scholarly journals Excitatory transmission onto AgRP neurons is regulated by cJun NH2-terminal kinase 3 in response to metabolic stress

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Santiago Vernia ◽  
Caroline Morel ◽  
Joseph C Madara ◽  
Julie Cavanagh-Kyros ◽  
Tamera Barrett ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
High Fat Diet ◽  
Leptin Receptor ◽  
Metabolic Stress ◽  
Homeostatic Regulation ◽  
High Fat ◽  
Jnk Signaling ◽  
Excitatory Transmission ◽  
Jnk Signaling Pathway

The cJun NH2-terminal kinase (JNK) signaling pathway is implicated in the response to metabolic stress. Indeed, it is established that the ubiquitously expressed JNK1 and JNK2 isoforms regulate energy expenditure and insulin resistance. However, the role of the neuron-specific isoform JNK3 is unclear. Here we demonstrate that JNK3 deficiency causes hyperphagia selectively in high fat diet (HFD)-fed mice. JNK3 deficiency in neurons that express the leptin receptor LEPRb was sufficient to cause HFD-dependent hyperphagia. Studies of sub-groups of leptin-responsive neurons demonstrated that JNK3 deficiency in AgRP neurons, but not POMC neurons, was sufficient to cause the hyperphagic response. These effects of JNK3 deficiency were associated with enhanced excitatory signaling by AgRP neurons in HFD-fed mice. JNK3 therefore provides a mechanism that contributes to homeostatic regulation of energy balance in response to metabolic stress.

Altered bone metabolism after high fat diet and exercise: role of Wnt signaling and insulin resistance

2016 ◽  
Author(s):  
Ann-Kristin Picke ◽  
Lykke Sylow ◽  
Lisbeth L V Moller ◽  
Rasmus Kjobsted ◽  
Erik Richter ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Wnt Signaling ◽  
Bone Metabolism ◽  
High Fat Diet ◽  
High Fat ◽  
Diet And Exercise

Loss of regulation of lipogenesis in the Zucker diabetic (ZDF) rat

2000 ◽  
Vol 279 (2) ◽  
pp. E425-E432 ◽  
Author(s):  
W.-N. Paul Lee ◽  
Sara Bassilian ◽  
Shu Lim ◽  
Laszlo G. Boros
Keyword(s):  
High Fat Diet ◽  
Leptin Receptor ◽  
De Novo ◽  
De Novo Lipogenesis ◽  
Chain Elongation ◽  
Deuterated Water ◽  
High Fat ◽  
Macronutrient Composition ◽  
Zdf Rat

We present here a study on the role of leptin in the regulation of lipogenesis by examining the effect of dietary macronutrient composition on lipogenesis in the leptin receptor-defective Zucker diabetic fatty rat (ZDF) and its lean litter mate (ZL). Animals were pair fed two isocaloric diets differing in their fat-to-carbohydrate ratio providing 10 and 30% energy as fat. Lipogenesis was measured in the rats using deuterated water and isotopomer analysis. From the deuterium incorporation into plasma palmitate, stearate, and oleate, we determined de novo synthesis of palmitate and synthesis of stearate by chain elongation and of oleate by desaturation. Because the macronutrient composition and the caloric density were controlled, changes in de novo lipogenesis under these dietary conditions represent adaptation to changes in the fat-to-carbohydrate ratio of the diet. De novo lipogenesis was normally suppressed in response to the high-fat diet in the ZL rat to maintain a relatively constant amount of lipids transported. The ZDF rat had a higher rate of lipogenesis, which was not suppressed by the high-fat diet. The results suggest an important hormonal role of leptin in the feedback regulation of lipogenesis.

scholarly journals CD44 contributes to hyaluronan-mediated insulin resistance in skeletal muscle of high-fat-fed C57BL/6 mice

2019 ◽  
Vol 317 (6) ◽  
pp. E973-E983 ◽  
Author(s):  
Annie Hasib ◽  
Chandani K. Hennayake ◽  
Deanna P. Bracy ◽  
Aimée R. Bugler-Lamb ◽  
Louise Lantier ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
High Fat Diet ◽  
Critical Role ◽  
Chow Diet ◽  
Wild Type ◽  
High Fat ◽  
Insulin Resistant ◽  
Beneficial Effects

Extracellular matrix hyaluronan is increased in skeletal muscle of high-fat-fed insulin-resistant mice, and reduction of hyaluronan by PEGPH20 hyaluronidase ameliorates diet-induced insulin resistance (IR). CD44, the main hyaluronan receptor, is positively correlated with type 2 diabetes. This study determines the role of CD44 in skeletal muscle IR. Global CD44-deficient ( cd44−/−) mice and wild-type littermates ( cd44+/+) were fed a chow diet or 60% high-fat diet for 16 wk. High-fat-fed cd44−/− mice were also treated with PEGPH20 to evaluate its CD44-dependent action. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp (ICv). High-fat feeding increased muscle CD44 protein expression. In the absence of differences in body weight and composition, despite lower clamp insulin during ICv, the cd44−/− mice had sustained glucose infusion rate (GIR) regardless of diet. High-fat diet-induced muscle IR as evidenced by decreased muscle glucose uptake (Rg) was exhibited in cd44+/+ mice but absent in cd44−/− mice. Moreover, gastrocnemius Rg remained unchanged between genotypes on chow diet but was increased in high-fat-fed cd44−/− compared with cd44+/+ when normalized to clamp insulin concentrations. Ameliorated muscle IR in high-fat-fed cd44−/− mice was associated with increased vascularization. In contrast to previously observed increases in wild-type mice, PEGPH20 treatment in high-fat-fed cd44−/− mice did not change GIR or muscle Rg during ICv, suggesting a CD44-dependent action. In conclusion, genetic CD44 deletion improves muscle IR, and the beneficial effects of PEGPH20 are CD44-dependent. These results suggest a critical role of CD44 in promoting hyaluronan-mediated muscle IR, therefore representing a potential therapeutic target for diabetes.

scholarly journals Role of Supplementary Selenium on the Induction of Insulin Resistance and Oxidative Stress in NSY Mice Fed a High Fat Diet

2018 ◽  
Vol 41 (1) ◽  
pp. 92-98 ◽  
Author(s):  
Koichi Murano ◽  
Hirofumi Ogino ◽  
Tomofumi Okuno ◽  
Tomohiro Arakawa ◽  
Hitoshi Ueno
Keyword(s):  
Oxidative Stress ◽  
Insulin Resistance ◽  
High Fat Diet ◽  
High Fat ◽  
And Oxidative Stress

scholarly journals NOX4 Deficiency Exacerbates the Impairment of Cystatin C-Dependent Hippocampal Neurogenesis by a Chronic High Fat Diet

Genes ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 567
Author(s):  
Piyanart Jiranugrom ◽  
Ik Dong Yoo ◽  
Min Woo Park ◽  
Ji Hwan Ryu ◽  
Jong-Seok Moon ◽  
...  
Keyword(s):  
Cystatin C ◽  
High Fat Diet ◽  
Metabolic Stress ◽  
Hippocampal Neurogenesis ◽  
High Fat ◽  
Nadph Oxidase 4 ◽  
Normal Physiological Condition ◽  
Normal Chow ◽  
Differentiation Marker

Hippocampal neurogenesis is linked with a cognitive process under a normal physiological condition including learning, memory, pattern separation, and cognitive flexibility. Hippocampal neurogenesis is altered by multiple factors such as the systemic metabolic changes. NADPH oxidase 4 (NOX4) has been implicated in the regulation of brain function. While the role of NOX4 plays in the brain, the mechanism by which NOX4 regulates hippocampal neurogenesis under metabolic stress is unclear. In this case, we show that NOX4 deficiency exacerbates the impairment of hippocampal neurogenesis by inhibiting neuronal maturation by a chronic high fat diet (HFD). NOX4 deficiency resulted in less hippocampal neurogenesis by decreasing doublecortin (DCX)-positive neuroblasts, a neuronal differentiation marker, and their branched-dendrites. Notably, NOX4 deficiency exacerbates the impairment of hippocampal neurogenesis by chronic HFD. Moreover, NOX4 deficiency had a significant reduction of Cystatin C levels, which is critical for hippocampal neurogenesis, under chronic HFD as well as normal chow (NC) diet. Furthermore, the reduction of Cystatin C levels was correlated with the impairment of hippocampal neurogenesis in NOX4 deficient and wild-type (WT) mice under chronic HFD. Our results suggest that NOX4 regulates the impairment of Cystatin C-dependent hippocampal neurogenesis under chronic HFD.

scholarly journals Double-Stranded RNA-Activated Protein Kinase Is a Key Modulator of Insulin Sensitivity in Physiological Conditions and in Obesity in Mice

Endocrinology ◽  
2012 ◽  
Vol 153 (11) ◽  
pp. 5261-5274 ◽  
Author(s):  
M. A. Carvalho-Filho ◽  
B. M. Carvalho ◽  
A. G. Oliveira ◽  
D. Guadagnini ◽  
M. Ueno ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Protein Phosphatase ◽  
High Fat Diet ◽  
Obese Mice ◽  
High Fat ◽  
Double Stranded Rna ◽  
Physiological Conditions ◽  
Phosphatase 2A

Abstract The molecular integration of nutrient- and pathogen-sensing pathways has become of great interest in understanding the mechanisms of insulin resistance in obesity. The double-stranded RNA-dependent protein kinase (PKR) is one candidate molecule that may provide cross talk between inflammatory and metabolic signaling. The present study was performed to determine, first, the role of PKR in modulating insulin action and glucose metabolism in physiological situations, and second, the role of PKR in insulin resistance in obese mice. We used Pkr−/− and Pkr+/+ mice to investigate the role of PKR in modulating insulin sensitivity, glucose metabolism, and insulin signaling in liver, muscle, and adipose tissue in response to a high-fat diet. Our data show that in lean Pkr−/− mice, there is an improvement in insulin sensitivity, and in glucose tolerance, and a reduction in fasting blood glucose, probably related to a decrease in protein phosphatase 2A activity and a parallel increase in insulin-induced thymoma viral oncogene-1 (Akt) phosphorylation. PKR is activated in tissues of obese mice and can induce insulin resistance by directly binding to and inducing insulin receptor substrate (IRS)-1 serine307 phosphorylation or indirectly through modulation of c-Jun N-terminal kinase and inhibitor of κB kinase β. Pkr−/− mice were protected from high-fat diet-induced insulin resistance and glucose intolerance and showed improved insulin signaling associated with a reduction in c-Jun N-terminal kinase and inhibitor of κB kinase β phosphorylation in insulin-sensitive tissues. PKR may have a role in insulin sensitivity under normal physiological conditions, probably by modulating protein phosphatase 2A activity and serine-threonine kinase phosphorylation, and certainly, this kinase may represent a central mechanism for the integration of pathogen response and innate immunity with insulin action and metabolic pathways that are critical in obesity.

scholarly journals Role of Hepatic Glucocorticoid Receptor in Metabolism in Models of 5αR1 Deficiency in Male Mice

Endocrinology ◽  
2019 ◽  
Vol 160 (9) ◽  
pp. 2061-2073 ◽  
Author(s):  
Tracy C S Mak ◽  
Dawn E W Livingstone ◽  
Mark Nixon ◽  
Brian R Walker ◽  
Ruth Andrew
Keyword(s):  
Insulin Resistance ◽  
Glucocorticoid Receptor ◽  
High Fat Diet ◽  
Liver Steatosis ◽  
Area Under The Curve ◽  
High Fat ◽  
Glucose Challenge ◽  
Glucocorticoid Metabolism ◽  
Challenge Area

Abstract Inhibition of 5α-reductases impairs androgen and glucocorticoid metabolism and induces insulin resistance in humans and rodents. The contribution of hepatic glucocorticoids to these adverse metabolic changes was assessed using a liver-selective glucocorticoid receptor (GR) antagonist, A-348441. Mice lacking 5α-reductase 1 (5αR1-KO) and their littermate controls were studied during consumption of a high-fat diet, with or without A-348441(120 mg/kg/d). Male C57BL/6 mice (age, 12 weeks) receiving dutasteride (1.8 mg/kg/d)) or vehicle with consumption of a high-fat diet, with or without A-348441, were also studied. In the 5αR1-KO mice, hepatic GR antagonism improved diet-induced insulin resistance but not more than that of the controls. Liver steatosis was not affected by hepatic GR antagonism in either 5αR1KO mice or littermate controls. In a second model of 5α-reductase inhibition using dutasteride and hepatic GR antagonism with A-348441 attenuated the excess weight gain resulting from dutasteride (mean ± SEM, 7.03 ± 0.5 vs 2.13 ± 0.4 g; dutasteride vs dutasteride plus A-348441; P < 0.05) and normalized the associated hyperinsulinemia after glucose challenge (area under the curve, 235.9 ± 17 vs 329.3 ± 16 vs 198.4 ± 25 ng/mL/min; high fat vs high fat plus dutasteride vs high fat plus dutasteride plus A-348441, respectively; P < 0.05). However, A-348441 again did not reverse dutasteride-induced liver steatosis. Thus, overall hepatic GR antagonism improved the insulin resistance but not the steatosis induced by a high-fat diet. Moreover, it attenuated the excessive insulin resistance caused by pharmacological inhibition of 5α-reductases but not genetic disruption of 5αR1. The use of dutasteride might increase the risk of type 2 diabetes mellitus and reduced exposure to glucocorticoids might be beneficial.

Role of brown adipose tissue in modulating adipose tissue inflammation and insulin resistance in high-fat diet fed mice

2019 ◽  
Vol 854 ◽  
pp. 354-364 ◽  
Author(s):  
Kripa Shankar ◽  
Durgesh Kumar ◽  
Sanchita Gupta ◽  
Salil Varshney ◽  
Sujith Rajan ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
High Fat Diet ◽  
Adipose Tissue Inflammation ◽  
High Fat ◽  
Tissue Inflammation ◽  
Brown Adipose

Abstract P312: The Essential Role Of Prak In Preserving Cardiac Function And Insulin Resistance In High Fat Diet-induced Diabetes

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Yu T Zhao ◽  
Jianfeng Du ◽  
Thomas J Zhao ◽  
Hao Wang ◽  
Marshall Kadin ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Cardiac Function ◽  
Western Blot ◽  
Knockout Mice ◽  
High Fat Diet ◽  
Metabolic Disorders ◽  
Tolerance Test ◽  
Wild Type ◽  
High Fat

Background: p38 regulated/activated protein kinase (PRAK) plays a crucial role in modulating cell death and survival. However, the role of PRAK in mediating cardiac dysfunction and metabolic disorders remains unclear. We examined the effects of deletion of PRAK on modulating cardiac function and insulin resistance in mice exposed to a high fat diet (HFD). Methods: Wild type and PRAK -/- mice at 8 weeks old were exposed to either chow food or HFD for a consecutive 16 weeks. Glucose tolerance test and insulin tolerance test were employed to assess insulin resistance. Echocardiography was employed to assess myocardial function. Western blot was used to determine the molecular signaling involved in phosphorylation of IRS-1, AMPKα, ERK-44/42, and irisin. Real time-PCR was used to assess the hypertrophic genes of the myocardium. Histological analysis was employed to assess the hypertrophic response, interstitial myocardial fibrosis, and apoptosis in the heart. Results: HFD induced metabolic stress is indicated by glucose intolerance and insulin intolerance. PRAK knockout aggravated insulin resistance, as indicated by glucose intolerance and insulin intolerance testing as compared to wild type littermates. As compared to wild type, hyperglycemia and hypercholesterolemia were manifested in PRAK-knockout mice following high fat diet intervention. High fat diet intervention displayed a decline in fractional shortening (FS) and ejection fraction (EF). However, deletion of PRAK exacerbated the decline in EF and FS as compared to wild type mice following HFD treatment. In addition, PRAK knockout mice enhanced the expression of myocardial hypertrophic genes including ANP, BNP, and βMHC in HFD treatment, which was also associated with an increase in cardiomyocyte size and interstitial fibrosis. Western blot indicated that deletion of PRAK induces decreases in phosphorylation of IRS-1, AMPKα, and ERK44/42 as compared to wild type controls. Conclusion: Our finding indicates that deletion of PRAK promoted myocardial dysfunction, cardiac remodeling, and metabolic disorders in response to HFD.

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