Effect of Brassica rapa var. rapifera on Insulin Resistance and Inflammatory Analysis of Visceral Adipose Tissue of Obese Wistar Rats Under Glucolipotoxicity Condition / Efecto de Brassica rapa var. rapifera sobre la Resistencia a la Insulina y el Análisis Inflamatorio del Tejido Adiposo Visceral de Ratas Wistar Obesas en Condiciones de Glucolipotoxicidad

SUMMARY: Obesity-related pathophysiologies such as insulin resistance and the metabolic syndrome show a markedly increased risk for type 2 diabetes and atherosclerotic cardiovascular disease. This risk appears to be linked to alterations in adipose tissue function, leading to chronic inflammation and the dysregulation of adipocyte-derived factors. Brassica rapa have been used in traditional medicine for the treatment of several diseases, including diabetes. This study aimed to investigate the effect of nutritional stress induced by a high-fat and high-sucrose diet on the pathophysiology of visceral adipose tissue and the therapeutic effect of Brassica rapa in male Wistar rats. We subjected experimental rats to a high-fat (10 %) high-sucrose (20 %)/per day for 11 months and treated them for 20 days with aqueous extract Br (AEBr) at 200 mg/kg at the end of the experiment. At the time of sacrifice, we monitored plasma and tissue biochemical parameters as well as the morpho-histopathology of visceral adipose tissue. We found AEBr corrected metabolic parameters and inflammatory markers in homogenized visceral adipose tissue and reduced hypertrophy, hyperplasia, and lipid droplets. These results suggest that AEBr enhances anti-diabetic, anti-inflammatory and a protective effect on adipose tissue morphology in type 2 diabetes and obesity.

La fisiopatología relacionadas con la obesidad, como la resistencia a la insulina y el síndrome metabólico, muestran un riesgo notablemente mayor de diabetes tipo 2 y enfermedad cardiovascular aterosclerótica. Este riesgo parece estar relacionado con alteraciones en la función del tejido adiposo, lo que lleva a una inflamación crónica y a la desregulación de los factores derivados de los adipocitos. Brassica rapa se ha utilizado en la medicina tradicional para el tratamiento de varias enfermedades, incluida la diabetes. Este estudio tuvo como objetivo investigar el efecto del estrés nutricional inducido por una dieta rica en grasas y sacarosa sobre la fisiopatología del tejido adiposo visceral y el efecto terapéutico de Brassica rapa en ratas Wistar macho. Sometimos a ratas experimentales a una dieta rica en grasas (10 %) y alta en sacarosa (20 %)/por día durante 11 meses y las tratamos durante 20 días con extracto acuoso de Br (AEBr) a 200 mg/kg al final del experimento. En el momento del sacrificio, monitoreamos los parámetros bioquímicos plasmáticos y tisulares, así como la morfohistopatología del tejido adiposo visceral. Encontramos parámetros metabólicos corregidos por AEBr y marcadores inflamatorios en tejido adiposo visceral homogeneizado y reducción de hipertrofia, hiperplasia y gotitas de lípidos. Estos resultados sugieren que AEBr mejora el efecto antidiabético, antiinflamatorio y protector sobre la morfología del tejido adiposo en la diabetes tipo 2 y la obesidad.

Neuroprotective effects of an Nrf2 agonist on high glucose-induced damage in HT22 cells

BACKGROUND: Oxidative stress is the hallmark of diabetic encephalopathy, which may be caused by hyperglycaemic toxicity. We aimed to discover pharmacologic targets to restore redox homeostasis. We identified the transcription factor Nrf2 as such a target. METHODS: HT22 cells were cultured in 25 or 50 mM D-glucose with various concentrations of sulforaphane (SFN) (from 1.25 to 5.0 µM). Cell viability was tested with the Cell Counting Kit-8 assay. Reactive oxygen species (ROS) production was detected with an inverted fluorescence microscope using the dichlorodihydrofluorescein-diacetate fluorescent probe. The expression of NF-E2-related factor 2 (Nrf2), haem oxygenase-1 (HO-1) and nuclear factor-κB (NF-κB) at the mRNA and protein levels was detected by reverse transcription quantitative polymerase chain reaction and western blotting. RESULT: We found that a high glucose concentration (50 mM) increased the generation of ROS, downregulated the expression of Nrf2/HO-1 and upregulated the expression of NF-κB. Moreover, HT22 cell viability significantly decreased after culture in high-glucose medium for 24, 48 and 72 h, whereas the activation of the Nrf2/HO-1 pathway using a pharmacological Nrf2 activator abrogated this high-glucose-induced toxicity. CONCLUSION: This study suggests that the activation of the Nrf2-ARE signalling pathway might be a therapeutic target for the treatment of diabetic encephalopathy.

The Glucotoxicity Protecting Effect of Ezetimibe in Pancreatic Beta Cells via Inhibition of CD36

Inhibition of CD36, a fatty acid transporter, has been reported to prevent glucotoxicity and ameliorate high glucose induced beta cell dysfunction. Ezetimibe is a selective cholesterol absorption inhibitor that blocks Niemann Pick C1-like 1 protein, but may exert its effect through suppression of CD36. We attempted to clarify the beneficial effect of ezetimibe on insulin secreting cells and to determine whether this effect is related to change of CD36 expression. mRNA expression of insulin and CD36, intracellular peroxide level and glucose stimulated insulin secretion (GSIS) under normal (5.6 mM) or high glucose (30 mM) condition in INS-1 cells and primary rat islet cells were compared. Changes of the aforementioned factors with treatment with ezetimibe (20 μM) under normal or high glucose condition were also assessed. mRNA expression of insulin was decreased with high glucose, which was reversed by ezetimibe in both INS-1 cells and primary rat islets. CD36 mRNA expression was increased with high glucose, but decreased by ezetimibe in INS-1 cells and primary rat islets. Three-day treatment with high glucose resulted in an increase in intracellular peroxide level; however, it was decreased by treatment with ezetimibe. Decrease in GSIS by three-day treatment with high glucose was reversed by ezetimibe. Palmitate uptake following exposure to high glucose conditions for three days was significantly elevated, which was reversed by ezetimibe in INS-1 cells. Ezetimibe may prevent glucotoxicity in pancreatic β-cells through a decrease in fatty acid influx via inhibition of CD36.

Glucotoxicidad y lipotoxicidad: factores en la patogénesis y evolución de la diabetes tipo 2 / Glucose and lipid toxicity: pathogenesis factors and evolution in type 2 diabetes

Glucose toxicity refers to the structural and functional damage in the beta cells and target tissues of insulin, caused by chronic hyperglycemia. These alterations cause a lower hormonal secretion and action (insulin resistance). Lipid toxicity refers to the damage caused by persistently high free fatty acid levels, as a consequence of triacylglycerol catabolism. Since elevated glucose and lipid levels cause a similar damage and interact, the term glucose and lipid toxicity refers to their additive effects. This toxicity can be implicated in the pathogenesis of type II diabetes and in the secondary failure of oral hypoglycemic drugs, leading to the requirement of insulin treatment. Insulin resistance with normal glucose levels, glucose intolerance and clinical diabetes are the three recognized stages in the development of type 2 diabetes. Considering that the first two stages are reversible, a good metabolic control to avoid glucose and lipid toxicity could revert or avoid the development of clinical diabetes

Gluco-lipotoxicidad y sus implicancias en la diabetes mellitus tipo 2 / Glycolipotoxicity and it implications in diabetes mellitus type 2

Se entiende por glucotoxicidad a los daños estructurales y funcionales debidos a la hiperglicemia crónica, que se producen en la célula beta y en los tejidos periféricos donde actúa la insulina; alteraciones que se traducen en una menor secreción y acción de la hormona (insulinorresistencia). La lipotoxicidad se relacionea con daños similares a consecuencia de altos niveles de ácidos grasos libres(AGL), productos del catabolismo de los triglicéridos. Debido a que la elevación permanente de la glucosa y de los AGL interactúan y tiene los mismos efectos deletéreos, se ha acuñado el término de gluco-lipotoxicidad, cuya importancia radica en que sería uno de los factores implicados en la patogénesis de la diabetes tipo 2(DM 2) y en la evolución de ésta al fracaso secundario a las drogas hipoglicemiantes orales. En la actualidad se acepta que la DM 2 se desarrolla en etapas: resistencia a la insulina con normoglicemia, intolerancia a la glucosa y diabetes clínica. Dado que los dos primeros períodos son reversibles, y que el déficit de secreción insulínica es parte de la historia natural de la DM 2, el controlar las glicemias elevadas y la lipólisis exagerada(gluco-lipotoxicidad), permitiría revertir o enlentecer estos procesos

The effects of high glucose concentration on angiotensin II- or transforming growth factor-beta-induced DNA synthesis, hypertrophy and collagen synthesis in cultured rat mesangial cells

Hyperglycemia is a principal characteristic of diabetes, and has an influence on many cellular functions. In order to investigate whether the intracellular signaling pathways inducing proliferation, hypertrophy and matrix synthesis of mesangial cells are altered in a diabetic environment, we evaluated the effects of a high concentration of extracellular glucose(25 mM; 450 mg/dl) on [3H]thymidine uptake, hypertrophy, and [3H]proline incorporation into a collagenase-sensitive protein, induced by angiotensin II(Ang II) or transforming growth factor(TGF)-beta, in cultured rat mesangial cells. The exposure to a high glucose concentration for 7 days significantly inhibited Ang II(10(-6) M)-induced [3H]thymidine uptake, compared to normal glucose concentration (5 mM)(M +/- SD., 1050 +/- 100 cpm/well vs 550 +/- 97, p 0.05). In conclusion, although the signaling pathway for DNA synthesis by Ang II or TGF-beta are influenced, possibly mediated by PKC-independent mechanism(s), the pathway inducing hypertrophy or collagen synthesis by both agents appears to be unchanged under the high extracellular glucose concentration in cultured rat mesangial cells.

Glucotoxicidad en la diabetes mellitus no dependiente de insulina / Glucose toxic effect upon non insuline dependent diabetes mellitus

Se ha encontrado defecto específico en el glucorreceptor de pacientes con diabetes mellitus no insulino dependiente (DMNID), aunque existe poca información de los efectos tóxicos de la glucosa sobre la función de la célula beta cuando ésta es estimulada por un agente diferente de la glucos. En el presente informe se analiza la respuesta de insulina en seis pacientes con DMNID crónicamente descompensados a una carga oral de 75 g de glucosa, y posteriormente a 1 mg de glucagon endovenoso, una vez compensados los pacientes, se repitió el mismo protocolo. La concentración de insulina sérica antes de la compensasión fue de 96 96 ñ 32 uU/mL, con una relación glucosa/insulina de 0.343 (p=NS); después de la compensación la concentración de insulina alcanzó 154 ñ 67 uU/mL, (