Chronic AT1 blockade improves hyperglycemia by decreasing adipocyte inflammation and decreasing hepatic PCK1 and G6PC1 expression in obese rats

2021 ◽  
Author(s):  
Ruben Rodriguez ◽  
Andrew Y Lee ◽  
Jose A Godoy-Lugo ◽  
Bridget Martinez ◽  
Hiroyuki Ohsaki ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Soleus Muscle ◽  
Hepatic Glucose Production ◽  
Dynamic Responses ◽  
Male Rats ◽  
Peripheral Tissues ◽  
Akt Phosphorylation ◽  
Tnf Α ◽  
Glucose Challenge ◽  
Time Point

Inappropriate activation of the renin-angiotensin system decreases glucose uptake in peripheral tissues. Chronic angiotensin receptor type 1 (AT1) blockade increases glucose uptake in skeletal muscle, decreases the abundance of large adipocytes, and macrophage infiltration in adipose. However, the contributions of each tissue to the improvement in hyperglycemia in response to AT1 blockade are not known. Therefore, we determined the static and dynamic responses of soleus muscle, liver, and adipose to an acute glucose challenge following the chronic blockade of AT1. We measured adipocyte morphology along with TNF-α expression, F4/80 and CD11c positive cells in adipose and measured insulin receptor (IR) phosphorylation and AKT phosphorylation in soleus muscle, liver, and retroperitoneal fat before (T0), 60 (T60), and 120 (T120) minutes after an acute glucose challenge in the following groups of male rats: LETO (lean control; n = 5/time point), (2) obese OLETF (n = 7-8/time point) and (3) OLETF + ARB (ARB; 10 mg olmesartan/kg/d; n = 7-8/time point). AT1 blockade decreased adipocyte TNF-α expression and F4/80 and CD11c positive cells. In retroperitoneal fat at T60, IR phosphorylation was 155% greater in ARB than in OLETF. Furthermore, in retroperitoneal fat AT1 blockade increased GLUT4 protein expression in ARB compared to OLETF. IR phosphorylation and AKT phosphorylation were not altered in the liver of OLETF, but AT1 blockade decreased hepatic PCK1 and G6PC1 mRNA expressions. Collectively, these results suggest that chronic AT1 blockade improves obesity-associated hyperglycemia in OLETF rats by improving adipocyte function and by decreasing hepatic glucose production via gluconeogenesis.

scholarly journals Glucose-dependent insulinotropic polypeptide directly induces glucose transport in rat skeletal muscle

2015 ◽  
Vol 309 (3) ◽  
pp. R295-R303 ◽  
Author(s):  
Laelie A. Snook ◽  
Emery M. Nelson ◽  
David J. Dyck ◽  
David C. Wright ◽  
Graham P. Holloway
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Soleus Muscle ◽  
Serum Insulin ◽  
Current Data ◽  
Signaling Mechanism ◽  
Akt Phosphorylation ◽  
Glucose Challenge ◽  
Muscle Glucose Transport

Several gastrointestinal proteins have been identified to have insulinotropic effects, including glucose-dependent insulinotropic polypeptide (GIP); however, the direct effects of incretins on skeletal muscle glucose transport remain largely unknown. Therefore, the purpose of the current study was to examine the role of GIP on skeletal muscle glucose transport and insulin signaling in rats. Relative to a glucose challenge, a mixed glucose+lipid oral challenge increased circulating GIP concentrations, skeletal muscle Akt phosphorylation, and improved glucose clearance by ∼35% ( P < 0.05). These responses occurred without alterations in serum insulin concentrations. In an incubated soleus muscle preparation, GIP directly stimulated glucose transport and increased GLUT4 accumulation on the plasma membrane in the absence of insulin. Moreover, the ability of GIP to stimulate glucose transport was mitigated by the addition of the PI 3-kinase (PI3K) inhibitor wortmannin, suggesting that signaling through PI3K is required for these responses. We also provide evidence that the combined stimulatory effects of GIP and insulin on soleus muscle glucose transport are additive. However, the specific GIP receptor antagonist (Pro3)GIP did not attenuate GIP-stimulated glucose transport, suggesting that GIP is not signaling through its classical receptor. Together, the current data provide evidence that GIP regulates skeletal muscle glucose transport; however, the exact signaling mechanism(s) remain unknown.

Maternal protein restriction during early lactation induces GLUT4 translocation and mTOR/Akt activation in adipocytes of adult rats

2008 ◽  
Vol 295 (3) ◽  
pp. E626-E636 ◽  
Author(s):  
Érica Patrícia Garcia-Souza ◽  
Simone Vargas da Silva ◽  
Gisele Barreto Félix ◽  
Ananda Lages Rodrigues ◽  
Marta Sampaio de Freitas ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
Glucose Uptake ◽  
Glucose Homeostasis ◽  
Insulin Signaling ◽  
Molecular Mechanisms ◽  
Experimental Studies ◽  
Male Rats ◽  
Early Lactation ◽  
Peripheral Tissues

Epidemiological and experimental studies have demonstrated that early postnatal nutrition has been associated with long-term effects on glucose homeostasis in adulthood. Recently, our group demonstrated that undernutrition during early lactation affects the expression and activation of key proteins of the insulin signaling cascade in rat skeletal muscle during postnatal development. To elucidate the molecular mechanisms by which undernutrition during early life leads to changes in insulin sensitivity in peripheral tissues, we investigated the insulin signaling in adipose tissue. Adipocytes were isolated from epididymal fat pads of adult male rats that were the offspring of dams fed either a normal or a protein-free diet during the first 10 days of lactation. The cells were incubated with 100 nM insulin before the assays for immunoblotting analysis, 2-deoxyglucose uptake, immunocytochemistry for GLUT4, and/or actin filaments. Following insulin stimulation, adipocytes isolated from undernourished rats presented reduced tyrosine phosphorylation of IR and IRS-1 and increased basal phosphorylation of IRS-2, Akt, and mTOR compared with controls. Basal glucose uptake was increased in adipocytes from the undernourished group, and the treatment with LY294002 induced only a partial inhibition both in basal and in insulin-stimulated glucose uptake, suggesting an involvement of phosphoinositide 3-kinase activity. These alterations were accompanied by higher GLUT4 content in the plasma membrane and alterations in the actin cytoskeleton dynamics. These data suggest that early postnatal undernutrition impairs insulin sensitivity in adulthood by promoting changes in critical steps of insulin signaling in adipose tissue, which may contribute to permanent changes in glucose homeostasis.

scholarly journals Peripheral insulin resistance in ILK-depleted mice by reduction of GLUT4 expression

2017 ◽  
Vol 234 (2) ◽  
pp. 115-128 ◽  
Author(s):  
Marco Hatem-Vaquero ◽  
Mercedes Griera ◽  
Andrea García-Jerez ◽  
Alicia Luengo ◽  
Julia Álvarez ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Chow Diet ◽  
Peripheral Tissues ◽  
Akt Phosphorylation ◽  
Glut4 Expression

The development of insulin resistance is characterized by the impairment of glucose uptake mediated by glucose transporter 4 (GLUT4). Extracellular matrix changes are induced when the metabolic dysregulation is sustained. The present work was devoted to analyze the possible link between the extracellular-to-intracellular mediator integrin-linked kinase (ILK) and the peripheral tissue modification that leads to glucose homeostasis impairment. Mice with general depletion of ILK in adulthood (cKD-ILK) maintained in a chow diet exhibited increased glycemia and insulinemia concurrently with a reduction of the expression and membrane presence of GLUT4 in the insulin-sensitive peripheral tissues compared with their wild-type littermates (WT). Tolerance tests and insulin sensitivity indexes confirmed the insulin resistance in cKD-ILK, suggesting a similar stage to prediabetes in humans. Under randomly fed conditions, no differences between cKD-ILK and WT were observed in the expression of insulin receptor (IR-B) and its substrate IRS-1 expressions. The IR-B isoform phosphorylated at tyrosines 1150/1151 was increased, but the AKT phosphorylation in serine 473 was reduced in cKD-ILK tissues. Similarly, ILK-blocked myotubes reduced their GLUT4 promoter activity and GLUT4 expression levels. On the other hand, the glucose uptake capacity in response to exogenous insulin was impaired when ILK was blocked in vivo and in vitro, although IR/IRS/AKT phosphorylation states were increased but not different between groups. We conclude that ILK depletion modifies the transcription of GLUT4, which results in reduced peripheral insulin sensitivity and glucose uptake, suggesting ILK as a molecular target and a prognostic biomarker of insulin resistance.

Alteration of intrapancreatic serotonin, homocysteine, TNF-α, and NGF levels as predisposing factors for diabetes following exposure to 900-MHz waves

2021 ◽  
pp. 074823372110226
Author(s):  
Gholamali Jelodar ◽  
Mansour Azimzadeh ◽  
Fatemeh Radmard ◽  
Narges Darvishhoo
Keyword(s):  
Cell Damage ◽  
Pancreatic Beta Cell ◽  
Predisposing Factors ◽  
Male Rats ◽  
Control Group ◽  
Predisposing Factor ◽  
Time Exposure ◽  
Tnf Α ◽  
Long Time ◽  
Short Time

Exposure to mobile phone radiation causes deleterious health effects on biological systems. The objects of this study were to investigate the effect of 900-MHz radiofrequency waves (RFW) emitted from base transceiver station antenna on intrapancreatic homocysteine (Hcy), tumor necrosis factor-α (TNF-α), and nerve growth factor (NGF) as predisposing factors involved in pancreatic beta cell damage. Thirty male rats (Sprague-Dawley, 200 ± 10 g) were randomly divided into the control (without any exposure) and exposed groups: short time (2 h/day), long time (4 h/day), and exposed to 900-MHz RFW for 30 consecutive days. On the last days of the experiment, animals were killed and pancreas tissue was dissected out for evaluation of serotonin, Hcy, TNF-α, and NGF. There was a significant decrease in the serotonin and NGF levels in the pancreatic tissue of exposed groups compared to the control group ( p < 0.05). Also, the levels of serotonin and NGF in the long-time exposure were significantly lower than the short-time exposure ( p < 0.05). However, levels of Hcy and TNF-α were significantly increased in the pancreas of exposed groups compared to the control groups ( p < 0.05). Exposure to 900-MHz RFW decreased pancreatic NGF and serotonin levels and increased the proinflammatory markers (Hcy and TNF-α), which can be a predisposing factor for type 2 diabetes.

scholarly journals Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Mayarling Francisca Troncoso ◽  
Mario Pavez ◽  
Carlos Wilson ◽  
Daniel Lagos ◽  
Javier Duran ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Cardiac Hypertrophy ◽  
Glucose Uptake ◽  
Male Rats ◽  
Cardiomyocyte Hypertrophy ◽  
Mrna Levels ◽  
Elevated Glucose ◽  
Amp Activated Protein Kinase ◽  
Cultured Cardiomyocytes

Abstract Background Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake—via AMP-activated protein kinase (AMPK)—after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR). Methods Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of β-myosin heavy chain (β-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR). Results Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated β-mhc, Hk2 and Pfk2 mRNA levels. Conclusion These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.

scholarly journals Evaluation of Pulp Repair after BiodentineTM Full Pulpotomy in a Rat Molar Model of Pulpitis

Biomedicines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 784
Author(s):  
Sandra Minic ◽  
Marion Florimond ◽  
Jérémy Sadoine ◽  
Anne Valot-Salengro ◽  
Catherine Chaussain ◽  
...  
Keyword(s):  
Immunohistochemical Analysis ◽  
Tricalcium Silicate ◽  
Male Rats ◽  
Enzyme Linked Immunosorbent Assay ◽  
E Coli ◽  
Inflammatory Conditions ◽  
Tnf Α ◽  
Pulp Inflammation ◽  
Characteristics Analysis ◽  
Pulp Repair

Dental pulp is a dynamic tissue able to heal after injury under moderate inflammatory conditions. Our study aimed to evaluate pulp repair under inflammatory conditions in rats. For this purpose, we developed a rat model of controlled pulpitis followed by pulpotomy with a tricalcium silicate-based cement. Fifty-four cavities were prepared on the occlusal face of the maxillary upper first molar of 27 eight-week-old male rats. E. coli lipopolysaccharides at 10 mg/mL or phosphate-buffered saline PBS was injected after pulp injury. Non-inflamed molars were used as controls. Levels of inflammation-related molecules were measured 6 and 24 h after induction by enzyme-linked immunosorbent assay of coronal pulp samples. Pulp capping and coronal obturation after pulpotomy were performed with tricalcium silicate-based cement. Four and fifteen days after pulpotomy, histological and immunohistochemical analysis was performed to assess pulp inflammation and repair processes. Our results showed significantly higher levels of innate inflammatory proteins (IL-1β, IL-6, TNF-α and CXCL-1) compared with those in controls. Moderate residual inflammation near the capping material was demonstrated by histology and immunohistochemistry, with the presence of few CD68-positive cells. We showed that, in this model of controlled pulpitis, pulpotomy with BiodentineTM allowed the synthesis at the injury site of a mineralized bridge formed from mineralized tissue secreted by cells displaying odontoblastic characteristics. Analysis of these data suggests overall that, with the limitations inherent to findings in animal models, pulpotomy with a silicate-based cement is a good treatment for controlling inflammation and enhancing repair in cases of controlled pulpitis.

scholarly journals Cardioprotective effects of Ginsenoside compound-Mc1 and Dendrobium Nobile Lindl against myocardial infarction in an aged rat model: Involvement of TLR4/NF-κB signaling pathway

2021 ◽  
Vol 19 ◽  
pp. 205873922110005
Author(s):  
Yongle Sun ◽  
Jing Geng ◽  
Deyu Wang
Keyword(s):  
Myocardial Infarction ◽  
Combination Therapy ◽  
Infarct Size ◽  
Signaling Pathway ◽  
Left Ventricular ◽  
Male Rats ◽  
Dendrobium Nobile ◽  
Tnf Α ◽  
Cardioprotective Effects ◽  
Dendrobium Nobile Lindl

Aging is the crucial co-morbidity that prevents the full cardioprotection against myocardial ischemia/reperfusion (I/R) injury. Combination therapy as a promising strategy may overcome this clinical problem. This study aimed to investigate the cardioprotective effects of Ginsenoside compound-Mc1 (GMc1) and Dendrobium Nobile Lindl (DNL) in myocardial I/R injury and explore the involvement of the TLR4/NF-κB signaling pathway in aged rats. In vivo I/R injury and myocardial infarction was established by temporary coronary ligation in 22–24 months’ old Sprague Dawley male rats. GMc1 (10 mg/kg) and DNL (80 mg/kg) were administered intraperitoneally for 4 weeks and orally for 14 days, respectively, before I/R injury. Infarct size was measured through triphenyl-tetrazolium-chloride staining. ELISA assay was conducted to quantify the levels of cardiotroponin, and myocardial content of TNF-α and glutathione. Western blotting was employed to detect the expression of TLR4/MyD88/NF-κB proteins. GMc1 and DNL significantly reduced the infarct size to a similar extent ( p < 0.05) but their combined effect was greater than individual ones ( p < 0.01). Combination therapy significantly restored the left ventricular end-diastolic and developed pressures at the end of reperfusion as compared with the untreated group ( p < 0.01). Although the GMc1 and DNL reduced the levels of inflammatory cytokine TNF-α and increased the contents of antioxidant glutathione significantly, their individual effects on the reduction of protein expression of TLR4/MyD88/NF-κB pathway were not consistent. However, their combination could significantly reduce all parameters of this inflammatory pathway as compared to untreated I/R rats ( p < 0.001). Therefore, the combined treatment with GMc1 and DNL increased the potency of each intervention in protecting the aged hearts against I/R injury. Reduction in the activity of the TLR4/MyD88/NF-κB signaling pathway and subsequent modulation of the activity of inflammatory cytokines and endogenous antioxidants play an important role in this cardioprotection.

scholarly journals NF-κB-Inducing Kinase (NIK) Mediates Skeletal Muscle Insulin Resistance: Blockade by Adiponectin

Endocrinology ◽  
2011 ◽  
Vol 152 (10) ◽  
pp. 3622-3627 ◽  
Author(s):  
Sanjeev Choudhary ◽  
Sandeep Sinha ◽  
Yanhua Zhao ◽  
Srijita Banerjee ◽  
Padma Sathyanarayana ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Kinase Activity ◽  
Pi3 Kinase ◽  
Dominant Negative ◽  
Muscle Insulin Resistance ◽  
Akt Phosphorylation ◽  
Skeletal Muscle Insulin Resistance ◽  
Obese Subjects

Enhanced levels of nuclear factor (NF)-κB-inducing kinase (NIK), an upstream kinase in the NF-κB pathway, have been implicated in the pathogenesis of chronic inflammation in diabetes. We investigated whether increased levels of NIK could induce skeletal muscle insulin resistance. Six obese subjects with metabolic syndrome underwent skeletal muscle biopsies before and six months after gastric bypass surgery to quantitate NIK protein levels. L6 skeletal myotubes, transfected with NIK wild-type or NIK kinase-dead dominant negative plasmids, were treated with insulin alone or with adiponectin and insulin. Effects of NIK overexpression on insulin-stimulated glucose uptake were estimated using tritiated 2-deoxyglucose uptake. NF-κB activation (EMSA), phosphatidylinositol 3 (PI3) kinase activity, and phosphorylation of inhibitor κB kinase β and serine-threonine kinase (Akt) were measured. After weight loss, skeletal muscle NIK protein was significantly reduced in association with increased plasma adiponectin and enhanced AMP kinase phosphorylation and insulin sensitivity in obese subjects. Enhanced NIK expression in cultured L6 myotubes induced a dose-dependent decrease in insulin-stimulated glucose uptake. The decrease in insulin-stimulated glucose uptake was associated with a significant decrease in PI3 kinase activity and protein kinase B/Akt phosphorylation. Overexpression of NIK kinase-dead dominant negative did not affect insulin-stimulated glucose uptake. Adiponectin treatment inhibited NIK-induced NF-κB activation and restored insulin sensitivity by restoring PI3 kinase activation and subsequent Akt phosphorylation. These results indicate that NIK induces insulin resistance and further indicate that adiponectin exerts its insulin-sensitizing effect by suppressing NIK-induced skeletal muscle inflammation. These observations suggest that NIK could be an important therapeutic target for the treatment of insulin resistance associated with inflammation in obesity and type 2 diabetes.

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