Nrf2 deficiency deteriorates diabetic kidney disease in Akita model mice.

Oxidative stress is an essential component in the progression of diabetic kidney disease (DKD), and the transcription factor NF-E2-related factor-2 (Nrf2) plays critical roles in protecting the body against oxidative stress. To clarify the roles of Nrf2 in protecting against DKD, in this study we prepared compound mutant mice with diabetes and loss of antioxidative defense. Specifically, we prepared compound Ins2Akita/+ (Akita) and Nrf2 knockout (Akita::Nrf2-/-) or Akita and Nrf2 induction (Akita::Keap1FA/FA) mutant mice. Eighteen-week-old Akita::Nrf2-/- mice showed more severe diabetic symptoms than Akita mice. In the Akita::Nrf2-/- mouse kidneys, the glomeruli showed distended capillary loops, suggesting enhanced mesangiolysis. Distal tubules showed dilation and an increase in 8-hydroxydeoxyguanosine-positive staining. In the Akita::Nrf2-/- mouse kidneys, the expression of glutathione (GSH) synthesis-related genes was decreased, and the actual GSH level was decreased in matrix-assisted laser desorption/ionization mass spectrometry imaging analysis. Akita::Nrf2-/- mice exhibited severe inflammation and enhancement of infiltrated macrophages in the kidney. To further examine the progression of DKD, we compared forty-week-old Akita mouse kidney compounds with Nrf2-knockout or Nrf2 mildly induced (Akita::Keap1FA/FA) mice. Nrf2-knockout Akita (Akita::Nrf2-/-) mice displayed severe medullary cast formation, but the formation was ameliorated in Akita::Keap1FA/FA mice. Moreover, in Akita::Keap1FA/FA mice, tubule injury and inflammation-related gene expression were significantly suppressed, which was evident in Akita::Nrf2-/- mouse kidneys. These results demonstrate that Nrf2 contributes to the protection of the kidneys against DKD by suppressing oxidative stress and inflammation.

Hyperbaric oxygen therapy mitigates left ventricular remodeling, upregulates MMP-2 and VEGF, and inhibits the induction of MMP-9, TGF-ß1, and TNF-α in streptozotocin-induced diabetic rat heart.

AIMS: Hyperbaric oxygen (HBO) therapy has been widely used for the adjunctive treatment of diabetic wounds, and is currently known to influence left ventricular (LV) function. However, morphological and molecular repercussions of the HBO in the diabetic myocardium remain to be described. We aimed to investigate whether HBO therapy would mitigate adverse LV remodeling caused by streptozotocin (STZ)-induced diabetes. MAIN METHODS: Sixty-day-old Male Wistar rats were divided into four groups: Control (n = 8), HBO (n = 7), STZ (n = 10), and STZ + HBO (n = 8). Diabetes was induced by a single STZ injection (60 mg/kg, i.p.). HBO treatment (100% oxygen at 2.5 atmospheres absolute, 60 min/day, 5 days/week) lasted for 5 weeks. LV morphology was evaluated using histomorphometry. Gene expression analyzes were performed for LV collagens I (Col1a1) and III (Col3a1), matrix metalloproteinases 2 (Mmp2) and 9 (Mmp9), and transforming growth factor-ß1 (Tgfb1). The Immunoexpression of cardiac tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) were also quantified. KEY FINDINGS: HBO therapy prevented LV concentric remodeling, heterogeneous myocyte hypertrophy, and fibrosis in diabetic rats associated with attenuation of leukocyte infiltration. HBO therapy also increased Mmp2 gene expression, and inhibited the induction of Tgfb1 and Mmp9 mRNAs caused by diabetes, and normalized TNF-α and VEGF protein expression. SIGNIFICANCE: HBO therapy had protective effects for the LV structure in STZ-diabetic rats and ameliorated expression levels of genes involved in cardiac collagen turnover, as well as pro-inflammatory and pro-angiogenic signaling.

Exercise and Urtica Dioica extract ameliorate mitochondrial function and the expression of cardiac muscle Nuclear Respiratory Factor 2 and Peroxisome proliferator-activated receptor Gamma Coactivator 1-alpha in STZ-induced diabetic rats.

INTRODUCTION: Diabetes mellitus can affect and disrupt the levels of PGC1α and NRF2 proteins in the mitochondrial biogenesis pathway. Considering the anti-diabetic properties of Urtica Dioica extract and exercise, this study aimed to investigate the beneficial effects of Urtica Dioica extract and endurance activity on PGC1α and NRF2 protein levels in the streptozotocin-induced diabetic rat heart tissue. MATERIALS AND METHODS: 58 male Wistar rats were divided into five groups (N = 12) including: healthy control (HC), diabetes control (DC), diabetes Urtica Dioica (D-UD), diabetes exercise training (DT), and diabetes exercise training Urtica Dioica (DT-UD). Diabetes was induced intraperitoneally by STZ (45 mg/kg) injection. Two weeks after the induction of diabetes, the rats were stimulated to carry out the exercise (moderate intensity/5day/week) and the gavage of UD extract (50 mg/kg/day) was administered to the rats for six weeks. In this study, the western blotting method was used to measure the levels of PGC1α and NRF2 proteins. Moreover, cardiography was used to evaluate the functional parameters of the heart (ejection fraction & fractional shortening). Finally, the bioluminescence and ELISA methods were used to determine the content of adenosine triphosphate and citrate synthase. RESULTS: The cardiac function parameters, the mitochondrial ATP and the CS content in DC group mice were impaired in comparison with the other study groups and showed a decreasing trend (P < 0.001). The treatment with EX + UD extract was able to minimize the rate of these disorders and acted as a protector of mitochondrial function. There were significant differences in the expression levels of NRF2 (F = 17.7, P = 0.001) and PGC-1α (F = 43.7, P = 0.001) mitochondrial proteins among the different groups. The levels of these proteins were significantly reduced in the DC group in comparison with the HC group (P < 0.001). The treatment with EX or UD extract increased the expression of PGC-1α and NRF2 proteins in the heart muscle of animals in the DT and D-UD groups in comparison with the DC group (P < 0.05). Moreover, the expression of these proteins was more pronounced in the DT-UD group. There was not a significant difference between the DT-UD group and the HC group regarding the expression of these proteins (P > 0.05). CONCLUSIONS: The results of this study showed that treatment with EX and UD extract could treat the disorders which were caused by diabetes in the parameters of cardiac function. Moreover, it was able to improve the expression of the levels of proteins which were involved in mitochondrial biogenesis and its function. Finally, this kind of treatment could attract more attention to the roles of EX and UD extract in the prevention of cardiovascular complications in future studies.

Role of heme oxygenase in the regulation of the renal hemodynamics in a model of sex-dependent programmed hypertension by maternal diabetes.

Intrauterine programming of cardiovascular and renal function occurs in diabetes because of the adverse maternal environment. Heme oxygenase 1 (HO-1) and -2 (HO-2) exert vasodilatory and antioxidant actions, particularly in conditions of elevated HO-1 expression or deficient nitric oxide levels. We evaluated whether the activity of the heme-HO system is differentially regulated by oxidative stress in the female offspring of diabetic mothers, contributing to the improved cardiovascular function in comparison with males. Diabetes was induced in pregnant rats by a single dose of streptozotocin (STZ, 50 mg/kg ip) in late gestation. Three-month-old male offspring from diabetic mothers (MODs) exhibited higher blood pressure (BP), higher renal vascular resistance (RVR), worse endothelium-dependent response to acetylcholine (ACH), and an increased constrictor response to phenylephrine (PHE) compared with those in age-matched female offspring of diabetic mothers (FODs), which were abolished by chronic tempol (1 mM) treatment. In anesthetized animals, stannous mesoporphyrin (SnMP; 40 µmol/kg iv) administration, to inhibit HO activity, increased RVR in FODs and reduced glomerular filtration rate (GFR) in MODs, without altering these parameters in control animals. When compared with MODs, FODs showed lower nitrotirosyne levels and higher HO-1 protein expression in renal homogenates. Indeed, chronic treatment with tempol in MODs prevented elevations in nitrotyrosine levels and the acute renal hemodynamics response to SnMP. Then, maternal diabetes results in sex-specific hypertension and renal alterations associated with oxidative stress mainly in adult male offspring, which are reduced in the female offspring by elevation in HO-1 expression and lower oxidative stress levels.

Effects of Maternal Diabetes and Diet on Gene Expression in the Murine Placenta.

Adverse exposures during pregnancy have been shown to contribute to susceptibility for chronic diseases in offspring. Maternal diabetes during pregnancy is associated with higher risk of pregnancy complications, structural birth defects, and cardiometabolic health impairments later in life. We showed previously in a mouse model that the placenta is smaller in diabetic pregnancies, with reduced size of the junctional zone and labyrinth. In addition, cell migration is impaired, resulting in ectopic accumulation of spongiotrophoblasts within the labyrinth. The present study had the goal to identify the mechanisms underlying the growth defects and trophoblast migration abnormalities. Based upon gene expression assays of 47 candidate genes, we were able to attribute the reduced growth of diabetic placenta to alterations in the Insulin growth factor and Serotonin signaling pathways, and provide evidence for Prostaglandin signaling deficiencies as the possible cause for abnormal trophoblast migration. Furthermore, our results reinforce the notion that the exposure to maternal diabetes has particularly pronounced effects on gene expression at midgestation time points. An implication of these findings is that mechanisms underlying developmental programming act early in pregnancy, during placenta morphogenesis, and before the conceptus switches from histiotrophic to hemotrophic nutrition.

Differential remodelling of mitochondrial subpopulations and mitochondrial dysfunction are a feature of early stage diabetes.

Mitochondrial dysfunction is a feature of type I and type II diabetes, but there is a lack of consistency between reports and links to disease development. We aimed to investigate if mitochondrial structure-function remodelling occurs in the early stages of diabetes by employing a mouse model (GENA348) of Maturity Onset Diabetes in the Young, exhibiting hyperglycemia, but not hyperinsulinemia, with mild left ventricular dysfunction. Employing 3-D electron microscopy (SBF-SEM) we determined that compared to wild-type, WT, the GENA348 subsarcolemma mitochondria (SSM) are ~ 2-fold larger, consistent with up-regulation of fusion proteins Mfn1, Mfn2 and Opa1. Further, in comparison, GENA348 mitochondria are more irregular in shape, have more tubular projections with SSM projections being longer and wider. Mitochondrial density is also increased in the GENA348 myocardium consistent with up-regulation of PGC1-α and stalled mitophagy (down-regulation of PINK1, Parkin and Miro1). GENA348 mitochondria have more irregular cristae arrangements but cristae dimensions and density are similar to WT. GENA348 Complex activity (I, II, IV, V) activity is decreased but the OCR is increased, potentially linked to a shift towards fatty acid oxidation due to impaired glycolysis. These novel data reveal that dysregulated mitochondrial morphology, dynamics and function develop in the early stages of diabetes.

CD74 ablation rescues type 2 diabetes mellitus-induced cardiac remodeling and contractile dysfunction through pyroptosis-evoked regulation of ferroptosis.

Type 2 diabetes mellitus (T2D) contributes to sustained inflammation and myopathic changes in the heart although the precise interplay between the two remains largely unknown. This study evaluated the impact of deficiency in CD74, the cognate receptor for the regulatory cytokine macrophage migration inhibitory factor (MIF), in T2D-induced cardiac remodeling and functional responses, and cell death domains involved. WT and CD74-/- mice were fed a high fat diet (60% calorie from fat) for 8 weeks prior to injection of streptozotocin (STZ, 35 mg/kg, i.p., 3 consecutive days) and were maintained for another 8 weeks. KEGG analysis for differentially expressed genes (DEGs) reported gene ontology term related to ferroptosis in T2D mouse hearts. T2D patients displayed elevated plasma MIF levels. Murine T2D exerted overt global metabolic derangements, cardiac remodeling, contractile dysfunction, apoptosis, pyroptosis, ferroptosis and mitochondrial dysfunction, ablation of CD74 attenuated T2D-induced cardiac remodeling, contractile dysfunction, various forms of cell death and mitochondrial defects without affecting global metabolic defects. CD74 ablation rescued T2D-evoked NLRP3-Caspase1 activation and oxidative stress but not dampened autophagy. In vitro evidence depicted that high glucose/high fat (HGHF) compromised cardiomyocyte function and promoted lipid peroxidation, the effects were ablated by inhibitors of NLRP3, pyroptosis, and ferroptosis but not by the mitochondrial targeted antioxidant mitoQ. Recombinant MIF mimicked HGHF-induced lipid peroxidation, GSH depletion and ferroptosis, the effects of which were reversed by inhibitors of MIF, NLRP3 and pyroptosis. Taken together, these data suggest that CD74 ablation protects against T2D-induced cardiac remodeling and contractile dysfunction through NLRP3/pyroptosis-mediated regulation of ferroptosis.

Downregulation of Erythrocyte miR-210 Induces Endothelial Dysfunction in Type 2 Diabetes.

Red blood cells (RBC) act as mediators of vascular injury in type 2 diabetes mellitus (T2DM). miR-210 plays a protective role in cardiovascular homeostasis and is decreased in whole blood of T2DM mice. We hypothesized that downregulation of RBC miR-210 induces endothelial dysfunction in T2DM. RBC were coincubated with arteries and endothelial cells ex vivo and transfused in vivo to identify the role of miR-210 and its target protein tyrosine phosphatase 1B (PTP1B) in endothelial dysfunction. RBC from patients with T2DM and diabetic rodents induced endothelial dysfunction ex vivo and in vivo. miR-210 levels were lower in human RBC from patients with T2DM (T2DM RBC) than in RBC from healthy subjects. Transfection of miR-210 in human T2DM RBC rescued endothelial function, whereas miR-210 inhibition in healthy subjects RBC or RBC from miR-210 knockout mice impaired endothelial function. Human T2DM RBC decreased miR-210 expression in endothelial cells. miR-210 expression in carotid artery plaques was lower in T2DM patients than in patients without diabetes. Endothelial dysfunction induced by downregulated RBC miR-210 involved PTP1B and reactive oxygen species. miR-210 mimic attenuated endothelial dysfunction induced by RBC via downregulating vascular PTP1B and oxidative stress in diabetic mice in vivo. These data reveal that the downregulation of RBC miR-210 is a novel mechanism driving the development of endothelial dysfunction in T2DM.

Vitamin D Combined with Pioglitazone Mitigates Type-2 Diabetes-induced Hepatic Injury Through Targeting Inflammation, Apoptosis, and Oxidative Stress.

Inflammation is a major pathophysiological factor in development of type-2 diabetes mellitus (T2DM). Vitamin D (VITD) plays an imperative role in modulation of several inflammatory responses. The current study aimed to investigate the possible beneficial effects of coadministration of VITD with pioglitazone (PIO), a PPAR-γ agonist, in fructose/streptozotocin (F/STZ) T2DM model in male Wistar rats. T2DM was induced by maintaining rats on 10% (w/v) fructose in drinking water for 9 weeks with an intraperitoneal injection of sub-diabetogenic dose of STZ (35 mg/kg) by the end of the fourth week. One week after STZ injection, PIO (10 mg/kg/day) alone or with VITD (500 IU/kg/day) was administered orally to diabetic rats till the end of the experiment. Blood samples were collected, livers were homogenized to determine biochemical parameters, and samples of livers were fixed in 10% formalin in saline for histological examination. Administration of PIO alone improved diabetes-induced inflammatory and oxidative states besides controlling hyperglycemia and decreasing apoptosis. Coadministration of VIT D with PIO promoted additional improvement in glycemic and lipid profiles, provided further control on diabetic-induced hepatic inflammation evident by downregulating TLR2, TLR4, and IKK-ß while upregulating IκB-α expression and reducing inflammatory cytokines namely; NF-κB, TNF-α, IL-6, and IL-1ß, decreasing apoptosis and oxidative stress by hampering caspase-3 and MDA contents, respectively, and improved liver histology than PIO alone. These beneficial effects of VIT D may expand its use by diabetics combined with antidiabetic drugs due to its anti-inflammatory, antioxidant, and antiapoptotic properties.

Animal models of diabetic microvascular complications: Relevance to clinical features.

Diabetes has become more common in recent years worldwide, and this growth is projected to continue in the future. The primary concern with diabetes is developing various complications, which significantly contribute to the disease's mortality and morbidity. Over time, the condition progresses from the pre-diabetic to the diabetic stage and then to the development of complications. Years and enormous resources are required to evaluate pharmacological interventions to prevent or delay the progression of disease or complications in humans. Appropriate screening models are required to gain a better understanding of both pathogenesis and potential therapeutic agents. Different species of animals are used to evaluate the pharmacological potentials and study the pathogenesis of the disease. Animal models are essential for research because they represent most of the structural, functional, and biochemical characteristics of human diseases. An ideal screening model should mimic the pathogenesis of the disease with identifiable characteristics. A thorough understanding of animal models is required for the experimental design to select an appropriate model. Each animal model has certain advantages and limitations. The present manuscript describes the animal models and their diagnostic characteristics to evaluate microvascular diabetic complications.

The effects of exercise training on cardiac matrix metalloproteinases activity and cardiac function in mice with diabetic cardiomyopathy.

AIM: To evaluate the effects of exercise training (ET) on cardiac extracellular matrix (ECM) proteins homeostasis and cardiac dysfunction in mice with diabetic cardiomyopathy. METHODS: Thirty-six male C57BL/6 mice were randomized into 3 groups for 8 weeks (12mice/group): Diabetic control-DC: Diabetes was induced by single streptozotocin injection (200 mg/kg i.p.); Diabetic exercise-DE: Diabetic mice underwent ET program on motorized-treadmill (6-times/week, 60min/session); Non-diabetic control-NDC: Vehicle-treated, sedentary, non-diabetic mice served as controls. Before euthanasia, all groups underwent transthoracic echocardiography (TTE). Post-mortem, left-ventricle (LV) samples were histologically analysed for ECM proteins (collagen, elastin), matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). RESULTS: DC group showed significantly higher cardiac contents of collagen and MMP-9 and lower elastic concentration than NDC (p < 0.001). The implementation of ET completely outweighed those diabetes-induced changes (DE vs NDC, p > 0.05). TIMP-1 levels significantly increased across all groups (DC: 18.98 ± 3.47%, DE: 24.24 ± 2.36%, NDC: 46.36 ± 5.91%; p < 0.05), while MMP-9/TIMP-1 ratio followed a reverse pattern. ET tended to increase MMP-2 concentrations versus DC (p = 0.055), but did not achieve non-diabetic levels (p < 0.05). TIMP-2 cardiac concentrations remained unaltered throughout the study (p > 0.05). Importantly, ET ameliorated both LV end-systolic internal diameter (LVESD) (p < 0.001) and the percentage of LV fractional shortening (FS%) (p = 0.006) compared to DC. Despite that favorable effect, the cardiac function level of DE group remained worse than NDC group (%FS: p = 0.002; LVESD: p < 0.001). CONCLUSION: Systemic ET may favorably change ECM proteins, MMP-9 and TIMP-1 cardiac concentrations in mice with diabetic cardiomyopathy. Those results were associated with partial improvement of echocardiography-assessed cardiac function, indicating a therapeutic effect of ET in diabetic cardiomyopathy.

Diabetic mice have retinal and choroidal blood flow deficits and electroretinogram deficits with impaired responses to hypercapnia.

PURPOSE: The purpose of this study was to investigate neuronal and vascular functional deficits in the retina and their association in a diabetic mouse model. We measured electroretinography (ERG) responses and choroidal and retinal blood flow (ChBF, RBF) with magnetic resonance imaging (MRI) in healthy and diabetic mice under basal conditions and under hypercapnic challenge. METHODS: Ins2Akita diabetic (Diab, n = 8) and age-matched, wild-type C57BL/6J mice (Ctrl, n = 8) were studied under room air and moderate hypercapnia (5% CO2). Dark-adapted ERG a-wave, b-wave, and oscillatory potentials (OPs) were measured for a series of flashes. Regional ChBF and RBF under air and hypercapnia were measured using MRI in the same mice. RESULTS: Under room air, Diab mice had compromised ERG b-wave and OPs (e.g., b-wave amplitude was 422.2±10.7 µV in Diab vs. 600.1±13.9 µV in Ctrl, p < 0.001). Under hypercapnia, OPs and b-wave amplitudes were significantly reduced in Diab (OPs by 30.3±3.0% in Diab vs. -3.0±3.6% in Ctrl, b-wave by 17.9±1.4% in Diab vs. 1.3±0.5% in Ctrl). Both ChBF and RBF had significant differences in regional blood flow, with Diab mice having substantially lower blood flow in the nasal region (ChBF was 5.4±1.0 ml/g/min in Diab vs. 8.6±1.0 ml/g/min in Ctrl, RBF was 0.91±0.10 ml/g/min in Diab vs. 1.52±0.24 ml/g/min in Ctrl). Under hypercapnia, ChBF increased in both Ctrl and Diab without significant group difference (31±7% in Diab vs. 17±7% in Ctrl, p > 0.05), but an increase in RBF was not detected for either group. CONCLUSIONS: Inner retinal neuronal function and both retinal and choroidal blood flow were impaired in Diab mice. Hypercapnia further compromised inner retinal neuronal function in diabetes, while the blood flow response was not affected, suggesting that the diabetic retina has difficulty adapting to metabolic challenges due to factors other than impaired blood flow regulation.

Metformin improves cognitive impairment in diabetic mice induced by a combination of streptozotocin and isoflurane anesthesia.

To investigate the protective effects of metformin on the diabetic mice with cognitive impairment induced by the combination of streptozotocin (STZ) and isoflurane anesthesia. The isoflurane-anesthetized cognitive impairment model mice were established and then observed via behavioral tests and histopathological examination. Then these model mice were randomly assigned to three groups, which received the PBS, low and high doses of metformin, respectively. The body weight, food and water consumption of model mice were measured every other day. The mechanisms of metformin on ameliorating the cognitive dysfunction were further investigated by histomorphological, biochemical and Western blot analysis. After 14-days treatment of metformin, the diabetic symptoms in STZ-induced diabetic mice were significantly alleviated. Metformin could restore the isoflurane- and STZ-induced hippocampal tissue damage, cognitive and memory impairment in exposed space via improving the oxidative stress, upregulating the contents of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) in the hippocampus tissues of diabetic mice. Furthermore, chronic treatment of metformin significantly down-regulated the expression of AGEs, RAGE, pNF-κB, iNOS, and COX-2. In conclusion, metformin can improve the isoflurane- and STZ-induced cognitive impairment in diabetic mice via improving oxidative stress and inhibiting the AGEs/RAGE/NF-κB signaling pathway.

Positive Lusitropic Effect of Quercetin on Isolated Ventricular Myocardia from Normal and Streptozotocin-Induced Diabetic Mice.

The lusitropic effect of quercetin was examined on isolated ventricular myocardial tissue preparations from normal and streptozotocin-induced diabetic mice. The time required for 90% relaxation of the myocardium, which was prolonged in the diabetic mice, was shortened by quercetin in both normal and diabetic myocardia. This effect of quercetin was completely inhibited by cyclopiazonic acid but not by SEA0400. These results indicated that quercetin accelerates myocardial relaxation through activation of the sarco-endoplasmic reticulum Ca2+-ATPase.

Tetrahydrocurcumin Upregulates the Adiponectin-AdipoR Pathway and Improves Insulin Signaling and Pancreatic ß-Cell Function in High-Fat Diet/Streptozotocin-Induced Diabetic Obese Mice.

Impairment of adiponectin production and function is closely associated with insulin resistance and type 2 diabetes, which are linked to obesity. Studies in animal models have documented the anti-diabetic effects of tetrahydrocurcumin (THC). Although several possible mechanisms have been proposed, the contribution of adiponectin signaling on THC-mediated antihyperglycemic effects remains unknown. Here, we report that adiposity, steatosis, and hyperglycemia were potently attenuated in high-fat diet/streptozotocin-induced diabetic obese mice after they received 20 and 100 mg/kg THC for 14 weeks. THC upregulated UCP-1 in adipose tissue and elevated adiponectin levels in the circulation. THC upregulated the AdipoR1/R2-APPL1-mediated pathway in the liver and skeletal muscle, which contributes to improved insulin signaling, glucose utilization, and lipid metabolism. Furthermore, THC treatment significantly (p < 0.05) preserved islet mass, reduced apoptosis, and restored defective insulin expression in the pancreatic ß-cells of diabetic obese mice, which was accompanied by an elevation of AdipoR1 and APPL1. These results demonstrated a potential mechanism underlying the beneficial effects of THC against hyperglycemia via the adiponectin-AdipoR pathway, and thus, may lead to a novel therapeutic use for type 2 diabetes.

Evaluación del efecto hipoglucemiante de una fracción peptídica de las semillas de chía (Salvia hispanica L) en ratas macho Wistar inducidas con aloxano / Evaluation of the hypoglycemic effect of a peptide fraction of chia seeds (Salvia hispánica L) in male Wistar rats induced with alloxan

Introducción: se han realizado investigaciones sobre la diabetes con péptidos de diferentes fuentes alimentarias en animales experimentales para aplicarse después en los seres humanos. Objetivo: la finalidad de este trabajo fue evaluar en ratas el efecto hipoglucemiante de una fracción peptídica de chía obtenida por hidrólisis enzimática. Materiales y métodos: de la harina de chía se obtuvo una fracción rica en proteína que fue hidrolizada con pepsina-pancreatina, generándose una fracción peptídica (> 10 kDa) por ultrafiltración. Se utilizaron cinco grupos de ratas (uno de normoglucémicas y cuatro de diabetizadas con aloxano). Se realizó una curva de tolerancia a la sacarosa, proporcionándoles el disacárido antes de la medición. La sangre se tomó de la punta de la cola a los 0, 30, 60, 90 y 120 minutos. Resultados: el contenido proteico de la harina fue del 49,51 %. La fracción peptídica (> 10 kDa) presentó un 91 % de proteína; de esta se suministró una dosis de 50 mg/kg que demostró una tendencia a la disminución de la glucosa sanguínea en la primera hora, aunque no se encontró significancia entre el blanco y las dosis evaluadas. No hubo disminución de la absorción de glucosa frente al fármaco de referencia. A los 120 min del periodo postprandial no se encontraron diferencias entre las dosis, el blanco y la acarbosa, lo que denota un retorno al estado basal. Los valores en las ratas diabetizadas fueron opuestos a los de la acarbosa, por lo que no existió relación entre el mecanismo de acción del fármaco con el efecto analizado. Conclusión: las fracciones peptídicas de chía de > 10 kDa no presentaron efecto hipoglucemiante con la dosis única suministrada. (AU)

Introduction: diabetes research with peptides from foods has been conducted in animal experiments to be later applied to humans. Objective: the main purpose of this work was to evaluate in rats the hypoglycemic effect of a peptide fraction of chia seeds derived by enzymatic hydrolysis. Materials and methods: from chia flour a protein-rich fraction was obtained, which was hydrolyzed with pepsin-pancreatin system enzymes to yield a peptide fraction (> 10 kDa) by ultrafiltration. Five rat groups (one normoglycemic and four diabetized with alloxan) were used. A sucrose tolerance curve was performed, providing the disaccharide before measurement. Blood was taken from the tip of the tail at 0 (before sugar), 30, 60, 90, and 120 minutes. Results: the protein content of chia flour was 49.51 %. The peptide fraction (> 10 kDa) had 91 % of protein. A dose of 50 mg/kg showed in rats a tendency to decrease blood glucose within the first hour, but no significance was found between the target and the doses evaluated. There was no decrease in glucose absorption vs. the reference drug. At 120 min postprandial, no differences were found between doses, water, and acarbose, showing a return to the baseline status. The tolerance curve in diabetic rats was opposite to that of acarbose, so there was no relationship between the drug's mechanism of action and this analyzed effect. Conclusion: the peptide fraction of chia of > 10 kDa showed no hypoglycemic effect at the single dose that was administered. (AU)

Diabetes and Cognitive Impairment: A Role for Glucotoxicity and Dopaminergic Dysfunction.

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia, responsible for the onset of several long-term complications. Recent evidence suggests that cognitive dysfunction represents an emerging complication of DM, but the underlying molecular mechanisms are still obscure. Dopamine (DA), a neurotransmitter essentially known for its relevance in the regulation of behavior and movement, modulates cognitive function, too. Interestingly, alterations of the dopaminergic system have been observed in DM. This review aims to offer a comprehensive overview of the most relevant experimental results assessing DA's role in cognitive function, highlighting the presence of dopaminergic dysfunction in DM and supporting a role for glucotoxicity in DM-associated dopaminergic dysfunction and cognitive impairment. Several studies confirm a role for DA in cognition both in animal models and in humans. Similarly, significant alterations of the dopaminergic system have been observed in animal models of experimental diabetes and in diabetic patients, too. Evidence is accumulating that advanced glycation end products (AGEs) and their precursor methylglyoxal (MGO) are associated with cognitive impairment and alterations of the dopaminergic system. Further research is needed to clarify the molecular mechanisms linking DM-associated dopaminergic dysfunction and cognitive impairment and to assess the deleterious impact of glucotoxicity.

Diacerein attenuates vascular dysfunction by reducing inflammatory response and insulin resistance in type 2 diabetic rats.

AIM: To examine the effect of diacerein on vascular dysfunction in type 2 diabetic rats and elucidate the mechanism of diacerein. METHODS: In a rat model, type 2 diabetes was induced by high-fat diet and streptozotocin. Vascular function was assessed in vascular reactivity experiment. The effect of diacerein (10 or 20 mg/kg/day) on blood glucose, inflammation and insulin signaling, and modulators in vascular tissue in diabetic rats were investigated by molecular and biochemical approaches. RESULTS: In this study, diacerein inhibited diabetes-induced vascular dysfunction. Diacerein treatment normalized blood glucose, insulin tolerance test, inflammatory cytokine levels and nitric oxide synthases expression in diabetic rats. Moreover, diacerein inhibited NF-κB and NLRP3 pathways and activated insulin signaling pathway related proteins IRS-1 and AKT in diabetic rats. CONCLUSION: Diacerein improved vascular function effectively in diabetic rats by suppressing inflammation and reducing insulin resistance. These results suggest that diacerein may represent a novel therapy for patients with diabetes.

Isoliquiritigenin attenuates acute renal injury through suppressing oxidative stress, fibrosis and JAK2/STAT3 pathway in streptozotocin-induced diabetic rats.

The aim of the current study was to evaluate the protective effects and mechanisms of isoliquiritigenin (ISO) on acute renal injury. CCK-8 assays were applied to assess the effects of ISO at different doses (20, 40, and 80 µg/mL) on oxidative damage in human renal HK-2 cells incubated with high glucose. After the diabetic nephropathy (DN) rat model was established, the model animals were randomly assigned to saline-treated control, three model groups received the 10, 20 and 40 mg/kg ISO, respectively, using the healthy Sprague-Dawley (SD) rats as normal control. The blood biochemical indexes, renal functions, oxidative stress, morphological changes, fibrosis- and JAK2/STAT3-related factors in DN model rats were all assessed. The cellular viability of the renal HK-2 cells with oxidative damages were all markedly ameliorated via the incubation of ISO between 10 and 80 µg/mL compared with negative control. In addition, the significantly down-regulated ROS content and up-regulated expression levels of GSH, SOD2, and GPX1 were all observed in ISO-treated groups. Long-term administration of ISO at different doses in DN rats effectively improved general diabetic characteristics and renal morphology. Furthermore, long-term administration of ISO could ameliorate excessive oxidation stress, down-regulate the expression levels of renal fibrosis- and inflammation-related factors, as well as inhibit the JAK2/STAT3 signaling pathway. In conclusion, ISO at all three dosages could efficiently improve the renal injury induced by STZ via ameliorating renal fibrosis, oxidative stress, and inhibiting JAK2/STAT3 signaling pathways in the DN rats.

Long Noncoding RNA 3632454L22Rik Contributes to Corneal Epithelial Wound Healing by Sponging miR-181a-5p in Diabetic Mice.

Purpose: This work explores the abnormal expression of long noncoding RNAs (lncRNAs), microRNAs (miRNAs) and messenger RNAs (mRNAs) in diabetic corneal epithelial cells (CECs) and constructs an associated competitive endogenous RNA (ceRNA) network. Moreover, we revealed that Rik may exert advantageous effects on diabetic corneal epithelial wound closure by sponging miR-181a-5p. Methods: We obtained the profiles of differentially expressed lncRNAs (DELs) of CECs of type 1 diabetic versus control corneas by microarray and summarized the differentially expressed miRNAs (DEmiRs) and differentially expressed genes (DEGs) data by published literature. Subsequently, the ceRNA network was constructed using bioinformatics analyses. The levels of lncRNA ENSMUST00000153610/3632454L22Rik (Rik) and miR-181a-5p were verified. The localization of Rik was identified with fluorescence in situ hybridization (FISH), and dual-luciferase assays proved the targeted relationship between Rik and miR-181a-5p. Furthermore, we validated the functional impact of Rik in vitro. Results: Overall, 111 upregulated and 117 downregulated DELs were detected in diabetic versus control CECs. The level of Rik located in both the cytoplasm and the nucleus was clearly downregulated, whereas miR-181a-5p was upregulated in vitro and in vivo in the diabetic group versus the control group. Rik can act as a ceRNA to bind to miR-181a-5p, thus promoting diabetic corneal epithelial wound healing in vitro. Conclusions: This work investigated the expression profile of DELs and constructed ceRNA networks of diabetic CECs for the first time. Furthermore, we revealed that Rik may positively impact diabetic corneal epithelial wound healing by sponging miR-181a-5p, providing a novel potential therapeutic target of diabetic keratopathy (DK).