Project description:Bezafibrate (BEZ), a pan activator of peroxisome proliferator-activated receptors (PPARs), is generally used to treat hyperlipidemia. Clinical trials on patients suffering from type 2 diabetes indicated that BEZ also has beneficial effects on glucose metabolism, but the underlying mechanisms remain elusive. Much less is known about the function of BEZ in type 1 diabetes. Here, we show that BEZ treatment markedly improves hyperglycemia, glucose and insulin tolerance in streptozotocin (STZ)-treated mice, an insulin-deficient mouse model of type 1 diabetes presenting with very high blood glucose levels. Furthermore, BEZ-treated mice also exhibited improved metabolic flexibility as well as an enhanced mitochondrial mass and function in the liver. Our data demonstrate a beneficial effect of BEZ treatment on STZ mice reducing diabetes and suggest that BEZ ameliorates impaired glucose metabolism possibly via augmented hepatic mitochondrial performance, improved insulin sensitivity and metabolic flexibility. We performed gene expression microarray analysis on liver tissue derived from streptozotocin-treated mice treated with bezafibrate in addition.
Project description:Bezafibrate (BEZ), a pan activator of peroxisome proliferator-activated receptors (PPARs), is generally used to treat hyperlipidemia. Clinical trials on patients suffering from type 2 diabetes indicated that BEZ also has beneficial effects on glucose metabolism, but the underlying mechanisms remain elusive. Much less is known about the function of BEZ in type 1 diabetes. Here, we show that BEZ treatment markedly improves hyperglycemia, glucose and insulin tolerance in streptozotocin (STZ)-treated mice, an insulin-deficient mouse model of type 1 diabetes presenting with very high blood glucose levels. Furthermore, BEZ-treated mice also exhibited improved metabolic flexibility as well as an enhanced mitochondrial mass and function in the liver. Our data demonstrate a beneficial effect of BEZ treatment on STZ mice reducing diabetes and suggest that BEZ ameliorates impaired glucose metabolism possibly via augmented hepatic mitochondrial performance, improved insulin sensitivity and metabolic flexibility.
Project description:Impaired resistance to insulin, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. The hampered metabolic adaptability triggers a further damage of insulin signaling. Since skeletal muscle is the main site of glucose uptake, effectiveness of T2D treatment depends in large on the improvement of insulin sensitivity and metabolic adaptability of the muscle. We have shown previously in mice fed an obesogenic high-fat diet that a combination treatment using n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinedione (TZD) anti-diabetic drugs preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether TZD rosiglitazone could elicit the additive beneficial effects on metabolic flexibility when combined with n-3 LC-PUFA. Adult male C57BL/6J mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various dietary treatments: (i) cHF+F, cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids; (ii) cHF+ROSI, cHF with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combination treatment. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the single treatments, with rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism, and n-3 LC PUFA supporting complete oxidation of fatty acids in mitochondria. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combination treatment using n-3 LC-PUFA and TZDs could improve the efficacy of the treatment of obese and diabetic patients.
Project description:Impaired resistance to insulin, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. The hampered metabolic adaptability triggers a further damage of insulin signaling. Since skeletal muscle is the main site of glucose uptake, effectiveness of T2D treatment depends in large on the improvement of insulin sensitivity and metabolic adaptability of the muscle. We have shown previously in mice fed an obesogenic high-fat diet that a combination treatment using n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinedione (TZD) anti-diabetic drugs preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether TZD rosiglitazone could elicit the additive beneficial effects on metabolic flexibility when combined with n-3 LC-PUFA. Adult male C57BL/6N mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various dietary treatments: (i) cHF+F, cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids; (ii) cHF+ROSI, cHF with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combination treatment. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the single treatments, with rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism, and n-3 LC PUFA supporting complete oxidation of fatty acids in mitochondria. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combination treatment using n-3 LC-PUFA and TZDs could improve the efficacy of the treatment of obese and diabetic patients.
Project description:Impaired resistance to insulin, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. The hampered metabolic adaptability triggers a further damage of insulin signaling. Since skeletal muscle is the main site of glucose uptake, effectiveness of T2D treatment depends in large on the improvement of insulin sensitivity and metabolic adaptability of the muscle. We have shown previously in mice fed an obesogenic high-fat diet that a combination treatment using n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinedione (TZD) anti-diabetic drugs preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether TZD rosiglitazone could elicit the additive beneficial effects on metabolic flexibility when combined with n-3 LC-PUFA. Adult male C57BL/6J mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various dietary treatments: (i) cHF+F, cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids; (ii) cHF+ROSI, cHF with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combination treatment. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the single treatments, with rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism, and n-3 LC PUFA supporting complete oxidation of fatty acids in mitochondria. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combination treatment using n-3 LC-PUFA and TZDs could improve the efficacy of the treatment of obese and diabetic patients. Male C57BL/6N mice had free access to water and Chow. Three-month-old mice were randomly assigned (8 animals per group) to cHF+ROSI diet (lipid content ~35% wt/wt) supplemented with 10 mg rosiglitazone/kg diet, or cHF+F+ROSI in which n-3 LC-PUFA concentrate (46% DHA, 14% EPA, wt/wt, as triglycerides; product EPAX 1050 TG) replaced 15% wt/wt of dietary lipids. The treatment lasted for 8 weeks, whereafter the animals were first fasted for 10 hours during the light phase of the day (between 8.00hr and 18.00hr), than re-fed Chow (starting at 18.00hr), and killed the following day by cervical dislocation under pentobarbital anesthesia (between 9.00hr and 11.00hr); the so-called 'diet-switch protocol'. Gastrocnemius muscle was isolated and used for total RNA isolation.
Project description:Leptin monotherapy (i.e. without the use of administered insulin and/or any other molecule) corrects ID-induced metabolic aberrancies and promotes survival of insulin deficient rodents. These results generated great interest in the possibility of treating insulin deficient patients with leptin and/or molecule(s) underlying its beneficial effects. Hence, with the goal of identifying circulating molecule(s) underlying the advantageous effect of leptin we performed quantitative proteomic analysis of plasma and identified S100A9 as a putative peripheral mediator of leptin action. Here, to identify circulating molecule(s) underlying the advantageous effect of leptin we compared the results obtained by quantitative proteomic analysis of plasma between 2 groups of mice: streptozotocin (STZ)-treated mice that underwent intracerebroventricular (icv) leptin treatment for 12 days (STZ-Leptin) and ii) STZ-treated mice that underwent icv leptin treatment for 10 days and were withdrawn from leptin treatment for the following two days (STZ-Leptin-STOP). STZ treatment led to a massive loss of pancreatic insulin-producing β-cells, diminished pancreatic Proinsulin mRNA level, and caused severe insulinopenia, and hyperglycemia. icv leptin administration normalized hyperglycemia. However, two days after leptin delivery was halted hyperglycemia reappeared. We hypothesized that change in plasmatic protein(s) content could underlie re-emergence of hyperglycemia following decrease of leptin action.
Project description:Phloridzin is a dihydrochalcone typically contained in apples. A diet containing 0.5 % phloridzin significantly improves hyperglycemia but not hypoinsulinemia and tissue lipid peroxidation in streptozotocin (STZ)-induced diabetic mice after 14 days. The phloridzin diet has no effect on the alteration of hepatic gene expression in STZ-induced diabetic mice. A quantitative RT-PCR analysis showed a reversal of the STZ induction of the sodium/glucose cotransporter gene Sglt1 and the drug-metabolizing enzyme genes Cyp2b10 and Ephx1 in the small intestine of mice fed a 0.5% phloridzin diet. These mice also showed a reversal of the STZ-mediated renal induction of the glucose-regulated facilitated glucose transporter gene Glut2. Dietary phloridzin improved the abnormal elevations in blood glucose level and the overexpression of Sglt1, Cyp2b10 and Ephx1 in the small intestine of STZ-induced diabetic mice. Six-week-old male mice were divided into 4 groups of 6 mice each, housed in groups of 3 per cage. After 1 week mice were intraperitoneally injected with STZ. Mice (n=6) in the untreated control group did not receive any treatment. After 1 week, 18 mice showing non-fasting blood glucose levels of 330-590 mg/dL were divided into 3 groups: one group was fed with AIN93G only (control group), the others with an AIN93G diet containing 0.1% or 0.5% phloridzin (Funakoshi, Tokyo, Japan) for 2 weeks.
Project description:Phloridzin is a dihydrochalcone typically contained in apples. A diet containing 0.5 % phloridzin significantly improves hyperglycemia but not hypoinsulinemia and tissue lipid peroxidation in streptozotocin (STZ)-induced diabetic mice after 14 days. The phloridzin diet has no effect on the alteration of hepatic gene expression in STZ-induced diabetic mice. A quantitative RT-PCR analysis showed a reversal of the STZ induction of the sodium/glucose cotransporter gene Sglt1 and the drug-metabolizing enzyme genes Cyp2b10 and Ephx1 in the small intestine of mice fed a 0.5% phloridzin diet. These mice also showed a reversal of the STZ-mediated renal induction of the glucose-regulated facilitated glucose transporter gene Glut2. Dietary phloridzin improved the abnormal elevations in blood glucose level and the overexpression of Sglt1, Cyp2b10 and Ephx1 in the small intestine of STZ-induced diabetic mice.
Project description:Impaired resistance to insulin, the key defect in type 2 diabetes (T2D), is associated with a low capacity to adapt fuel oxidation to fuel availability, i.e., metabolic inflexibility. The hampered metabolic adaptability triggers a further damage of insulin signaling. Since skeletal muscle is the main site of glucose uptake, effectiveness of T2D treatment depends in large on the improvement of insulin sensitivity and metabolic adaptability of the muscle. We have shown previously in mice fed an obesogenic high-fat diet that a combination treatment using n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) and thiazolidinedione (TZD) anti-diabetic drugs preserved metabolic health and synergistically improved muscle insulin sensitivity. We investigated here whether TZD rosiglitazone could elicit the additive beneficial effects on metabolic flexibility when combined with n-3 LC-PUFA. Adult male C57BL/6N mice were fed an obesogenic corn oil-based high-fat diet (cHF) for 8 weeks, or randomly assigned to various dietary treatments: (i) cHF+F, cHF with n-3 LC-PUFA concentrate replacing 15% of dietary lipids; (ii) cHF+ROSI, cHF with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, or chow-fed. Indirect calorimetry demonstrated superior preservation of metabolic flexibility to carbohydrates in response to the combination treatment. Metabolomic and gene expression analyses in the muscle suggested distinct and complementary effects of the single treatments, with rosiglitazone augmenting insulin sensitivity by the modulation of branched-chain amino acid metabolism, and n-3 LC PUFA supporting complete oxidation of fatty acids in mitochondria. These beneficial metabolic effects were associated with the activation of the switch between glycolytic and oxidative muscle fibers, especially in the cHF+F+ROSI mice. Our results further support the idea that the combination treatment using n-3 LC-PUFA and TZDs could improve the efficacy of the treatment of obese and diabetic patients. Male C57BL/6N mice had free access to water and Chow. Three-month-old mice were randomly assigned (8 animals per group) to cHF diet (lipid content ~35% wt/wt) or to the following 'treatments' by isocaloric cHF-based diets, namely (i) cHF+F, cHF diet supplemented with n-3 LC-PUFA concentrate (46% DHA, 14% EPA, wt/wt, as triglycerides; product EPAX 1050 TG), which replaced 15% wt/wt of dietary lipids; (ii) cHF+ROSI, cHF diet supplemented with 10 mg rosiglitazone/kg diet; and (iii) cHF+F+ROSI, cHF diet supplemented with both n-3 LC-PUFA concentrate and rosiglitazone. cHF+ROSI at a higher dose, namely 100 mg rosiglitazone/kg diet was also included in the study, but not in the final microarray analysis. The treatment lasted for 8 weeks, whereafter the animals were first fasted for 10 hours during the light phase of the day (between 8.00hr and 18.00hr), than re-fed Chow (starting at 18.00hr), and killed the following day by cervical dislocation under pentobarbital anesthesia (between 9.00hr and 11.00hr); the so-called 'diet-switch protocol'. Gastrocnemius muscle was isolated and used for total RNA isolation.
Project description:In addition to high intracellular glucose level, the diabetic state is also characterized by altered metabolites, which are pivotal regulators of glucotoxic pathways. In this study we analyzed Bezafibrate (BEZ) treated Streptozotocin (STZ) mice, which showed improved glucose metabolism compared to untreated STZ controls. In order to identify the key molecules and pathways, which participate in the beneficial effects of BEZ, we analyzed the skeletal muscle, white adipose tissue (WAT) and liver samples of BEZ-treated mice using non-targeted metabolomics (NMR spectroscopy), targeted metabolomics (mass spectrometry), microarrays and enzyme activity measurements with a particular focus on the liver. The analysis of muscle and WAT demonstrated that BEZ improved the expressions of genes and levels of metabolites, which could partly regulate the beneficial effects of BEZ on the glucose metabolism. Furthermore, in the liver, BEZ treatment reduced the elevated hepatic fumarate level of STZ mice, which was accompanied by a decreased expression of urea cycle genes. Since the urea cycle is involved in the production of fumarate, which is shown to be participated in glucotoxic pathways, our data suggest that BEZ could attenuate the urea cycle, reduce fumarate level and in turn ameliorate glucotoxicity in the liver of STZ mice