centre for Diabetes, National University of La Plata School of Medicine, La Plata, Argentina
| | - Juan José Gagliardino
- CENEXA (UNLP-CONICET CCT LA PLATA), PAHO/WHO Collaborating Centre for Diabetes, National University of La Plata School of Medicine, La Plata, Argentina
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Combination of omeprazole with GLP-1 agonist therapy improves insulin sensitivity and antioxidant activity in liver in type 1 diabetic mice. Pharmacol Rep 2014; 65:927-36. [PMID: 24145087 DOI: 10.1016/s1734-1140(13)71074-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 02/05/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND Combination with suitable pharmacological agents can improve the antiobesity and antidiabetic actions of glucagon like peptide-1 (GLP-1) based therapies. GLP-1 agonist exendin-4 may have insulin-independent effects on amelioration of insulin resistance and hepatic steatosis by virtue of its action on hepatic GLP-1 receptors, and these effects can be improved by combination with proton pump inhibitors. However, it was not assessed whether omeprazole can improve the peripheral actions of exendin-4 in the state of insulin deficiency. METHODS We investigated the effects of combination of omeprazole with GLP-1 agonist exendin-4 in multiple low-dose streptozotocin (STZ)-induced diabetes in C57BL/KsJ mice, a model of type 1 diabetes. Male diabetic mice were treated with exendin-4 and/or omeprazole for a period of 4 weeks. RESULTS Omeprazole treatment had no significant effect on lowering the blood glucose levels of diabetic mice, when compared to control, although it improved the antihyperglycemic actions of exendin-4. Similarly, serum triglycerides and total cholesterols levels were significantly lower in the combination treated mice compared to either exendin-4 and omeprazole alone. In addition, the combination treatment significantly ameliorated lipid peroxidation and hepatic triglycerides in diabetic mice compared to either exendin-4 and omeprazole alone. The improvement in hepatic insulin sensitivity, as indicated by insulin tolerance test (ITT) and pyruvate tolerance test (IPPTT), was correlated with the expression of nuclear factor erythroid-related factor 2 (Nrf2) and insulin receptor substrate-1 (IRS-1) and the combination treatment significantly improved the insulin sensitivity in comparison to vehicle control. CONCLUSION We conclude that combination with omeprazole improves the insulin sensitizing actions of GLP-1 therapy and these effects are partially mediated through the decrease in hepatic steatosis and improvement in antioxidant status in the liver.
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Effect of low molecular weight galactomannans from fenugreek seeds on animal models of diabetes mellitus. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.biomag.2013.06.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Edgerton DS, An Z, Johnson KMS, Farmer T, Farmer B, Neal D, Cherrington AD. Effects of intraportal exenatide on hepatic glucose metabolism in the conscious dog. Am J Physiol Endocrinol Metab 2013; 305:E132-9. [PMID: 23673158 PMCID: PMC3725568 DOI: 10.1152/ajpendo.00160.2013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Incretins improve glucose metabolism through multiple mechanisms. It remains unclear whether direct hepatic effects are an important part of exenatide's (Ex-4) acute action. Therefore, the objective of this study was to determine the effect of intraportal delivery of Ex-4 on hepatic glucose production and uptake. Fasted conscious dogs were studied during a hyperglycemic clamp in which glucose was infused into the hepatic portal vein. At the same time, portal saline (control; n = 8) or exenatide was infused at low (0.3 pmol·kg⁻¹·min⁻¹, Ex-4-low; n = 5) or high (0.9 pmol·kg⁻¹·min⁻¹, Ex-4-high; n = 8) rates. Arterial plasma glucose levels were maintained at 160 mg/dl during the experimental period. This required a greater rate of glucose infusion in the Ex-4-high group (1.5 ± 0.4, 2.0 ± 0.7, and 3.7 ± 0.7 mg·kg⁻¹·min⁻¹ between 30 and 240 min in the control, Ex-4-low, and Ex-4-high groups, respectively). Plasma insulin levels were elevated by Ex-4 (arterial: 4,745 ± 428, 5,710 ± 355, and 7,262 ± 1,053 μU/ml; hepatic sinusoidal: 14,679 ± 1,700, 15,341 ± 2,208, and 20,445 ± 4,020 μU/ml, 240 min, area under the curve), whereas the suppression of glucagon was nearly maximal in all groups. Although glucose utilization was greater during Ex-4 infusion (5.92 ± 0.53, 6.41 ± 0.57, and 8.12 ± 0.54 mg·kg⁻¹·min⁻¹), when indices of hepatic, muscle, and whole body glucose uptake were expressed relative to circulating insulin concentrations, there was no indication of insulin-independent effects of Ex-4. Thus, this study does not support the notion that Ex-4 generates acute changes in hepatic glucose metabolism through direct effects on the liver.
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Affiliation(s)
- Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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Dhanesha N, Joharapurkar A, Shah G, Kshirsagar S, Patel V, Patel K, Bahekar R, Jain M. Treatment with exendin-4 improves the antidiabetic efficacy and reverses hepatic steatosis in glucokinase activator treated db/db mice. Eur J Pharmacol 2013; 714:188-92. [PMID: 23810686 DOI: 10.1016/j.ejphar.2013.06.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 05/29/2013] [Accepted: 06/08/2013] [Indexed: 01/27/2023]
Abstract
The glucokinase activators improve the fasting as well as postprandial glucose control and are important investigational drugs for the treatment of diabetes. However, recent studies have implicated that continuous activation of glucokinase with a small molecule activator can increase hepatic triglycerides and the long term glucose control is not achieved. In this study, we investigated the effect of combination of glucokinase activator (GKA, Piragliatin) with GLP-1 receptor agonist exendin-4 (Ex-4) in male db/db mice. Twelve weeks combination treatment in the db/db mice resulted in a significant decrease in body weight gain, food consumption, random glucose and %HbA1c. The decrease in serum glucose and %HbA1c in combination group was more profound and significantly different than that of individual treatment (GKA or Ex-4) group. GKA treatment increased hepatic triglycerides, whereas combination of Ex-4 with GKA attenuated hepatic steatosis. The combination of GKA with Ex-4 reduced the hepatic lipid accumulation, improved the insulin sensitivity, and reduced hepatic glucose production in db/db mice. Overall, our data indicate that combination of GKA and GLP-1 receptor agonist Ex-4 improves glucose homeostasis, shows antiobesity activity, without causing harmful side effects like fatty liver.
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Affiliation(s)
- Nirav Dhanesha
- Department of Pharmacology & Toxicology, Zydus Research Centre, Cadila Healthcare Limited, Sarkhej-Bavla N.H. No. 8A, Moraiya, Ahmedabad 382210, India
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12
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ThanThan S, Asada Y, Saito T, Ochiiwa K, Zhao H, Yannaing S, Kuwayama H. Oxyntomodulin attenuates exendin-4-induced hypoglycemia in cattle. Domest Anim Endocrinol 2013; 44:70-80. [PMID: 23122871 DOI: 10.1016/j.domaniend.2012.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 09/07/2012] [Accepted: 09/12/2012] [Indexed: 10/27/2022]
Abstract
Oxyntomodulin (OXM), glucagon, glucagon-like peptide-1 (GLP-1), and exendin-4 (Ex-4) are peptide hormones that regulate glucose homeostasis in monogastric and ruminant animals. Recently, we reported that the insulin-releasing effects of OXM and glucagon in cattle are mediated through both GLP-1 and glucagon receptors. The purpose of this study was to examine the mechanisms of the glucoregulatory actions induced by Ex-4, GLP-1, OXM, and glucagon and the interrelationships among these hormones in cattle. Two experiments were performed in Holstein cattle. In Experiment 1, we initially assessed the effects of intravenous (iv) bolus injection of 0, 0.25, 1, and 2 μg/kg body weight (BW) of Ex-4, GLP-1, and OXM on insulin and glucose concentrations in 3-mo-old intact male Holstein calves. In Experiment 2, we studied insulin and glucose responses to iv coinjection of 0.25 μg of Ex-4 or GLP-1/kg BW with 2 μg of OXM or glucagon/kg BW in 4-mo-old Holstein steers. Administration of peptides and blood sampling were done via a jugular catheter. Plasma was separated and the concentrations of peptides and glucose in plasma were analyzed using radioimmunoassay and enzymatic methods, respectively. Results showed that the potent glucoregulatory action of Ex-4 in 4-mo-old steers was delayed and attenuated when Ex-4 was coinjected with OXM. The decline in plasma glucose concentrations began at 5 min in the Ex-4-injected group (P < 0.05) vs 15 min in the Ex-4 + OXM-injected group (P < 0.05). Plasma concentrations of glucose at 30 min were reduced 26% from basal concentrations in the Ex-4-injected group and 13% in the Ex-4 + OXM-injected group (P < 0.001). Results also showed that the glucose concentrations initially increased in the Ex-4 + glucagon-treated group, but declined to a relatively hypoglycemic condition by 90 to 120 min. In contrast, the glucose concentrations at specific time points between the GLP-1 + OXM-injected group and the OXM-injected group did not differ. Similarly, the glucose concentrations in the GLP-1 + glucagon-injected group did not differ from those in the glucagon-injected group. Because OXM and glucagon mediate glucose concentrations via the glucagon receptor, it is suggested that the potent glucose-lowering action of Ex-4 might include the glucagon receptor antagonistic action of Ex-4.
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Affiliation(s)
- S ThanThan
- Department of Life Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan
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Markwardt ML, Nkobena A, Ding SY, Rizzo MA. Association with nitric oxide synthase on insulin secretory granules regulates glucokinase protein levels. Mol Endocrinol 2012; 26:1617-29. [PMID: 22771492 PMCID: PMC3434526 DOI: 10.1210/me.2012-1183] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 06/19/2012] [Indexed: 11/19/2022] Open
Abstract
Glucokinase (GCK) association with insulin-secretory granules is controlled by interaction with nitric oxide synthase (NOS) and is reversed by GCK S-nitrosylation. Nonetheless, the function of GCK sequestration on secretory granules is unknown. Here we report that the S-nitrosylation blocking V367M mutation prevents GCK accumulation on secretory granules by inhibiting association with NOS. Expression of this mutant is reduced compared with a second S-nitrosylation blocking GCK mutant (C371S) that accumulates to secretory granules and is expressed at levels greater than wild type. Even so, the rate of degradation for wild type and mutant GCK proteins were not significantly different from one another, and neither mutation disrupted the ability of GCK to be ubiquitinated. Furthermore, gene silencing of NOS reduced endogenous GCK content but did not affect β-actin content. Treatment of GCK(C371S) expressing cells with short interfering RNA specific for NOS also blocked accumulation of this protein to secretory granules and reduced expression levels to that of GCK(V367M). Conversely, cotransfection of catalytically inactive NOS increased GCK-mCherry levels. Expression of GCK(C371S) in βTC3 cells enhanced glucose metabolism compared with untransfected cells and cells expressing wild type GCK, even though this mutant has slightly reduced enzymatic activity in vitro. Finally, molecular dynamics simulations revealed that V367M induces conformational changes in GCK that are similar to S-nitrosylated GCK, thereby suggesting a mechanism for V367M-inhibition of NOS association. Our findings suggest that sequestration of GCK on secretory granules regulates cellular GCK protein content, and thus cellular GCK activity, by acting as a storage pool for GCK proteins.
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Affiliation(s)
- Michele L Markwardt
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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