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Lee HA, Lee JK, Han JS. Betulinic acid improves TNF- α-induced insulin resistance by inhibiting negative regulator of insulin signalling and inflammation-activated protein kinase in 3T3-L1 adipocytes. Arch Physiol Biochem 2024; 130:452-459. [PMID: 36070616 DOI: 10.1080/13813455.2022.2120503] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/17/2022] [Accepted: 08/29/2022] [Indexed: 11/02/2022]
Abstract
CONTEXT Obesity is related to insulin resistance, and adipose tissue-secreted TNF-α may play a role in inducing obesity. TNF-α activates inflammatory protein kinase and impairs insulin signalling. OBJECTIVES We investigated the effect of betulinic acid on insulin resistance caused by TNF-α treatment in 3T3-L1 adipocytes. MATERIAL AND METHODS 3T3-L1 was exposed to TNF-α in the presence and absence of betulinic acid. Various parameters such as glucose uptake assay, cell viability, expression of proteins involved in insulin resistance were studied. RESULTS Betulinic acid increased glucose uptake in TNF-α pre-treated cells and inhibited the activation of PTP1B and JNK and reduced IκBα degradation. Tyrosine phosphorylation was increased, and serine phosphorylation was decreased in IRS-1. DISCUSSION Betulinic acid restored TNF-α impaired insulin signalling and increased PI3K activation and phosphorylation of Akt and increased plasma membrane expression of GLUT 4, which stimulated glucose uptake concentration-dependently. CONCLUSION These results suggest that betulinic acid is effective at improving TNF-α-induced insulin resistance in adipocytes via inhibiting the activation of negative regulator of insulin signalling and inflammation-activated protein kinase and may potentially improve insulin resistance.
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Affiliation(s)
- Hyun-Ah Lee
- Department of Food Science and Nutrition, Pusan National University, Busan, Republic of Korea
| | - Jung-Kyung Lee
- Department of Food Science and Nutrition, Pusan National University, Busan, Republic of Korea
| | - Ji-Sook Han
- Department of Food Science and Nutrition, Pusan National University, Busan, Republic of Korea
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Kim HL, Jung Y, Kim HI, Sung NY, Kim MJ, Han IJ, Kim G, Nho EY, Park SY, Han Y, Jung JH, Kim DS, Park J. Antidiabetic Effect of Fermented Mesembryanthemum crystallinum L. in db/ db Mice Involves Regulation of PI3K-Akt Pathway. Curr Issues Mol Biol 2023; 45:6415-6431. [PMID: 37623224 PMCID: PMC10453056 DOI: 10.3390/cimb45080405] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 07/29/2023] [Accepted: 07/31/2023] [Indexed: 08/26/2023] Open
Abstract
Type 2 diabetes (T2D) is a serious health issue with increasing incidences worldwide. However, current medications have limitations due to side effects such as decreased appetite, stomach pain, diarrhea, and extreme tiredness. Here, we report the effect of fermented ice plant (FMC) in the T2M mouse model of db/db mice. FMC showed a greater inhibition of lipid accumulation compared to unfermented ice plant extract. Two-week oral administration with FMC inhibited body weight gain, lowered fasting blood glucose, and improved glucose tolerance. Serum parameters related to T2D including insulin, glycosylated hemoglobin, adiponectin, and cholesterols were improved as well. Histological analysis confirmed the protective effect of FMC on pancreas and liver destruction. FMC treatment significantly increased the expression and phosphorylation of IRS-1, PI3K, and AKT. Additionally, AMP-activated protein kinase phosphorylation and nuclear factor erythroid 2-related factor 2 were also increased in the liver tissues of db/db mice treated with FMC. Overall, our results indicate the anti-diabetic effect of FMC; therefore, we suggest that FMC may be useful as a therapeutic agent for T2D.
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Affiliation(s)
- Hye-Lin Kim
- College of Korean Medicine, Kyung Hee University, Seoul 02453, Republic of Korea
| | - Yunu Jung
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - Hyo In Kim
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Nak-Yun Sung
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - Min-Jee Kim
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - In-Jun Han
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - Geon Kim
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - Eun Yeong Nho
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - Sang-Yun Park
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - Yohan Han
- College of Korean Medicine, Kyung Hee University, Seoul 02453, Republic of Korea
| | - Ji Hoon Jung
- College of Korean Medicine, Kyung Hee University, Seoul 02453, Republic of Korea
| | - Dong-Sub Kim
- Division of Natural Product Research, Korea Prime Pharmacy Co., Ltd., Suwon 16229, Republic of Korea (E.Y.N.); (S.-Y.P.)
| | - Jinbong Park
- College of Korean Medicine, Kyung Hee University, Seoul 02453, Republic of Korea
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Yoo J, Park JE, Han JS. HMC Ameliorates Hyperglycemia via Acting PI3K/AKT Pathway and Improving FOXO1 Pathway in ob/ob Mice. Nutrients 2023; 15:2023. [PMID: 37432173 DOI: 10.3390/nu15092023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/14/2023] [Accepted: 04/21/2023] [Indexed: 07/12/2023] Open
Abstract
Type 2 diabetes is a disease characterized by hyperglycemia and is a growing health problem worldwide. Since many known diabetes drugs are side effects, it is necessary to develop natural substances with guaranteed safety. HM-chromanone isolated from Portulaca oleracea L. is a homoisoflavonoid compound. We investigated the effects of HM-chromanone on hyperglycemia and its mechanism in C57BL/6J ob/ob mice. C57BL/6J-Jms Slc mice were used as the control group, and C57BL/6J-ob/ob mice were divided into three groups: ob/ob (control), metformin (Met; positive control), and HM-chromanone (HMC). Fasting blood glucose was lower in the HMC group than those in the ob/ob group. Insulin resistance was improved by reducing HbA1c, plasma insulin, and HOMA-IR levels in the HMC group. HMC administration decreased the phosphorylation of IRS-1ser307 and increased the phosphorylation of IRS-1tyr612, PI3K, phosphorylation of AKTser473, and PM-GLUT4 in the skeletal muscles of ob/ob mice, indicating improved insulin signaling. HMC administration also increased the phosphorylation of FOXO1 in the liver of ob/ob mice. This inhibited PEPCK and G6pase involved in gluconeogenesis and regulated phosphorylation of glycogen synthase kinase 3β and glycogen synthase involved in glycogen synthesis. In conclusion, HM-chromanone ameliorates hyperglycemia by PI3K/AKT and improves the FOXO1 in ob/ob mice.
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Affiliation(s)
- Jeong Yoo
- Department of Food Science and Nutrition, Kimchi Research Institute, Pusan National University, Busan 46241, Republic of Korea
| | - Jae Eun Park
- Department of Food Science and Nutrition, Kimchi Research Institute, Pusan National University, Busan 46241, Republic of Korea
| | - Ji Sook Han
- Department of Food Science and Nutrition, Kimchi Research Institute, Pusan National University, Busan 46241, Republic of Korea
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Mao G, Tang J, Liao T, Shi X, Dong F, Feng W, Chen Y, Zhao T, Wu X, Yang L. Metabolism toxicity and susceptibility of decabromodiphenyl ether (BDE-209) exposure on BRL cells with insulin resistance. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:91306-91324. [PMID: 35896870 DOI: 10.1007/s11356-022-21980-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by insulin resistance (IR) and has attracted worldwide attention due to its high prevalence. As a typical persistent organic pollutant, decabromodiphenyl ether (BDE-209) has been detected in food and human samples, and the concentration trends increase year by year. In addition, it has been proved to have the potential to increase the risk of IR, but it is rarely reported whether it could aggravate IR in T2DM. Therefore, in this study, the IR-BRL (buffalo rat liver cells with IR) model was applied to study the metabolism toxicity and susceptibility of BDE-209. Results showed that BDE-209 could inhibit glucose absorption and increase the levels of serum total cholesterol (TC) and triglyceride (TG), ultimately leading to the disorder of glucolipid metabolism in IR-BRL cells. Besides, it also could cause cell damage by increasing the levels of aspartate transaminase (AST), alanine aminotransferase (ALT), and malondialdehyde (MDA) in cells. Moreover, its potential mechanisms were to: (1) affect the transport of glucose, synthesis of glycogen and fatty acid via IRS-1/GLUT4 and IRS-1/PI3K/AKT/GSK-3β pathways; (2) impact the proliferation and differentiation by regulating the expression of Mek1/2, Erk1/2, and mTOR proteins and genes. Furthermore, susceptibility analysis showed that there was a significant synergism interaction between IR and BDE-209, which suggested that IR-BRL cells were more susceptible to the metabolism toxicity induced by BDE-209.
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Affiliation(s)
- Guanghua Mao
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China.
| | - Junjie Tang
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - Taotao Liao
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - Xiaoxiang Shi
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - FangYuan Dong
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - Weiwei Feng
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
- Institute of Environmental Health and Ecological Safety, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - Yao Chen
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
- Institute of Environmental Health and Ecological Safety, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - Ting Zhao
- School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - Xiangyang Wu
- School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
- Institute of Environmental Health and Ecological Safety, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
| | - Liuqing Yang
- School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Rd, Zhenjiang, 212013, China
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Primary Adipocytes as a Model for Insulin Sensitivity. Methods Mol Biol 2019. [PMID: 31586333 DOI: 10.1007/978-1-4939-9882-1_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Obesity and its comorbidity insulin resistance lead to the development of chronic metabolic diseases, such as impaired fasted blood glucose and type 2 diabetes. Adipose tissue plays an important role in whole-body glucose homeostasis, particularly in obese individuals; therefore, many in vivo models of type 2 diabetes are obese, such as Lepob/ob and Leprdb/db mice or ZDF rats. Primary adipocytes therefore represent an attractive in vitro model to study insulin-mediated glucose uptake to investigate the mechanisms of insulin resistance and explore the potential insulin-sensitizing properties of new antidiabetic drugs.Primary adipocytes are isolated by collagenase digestion of adipose tissue, Glucose transport is evaluated by the measurement of intracellular uptake of a tracer (D-[U14C] glucose). The uptake of [U-14 C] glucose reflects directly glucose transport.In this chapter, we will describe the protocol for the isolation of primary rodent adipocytes and the measurement of basal and insulin-stimulated glucose uptake.
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Jwa Kum Whan Attenuates Nonalcoholic Fatty Liver Disease by Modulating Glucose Metabolism and the Insulin Signaling Pathway. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 2019:4589810. [PMID: 30881473 PMCID: PMC6387703 DOI: 10.1155/2019/4589810] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/22/2019] [Indexed: 02/06/2023]
Abstract
Over the last decade, the link between nonalcoholic fatty liver disease (NAFLD) and insulin resistance has attracted considerable attention. Caused by chronic hyperglycemic stress, insulin resistance (IR) impairs insulin signal transduction and leads to the development of NAFLD. Jwa Kum Whan (JKW), a herbal formula in Traditional Korean Medicine, consists of two medicinal herbs that possess notable effects against hyperglycemia and IR. In this study, we sought to determine the pharmacological effects of JKW, and the mechanisms responsible, on hepatic steatosis in free fatty acids (FFAs)-stimulated HepG2 cells and in high-fat diet (HFD)-fed obese mice. Treatment with JKW significantly decreased intracellular lipid accumulation in vitro. Furthermore, JKW significantly triggered the phosphorylation of insulin receptor substrate-1 (IRS-1) and phosphoinositide 3-kinase (PI3K) and modulated glucose and lipid metabolism via an AMP-activated protein kinase (AMPK) signaling pathway. Analysis of serum parameters in HFD-fed mice showed that JKW improved glucose levels and insulin resistance index (HOMA-IR). In addition, JKW successfully reduced hepatic triglyceride (TG) and cholesterol accumulation. Our results suggest that JKW alleviates NAFLD by modulating the insulin signaling pathway and glucose metabolism. These findings provide a scientific rationale for the potential use of JKW for the treatment and prevention of NAFLD.
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Lee J, Lee HJ, Lee JJ. Coating rice with mulberry leaves rich in deoxynojirimycin ameliorates hyperglycemia and dyslipidemia in C57BL/KsJ db/db mice. Nutr Res Pract 2018; 12:469-478. [PMID: 30515274 PMCID: PMC6277312 DOI: 10.4162/nrp.2018.12.6.469] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 06/07/2018] [Accepted: 08/01/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND/OBJECTIVES Mulberry leaf (ML) has been shown to have an inhibitory effect on α-glucosidase, and suppresses postprandial hyperglycemia, which may be related to its deoxynojirimycin (DNJ) content. This study was conducted to investigate the hypoglycemic and dyslipidemic effects of rice coated with ML rich in DNJ in a type 2 diabetes mouse model. MATERIALS/METHODS The mice were divided into four groups (n = 8 each): non-diabetic normal control (NC); diabetic control (DM-C), fed with 10% polished rice powder (DM-R); and fed with 10% polished rice powder coated with DNJ-rich ML (DM-DNJR). RESULTS Supplementation with DNJR for six weeks decreased levels of fasting blood glucose, plasma insulin, triglyceride, total cholesterol, and blood glycosylated hemoglobin; conversely, levels of glucagon-like peptide-1 and high-density lipoprotein-cholesterol showed an increase in the same treatment. In addition, weights of mesenteric, epididymal, and total adipose tissues decreased with DNJR supplementation, when compared with diabetic control db/db mice, while maltase, lactase, and sucrase activity in the small intestine were inhibited. The anti-diabetic effects were marginally greater in the DM-DNJR group than in the DM-R group. CONCLUSIONS These results suggest that rice coated with ML rich in DNJ can reduce hyperglycemia and hyperlipidemia in db/db mice, and may prove useful for individuals with diabetes.
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Affiliation(s)
- Joomin Lee
- Department of Food and Nutrition, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea
| | - Hyun-Joo Lee
- Department of Nutrition and Culinary Science, Hankyong National University, Gyeonggi 17579, Korea
| | - Jae-Joon Lee
- Department of Food and Nutrition, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea
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Abstract
The thiazolidinediones (TZDs) rosiglitazone and pioglitazone are new oral antidiabetic agents with `insulin sensitising' activity for the treatment of type 2 diabetes. Rosiglitazone and pioglitazone produce a slowly generated antihyperglycaemic effect which is often accompanied by decreases in circulating insulin and free fatty acids. Circulating triglycerides may also decline, while low-density and high-density lipoprotein cholesterol concentrations are either unchanged or slightly increased, with little alteration to their ratio. The blood glucose-lowering efficacy of TZDs is typically additive or possibly more than additive to the effects of other classes of antidiabetic agents. In Europe rosiglitazone and pioglitazone can be used in combination with metformin or a sulphonylurea, whilst in the USA these TZDs can also be prescribed as monotherapy and pioglitazone in combination with insulin. Because TZDs tend to cause fluid retention they are excluded for patients with cardiac insufficiency. TZDs act via the nuclear peroxisome proliferator-activated receptor-gamma (PPARγ), which mediates the transcription of certain genes that are also responsive to insulin, enabling these agents to improve insulin action.
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Affiliation(s)
- Clifford J Bailey
- Diabetes Group, School of Pharmacy, Aston University, Birmingham B4 7ET,
| | - Caroline Day
- Diabetes Group, School of Pharmacy, Aston University, Birmingham B4 7ET
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Bhasker S, Madhav H, Chinnamma M. Molecular evidence of insulinomimetic property exhibited by steviol and stevioside in diabetes induced L6 and 3T3L1 cells. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2015; 22:1037-1044. [PMID: 26407946 DOI: 10.1016/j.phymed.2015.07.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 07/13/2015] [Accepted: 07/21/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND The defective responsiveness of body tissues to insulin involves the insulin receptors of cell membranes. The binding of insulin to its receptor induce an increase of high affinity glucose transporter molecules in target cell surface that enhance the uptake of glucose in to these cells. The WHO expert committee recommended the importance to investigate the hypoglycemic agents from plant origin, which are used in traditional medicine for the treatment of diabetes. Stevioside, a natural sweetener and a diterpene glycoside extracted from Stevia rebaudiana (Bertoni) has been used as an anti-hyperglycemic agent for the treatment of diabetes for decades. HYPOTHESIS To reveal the molecular mechanism underlying the insulinomimetic activity of stevioside and its aglycone metabolite, steviol using cell line models. STUDY DESIGN Efficacy of stevioside and steviol in inducing glucose absorption was studied at transcript level, protein level and by measuring glucose absorption in the cell using in-vitro cell line studies. METHOD Quantification of glucose transporter (GLUT4) transcript was done in 3T3-L1 adipocytes and L6 myotubes by qPCR using RPL23 as the internal control. GLUT4 protein was quantified using anti GLUT4 antibody by ELISA and radioactive glucose uptake studies were done to measure the rate of glucose absorption. RESULTS The absolute and relative quantitation of GLUT4 gene by qPCR showed the activation of GLUT4 transcript at lower concentration of steviol (1 µM) and higher concentration of stevioside (100 µM) in both L6 myotubes and 3T3-L1 adipocytes. The increased level of glut4 protein and the glucose uptake in both the cell lines using the same concentration of steviol and stevioside further supports the qPCR data. The copy number and the expression level of GLUT4 gene, the amount of GLUT4 protein and the glucose uptake efficacy support the insulinomimetic effect of steviol and stevioside. CONCLUSION The results of the study clearly demonstrate the functional similarity of steviol and stevioside with that of insulin in controlling the level of glucose in both the cell lines. In other words, the insulinomimetic property of stevioside and steviol was evident from the data.
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Affiliation(s)
- Salini Bhasker
- SCMS Institute of Bioscience and Biotechnology Research and Development, South Kalamassery, Cochin, 682033, Kerala, India
| | - Harish Madhav
- SCMS Institute of Bioscience and Biotechnology Research and Development, South Kalamassery, Cochin, 682033, Kerala, India
| | - Mohankumar Chinnamma
- SCMS Institute of Bioscience and Biotechnology Research and Development, South Kalamassery, Cochin, 682033, Kerala, India.
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Lee HJ, Kim AR, Lee JJ. Effects of ramie leaf extract on blood glucose and lipid metabolism in db/db mice. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/s13765-014-4193-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rifa'i M, Widodo N. Significance of propolis administration for homeostasis of CD4(+)CD25(+) immunoregulatory T cells controlling hyperglycemia. SPRINGERPLUS 2014; 3:526. [PMID: 25279317 PMCID: PMC4179640 DOI: 10.1186/2193-1801-3-526] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/05/2014] [Indexed: 01/10/2023]
Abstract
In the present study, we examined the effect of ethanolic soluble derivative of propolis (EEP) extract on immunological function in diabetic mouse models with the aim of highlighting the role of regulatory T cell, the change of cell surface molecule, and in vivo productions of IFN-γ. Murine models of diabetes mellitus (DM) were created by injecting normal mice with S961 peptide. Normal BALB/c mice were injected intraperitoneally with peptide S961 300 mg/kg body weight (BW) twice a day for eight days. On day 15, the spleen was isolated; then, cell surface molecules and regulatory T cells were analyzed using flow cytometry. The histopathological changes were monitored in the liver of treated and control mice. Afterward, we tested the ability of propolis as an immunomodulator that initiate normality metabolism and homeostasis. The propolis decreased blood sugar levels and increased the number of naïve T cells expressing CD62L molecule by suppressing the development of effector cells in diabetic mice. However, the propolis stimulated development of effector cells, which was indicated by increasing the number of CD4+CD25+ T cells in normal mice. Moreover, the propolis increased the production of IFN-γ in normal mice, whereas in mouse models of diabetes mellitus propolis tends to suppress the production of IFN-γ. The histological analysis of the liver shows that at a dose of 50–200 mg/kg BW propolis does not show a toxic effect so that the dose is categorized safe. Therefore, the ethanolic soluble derivative of propolis (EEP) extract warrant for further exploited as an antidiabetic agent that safe for human.
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Affiliation(s)
- Muhaimin Rifa'i
- Biology Department, Faculty of Mathematics and Natural Sciences, The University of Brawijaya, Jl Veteran, Malang, 65145 Indonesia
| | - Nashi Widodo
- Biology Department, Faculty of Mathematics and Natural Sciences, The University of Brawijaya, Jl Veteran, Malang, 65145 Indonesia
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Li Y, Shao M, Zheng X, Kong W, Zhang J, Gong M. Self-assembling peptides improve the stability of glucagon-like peptide-1 by forming a stable and sustained complex. Mol Pharm 2013; 10:3356-65. [PMID: 23859692 DOI: 10.1021/mp4001734] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The multiple physiological characterizations of glucagon-like peptide-1 (GLP-1) make it a promising drug candidate for the treatment of T2DM. However, the short half-life of GLP-1 limits its clinical utility. Self-assembling peptides are presumed to wrap GLP-1 peptide, and this helps to prolong the stability of GLP-1 consequently. The aim of this study was to investigate whether self-assembling peptides could be applied to prolong the half-life of GLP-1 as sustained release preparations. In this study, five different self-assembling peptides were employed. The formation of the complexes was monitored using gel filtration and mass spectrometry and was simulated by Molecular Dynamics. Stabilization, insulin secretion stimulation, and glucose tolerance tests were performed to investigate the physiological characteristics retained by GLP-1 following complex formation with self-assembling peptides. Our findings revealed that, among the five different self-assembling peptides tested, complex of Pep-1 and GLP-1 exhibited a remarkable extension in the half-life of GLP-1. In addition, the experimental animals treated with a GLP-1/Pep-1 complex exhibited better blood glucose clearance activity over a greater duration of time than the animals treated with GLP-1 alone. Based on our results, an adjustment of the Pep-1 and GLP-1 ratios is presumed to be able to control the half-life of GLP-1 (e.g., medium-acting and long-acting). Collectively, the findings in this study suggest that the self-assembling peptide Pep-1 could serve as a powerful drug preparation tool to extend the short half-life of therapeutic peptides.
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Affiliation(s)
- Ying Li
- Tianjin Neurological Institute, Tianjin Medical University General Hospital, China
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Kanagasabapathy G, Kuppusamy UR, Abd Malek SN, Abdulla MA, Chua KH, Sabaratnam V. Glucan-rich polysaccharides from Pleurotus sajor-caju (Fr.) Singer prevents glucose intolerance, insulin resistance and inflammation in C57BL/6J mice fed a high-fat diet. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 12:261. [PMID: 23259700 PMCID: PMC3553037 DOI: 10.1186/1472-6882-12-261] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 12/13/2012] [Indexed: 01/22/2023]
Abstract
Background Pleurotus sajor-caju (P. sajor-caju) has been extremely useful in the prevention of diabetes mellitus due to its low fat and high soluble fiber content for thousands of years. Insulin resistance is a key component in the development of diabetes mellitus which is caused by inflammation. In this study, we aimed to investigate the in vivo efficacy of glucan-rich polysaccharide of P. sajor-caju (GE) against diabetes mellitus and inflammation in C57BL/6J mice fed a high-fat diet. Methods Diabetes was induced in C57BL/6J mice by feeding a high-fat diet. The mice were randomly assigned to 7 groups (n=6 per group). The control groups in this study were ND (for normal diet) and HFD (for high-fat diet). The treated groups were ND240 (for normal diet) (240 mg/kg b.w) and HFD60, HFD120 and HFD240 (for high-fat), where the mice were administrated with three dosages of GE (60, 120, 240 mg GE/kg b.w respectively). Metformin (2 mg/kg b.w) served as positive control. The glucose tolerance test, glucose and insulin levels were measured at the end of 16 weeks. Expressions of genes for inflammatory markers, GLUT-4 and adiponectin in the adipose tissue of the mice were assessed. One-way ANOVA and Duncan’s multiple range tests (DMRT) were used to determine the significant differences between groups. Results GE treated groups improved the glucose tolerance, attenuated hyperglycemia and hyperinsulinemia in the mice by up-regulating the adiponectin and GLUT-4 gene expressions. The mice in GE treated groups did not develop insulin resistance. GE also down-regulated the expression of inflammatory markers (IL-6, TNF-α, SAA2, CRP and MCP-1) via attenuation of nuclear transcription factors (NF-κB). Conclusion Glucan-rich polysaccharide of P. sajor-caju can serve as a potential agent for prevention of glucose intolerance, insulin resistance and inflammation.
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Fidan E, Onder Ersoz H, Yilmaz M, Yilmaz H, Kocak M, Karahan C, Erem C. The effects of rosiglitazone and metformin on inflammation and endothelial dysfunction in patients with type 2 diabetes mellitus. Acta Diabetol 2011; 48:297-302. [PMID: 21424914 DOI: 10.1007/s00592-011-0276-y] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/04/2011] [Indexed: 02/08/2023]
Abstract
Diabetic patients have a markedly increased risk of cardiovascular disease compared with non-diabetics. Two drug groups today target insulin resistance; biguanides and thiazolidinediones. In addition, these may have other effects on cardiovascular risk factors. The aim of this study was to evaluate the effects of metformin and rosiglitazone on non-traditional cardiovascular risk factors. Forty type 2 diabetic patients were randomized into metformin and rosiglitazone groups. After receiving the optimal doses, the patients were monitored for 12 weeks. Biochemical parameters, lipid parameters, CRP, insulin, c-peptide, and HbA1c levels were analyzed. VWF, PAI-1, ICAM-1, TNF-α, IL-6, E-selectin, and fibrinogen levels were measured in order to assess coagulation status and endothelial dysfunction. In the metformin group, body mass index, PPG, HbA1c, IL-6, ICAM-1, and TNF-α levels were significantly decreased after 12 weeks compared with the basal levels. IL-6 levels decreased from 75 pg/ml ± 20 to 42 pg/ml ± 9 (P 0.023) and TNF- α levels from 61 pg/ml ± 31 to 39 pg/ml ± 10 (P 0.018). In the rosiglitazone group, FPG, PPG, HbA1c, insulin, HOMA-IR, IL-6, and TNF-α levels decreased significantly after 12 weeks compared with the basal levels. IL-6 levels decreased from 78 pg/ml ± 21 to 41 pg/ml ± 9 (P 0.028) and TNF-α levels from 62 pg/ml ± 19 to 37 pg/ml ± 10 (P 0.012). At the end of the study, no significant differences were determined between groups. Insulin resistance and type 2 diabetes are strongly associated with low grade inflammation. Both metformin and rosiglitazone were effective in controlling inflammatory markers in addition to metabolic parameters.
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Affiliation(s)
- Evren Fidan
- Department of Internal Medicine and Medical Oncology, Faculty of Medicine, Karadeniz Technical University, Trabzon, 61080, Turkey.
| | - H Onder Ersoz
- Division of Endocrinology and Metabolism, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Mustafa Yilmaz
- Division of Hematology, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Hulya Yilmaz
- Department of Biochemistry,Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Mustafa Kocak
- Division of Endocrinology and Metabolism, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Caner Karahan
- Department of Biochemistry,Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Cihangir Erem
- Division of Endocrinology and Metabolism, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
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15
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Ait-Omar A, Monteiro-Sepulveda M, Poitou C, Le Gall M, Cotillard A, Gilet J, Garbin K, Houllier A, Château D, Lacombe A, Veyrie N, Hugol D, Tordjman J, Magnan C, Serradas P, Clément K, Leturque A, Brot-Laroche E. GLUT2 accumulation in enterocyte apical and intracellular membranes: a study in morbidly obese human subjects and ob/ob and high fat-fed mice. Diabetes 2011; 60:2598-607. [PMID: 21852673 PMCID: PMC3178286 DOI: 10.2337/db10-1740] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE In healthy rodents, intestinal sugar absorption in response to sugar-rich meals and insulin is regulated by GLUT2 in enterocyte plasma membranes. Loss of insulin action maintains apical GLUT2 location. In human enterocytes, apical GLUT2 location has not been reported but may be revealed under conditions of insulin resistance. RESEARCH DESIGN AND METHODS Subcellular location of GLUT2 in jejunal enterocytes was analyzed by confocal and electron microscopy imaging and Western blot in 62 well-phenotyped morbidly obese subjects and 7 lean human subjects. GLUT2 locations were assayed in ob/ob and ob/+ mice receiving oral metformin or in high-fat low-carbohydrate diet-fed C57Bl/6 mice. Glucose absorption and secretion were respectively estimated by oral glucose tolerance test and secretion of [U-(14)C]-3-O-methyl glucose into lumen. RESULTS In human enterocytes, GLUT2 was consistently located in basolateral membranes. Apical GLUT2 location was absent in lean subjects but was observed in 76% of obese subjects and correlated with insulin resistance and glycemia. In addition, intracellular accumulation of GLUT2 with early endosome antigen 1 (EEA1) was associated with reduced MGAT4a activity (glycosylation) in 39% of obese subjects on a low-carbohydrate/high-fat diet. Mice on a low-carbohydrate/high-fat diet for 12 months also exhibited endosomal GLUT2 accumulation and reduced glucose absorption. In ob/ob mice, metformin promoted apical GLUT2 and improved glucose homeostasis. Apical GLUT2 in fasting hyperglycemic ob/ob mice tripled glucose release into intestinal lumen. CONCLUSIONS In morbidly obese insulin-resistant subjects, GLUT2 was accumulated in apical and/or endosomal membranes of enterocytes. Functionally, apical GLUT2 favored and endosomal GLUT2 reduced glucose transepithelial exchanges. Thus, altered GLUT2 locations in enterocytes are a sign of intestinal adaptations to human metabolic pathology.
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Affiliation(s)
- Amal Ait-Omar
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Milena Monteiro-Sepulveda
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Christine Poitou
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Nutrition and Endocrinology Department, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France; Centre Recherche en Nutrition Humaine (CRNH) Ile de France, Paris, France
| | - Maude Le Gall
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Aurélie Cotillard
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Jules Gilet
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Kevin Garbin
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Anne Houllier
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Danièle Château
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Amélie Lacombe
- Centre National de la Recherche Scientifique (EAC4413), Université Paris-Diderot, Paris, France
| | - Nicolas Veyrie
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Surgery Department, Assistance Publique-Hôpitaux de Paris, Hôtel-Dieu Hospital, Paris, France
| | - Danielle Hugol
- Pathology Department, Assistance Publique-Hôpitaux de Paris, Hôtel-Dieu Hospital, Paris, France
| | - Joan Tordjman
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Christophe Magnan
- Centre National de la Recherche Scientifique (EAC4413), Université Paris-Diderot, Paris, France
| | - Patricia Serradas
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Karine Clément
- INSERM, U872, Team 7 Nutriomique, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Nutrition and Endocrinology Department, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France; Centre Recherche en Nutrition Humaine (CRNH) Ile de France, Paris, France
| | - Armelle Leturque
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
| | - Edith Brot-Laroche
- INSERM, U872, Team 9, Paris, France; Centre de Recherche des Cordeliers, Université Pierre et Marie Curie-Paris 6, UMR S 872, Paris, France
- Corresponding author: Edith Brot-Laroche,
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16
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Effects of encapsulated propolis on blood glycemic control, lipid metabolism, and insulin resistance in type 2 diabetes mellitus rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2011; 2012:981896. [PMID: 21716678 PMCID: PMC3118452 DOI: 10.1155/2012/981896] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 03/15/2011] [Accepted: 04/13/2011] [Indexed: 11/18/2022]
Abstract
The present study investigates the encapsulated propolis on blood glycemic control, lipid metabolism, and insulin resistance in type 2 diabetes mellitus (T2DM) rats. The animal characteristics and biological assays of body weight, fasting blood glucose (FBG), fasting serum insulin (FINS), insulin act index (IAI), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured and euglycemic hyperinsulinemic glucose clamp technique were used to determine these effects. Our findings show that oral administration of encapsulated propolis can significantly inhibit the increasing of FBG and TG in T2DM rats and can improve IAI and M value in euglycemic hyperinsulinemic clamp experiment. There was no significant effects on body weight, TC, HDL-C, and LDL-C in T2DM rats treated with encapsulated propolis. In conclusion, the results indicate that encapsulated propolis can control blood glucose, modulate lipid metabolism, and improve the insulin sensitivity in T2DM rats.
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17
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Shin JH, Jung KM, Lee SJ, Yang SM, Rue GH, Sung NJ. Biological Activities of Dried Garlic, Red Ginseng and Their Mixture. ACTA ACUST UNITED AC 2009. [DOI: 10.3746/jkfn.2009.38.12.1633] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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18
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Kim HJ, Kim KS, Lee TJ, Kim YC. Antidiabetic Effects of Corni Fructus Extract on Blood Glucose and Insulin Resistance in db/db Mice. Toxicol Res 2009; 25:93-99. [PMID: 32038825 PMCID: PMC7006319 DOI: 10.5487/tr.2009.25.2.093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 05/28/2009] [Indexed: 11/20/2022] Open
Abstract
This study investigated the effect of Corni Fructus (Cornus officinalis Sieb, et Zucc.) extract on blood glucose and insulin resistance in db/db mice. Seven weeks old male mice were divided into normal control group (NC), diabetic control group (DC) and Corni Fructus treated diabetic group (DCF). Over an 8-week experimental period, Corni Fructus extract was administered orally at 500 mg/kg BW/day. Corni Fructus inhibited increase in blood glucose level during the OGTT (oral glucose tolerance test). At 8 weeks after beginning of the experiment, blood glucose level in the DCF group was significantly lower (p<0.01) than the DC group. Final fasting serum glucose and triglyceride in the DCF group were significantly lower (p<0.05) than the DC group by 32% and 41% respectively. Serum insulin did not differ among the NC, DC and DCF groups. The mRNA expression of adiponectin, GLUT 4 and PPAR-γ in adipose tissue in the DC group were significantly lower than the NC group and they were higher in the DCF group than the DC group by 76%, 130% (p<0.05) and 43%, respectively. In conclusion, these results indicated that Corni Fructus would have antidiabetic effects via improving insulin resistance in favor of higher glucose utilization and reducing blood glucose level in db/db mice.
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Affiliation(s)
- Hye Jeong Kim
- 15Department of Public Health, College of Natural Sciences, Keimyung University, 2800 Dalgubeoldaero, Dalseo-gu, Daegu, 704-701 Korea.,25Division of Human Blood Safety Surveillance, Korea Centers for Disease Control & Prevention, Seoul, 122-701 Korea
| | - Kil-Soo Kim
- 35College of Veterinary Medicine, Kyungpook National University, Daegu, 702-701 Korea
| | - Tae-Jong Lee
- 45Dept. of Pathology, Daegu Fatima Hospital, Daegu, 701-600 Korea
| | - Young Chul Kim
- 15Department of Public Health, College of Natural Sciences, Keimyung University, 2800 Dalgubeoldaero, Dalseo-gu, Daegu, 704-701 Korea
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19
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Choe M, Kim DJ, Lee HJ, You JK, Seo DJ, Lee JH, Chung MJ. A Study on the Glucose-regulating Enzymes and Antioxidant Activities of Water Extracts from Medicinal Herbs. ACTA ACUST UNITED AC 2008. [DOI: 10.3746/jkfn.2008.37.5.542] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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20
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Aston-Mourney K, Proietto J, Morahan G, Andrikopoulos S. Too much of a good thing: why it is bad to stimulate the beta cell to secrete insulin. Diabetologia 2008; 51:540-5. [PMID: 18246324 DOI: 10.1007/s00125-008-0930-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Accepted: 01/07/2008] [Indexed: 12/21/2022]
Abstract
In many countries, first- or second-line pharmacological treatment of patients with type 2 diabetes consists of sulfonylureas (such as glibenclamide [known as glyburide in the USA and Canada]), which stimulate the beta cell to secrete insulin. However, emerging evidence suggests that forcing the beta cell to secrete insulin at a time when it is struggling to cope with the demands of obesity and insulin resistance may accelerate its demise. Studies on families with persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI), the primary defect of which is hypersecretion of insulin, have shown that overt diabetes can develop later in life despite normal insulin sensitivity. In addition, in vitro experiments have suggested that reducing insulin secretion from islets isolated from patients with diabetes can restore insulin pulsatility and improve function. This article will explore the hypothesis that forcing the beta cell to hypersecrete insulin may be counterproductive and lead to dysfunction and death via mechanisms that may involve the endoplasmic reticulum and oxidative stress. We suggest that, in diabetes, therapeutic approaches should be targeted towards relieving the demand on the beta cell to secrete insulin.
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Affiliation(s)
- K Aston-Mourney
- The University of Melbourne Department of Medicine (AH/NH), Heidelberg Repatriation Hospital, Building 24, 300 Waterdale Road, Heidelberg Heights VIC 3081, Australia
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21
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Hwang JY, Han JS. Inhibitory Effects of Sasa borealis Leaves Extracts on Carbohydrate Digestive Enzymes and Postprandial Hyperglycemia. ACTA ACUST UNITED AC 2007. [DOI: 10.3746/jkfn.2007.36.8.989] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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22
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Docking Studies on Formylchromone Derivatives as Protein Tyrosine Phosphatase 1B (PTP1B) Inhibitors. B KOREAN CHEM SOC 2007. [DOI: 10.5012/bkcs.2007.28.7.1141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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23
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Nair PC, Sobhia ME. CoMFA based de novo design of pyridazine analogs as PTP1B inhibitors. J Mol Graph Model 2007; 26:117-23. [PMID: 17140831 DOI: 10.1016/j.jmgm.2006.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 10/05/2006] [Accepted: 10/18/2006] [Indexed: 11/30/2022]
Abstract
PTP1B plays an important role as a negative regulator in insulin and leptin signaling pathways. Potent and orally active PTP1B inhibitors can act as potential agents for the treatment of Type 2 diabetes and obesity. CoMFA (Comparative Molecular Field Analysis) and de novo ligand design using LeapFrog (LF) studies were performed on pyridazine analogs, reported to be selective and non-competitive inhibitors of PTP1B. A robust model was developed which produced statistically significant results with cross-validated and conventional correlation coefficients of 0.619 and 0.990, respectively. Further, the robustness of the model was verified by bootstrapping analysis. LeapFrog (LF) program is a de novo drug discovery tool, which uses CoMFA maps to generate hypothetical cavity and ligands. As the crystal structure of PTP1B-pyridazine complex is not yet known, the contours of CoMFA model was used to serve as a pharmacophoric model to generate hypothetical cavity for LeapFrog calculations. Ligands were optimized using this concept.
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Affiliation(s)
- Pramod C Nair
- Centre for Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160062, India
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24
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Harris F, Biswas S, Singh J, Dennison S, Phoenix DA. Calpains and their multiple roles in diabetes mellitus. Ann N Y Acad Sci 2007; 1084:452-80. [PMID: 17151322 DOI: 10.1196/annals.1372.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Type 2 diabetes mellitus (T2DM) can lead to death without treatment and it has been predicted that the condition will affect 215 million people worldwide by 2010. T2DM is a multifactorial disorder whose precise genetic causes and biochemical defects have not been fully elucidated, but at both levels, calpains appear to play a role. Positional cloning studies mapped T2DM susceptibility to CAPN10, the gene encoding the intracellular cysteine protease, calpain 10. Further studies have shown a number of noncoding polymorphisms in CAPN10 to be functionally associated with T2DM while the identification of coding polymorphisms, suggested that mutant calpain 10 proteins may also contribute to the disease. Here we review recent studies, which in addition to the latter enzyme, have linked calpain 5, calpain 3, and its splice variants, calpain 2 and calpain 1 to T2DM-related metabolic pathways along with T2DM-associated phenotypes, such as obesity and impaired insulin secretion, and T2DM-related complications, such as epithelial dysfunction and diabetic cataract.
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Affiliation(s)
- Frederick Harris
- Department of Forensic and Investigative Science, University of Central Lancashire, Preston, PR1 2HE, United Kingdom
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25
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Abstract
Insulin resistance typically reflects multiple defects of insulin receptor and post-receptor signalling that impair a diverse range of metabolic and vascular actions. Many potential intervention targets and compounds with therapeutic activity have been described. Proof of principle for a non-peptide insulin mimetic has been demonstrated by specific activation of the intracellular B-subunit of the insulin receptor. Potentiation of insulin action has been achieved with agents that enhance phosphorylation and prolong the tyrosine kinase activity of the insulin receptor and its protein substrates after activation by insulin. These include inhibitors of phosphatases and serine kinases that normally prevent or terminate tyrosine kinase signalling. Additional approaches involve increasing the activity of phosphatidylinositol 3-kinase and other downstream components of the insulin signalling pathways. Experimental interventions to remove signalling defects caused by cytokines, certain adipocyte hormones, excess fatty acids, glucotoxicity and negative feedback by distal signalling steps have also indicated therapeutic possibilities. Several hormones, metabolic enzymes, minerals, co-factors and transcription co-activators have shown insulin-sensitising potential. Since insulin resistance affects many metabolic and cardiovascular diseases, it provides an opportunity for simultaneous therapeutic attack on a broad front.
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Affiliation(s)
- Clifford J Bailey
- Deabetes Research Group, School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK.
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26
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Effects of Silk Protein Hydrolysates on Blood Glucose and Serum Lipid in db/db Diabetic Mice. ACTA ACUST UNITED AC 2006. [DOI: 10.3746/jkfn.2006.35.10.1343] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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27
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Martineau LC, Couture A, Spoor D, Benhaddou-Andaloussi A, Harris C, Meddah B, Leduc C, Burt A, Vuong T, Mai Le P, Prentki M, Bennett SA, Arnason JT, Haddad PS. Anti-diabetic properties of the Canadian lowbush blueberry Vaccinium angustifolium Ait. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2006; 13:612-23. [PMID: 16979328 DOI: 10.1016/j.phymed.2006.08.005] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Incidence of type II diabetes is rapidly increasing worldwide. In order to identify complementary or alternative approaches to existing medications, we studied anti-diabetic properties of Vaccinium angustifolium Ait., a natural health product recommended for diabetes treatment in Canada. Ethanol extracts of root, stem, leaf, and fruit were tested at 12.5 microg/ml for anti-diabetic activity in peripheral tissues and pancreatic beta cells using a variety of cell-based bioassays. Specifically, we assessed: (1) deoxyglucose uptake in differentiated C2C12 muscle cells and 3T3-L1 adipocytes; (2) glucose-stimulated insulin secretion (GSIS) in beta TC-tet pancreatic beta cells; (3) beta cell proliferation in beta TC-tet cells; (4) lipid accumulation in differentiating 3T3-L1 cells; (5) protection against glucose toxicity in PC12 cells. Root, stem, and leaf extracts significantly enhanced glucose transport in C2C12 cells by 15-25% in presence and absence of insulin after 20 h of incubation; no enhancement resulted from a 1 h exposure. In 3T3 cells, only the root and stem extracts enhanced uptake, and this effect was greater after 1 h than after 20 h; uptake was increased by up to 75% in absence of insulin. GSIS was potentiated by a small amount in growth-arrested beta TC-tet cells incubated overnight with leaf or stem extract. However, fruit extracts were found to increase 3H-thymidine incorporation in replicating beta TC-tet cells by 2.8-fold. Lipid accumulation in differentiating 3T3-L1 cells was accelerated by root, stem, and leaf extracts by as much as 6.5-fold by the end of a 6-day period. Stem, leaf, and fruit extracts reduced apoptosis by 20-33% in PC12 cells exposed to elevated glucose for 96 h. These results demonstrate that V. angustifolium contains active principles with insulin-like and glitazone-like properties, while conferring protection against glucose toxicity. Enhancement of proliferation in beta cells may represent another potential anti-diabetic property. Extracts of the Canadian blueberry thus show promise for use as a complementary anti-diabetic therapy.
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Affiliation(s)
- Louis C Martineau
- Department of Pharmacology and Membrane Protein Study Group, Université de Montréal, and Montreal Diabetes Research Center, Centre de recherche du Centre Hospitalier de l'Université de Montréal, QC, Canada
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28
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Lee MS, Kang SK, Lee BC, Hwang WS. The Beneficial Effects of Insulin and Metformin on In Vitro Developmental Potential of Porcine Oocytes and Embryos. Biol Reprod 2005; 73:1264-8. [PMID: 16107611 DOI: 10.1095/biolreprod.105.041186] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
To investigate whether insulin and/or metformin improve the developmental competence of porcine oocytes and embryos, insulin (100 ng/ml) and/or metformin (10(-5) M) were supplemented during in vitro maturation (IVM) and/or in vitro culture (IVC) periods. Insulin (33 to 34% vs. 21%) or insulin plus metformin (27 to 39% vs. 21%) significantly (P < 0.01) increased the rates of blastocyst formation, whereas metformin alone had no effect when added during the first half (0-22 h), the latter half (22-44 h), or the entire (0-44 h) maturation period. No additional effect of insulin plus metformin on increasing blastocyst formation was observed compared to insulin alone. When supplemented during IVC, insulin (34% vs. 23%) or insulin plus metformin (35% vs. 23%) significantly (P < 0.05) increased the rates of blastocyst formation, whereas metformin alone had no effect. Compared to insulin alone, no additional effect of insulin plus metformin on increasing blastocyst formation was observed. When added during the entire IVM and IVC, insulin (40% vs. 24%) or insulin plus metformin (52% vs. 21%) significantly increased the rates of blastocyst formation, whereas metformin alone had no effect. In addition, the effect of insulin was enhanced when supplemented with metformin compared to insulin alone (52% vs. 40%). After IVM, oocyte glutathione (GSH) content and tyrosine kinase activity were measured. Insulin significantly (P < 0.01) increased oocyte GSH content (6.2 pmol vs. 4.3 pmol) and metformin significantly (P < 0.01) enhanced the action of insulin on GSH content (7.3 pmol vs. 6.2 pmol) and tyrosine kinase activity (1.9 arbitrary units [AU] vs. 1.5 AU) when compared to insulin alone. In conclusion, insulin increased the developmental potential of porcine oocytes and embryos, and metformin enhanced the action of insulin when supplemented during the entire IVM and IVC. The effects of insulin and metformin were associated with oocyte GSH content and tyrosine kinase activity.
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Affiliation(s)
- Myeong Seop Lee
- Department of Theriogenology and Biotechnology, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea
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29
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Ooie T, Kajimoto M, Takahashi N, Shinohara T, Taniguchi Y, Kouno H, Wakisaka O, Yoshimatsu H, Saikawa T. Effects of insulin resistance on geranylgeranylacetone-induced expression of heat shock protein 72 and cardioprotection in high-fat diet rats. Life Sci 2005; 77:869-81. [PMID: 15921703 DOI: 10.1016/j.lfs.2004.12.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Accepted: 12/13/2004] [Indexed: 11/15/2022]
Abstract
We investigated the effects of insulin resistance on the expression of heat-shock proteins (HSPs) and myocardial protection against ischemia/reperfusion injury. Male Sprague-Dawley rats received normal chow (CNT) or high-fat (HiF) diet. HiF diet for 6 weeks resulted in the development of insulin resistance, which was evaluated by oral glucose test and insulin tolerance test. Twenty-four hour after oral administration of geranylgeranylacetone (GGA) (200 mg/kg), the heart was isolated and perfused retrogradely with two different doses of insulin (0.1 or 1 mU/ml). Myocardial expression of HSP72 was examined using Western blot analysis. In the HiF group, the expression of HSP72 in response to GGA was decreased. The recovery of left ventricular developed pressure (LVDP) 30 min after reperfusion was tended to be lower in HiF group than in CNT group. Although GGA improved the recovery of LVDP in both CNT and HiF rats, LVDP during reperfusion period was significantly lower in HiF group than in CNT group. High-dose insulin perfusion caused deterioration of post-ischemic functional recovery and LVDP was not different between the two groups, but GGA-induced cardioprotection was preserved irrespective of the dose of insulin both in the CNT and HiF rats. This is the first demonstration that expression of HSP72 was depressed in the heart and that reduced HSP72 was related with less cardioprotection against ischemic insult in high-fat diet-induced insulin resistance rats.
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Affiliation(s)
- Tatsuhiko Ooie
- Department of Laboratory Medicine, Faculty of Medicine, Oita University, 1-1, Hasama, Oita, 879-5593, Japan.
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Bailey CJ, Day C. Avandamet: combined metformin-rosiglitazone treatment for insulin resistance in type 2 diabetes. Int J Clin Pract 2004; 58:867-76. [PMID: 15529521 DOI: 10.1111/j.1742-1241.2004.00318.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Insulin resistance is a major endocrinopathy underlying the development of hyperglycaemia and cardiovascular disease in type 2 diabetes. Metformin (a biguanide) and rosiglitazone (a thiazolidinedione) counter insulin resistance, acting by different cellular mechanisms. The two agents can be used in combination to achieve additive glucose-lowering efficacy in the treatment of type 2 diabetes, without stimulating insulin secretion and without causing hypoglycaemia. Both agents also reduce a range of atherothrombotic factors and markers, indicating a lower cardiovascular risk. Early intervention with metformin is already known to reduce myocardial infarction and increase survival in overweight type 2 patients. Recently, a single-tablet combination of metformin and rosiglitazone, Avandamet, has become available. Avandamet is suitable for type 2 diabetic patients who are inadequately controlled by monotherapy with metformin or rosiglitazone. Patients already receiving separate tablets of metformin and rosiglitazone may switch to the single-tablet combination for convenience. Also, early introduction of the combination before maximal titration of one agent can reduce side effects. Use of Avandamet requires attention to the precautions for both metformin and rosiglitazone, especially renal, cardiac and hepatic competence. In summary, Avandamet is a single-tablet metformin-rosiglitazone combination that doubly targets insulin resistance as therapy for hyperglycaemia and vascular risk in type 2 diabetes.
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Affiliation(s)
- C J Bailey
- School of Life and Health Sciences, Aston University, Birmingham, UK.
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Shim YS, Kim KC, Chi DY, Lee KH, Cho H. Formylchromone derivatives as a novel class of protein tyrosine phosphatase 1B inhibitors. Bioorg Med Chem Lett 2003; 13:2561-3. [PMID: 12852966 DOI: 10.1016/s0960-894x(03)00479-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Formylchromone inhibits a human protein tyrosine phosphatase PTP1B with a IC(50) value of 73 microM. The chemical reactivity of formylchromone was adjusted by substitution at various positions of the formylchromone skeleton. In an initial assessment of the structure-activity relationship, the most potent inhibitor showed an IC(50) of 4.3 microM against PTP1B and strong or medium selectivity against other human PTPases, LAR and TC-PTP. This compound, however, was not selective against microbial PTPases, YPTP1 and YOP. The potency and selectivity of the formylchromone derivatives expecting further improvements provides a novel pharmacophore for the design of drugs for the treatment of type 2 diabetes and obesity.
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Affiliation(s)
- Yi Sup Shim
- Department of Chemistry and Institute of Molecular Cell Biology, Inha University, 253 Yonghyun-dong, Nam-ku, Incheon 402-751, South Korea
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Campbell RK, White J. Counseling patients with type 2 diabetes and insulin resistance in the outpatient setting. DIABETES EDUCATOR 2002; 28:938-43, 947-50, 952-4 passim. [PMID: 12526635 DOI: 10.1177/014572170202800609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Insulin resistance is a major health concern. Besides being a leading risk factor for type 2 diabetes, it is also associated with hypertension, dyslipidemia, obesity, and cardiovascular disease. Making lifestyle changes can reduce insulin resistance and help prevent the onset of diabetes. For those with type 2 diabetes, treatment with insulin-sensitizing drugs, such as the TZDs and biguanides, can improve glycemic control and prevent some of the adverse consequences of the disease. Adherence to both lifestyle and medication regimens is very important and should be actively supported by all members of the healthcare team. Diabetes educators, including pharmacists, can increase awareness of the underlying pathophysiology and clinical implications of insulin resistance. Diabetes educators also play a vital role in counseling patients with type 2 diabetes on strategies that reduce their risk of hyperglycemic complications and in providing support, education, and guidance. By understanding the disease and its management, diabetes educators can contribute to improved outcomes and help to reduce the impact of this worldwide epidemic.
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Affiliation(s)
- R Keith Campbell
- The College of Pharmacy, Washington State University, Pullman, Washington (Mr Campbell)
| | - John White
- The College of Pharmacy, Washington State University, Spokane, Washington (Dr White)
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Marre M, Howlett H, Lehert P, Allavoine T. Improved glycaemic control with metformin-glibenclamide combined tablet therapy (Glucovance) in Type 2 diabetic patients inadequately controlled on metformin. Diabet Med 2002; 19:673-80. [PMID: 12147149 DOI: 10.1046/j.1464-5491.2002.00774.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To evaluate the efficacy and safety of two dosage strengths of a single-tablet metformin-glibenclamide (glyburide) combination, compared with the respective monotherapies, in patients with Type 2 diabetes mellitus (DM) inadequately controlled by metformin monotherapy. METHODS In this 16-week, double-blind, multicentre, parallel-group trial, 411 patients were randomized to receive metformin 500 mg, glibenclamide 5 mg, metformin-glibenclamide 500 mg/2.5 mg or metformin-glibenclamide 500 mg/5 mg, titrated with the intention to achieve fasting plasma glucose (FPG) < or = 7 mmol/l. RESULTS Decreases in glycated haemoglobin (HbA1c) and FPG were greater (P < 0.05) for metformin-glibenclamide 500 mg/2.5 mg (-1.20% and -2.62 mmol/l) and 500 mg/5 mg (-0.91% and -2.34 mmol/l), compared with metformin (-0.19% and -0.57 mmol/l) or glibenclamide (-0.33% and -0.73 mmol/l). HbA1c < 7% was achieved by 75% and 64% of patients receiving metformin-glibenclamide 500 mg/2.5 mg and 500 mg/5 mg, respectively, compared with 42% for glibenclamide and 38% for metformin (P = 0.001). These benefits were achieved at lower mean doses of metformin or glibenclamide with metformin-glibenclamide 500 mg/2.5 mg and 500 mg/5 mg (1225 mg/6.1 mg and 1170 mg/11.7 mg) than with glibenclamide (13.4 mg) or metformin (1660 mg). Treatment-related serious adverse events occurred in two patients receiving glibenclamide. Plasma lipid profiles were unaffected and mean changes in body weight were < or = 1.0 kg. CONCLUSIONS Intensive management of Type 2 DM with a new metformin-glibenclamide combination tablet improved glycaemic control and facilitated the attainment of glycaemic targets at lower doses of metformin or glibenclamide compared with the respective monotherapies, without compromising tolerability.
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Affiliation(s)
- Michel Marre
- Diabetology-Endocrinology-Metabolism Unit, Hospital of Xavier Bichat, 46 Rue Henri Huchard, 75877 Paris Cedex 18, France
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Abstract
Decreased insulin sensitivity plays a major role in various human diseases. particularly type 2 diabetes mellitus, and is associated with a higher risk of atherosclerosis and cardiovascular complications. Thiazolidinediones, more commonly termed glitazones, are the first drugs to specifically target muscular insulin resistance. They have proven efficacy for reducing plasma glucose levels in patients with type 2 diabetes mellitus treated with diet alone, sulphonylureas, metformin or insulin. In addition, they are associated with some improvement of the cardiovascular risk profile. However, troglitazone, the first compound approved by the Food and Drug Administration in the US, proved to be hepatotoxic and was withdrawn from the market after the report of several dozen deaths or cases of severe hepatic failure requiring liver transplantation. It remains unclear whether or not hepatotoxicity is a class effect or is related to unique properties of troglitazone. Rosiglitazone and pioglitazone, two other glitazones, appear to have similar efficacy with regard to blood glucose control in patients with type 2 diabetes mellitus as compared with troglitazone. In controlled clinical trials, the incidence of significant (> or =3 x upper limit of normal) increases in liver enzyme levels (ALT in particular) was similar with rosiglitazone or pioglitazone as compared with placebo, whereas troglitazone was associated with a 3-fold greater incidence. In contrast to the numerous case reports of acute liver failure in patients receiving troglitzone, only a few case reports of hepatotoxicity have been reported in patients treated with rosiglitazone until now, with a causal relationship remaining uncertain. Furthermore, no single case of severe hepatotoxicity has been reported yet with pioglitazone. It should be mentioned that troglitazone, unlike pioglitazone and rosiglitazone, induces the cytochrome P450 isoform 3A4, which is partly responsible for its metabolism, and may be prone to drug interactions. Importantly enough, obesity, insulin resistance and type 2 diabetes mellitus are associated with liver abnormalities, especially non-alcoholic steatohepatitis, independent of any pharmacological treatment. This association obviously complicates the selection of patients who are good candidates for a treatment with glitazones as well as the monitoring of liver tests after initiation of therapy with any thiazolidinedione compound. While regular monitoring of liver enzymes is still recommended and more long term data are desirable, current evidence from clinical trials and postmarketing experience in the US supports the conclusion that rosiglitazone and pioglitazone do not share the hepatotoxic profile of troglitazone.
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Affiliation(s)
- A J Scheen
- Department of Medicine, CHU Sart Tilman, Liège, Belgium.
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Reflexiones sobre la hiperinsulinemia en la hipertensión arterial. HIPERTENSION Y RIESGO VASCULAR 2002. [DOI: 10.1016/s1889-1837(02)71240-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
A role for protein tyrosine phosphatases in the negative regulation of insulin signaling and a putative involvement in the insulin resistance associated with type 2 diabetes have been postulated since their discovery. The recent demonstration that mice lacking the protein tyrosine phosphatase-1B (PTP-1B) have enhanced insulin sensitivity validates this. Furthermore, when fed a high fat diet, these mice maintained insulin sensitivity and were resistant to obesity, suggesting that inhibition of PTP-1B activity could be a novel way of treating type 2 diabetes and obesity. This commentary reviews our current knowledge of PTP-1B in insulin signaling and its role in diabetes and discusses the development of potent and selective PTP-1B inhibitors.
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Affiliation(s)
- B P Kennedy
- Department of Biochemistry and Molecular Biology, Merck Frosst Center for Therapeutic Research, Pointe Claire-Dorval, H9R 4P8, Quebec, Canada.
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Abstract
The heterogeneous pathogenesis and progressive natural history of type 2 diabetes mellitus (T2DM) contrive a formidable therapeutic challenge. Dual endocrine deficits of impaired insulin action (insulin resistance) and inadequate insulin secretion create an environment of chronic hyperglycaemia and general metabolic disarray. This inflicts a heavy burden of morbidity and premature mortality from cardiovascular diseases, microvascular disorders (e.g. retinopathy and nephropathy) and neuropathic conditions. Improving glycaemic control delays the onset and reduces the severity of these long-term complications. However, even with intensive use of current antidiabetic agents more than 50% of T2DM patients suffer poor glycaemic control and 18% develop serious complications within six years of diagnosis. Clearly, there is a need for new antidiabetic agents.
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Affiliation(s)
- C J Bailey
- School of Life and Health Sciences, Aston University, Birmingham, UK B4
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Nattrass M, Bailey CJ. New agents for Type 2 diabetes. BAILLIERE'S BEST PRACTICE & RESEARCH. CLINICAL ENDOCRINOLOGY & METABOLISM 1999; 13:309-29. [PMID: 10761869 DOI: 10.1053/beem.1999.0023] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Current agents for the treatment of Type 2 diabetes mellitus improve the metabolic profile but do not reinstate normality. They also reduce chronic diabetic complications, but they do not eliminate them. Thus, new agents with novel actions are required to complement and extend the capabilities of existing treatments. Insulin resistance and beta-cell failure, which are crucial components in the pathogenesis of Type 2 diabetes, remain the underlying targets for new drugs. Recently introduced agents include a short-acting non-sulphonylurea insulin-releaser, repaglinide, which synchronizes insulin secretion with meal digestion in order to reduce post-prandial hyperglycaemia. The thiazolidinedione drugs, troglitazone, rosiglitazone and pioglitazone represent a new class of agonists for the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma). PPARgamma increases the transcription of certain insulin-sensitive genes, thereby improving insulin sensitivity. The intestinal lipase inhibitor orlistat and the satiety-inducer sibutramine are new weight-reducing agents that may benefit glycaemic control in obese Type 2 diabetes patients. Several further new insulin-releasing agents, and agents to retard carbohydrate digestion and modify lipid metabolism stand poised to enter the market. The extent to which they will benefit glycaemic control remains to be seen. However, the prospect of permanently arresting or reversing the progressive deterioration of Type 2 diabetes continues to evade therapeutic capture.
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Affiliation(s)
- M Nattrass
- Diabetes Resource Centre, Selly Oak Hospital, Birmingham, UK
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