scholarly journals Peripheral Dopamine Directly Acts on Insulin-Sensitive Tissues to Regulate Insulin Signaling and Metabolic Function

2021 ◽  
Vol 12 ◽  
Author(s):  
Gabriela Tavares ◽  
Fatima. O. Martins ◽  
Bernardete. F. Melo ◽  
Paulo Matafome ◽  
Silvia. V. Conde
Keyword(s):  
Adipose Tissue ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Dopamine Receptor ◽  
Soleus Muscle ◽  
Metabolic Function ◽  
Direct Effects ◽  
Brown Adipose ◽  
Dopamine Receptor 1

Dopamine is a key regulator of glucose metabolism in the central nervous system. However, dopamine is also present in the periphery and may have direct effects on insulin-sensitive tissues. Dopamine receptor 2 (D2R) agonist bromocriptine is a FDA-approved drug for type 2 diabetes. Herein, we explored the role of peripheral dopamine and its receptors in regulating glucose uptake and metabolism on insulin-sensitive tissues. Peripheral dopamine effect in [3H]2-deoxyglucose uptake in insulin-sensitive tissues was tested in vivo in rats. Direct effects on [3H]2-deoxyglucose uptake, insulin receptor phosphorylation, and regulation of metabolic function were tested ex vivo in the liver, soleus muscle, and white and brown adipose tissues. Bromocriptine and the antagonists domperidone, D2R antagonist, and haloperidol, antagonist of both dopamine receptor 1 (D1R) and D2R, were used to disclose dopamine receptors’ involvement.Peripheral dopamine increases glucose uptake in vivo. Ex vivo, only dopamine increased glucose uptake in the soleus, while bromocriptine increased it in the liver; the effects were reverted by haloperidol and domperidone, respectively. In adipose tissue, domperidone reverted dopamine- and bromocriptine-mediated potentiation of insulin-induced glucose uptake, but in turn increased the insulin receptor, Akt, AMPK, HSL, ACC, and ACL, phosphorylation. In the soleus muscle, AMPK-phosphorylation increased with bromocriptine and dopamine whose effects were suppressed by domperidone and haloperidol.In conclusion, peripheral dopamine stimulates glucose uptake with its receptors being differentially involved in glucose uptake in insulin-sensitive tissues. Dopamine also has a role in lipid metabolism in white adipose tissue. Altogether, these results suggest that peripheral modulation of the dopaminergic system should be further evaluated as a putative therapeutic approach for metabolic disorders.

scholarly journals RalA controls glucose homeostasis by regulating glucose uptake in brown fat

2018 ◽  
Vol 115 (30) ◽  
pp. 7819-7824 ◽  
Author(s):  
Yuliya Skorobogatko ◽  
Morgan Dragan ◽  
Claudia Cordon ◽  
Shannon M. Reilly ◽  
Chao-Wei Hung ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Brown Fat ◽  
Specific Chemical ◽  
Diet Induced Obesity ◽  
Brown Adipose ◽  
Chemical Inhibitors ◽  
Glucose Transporter Glut4

Insulin increases glucose uptake into adipose tissue and muscle by increasing trafficking of the glucose transporter Glut4. In cultured adipocytes, the exocytosis of Glut4 relies on activation of the small G protein RalA by insulin, via inhibition of its GTPase activating complex RalGAP. Here, we evaluate the role of RalA in glucose uptake in vivo with specific chemical inhibitors and by generation of mice with adipocyte-specific knockout of RalGAPB. RalA was profoundly activated in brown adipose tissue after feeding, and its inhibition prevented Glut4 exocytosis. RalGAPB knockout mice with diet-induced obesity were protected from the development of metabolic disease due to increased glucose uptake into brown fat. Thus, RalA plays a crucial role in glucose transport in adipose tissue in vivo.

scholarly journals Dopamine receptor D1- and D2-agonists do not spark brown adipose tissue thermogenesis in mice

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Francesca-Maria Raffaelli ◽  
Julia Resch ◽  
Rebecca Oelkrug ◽  
K. Alexander Iwen ◽  
Jens Mittag
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Dopamine Receptor ◽  
Ex Vivo ◽  
Potential Target ◽  
D2 Agonist ◽  
Obesity And Diabetes ◽  
Brown Adipose

AbstractBrown adipose tissue (BAT) thermogenesis is considered a potential target for treatment of obesity and diabetes. In vitro data suggest dopamine receptor signaling as a promising approach; however, the biological relevance of dopamine receptors in the direct activation of BAT thermogenesis in vivo remains unclear. We investigated BAT thermogenesis in vivo in mice using peripheral administration of D1-agonist SKF38393 or D2-agonist Sumanirole, infrared thermography, and in-depth molecular analyses of potential target tissues; and ex vivo in BAT explants to identify direct effects on key thermogenic markers. Acute in vivo treatment with the D1- or D2-agonist caused a short spike or brief decrease in BAT temperature, respectively. However, repeated daily administration did not induce lasting effects on BAT thermogenesis. Likewise, neither agonist directly affected Ucp1 or Dio2 mRNA expression in BAT explants. Taken together, the investigated agonists do not seem to exert lasting and physiologically relevant effects on BAT thermogenesis after peripheral administration, demonstrating that D1- and D2-receptors in iBAT are unlikely to constitute targets for obesity treatment via BAT activation.

scholarly journals Thyroid Hormone Effects on Glucose Disposal in Patients With Insulin Receptor Mutations

2019 ◽  
Vol 105 (3) ◽  
pp. e158-e171 ◽  
Author(s):  
Yevgeniya S Kushchayeva ◽  
Megan Startzell ◽  
Elaine Cochran ◽  
Sungyoung Auh ◽  
Hilal Sekizkardes ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Thyroid Hormone ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Receptor Gene ◽  
Whole Body ◽  
Glucose Disposal ◽  
Isotopic Tracers ◽  
Insulin Receptor Gene ◽  
Brown Adipose

Abstract Context Patients with mutations of the insulin receptor gene (INSR) have extreme insulin resistance and are at risk for early morbidity and mortality from diabetes complications. A case report suggested that thyroid hormone could improve glycemia in INSR mutation in part by increasing brown adipose tissue (BAT) activity and volume. Objective To determine if thyroid hormone increases tissue glucose uptake and improves hyperglycemia in INSR mutation. Design Single-arm, open-label study of liothyronine. Setting National Institutes of Health. Participants Patients with homozygous (n = 5) or heterozygous (n = 2) INSR mutation. Intervention Liothyronine every 8 hours for 2 weeks (n = 7); additional 6 months’ treatment in those with hemoglobin A1c (HbA1c) > 7% (n = 4). Outcomes Whole-body glucose uptake by isotopic tracers; tissue glucose uptake in muscle, white adipose tissue (WAT) and BAT by dynamic [18F] fluorodeoxyglucose positron emission tomography/computed tomography; HbA1c. Results There was no change in whole-body, muscle, or WAT glucose uptake from baseline to 2 weeks of liothyronine. After 6 months, there was no change in HbA1c (8.3 ± 1.2 vs 9.1 ± 3.0%, P = 0.27), but there was increased whole-body glucose disposal (22.8 ± 4.9 vs 30.1 ± 10.0 µmol/kg lean body mass/min, P = 0.02), and muscle (0.7 ± 0.1 vs 2.0 ± 0.2 µmol/min/100 mL, P < 0.0001) and WAT glucose uptake (1.2 ± 0.2 vs 2.2 ± 0.3 µmol/min/100 mL, P < 0.0001). BAT glucose uptake could not be quantified because of small volume. There were no signs or symptoms of hyperthyroidism. Conclusion Liothyronine administered at well-tolerated doses did not improve HbA1c. However, the observed increases in muscle and WAT glucose uptake support the proposed mechanism that liothyronine increases tissue glucose uptake. More selective agents may be effective at increasing tissue glucose uptake without thyroid hormone–related systemic toxicity. Clinical Trial Registration Number: NCT02457897; https://clinicaltrials.gov/ct2/show/NCT02457897.

Fatty acid synthesis and generation of glycerol-3-phosphate in brown adipose tissue from rats fed a cafeteria diet

2008 ◽  
Vol 86 (7) ◽  
pp. 416-423 ◽  
Author(s):  
Valéria E. Chaves ◽  
Danúbia Frasson ◽  
Maria E.S. Martins-Santos ◽  
Luiz C.C. Navegantes ◽  
Victor D. Galban ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Glucose Uptake ◽  
Fatty Acid Synthesis ◽  
Fatty Acid Content ◽  
Acid Synthesis ◽  
Cafeteria Diet ◽  
Brown Adipose

In vivo fatty acid synthesis and the pathways of glycerol-3-phosphate (G3P) production were investigated in brown adipose tissue (BAT) from rats fed a cafeteria diet for 3 weeks. In spite of BAT activation, the diet promoted an increase in the carcass fatty acid content. Plasma insulin levels were markedly increased in cafeteria diet-fed rats. Two insulin-sensitive processes, in vivo fatty acid synthesis and in vivo glucose uptake (which was used to evaluate G3P generation via glycolysis) were increased in BAT from rats fed the cafeteria diet. Direct glycerol phosphorylation, evaluated by glycerokinase (GyK) activity and incorporation of [U-14C]glycerol into triacylglycerol (TAG)–glycerol, was also markedly increased in BAT from these rats. In contrast, the cafeteria diet induced a marked reduction of BAT glyceroneogenesis, evaluated by phosphoenolpyruvate carboxykinase-C activity and incorporation of [1-14C]pyruvate into TAG–glycerol. BAT denervation resulted in an approximately 50% reduction of GyK activity, but did not significantly affect BAT in vivo fatty acid synthesis, in vivo glucose uptake, or glyceroneogenesis. The data suggest that the supply of G3P for BAT TAG synthesis can be adjusted independently from the sympathetic nervous system and solely by reciprocal changes in the generation of G3P via glycolysis and via glyceroneogenesis, with no participation of direct phosphorylation of glycerol by GyK.

scholarly journals A Diurnal Rhythm in Glucose Uptake in Brown Adipose Tissue Revealed by In Vivo PET-FDG Imaging

Obesity ◽  
2012 ◽  
Vol 20 (7) ◽  
pp. 1527-1529 ◽  
Author(s):  
Daan R. van der Veen ◽  
Jinping Shao ◽  
Sarah Chapman ◽  
W. Matthew Leevy ◽  
Giles E. Duffield
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Glucose Uptake ◽  
Diurnal Rhythm ◽  
Brown Adipose

scholarly journals Nutrient Responsive Nesfatin-1 Regulates Energy Balance and Induces Glucose-Stimulated Insulin Secretion in Rats

Endocrinology ◽  
2011 ◽  
Vol 152 (10) ◽  
pp. 3628-3637 ◽  
Author(s):  
R. Gonzalez ◽  
R. L. S. Perry ◽  
X. Gao ◽  
M. P. Gaidhu ◽  
R. G. Tsushima ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Insulin Secretion ◽  
Glucose Uptake ◽  
Pancreatic Islets ◽  
Whole Body ◽  
Isolated Pancreatic Islets ◽  
Brown Adipose ◽  
Glucose Stimulated Insulin Secretion ◽  
Body Energy

Nesfatin-1 is a recently discovered anorexigen, and we first reported nesfatin-like immunoreactivity in the pancreatic β-cells. The aim of this study was to characterize the effects of nesfatin-1 on whole-body energy homeostasis, insulin secretion, and glycemia. The in vivo effects of continuous peripheral delivery of nesfatin-1 using osmotic minipumps on food intake and substrate partitioning were examined in ad libitum-fed male Fischer 344 rats. The effects of nesfatin-1 on glucose-stimulated insulin secretion (GSIS) were examined in isolated pancreatic islets. L6 skeletal muscle cells and isolated rat adipocytes were used to assess the effects of nesfatin-1 on basal and insulin-mediated glucose uptake as well as on major steps of insulin signaling in these cells. Nesfatin-1 reduced cumulative food intake and increased spontaneous physical activity, whole-body fat oxidation, and carnitine palmitoyltransferase I mRNA expression in brown adipose tissue but did not affect uncoupling protein 1 mRNA in the brown adipose tissue. Nesfatin-1 significantly enhanced GSIS in vivo during an oral glucose tolerance test and improved insulin sensitivity. Although insulin-stimulated glucose uptake in L6 muscle cells was inhibited by nesfatin-1 pretreatment, basal and insulin-induced glucose uptake in adipocytes from nesfatin-1-treated rats was significantly increased. In agreement with our in vivo results, nesfatin-1 enhanced GSIS from isolated pancreatic islets at both normal (5.6 mm) and high (16.7 mm), but not at low (2 mm), glucose concentrations. Furthermore, nesfatin-1/nucleobindin 2 release from rat pancreatic islets was stimulated by glucose. Collectively, our data indicate that glucose-responsive nesfatin-1 regulates insulin secretion, glucose homeostasis, and whole-body energy balance in rats.

The PPARγ agonist rosiglitazone enhances rat brown adipose tissue lipogenesis from glucose without altering glucose uptake

2009 ◽  
Vol 296 (5) ◽  
pp. R1327-R1335 ◽  
Author(s):  
William T. Festuccia ◽  
Pierre-Gilles Blanchard ◽  
Véronique Turcotte ◽  
Mathieu Laplante ◽  
Meltem Sariahmetoglu ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Glucose Uptake ◽  
Mrna Levels ◽  
Pparγ Agonist ◽  
Brown Adipose ◽  
Lipin 1 ◽  
The Impact

We investigated the mechanisms whereby peroxisome proliferator-activated receptor-γ (PPARγ) agonism affects glucose and lipid metabolism in brown adipose tissue (BAT) by studying the impact of PPARγ activation on BAT glucose uptake and metabolism, lipogenesis, and mRNA levels plus activities of enzymes involved in triacylglycerol (TAG) synthesis. Interscapular BAT of rats treated or not with rosiglitazone (15 mg·kg−1·day−1, 7 days) was evaluated in vivo for glucose uptake and lipogenesis and in vitro for glucose metabolism, gene expression, and activities of glycerolphosphate acyltransferase (GPAT), phosphatidate phosphatase-1 (PAP or lipin-1), and diacylglycerol acyltransferase (DGAT). Rosiglitazone increased BAT mass without affecting whole tissue glucose uptake. BAT glycogen content (−80%), its synthesis from glucose (−50%), and mRNA levels of UDP-glucose pyrophosphorylase (−40%), which generates UDP-linked glucose for glycogen synthesis, were all reduced by rosiglitazone. In contrast, BAT TAG-glycerol synthesis in vivo and glucose incorporation into TAG-glycerol in vitro were stimulated by the agonist along with the activities and mRNA levels of glycerol 3-phosphate-generating phosphoenolpyruvate carboxykinase and glycerokinase. Furthermore, rosiglitazone markedly increased the activities of GPAT and DGAT but not those of lipin-1-mediated PAP-1, enzymes involved in the sequential acylation of glycerol 3-phosphate and TAG synthesis. Because an adequate supply of fatty acids is essential for BAT nonshivering thermogenesis, the enhanced ability of BAT to synthesize TAG under PPARγ activation may constitute an important mechanism by which lipid substrates are stored in preparation for an eventual thermogenic activation.

scholarly journals Relationship of brown adipose tissue perfusion and function: a study through β2-adrenoreceptor stimulation

2016 ◽  
Vol 120 (8) ◽  
pp. 825-832 ◽  
Author(s):  
Laura Ernande ◽  
Kristin I. Stanford ◽  
Robrecht Thoonen ◽  
Haihua Zhang ◽  
Maëva Clerte ◽  
...  
Keyword(s):  
Blood Flow ◽  
Adipose Tissue ◽  
Oxygen Consumption ◽  
Brown Adipose Tissue ◽  
Glucose Uptake ◽  
Direct Effect ◽  
Brown Adipocytes ◽  
Bat Activity ◽  
Brown Adipose

Brown adipose tissue (BAT) activation increases glucose and lipid consumption; as such, it is been considered as a potential therapy to decrease obesity. BAT is highly vascularized and its activation is associated with a necessary increase in blood flow. However, whether increasing BAT blood flow per se increases BAT activity is unknown. To examine this hypothesis, we investigated whether an isolated increase in BAT blood flow obtained by β2-adrenoreceptor (β2-AR) stimulation with salbutamol increased BAT activity. BAT blood flow was estimated in vivo in mice using contrast-enhanced ultrasound. The absence of direct effect of salbutamol on the function of isolated brown adipocytes was assessed by measuring oxygen consumption. The effect of salbutamol on BAT activity was investigated by measuring BAT glucose uptake in vivo. BAT blood flow increased by 2.3 ± 0.6-fold during β2-AR stimulation using salbutamol infusion in mice ( P = 0.003). β2-AR gene expression was detectable in BAT but was extremely low in isolated brown adipocytes. Oxygen consumption of isolated brown adipocytes did not change with salbutamol exposure, confirming the absence of a direct effect of β2-AR agonist on brown adipocytes. Finally, β2-AR stimulation by salbutamol increased BAT glucose uptake in vivo (991 ± 358 vs. 135 ± 49 ng glucose/mg tissue/45 min in salbutamol vs. saline injected mice, respectively, P = 0.046). In conclusion, an increase in BAT blood flow without direct stimulation of the brown adipocytes is associated with increased BAT metabolic activity. Increasing BAT blood flow might represent a new therapeutic target in obesity.

scholarly journals Role of hypoxia in obesity-induced disorders of glucose and lipid metabolism in adipose tissue

2009 ◽  
Vol 296 (2) ◽  
pp. E333-E342 ◽  
Author(s):  
Jun Yin ◽  
Zhanguo Gao ◽  
Qing He ◽  
Dequan Zhou ◽  
ZengKui Guo ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Fatty Acid Uptake ◽  
Acid Uptake ◽  
Interstitial Oxygen ◽  
Obese Mice ◽  
Cell Type Specificity

Recent studies suggest that adipose tissue hypoxia (ATH) may contribute to endocrine dysfunction in adipose tissue of obese mice. In this study, we examined hypoxia's effects on metabolism in adipocytes. We determined the dynamic relationship of ATH and adiposity in ob/ob mice. The interstitial oxygen pressure (Po2) was monitored in the epididymal fat pads for ATH. During weight gain from 39.5 to 55.5 g, Po2 declined from 34.8 to 20.1 mmHg, which are 40–60% lower than those in the lean mice. Insulin receptor-β (IRβ) and insulin receptor substrate-1 (IRS-1) were decreased in the adipose tissue of obese mice, and the alteration was observed in 3T3-L1 adipocytes after hypoxia (1% oxygen) treatment. Insulin-induced glucose uptake and Akt Ser473 phosphorylation was blocked by hypoxia in the adipocytes. This effect of hypoxia exhibited cell type specificity, as it was not observed in L6 myotubes and βTC6 cells. In response to hypoxia, free fatty acid (FFA) uptake was reduced and lipolysis was increased in 3T3-L1 adipocytes. The molecular mechanism of decreased fatty acid uptake may be related to inhibition of fatty acid transporters (FATP1 and CD36) and transcription factors (PPARγ and C/EBPα) by hypoxia. The hypoxia-induced lipolysis was observed in vivo after femoral arterial clamp. Necrosis and apoptosis were induced by hypoxia in 3T3-L1 adipocytes. These data suggest that ATH may promote FFA release and inhibit glucose uptake in adipocytes by inhibition of the insulin-signaling pathway and induction of cell death.

Phosphatidylinositol 3-kinase and dynamics of insulin resistance in denervated slow and fast muscles in vivo

1997 ◽  
Vol 272 (4) ◽  
pp. E661-E670 ◽  
Author(s):  
J. S. Elmendorf ◽  
A. Damrau-Abney ◽  
T. R. Smith ◽  
T. S. David ◽  
J. Turinsky
Keyword(s):  
Insulin Receptor ◽  
Glucose Uptake ◽  
Soleus Muscle ◽  
Phosphatidylinositol 3 Kinase ◽  
Plantaris Muscle ◽  
Glut 1 ◽  
Glut 4 ◽  
Denervated Muscles ◽  
Phosphatidylinositol 3

Regulation of glucose uptake by 1- and 3-day denervated soleus (slow-twitch) and plantaris (fast-twitch) muscles in vivo was investigated. One day after denervation, soleus and plantaris muscles exhibited 62 and 65% decreases in insulin-stimulated 2-deoxyglucose uptake, respectively, compared with corresponding control muscles. At this interval, denervated muscles showed no alterations in insulin receptor binding and activity, amount and activity of phosphatidylinositol 3-kinase, and amounts of GLUT-1 and GLUT-4. Three days after denervation, there was no increase in 2-deoxyglucose uptake in response to insulin in soleus muscle, whereas plantaris muscle exhibited a 158% increase in basal and an almost normal absolute increment in insulin-stimulated uptake. Despite these differences, denervated soleus and plantaris muscles exhibited comparable decreases in insulin-stimulated activities of the insulin receptor (approximately 40%) and phosphatidylinositol 3-kinase (approximately 50%) and a pronounced decrease in GLUT-4. An increase in GLUT-1 in plantaris, but not soleus, muscle 3 days after denervation is consistent with augmented basal 2-deoxyglucose uptake in plantaris muscle at this interval. These results demonstrate that, in denervated muscles, there is a clear dissociation between insulin-stimulated 2-deoxyglucose uptake and upstream events involved in insulin-stimulated glucose uptake.

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