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Khedr NF, Ebeid AM, Khalil RM. New insights into weight management by orlistat in comparison with cinnamon as a natural lipase inhibitor. Endocrine 2020; 67:109-116. [PMID: 31721089 DOI: 10.1007/s12020-019-02127-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 10/30/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND AND OBJECTIVES Orlistat which is taken by obese patients may present some therapeutic assistance through its inhibition of lipase activity. Otherwise, a natural lipase inhibitor as cinnamon is widely used traditional medicine to decrease cholesterol and body weight. The current study aimed to investigate the weight management of orlistat in comparison with cinnamon through different obesity related targets. METHODS Subjects were divided into: Group 1: subjects received cinnamon capsules for 60 days. Group 2: subjects were received orlistat twice daily for 30 days, then once daily for another 30 days. Blood samples were collected at baseline and after 2 months. RESULTS Both orlistat and cinnamon groups showed a significant reduction in BMI, lipid profile, and lipase activity compared with baseline. Orlistat group showed significant elevation (p < 0.001) in glucagon, insulin-degrading enzyme (IDE) and dopamine level concomitant with the decrease of serum glutamate compared with baseline level of the same group and cinnamon group. However, cinnamon reduced serum insulin level and insulin resistance (IR) compared with baseline level of the same group and orlistat group. CONCLUSIONS Orlistat can be used in weight management not only for its pancreatic lipase inhibition but also, due to its indirect appetite reduction effect through elevated glucagon, IDE and dopamine levels and its inhibitory effect on glutamate neurotransmitter, whereas, cinnamon improves BMI and glycaemic targets.
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Affiliation(s)
- Naglaa F Khedr
- Biochemistry Department, Faculty of Pharmacy, Tanta University, Tanta, Egypt.
| | - Abla M Ebeid
- Clinical Pharmacy Department, Faculty of Pharmacy, Delta University for Science and Technology, Gamasaa, Egypt
| | - Rania M Khalil
- Biochemistry Department, Faculty of Pharmacy, Delta University for Science and Technology, Gamasaa, Egypt
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Sikimic J, Hoffmeister T, Gresch A, Kaiser J, Barthlen W, Wolke C, Wieland I, Lendeckel U, Krippeit-Drews P, Düfer M, Drews G. Possible New Strategies for the Treatment of Congenital Hyperinsulinism. Front Endocrinol (Lausanne) 2020; 11:545638. [PMID: 33193079 PMCID: PMC7653201 DOI: 10.3389/fendo.2020.545638] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 10/02/2020] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVE Congenital hyperinsulinism (CHI) is a rare disease characterized by persistent hypoglycemia as a result of inappropriate insulin secretion, which can lead to irreversible neurological defects in infants. Poor efficacy and strong adverse effects of the current medications impede successful treatment. The aim of the study was to investigate new approaches to silence β-cells and thus attenuate insulin secretion. RESEARCH DESIGN AND METHODS In the scope of our research, we tested substances more selective and more potent than the gold standard diazoxide that also interact with neuroendocrine ATP-sensitive K+ (KATP) channels. Additionally, KATP channel-independent targets as Ca2+-activated K+ channels of intermediate conductance (KCa3.1) and L-type Ca2+ channels were investigated. Experiments were performed using human islet cell clusters isolated from tissue of CHI patients (histologically classified as pathological) and islet cell clusters obtained from C57BL/6N (WT) or SUR1 knockout (SUR1-/-) mice. The cytosolic Ca2+ concentration ([Ca2+]c) was used as a parameter for the pathway regulated by electrical activity and was determined by fura-2 fluorescence. The mitochondrial membrane potential (ΔΨ) was determined by rhodamine 123 fluorescence and single channel currents were measured by the patch-clamp technique. RESULTS The selective KATP channel opener NN414 (5 µM) diminished [Ca2+]c in isolated human CHI islet cell clusters and WT mouse islet cell clusters stimulated with 10 mM glucose. In islet cell clusters lacking functional KATP channels (SUR1-/-) the drug was without effect. VU0071063 (30 µM), another KATP channel opener considered to be selective, lowered [Ca2+]c in human CHI islet cell clusters. The compound was also effective in islet cell clusters from SUR1-/- mice, showing that [Ca2+]c is influenced by additional effects besides KATP channels. Contrasting to NN414, the drug depolarized ΔΨ in murine islet cell clusters pointing to severe interference with mitochondrial metabolism. An opener of KCa3.1 channels, DCEBIO (100 µM), significantly decreased [Ca2+]c in SUR1-/- and human CHI islet cell clusters. To target L-type Ca2+ channels we tested two already approved drugs, dextromethorphan (DXM) and simvastatin. DXM (100 µM) efficiently diminished [Ca2+]c in stimulated human CHI islet cell clusters as well as in stimulated SUR1-/- islet cell clusters. Similar effects on [Ca2+]c were observed in experiments with simvastatin (7.2 µM). CONCLUSIONS NN414 seems to provide a good alternative to the currently used KATP channel opener diazoxide. Targeting KCa3.1 channels by channel openers or L-type Ca2+ channels by DXM or simvastatin might be valuable approaches for treatment of CHI caused by mutations of KATP channels not sensitive to KATP channel openers.
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Affiliation(s)
- Jelena Sikimic
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Theresa Hoffmeister
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Anne Gresch
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Julia Kaiser
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Winfried Barthlen
- Department of Pediatric Surgery, University Medicine Greifswald, Greifswald, Germany
| | - Carmen Wolke
- Institute of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany
| | - Ilse Wieland
- Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
| | - Uwe Lendeckel
- Institute of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany
| | - Peter Krippeit-Drews
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
- *Correspondence: Peter Krippeit-Drews,
| | - Martina Düfer
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Gisela Drews
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
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Lee GH, Lee HY, Li B, Kim HR, Chae HJ. Bax inhibitor-1-mediated inhibition of mitochondrial Ca2+ intake regulates mitochondrial permeability transition pore opening and cell death. Sci Rep 2014; 4:5194. [PMID: 24899098 PMCID: PMC4046133 DOI: 10.1038/srep05194] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 05/20/2014] [Indexed: 12/13/2022] Open
Abstract
A recently studied endoplasmic reticulum (ER) stress regulator, Bax inhibitor-1 (BI-1) plays a regulatory role in mitochondrial Ca2+ levels. In this study, we identified ER-resident and mitochondria-associated ER membrane (MAM)-resident populations of BI-1. ER stress increased mitochondrial Ca2+ to a lesser extent in BI-1–overexpressing cells (HT1080/BI-1) than in control cells, most likely as a result of impaired mitochondrial Ca2+ intake ability and lower basal levels of intra-ER Ca2+. Moreover, opening of the Ca2+-induced mitochondrial permeability transition pore (PTP) and cytochrome c release were regulated by BI-1. In HT1080/BI-1, the basal mitochondrial membrane potential was low and also resistant to Ca2+ compared with control cells. The activity of the mitochondrial membrane potential-dependent mitochondrial Ca2+ intake pore, the Ca2+ uniporter, was reduced in the presence of BI-1. This study also showed that instead of Ca2+, other cations including K+ enter the mitochondria of HT1080/BI-1 through mitochondrial Ca2+-dependent ion channels, providing a possible mechanism by which mitochondrial Ca2+ intake is reduced, leading to cell protection. We propose a model in which BI-1–mediated sequential regulation of the mitochondrial Ca2+ uniporter and Ca2+-dependent K+ channel opening inhibits mitochondrial Ca2+ intake, thereby inhibiting PTP function and leading to cell protection.
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Affiliation(s)
- Geum-Hwa Lee
- Department of Pharmacology and Cardiovascular Research Institute, Medical School, Chonbuk National University, Jeonju, 561-181, Republic of Korea
| | - Hwa-Young Lee
- Department of Pharmacology and Cardiovascular Research Institute, Medical School, Chonbuk National University, Jeonju, 561-181, Republic of Korea
| | - Bo Li
- Department of Pharmacology and Cardiovascular Research Institute, Medical School, Chonbuk National University, Jeonju, 561-181, Republic of Korea
| | - Hyung-Ryong Kim
- Department of Dental Pharmacology and Wonkwang Dental Research Institute, School of Dentistry, Wonkwang University, Iksan, 570-749, Republic of Korea
| | - Han-Jung Chae
- Department of Pharmacology and Cardiovascular Research Institute, Medical School, Chonbuk National University, Jeonju, 561-181, Republic of Korea
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Park YS, Bang JY, Hwang BY, Ryu HY, Jeong SM, Park PH. The effect of mitochondrial adenosine triphosphate-sensitive potassium (K(ATP)) channel blocker on ischemic preconditioning in hypoxic-ischemic brain injury model of neonatal rat. Korean J Anesthesiol 2009; 57:729-736. [PMID: 30625957 DOI: 10.4097/kjae.2009.57.6.729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A brief episode of cerebral ischemia confers transient ischemic tolerance to a subsequent ischemic challenge that is otherwise lethal to them. This study was purposed to evaluate the effect of mitochondrial adenosine triphosphate-sensitive potassium (KATP) channel blocker on ischemic preconditioning in hypoxic-ischemic brain injury model of neonatal rat. METHODS Seven-day old Sprague-Dawley rat pups were used. The rats were divided into five groups; control group (n = 91), pretreatment hypoxic preconditioning group (n = 43), pretreatment ischemic preconditioning group (n = 52), hypoxic preconditioning group (n = 39), and ischemic preconditioning group (n = 51). Rats in the pretreatment hypoxic preconditioning group and pretreatment ischemic preconditioning group were treated by an intraperitoneal injection with 5-hydroxydecanoate (60 mg/kg). Thirty minutes after injection, right common carotid artery was temporarily occluded for ten minutes in pretreatment ischemic preconditioning group. Rats in the pretreatment hypoxic preconditioning group and hypoxic preconditioning group underwent hypoxia (8% oxygen/92% nitrogen) for four hours. Twenty-four hours after the preconditioning, rats from all groups were exposed to right common carotid artery ligation followed by 2.5 hour hypoxia. On the 1st day after hypoxic-ischemic brain injury, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling (TUNEL) reaction was evaluate as apoptotic markers and triphenyl tetrazolium chloride (TTC) was done to measure necrotic tissue. All rats were sacrificed 2 weeks after hypoxic-ischemia brain injury and the brains were examined for morphologic study. RESULTS There were no differenced in survival rate, infarct area, number of TUNEL positive cells and morphologic score either between hypoxic preconditioning group and pretreatment hypoxic preconditioning group or between ischemic preconditioning group and pretreatment ischemic preconditioning group. CONCLUSIONS The results suggests that mitochondrial K(ATP) channel blocker, 5-hydroxydecanoate, does not change hypoxic-ischemic preconditioning in the neonatal rat.
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Affiliation(s)
- Young Soo Park
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan School of Medicine, Seoul, Korea.
| | - Ji Yeon Bang
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan School of Medicine, Seoul, Korea.
| | - Bo Young Hwang
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan School of Medicine, Seoul, Korea.
| | - Hae Young Ryu
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan School of Medicine, Seoul, Korea.
| | - Sung Moon Jeong
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan School of Medicine, Seoul, Korea.
| | - Pyung Hwan Park
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan School of Medicine, Seoul, Korea.
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Gier B, Krippeit-Drews P, Sheiko T, Aguilar-Bryan L, Bryan J, Düfer M, Drews G. Suppression of KATP channel activity protects murine pancreatic beta cells against oxidative stress. J Clin Invest 2009; 119:3246-56. [PMID: 19805912 DOI: 10.1172/jci38817] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 07/29/2009] [Indexed: 12/21/2022] Open
Abstract
The enhanced oxidative stress associated with type 2 diabetes mellitus contributes to disease pathogenesis. We previously identified plasma membrane-associated ATP-sensitive K+ (KATP) channels of pancreatic beta cells as targets for oxidants. Here, we examined the effects of genetic and pharmacologic ablation of KATP channels on loss of mouse beta cell function and viability following oxidative stress. Using mice lacking the sulfonylurea receptor type 1 (Sur1) subunit of KATP channels, we found that, compared with insulin secretion by WT islets, insulin secretion by Sur1-/- islets was less susceptible to oxidative stress induced by the oxidant H2O2. This was likely, at least in part, a result of the reduced ability of H2O2 to hyperpolarize plasma membrane potential and reduce cytosolic free Ca2+ concentration ([Ca2+]c) in the Sur1-/- beta cells. Remarkably, Sur1-/- beta cells were less prone to apoptosis induced by H2O2 or an NO donor than WT beta cells, despite an enhanced basal rate of apoptosis. This protective effect was attributed to upregulation of the antioxidant enzymes SOD, glutathione peroxidase, and catalase. Upregulation of antioxidant enzymes and reduced sensitivity of Sur1-/- cells to H2O2-induced apoptosis were mimicked by treatment with the sulfonylureas tolbutamide and gliclazide. Enzyme upregulation and protection against oxidant-induced apoptosis were abrogated by agents lowering [Ca2+]c. Sur1-/- mice were less susceptible than WT mice to streptozotocin-induced beta cell destruction and subsequent hyperglycemia and death, which suggests that loss of KATP channel activity may protect against streptozotocin-induced diabetes in vivo.
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Affiliation(s)
- Belinda Gier
- Institute of Pharmacy, Department of Pharmacology, University of Tübingen, Tübingen, Germany
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Possible role of an ischemic preconditioning-like response mechanism in KATP channel opener-mediated protection against streptozotocin-induced suppression of rat pancreatic islet function. Biochem Pharmacol 2008; 76:1748-56. [DOI: 10.1016/j.bcp.2008.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 09/03/2008] [Accepted: 09/03/2008] [Indexed: 11/18/2022]
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Watanabe M, Katsura KI, Ohsawa I, Mizukoshi G, Takahashi K, Asoh S, Ohta S, Katayama Y. Involvement of mitoKATP channel in protective mechanisms of cerebral ischemic tolerance. Brain Res 2008; 1238:199-207. [DOI: 10.1016/j.brainres.2008.08.038] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 08/11/2008] [Accepted: 08/11/2008] [Indexed: 12/30/2022]
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Ma Z, Portwood N, Brodin D, Grill V, Björklund A. Effects of diazoxide on gene expression in rat pancreatic islets are largely linked to elevated glucose and potentially serve to enhance beta-cell sensitivity. Diabetes 2007; 56:1095-106. [PMID: 17229937 DOI: 10.2337/db06-0322] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Diazoxide enhances glucose-induced insulin secretion from beta-cells through mechanisms that are not fully elucidated. Here, we used microarray analysis (Affymetrix) to investigate effects of diazoxide. Pancreatic islets were cultured overnight at 27, 11, or 5.5 mmol/l glucose with or without diazoxide. Inclusion of diazoxide upregulated altogether 211 genes (signal log(2) ratio > or =0.5) and downregulated 200 genes (signal log(2) ratio -0.5 or lower), and 92% of diazoxide's effects (up- and downregulation) were observed only after coculture with 11 or 27 mmol/l glucose. We found that 11 mmol/l diazoxide upregulated 97 genes and downregulated 21 genes. Increasing the glucose concentration to 27 mmol/l markedly shifted these proportions toward downregulation (101 genes upregulated and 160 genes downregulated). At 27 mmol/l glucose, most genes downregulated by diazoxide were oppositely affected by glucose (80%). Diazoxide influenced expression of several genes central to beta-cell metabolism. Diazoxide downregulated genes of fatty acid oxidation, upregulated genes of fatty acid synthesis, and downregulated uncoupling protein 2 and lactic acid dehydrogenase. Diazoxide upregulated certain genes known to support beta-cell functionality, such as NKX6.1 and PDX1. Long-term elevated glucose is permissive for most of diazoxide's effects on gene expression, the proportion of effects shifting to downregulation with increasing glucose concentration. Effects of diazoxide on gene expression could serve to enhance beta-cell functionality during continuous hyperglycemia.
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Affiliation(s)
- Zuheng Ma
- Endocrine and Diabetes Unit, Department of Molecular Medicine and Surgery, Karolinska Hospital, Karolinska Institutet, Stockholm, Sweden
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Huang Q, Bu S, Yu Y, Guo Z, Ghatnekar G, Bu M, Yang L, Lu B, Feng Z, Liu S, Wang F. Diazoxide prevents diabetes through inhibiting pancreatic beta-cells from apoptosis via Bcl-2/Bax rate and p38-beta mitogen-activated protein kinase. Endocrinology 2007; 148:81-91. [PMID: 17053028 DOI: 10.1210/en.2006-0738] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Increased apoptosis of pancreatic beta-cells plays an important role in the occurrence and development of type 2 diabetes. We examined the effect of diazoxide on pancreatic beta-cell apoptosis and its potential mechanism in Otsuka Long Evans Tokushima Fatty (OLETF) rats, an established animal model of human type 2 diabetes, at the prediabetic and diabetic stages. We found a significant increase with age in the frequency of apoptosis, the sequential enlargement of islets, and the proliferation of the connective tissue surrounding islets, accompanied with defective insulin secretory capacity and increased blood glucose in untreated OLETF rats. In contrast, diazoxide treatment (25 mg.kg(-1).d(-1), administered ip) inhibited beta-cell apoptosis, ameliorated changes of islet morphology and insulin secretory function, and increased insulin stores significantly in islet beta-cells whether diazoxide was used at the prediabetic or diabetic stage. Linear regression showed the close correlation between the frequency of apoptosis and hyperglycemia (r = 0.913; P < 0.0001). Further study demonstrated that diazoxide up-regulated Bcl-2 expression and p38beta MAPK, which expressed at very low levels due to the high glucose, but not c-jun N-terminal kinase and ERK. Hence, diazoxide may play a critical role in protection from apoptosis. In this study, we demonstrate that diazoxide prevents the onset and development of diabetes in OLETF rats by inhibiting beta-cell apoptosis via increasing p38beta MAPK, elevating Bcl-2/Bax ratio, and ameliorating insulin secretory capacity and action.
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Affiliation(s)
- Qin Huang
- Department of Endocrinology, Changhai Hospital, Shanghai 200433, People's Republic of China.
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El-Kholy W, MacDonald PE, Fox JM, Bhattacharjee A, Xue T, Gao X, Zhang Y, Stieber J, Li RA, Tsushima RG, Wheeler MB. Hyperpolarization-activated cyclic nucleotide-gated channels in pancreatic beta-cells. Mol Endocrinol 2006; 21:753-64. [PMID: 17158221 DOI: 10.1210/me.2006-0258] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels mediate the pacemaker current (Ih or If) observed in electrically rhythmic cardiac and neuronal cells. Here we describe a hyperpolarization-activated time-dependent cationic current, beta-Ih, in pancreatic beta-cells. Transcripts for HCN1-4 were detected by RT-PCR and quantitative PCR in rat islets and MIN6 mouse insulinoma cells. beta-Ih in rat beta-cells and MIN6 cells displayed biophysical and pharmacological properties similar to those of HCN currents in cardiac and neuronal cells. Stimulation of cAMP production with forskolin/3-isobutyl-1-methylxanthine (50 microM) or dibutyryl-cAMP (1 mM) caused a significant rightward shift in the midpoint activation potential of beta-Ih, whereas expression of either specific small interfering (si)RNA against HCN2 (siHCN2b) or a dominant-negative HCN channel (HCN1-AAA) caused a near-complete inhibition of time-dependent beta-Ih. However, expression of siHCN2b in MIN6 cells had no affect on glucose-stimulated insulin secretion under normal or cAMP-stimulated conditions. Blocking beta-Ih in intact rat islets also did not affect membrane potential behavior at basal glucose concentrations. Taken together, our experiments provide the first evidence for functional expression of HCN channels in the pancreatic beta-cell.
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Affiliation(s)
- Wasim El-Kholy
- Department of Medicine, University of Toronto, Toronto, Canada M5S 1A8
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Hägerkvist R, Sandler S, Mokhtari D, Welsh N. Amelioration of diabetes by imatinib mesylate (Gleevec): role of beta-cell NF-kappaB activation and anti-apoptotic preconditioning. FASEB J 2006; 21:618-28. [PMID: 17135364 DOI: 10.1096/fj.06-6910com] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It was recently reported that tyrosine kinase inhibitor imatinib mesylate (Gleevec) improves Type 2 diabetes, possibly by decreasing insulin resistance. However, as both Type 2 and Type 1 diabetes are characterized by beta-cell dysfunction and death, we investigated whether imatinib counteracts diabetes by maintaining beta-cell function. We observed that imatinib counteracted diabetes in two animal models, the streptozotocin-injected mouse and the nonobese diabetes mouse, and that this was paralleled by a partial preservation of the beta-cell mass. In addition, imatinib decreased the death of human beta-cells in vitro when exposed to NO, cytokines, and streptozotocin. The imatinib effect was mimicked by siRNA-mediated knockdown of c-Abl mRNA. Imatinib enhanced beta-cell survival by promoting a state similar to ischemic preconditioning, as evidenced by NF-kappaB activation, increased NO and reactive oxygen species production, and depolarization of the inner mitochondrial membrane. Imatinib did not suppress islet cell death in the presence of an NF-kappaB inhibitor, suggesting that NF-kappaB activation is a necessary step in the antiapoptotic action of imatinib. We conclude that imatinib mediates beta-cell survival and that this could contribute to the beneficial effects observed in diabetes.
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Affiliation(s)
- Robert Hägerkvist
- Department of Medical Cell Biology, Uppsala University, Biomedicum, P.O. Box 571, SE-75123 Uppsala, Sweden
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Kwon G, Marshall CA, Liu H, Pappan KL, Remedi MS, McDaniel ML. Glucose-stimulated DNA synthesis through mammalian target of rapamycin (mTOR) is regulated by KATP channels: effects on cell cycle progression in rodent islets. J Biol Chem 2005; 281:3261-7. [PMID: 16344552 DOI: 10.1074/jbc.m508821200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aim of this study was to define metabolic signaling pathways that mediate DNA synthesis and cell cycle progression in adult rodent islets to devise strategies to enhance survival, growth, and proliferation. Since previous studies indicated that glucose-stimulated activation of mammalian target of rapamycin (mTOR) leads to [3H]thymidine incorporation and that mTOR activation is mediated, in part, through the K(ATP) channel and changes in cytosolic Ca2+, we determined whether glyburide, an inhibitor of K(ATP) channels that stimulates Ca2+ influx, modulates [3H]thymidine incorporation. Glyburide (10-100 nm) at basal glucose stimulated [3H]thymidine incorporation to the same magnitude as elevated glucose and further enhanced the ability of elevated glucose to increase [3H]thymidine incorporation. Diazoxide (250 microm), an activator of KATP channels, paradoxically potentiated glucose-stimulated [3H]thymidine incorporation 2-4-fold above elevated glucose alone. Cell cycle analysis demonstrated that chronic exposure of islets to basal glucose resulted in a typical cell cycle progression pattern that is consistent with a low level of proliferation. In contrast, chronic exposure to elevated glucose or glyburide resulted in progression from G0/G1 to an accumulation in S phase and a reduction in G2/M phase. Rapamycin (100 nm) resulted in an approximately 62% reduction of S phase accumulation. The enhanced [3H]thymidine incorporation with chronic elevated glucose or glyburide therefore appears to be associated with S phase accumulation. Since diazoxide significantly enhanced [3H]thymidine incorporation without altering S phase accumulation under chronic elevated glucose, this increase in DNA synthesis also appears to be primarily related to an arrest in S phase and not cell proliferation.
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Affiliation(s)
- Guim Kwon
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Méndez JD, Hernández RDH. l-Arginine and polyamine administration protect β-cells against alloxan diabetogenic effect in Sprague–Dawley rats. Biomed Pharmacother 2005; 59:283-9. [PMID: 15996850 DOI: 10.1016/j.biopha.2005.05.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Indexed: 11/30/2022] Open
Abstract
In the searching for new substances with the capacity to protect beta-cells from the toxic effects of alloxan, we evaluated the effect of L-arginine and the polyamines putrescine, spermidine and spermine in a murine experimental model of diabetes. Diabetes was induced by the i.p. injection of either 200 mg/kg (24-h experiments) or 120 mg/kg (12 days experiments) body weight. L-Arginine and polyamines were administered 10 min before or 10 min after alloxan administration, once its half-life had elapsed, respectively. In the 24-h study, serum glucose (199.8+/-27.6 mg/dl) and triglyceride (54.6+/-4.9 mg/dl) concentrations showed a protective effect of spermine, as these parameters were not too high (P < or = 0.05), compared to the alloxan-treated group (415.4+/-47.8 and 90.2+/-11.6 mg/dl, respectively), and were closer to glucose (132.3+/-6.0 mg/dl) and similar to triglycerides (63.8+/-7.1 mg/dl) of the control group. A similar pattern was observed on the parameters measured when L-arginine and polyamines were administered daily for 12 days, starting 10 min after a single alloxan administration, which provides evidence that L-arginine and polyamines are effective in impeding the increase in serum glucose, triglyceride and cholesterol concentration showed on day 3 by the alloxan-treated group, as well as a higher acinar cell regenerative capacity as determined by immunohistochemical techniques. Spermine turning out to be more effective than L-arginine, putrescine or spermidine in counteracting the marked hyperglycemia and triglyceridemia showed by the alloxan-treated group and similar in effect when evaluating cholesterolemia. These results show a clear protective role of L-arginine and polyamines over the pancreatic beta-cell, in addition to the induction of neogenesis from both ductal and acinar cells that leads to the recovery of endocrine pancreatic function in rats with experimental diabetes.
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Affiliation(s)
- José D Méndez
- Medical Research Unit in Metabolic Diseases, National Medical Center, Mexican Institute of Social Security, P.O. Box A-047, Mexico City, 06703 D.F., Mexico.
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Maedler K, Donath MY. Beta-cells in type 2 diabetes: a loss of function and mass. HORMONE RESEARCH 2005; 62 Suppl 3:67-73. [PMID: 15539803 DOI: 10.1159/000080503] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes mellitus manifests itself in individuals who lose the ability to produce sufficient amounts of insulin to maintain normoglycaemia in the face of insulin resistance. The ability to secrete adequate amounts of insulin depends on beta-cell function and mass. Chronic hyperglycaemia is detrimental to pancreatic beta-cells, causing impaired insulin secretion and playing an essential role in the regulation of beta-cell turnover. This paper will address the effect of chronically elevated glucose levels on beta-cell turnover and function. In previous studies we have shown that elevated glucose concentrations induce apoptosis in human beta-cells due to an interaction between constitutively expressed Fas ligand and upregulated Fas. Human beta-cells produce interleukin (IL)-1beta in response to high glucose concentrations, independently of an immune-mediated process. This was antagonized by the IL-1 receptor antagonist (IL-1Ra), a naturally occurring anti-inflammatory cytokine also found in the beta-cell. Therefore the balance of IL-1beta and IL-1Ra may play a crucial role in the pathogenesis of diabetes. Inhibition of glucotoxicity represents a promising therapeutic stratagem in diabetes therapy to preserve functional beta-cell mass.
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Affiliation(s)
- K Maedler
- Division of Endocrinology and Diabetes, University Hospital Zürich, Switzerland.
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Tagmose TM, Schou SC, Mogensen JP, Nielsen FE, Arkhammar POG, Wahl P, Hansen BS, Worsaae A, Boonen HCM, Antoine MH, Lebrun P, Hansen JB. Arylcyanoguanidines as activators of Kir6.2/SUR1K ATP channels and inhibitors of insulin release. J Med Chem 2004; 47:3202-11. [PMID: 15163199 DOI: 10.1021/jm031018y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phenylcyanoguanidines substituted with lipophilic electron-withdrawing functional groups, e.g. N-cyano-N'-[3,5-bis-(trifluoromethyl)phenyl]-N' '-(cyclopentyl)guanidine (10) and N-cyano-N'-(3,5-dichlorophenyl)-N' '-(3-methylbutyl)guanidine (12) were synthesized and investigated for their ability to inhibit insulin release from beta cells, to repolarize beta cell membrane potential, and to relax precontracted rat aorta rings. Structural modifications gave compounds, which selectively inhibit insulin release from betaTC6 cells (e.g. compound 10: IC(50) = 5.45 +/- 1.9 microM) and which repolarize betaTC3 beta cells (10: IC(50) = 4.7 +/- 0.5 microM) without relaxation of precontracted aorta rings (10: IC(50) > 300 microM). Inhibition of insulin release from rat islets was observed in the same concentration level as for betaTC6 cells (10: IC(50) = 1.24 +/- 0.1 microM, 12: IC(50) = 3.8 +/- 0.4 microM). Compound 10 (10 microM) inhibits calcium outflow and insulin release from perifused rat pancreatic islets. The mechanisms of action of 10 and 12 were further investigated. The compounds depolarize mitochondrial membrane from smooth muscle cells and beta cell and stimulate glucose utilization and mitochondrial respiration in isolated liver cells. Furthermore, 10 was studied in a patch clamp experiment and was found to activate Kir6.2/SUR1 and inhibit Kir6.2/SUR2B type of K(ATP) channels. These studies indicate that the observed effects of the compounds on beta cells result from activation of K(ATP) channels of the cell membrane in combination with a depolarization of mitochondrial membranes. It also highlights that small structural changes can dramatically shift the efficacy of the cyanoguanidine type of selective activators of Kir6.2/SUR2 potassium channels.
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Affiliation(s)
- Tina M Tagmose
- Discovery, Novo Nordisk A/S, Novo Nordisk Park, DK 2760 Måløv, Denmark
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Niki I. [Contribution of diabetic research to versatile strategies for the treatment of diabetes mellitus]. Nihon Yakurigaku Zasshi 2003; 122:228-35. [PMID: 12939540 DOI: 10.1254/fpj.122.228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Diabetes mellitus is a very common life-style-related disease. Both genetic and environmental factors are strongly involved in its etiology and pathogenesis, and patients suffering from this disease are rapidly increasing in number. Since the discoveries of insulin in the 1920s and of antidiabetic sulphonylureas in the 1950s, these agents have been widely used for the treatment of diabetes mellitus. For the use of insulin, however, diabetic patients are imposed to inject insulin daily, and long-term use of sulphonylureas is suggested to impair pancreatic B cell functions. In order to overcome these problems and to achieve the fine control of blood glucose levels, many attempts for novel antidiabetic treatments are currently ongoing, and versatile therapeutic strategies for the treatment are expected to prevent the progression of this disease and resultant diabetic complications that severely affect the individuals' QOL. This paper overviews what diabetic research has done for its treatment and what it will do in the future.
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Affiliation(s)
- Ichiro Niki
- Department of Pharmacology, Oita Medical University, Hasama, Japan.
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Current literature in diabetes. Diabetes Metab Res Rev 2003; 19:333-40. [PMID: 12879412 DOI: 10.1002/dmrr.349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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