scholarly journals Leptin Activates a Novel CNS Mechanism for Insulin-Independent Normalization of Severe Diabetic Hyperglycemia

Endocrinology ◽  
2010 ◽  
Vol 152 (2) ◽  
pp. 394-404 ◽  
Author(s):  
Jonathan P. German ◽  
Joshua P. Thaler ◽  
Brent E. Wisse ◽  
Shinsuke Oh-I ◽  
David A. Sarruf ◽  
...  
Keyword(s):  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Underlying Mechanism ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Uncontrolled Diabetes ◽  
Urinary Glucose ◽  
Hepatic Glucose ◽  
Glucose Excretion ◽  
The Brain

Abstract The brain has emerged as a target for the insulin-sensitizing effects of several hormonal and nutrient-related signals. The current studies were undertaken to investigate mechanisms whereby leptin lowers circulating blood glucose levels independently of insulin. After extending previous evidence that leptin infusion directly into the lateral cerebral ventricle ameliorates hyperglycemia in rats with streptozotocin-induced uncontrolled diabetes mellitus, we showed that the underlying mechanism is independent of changes of food intake, urinary glucose excretion, or recovery of pancreatic β-cells. Instead, leptin action in the brain potently suppresses hepatic glucose production while increasing tissue glucose uptake despite persistent, severe insulin deficiency. This leptin action is distinct from its previously reported effect to increase insulin sensitivity in the liver and offers compelling evidence that the brain has the capacity to normalize diabetic hyperglycemia in the presence of sufficient amounts of central nervous system leptin.

scholarly journals A HYPOMETABOLIC DEFENSE STRATEGY AGAINST PLASMODIUM INFECTION

2021 ◽  
Author(s):  
Susana Ramos ◽  
Temitope W. Ademolue ◽  
Elisa Jentho ◽  
Qian Wu ◽  
Joel Guerra ◽  
...  
Keyword(s):  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Organ Damage ◽  
Defense Strategy ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Immune Mediated ◽  
Hepatic Glucose ◽  
Reduce Blood Glucose ◽  
Hypometabolic State

SUMMARYHypoglycemia is a clinical hallmark of severe malaria, the often-lethal presentation of Plasmodium falciparum infection of humans. Here we report that mice reduce blood glucose levels in response to Plasmodium infection via a coordinated response whereby labile heme, an alarmin produced via hemolysis, induces anorexia and represses hepatic glucose production (HGP). While protective against unfettered immune-mediated inflammation, organ damage and anemia, when sustained over time heme-driven repression of HGP can progress towards hypoglycemia, compromising host energy expenditure and thermoregulation. This hypometabolic state arrests the development of asexual stages of Plasmodium spp., which undergo pyknosis and develop mitochondrial dysfunction. In response, Plasmodium activates a transcriptional program reducing its virulence and inducing sexual differentiation towards the production of transmissible gametocytes. We infer that malaria-associated hypoglycemia represents a trade-off of an evolutionarily conserved defense strategy restricting Plasmodium spp. from accessing host-derived glucose and balancing parasite virulence and transmission.

Inhibition of Foxo1 function is associated with improved fasting glycemia in diabetic mice

2003 ◽  
Vol 285 (4) ◽  
pp. E718-E728 ◽  
Author(s):  
Jennifer Altomonte ◽  
Anja Richter ◽  
Sonal Harbaran ◽  
Jenny Suriawinata ◽  
Jun Nakae ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Cultured Cells ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Diabetic Mice ◽  
Hepatic Expression ◽  
Glucose Levels ◽  
Fasting Glycemia ◽  
Blood Glucose Levels ◽  
Hepatic Glucose

Excessive hepatic glucose production is a contributing factor to fasting hyperglycemia in diabetes. Insulin suppresses hepatic glucose production by inhibiting the expression of two gluconeogenic enzymes, phospho enolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G-6-Pase). The forkhead transcription factor Foxo1 has been implicated as a mediator of insulin action in regulating hepatic gluconeogenesis, and a Foxo1 mutant (Foxo1-Δ256), devoid of its carboxyl domain, has been shown to interfere with Foxo1 function and inhibit gluconeogenic gene expression in cultured cells. To study the effect of Foxo1-Δ256 on glucose metabolism in animals, the Foxo1-Δ256 cDNA was delivered to the livers of mice by adenovirus-mediated gene transfer. Hepatic Foxo1-Δ256 production resulted in inhibition of gluconeogenic activity, as evidenced by reduced PEPCK and G-6-Pase expression in the liver. Mice treated with the Foxo1-Δ256 vector exhibited significantly reduced blood glucose levels. In contrast, blood glucose levels in control vector-treated animals remained unchanged, which coincided with the lack of alterations in the expression levels of PEPCK and G-6-Pase. When tested in diabetic db/db mice, hepatic production of Foxo1-Δ256 was shown to reduce fasting hyperglycemia. Furthermore, we showed that hepatic Foxo1 expression was deregulated as a result of insulin resistance in diabetic mice and that Foxo1-Δ256 interfered with Foxo1 function via competitive binding to target promoters. These results demonstrated that functional inhibition of Foxo1, caused by hepatic expression of its mutant, is associated with reduced hepatic gluconeogenic activity and improved fasting glycemia in diabetic mice.

scholarly journals Cell Autonomous Dysfunction and Insulin Resistance in Pancreatic α Cells

2019 ◽  
Vol 20 (15) ◽  
pp. 3699 ◽  
Author(s):  
Norikiyo Honzawa ◽  
Kei Fujimoto ◽  
Tadahiro Kitamura
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Blood Glucose ◽  
Current Knowledge ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Hepatic Glucose

To date, type 2 diabetes is considered to be a “bi-hormonal disorder” rather than an “insulin-centric disorder,” suggesting that glucagon is as important as insulin. Although glucagon increases hepatic glucose production and blood glucose levels, paradoxical glucagon hypersecretion is observed in diabetes. Recently, insulin resistance in pancreatic α cells has been proposed to be associated with glucagon dysregulation. Moreover, cell autonomous dysfunction of α cells is involved in the etiology of diabetes. In this review, we summarize the current knowledge about the physiological and pathological roles of glucagon.

scholarly journals Berberine Attenuates Hyperglycemia by Inhibiting the Hepatic Glucagon Pathway in Diabetic Mice

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Ying Zhong ◽  
Jing Jin ◽  
Peiyu Liu ◽  
Yu Song ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Intracellular Camp ◽  
Diabetic Mice ◽  
Hepatic Gluconeogenesis ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Hepatic Glucose ◽  
Glucose Output

Dysregulated glucagon drives hyperfunction in hepatic glucose output, which is the main cause of persistent hyperglycemia in type 2 diabetes. Berberine (Zhang et al., 2010) has been used as a hypoglycemic agent, yet the mechanism by which BBR inhibits hepatic gluconeogenesis remains incompletely understood. In this study, we treated diabetic mice with BBR, tested blood glucose levels, and then performed insulin, glucose lactate, and glucagon tolerance tests. Intracellular cAMP levels in hepatocytes were determined by ELISA, hepatic gluconeogenetic genes were assayed by RT-qPCR, and the phosphorylation of CREB, which is the transcriptional factor controlling the expression of gluconeogenetic genes, was detected by western blot. BBR reduced blood glucose levels, improved insulin and glucose tolerance, and suppressed lactate- and glucagon-induced hepatic gluconeogenesis in ob/ob and STZ-induced diabetic mice. Importantly, BBR blunted glucagon-induced glucose production and gluconeogenic gene expression in hepatocytes, presumably through reducing cAMP, which resulted in the phosphorylation of CREB. By utilizing a cAMP analogue, adenylate cyclase (AC), to activate cAMP synthetase, and an inhibitor of the cAMP degradative enzyme, phosphodiesterase (PDE), we revealed that BBR accelerates intracellular cAMP degradation. BBR reduces the intracellular cAMP level by activating PDE, thus blocking activation of downstream CREB and eventually downregulating gluconeogenic genes to restrain hepatic glucose production.

Effect of a selective rise in sinusoidal norepinephrine on HGP is due to an increase in glycogenolysis

1998 ◽  
Vol 274 (1) ◽  
pp. E162-E171 ◽  
Author(s):  
Chang An Chu ◽  
Dana K. Sindelar ◽  
Doss W. Neal ◽  
Eric J. Allen ◽  
E. Patrick Donahue ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Control Group ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Molar Basis ◽  
Hepatic Glucose ◽  
The Difference ◽  
Over Time

To determine the effect of a selective rise in liver sinusoidal norepinephrine (NE) on hepatic glucose production (HGP), norepinephrine (50 ng ⋅ kg−1 ⋅ min−1) was infused intraportally (Po-NE) for 3 h into five 18-h-fasted conscious dogs with a pancreatic clamp. In the control protocol, NE (0.2 ng ⋅ kg−1 ⋅ min−1) and glucose were infused peripherally to match the arterial NE and blood glucose levels in the Po-NE group. Hepatic sinusoidal NE levels rose ∼30-fold in the Po-NE group but did not change in the control group. The arterial NE levels did not change significantly in either group. During the portal NE infusion, HGP increased from 1.9 ± 0.2 to 3.5 ± 0.4 mg ⋅ kg−1 ⋅ min−1(15 min; P < 0.05) and then gradually fell to 2.4 ± 0.4 mg ⋅ kg−1 ⋅ min−1by 3 h. HGP in the control group did not change (2.0 ± 0.2 to 2.0 ± 0.2 mg ⋅ kg−1 ⋅ min−1) for 15 min but then gradually fell to 1.1 ± 0.2 mg ⋅ kg−1 ⋅ min−1by the end of the study. Because the fall in HGP from 15 min on was parallel in the two groups, the effect of NE on HGP (the difference between HGP in the two groups) did not decline over time. Gluconeogenesis did not change significantly in either group. In conclusion, elevation in hepatic sinusoidal NE significantly increases HGP by selectively stimulating glycogenolysis. Compared with the previously determined effects of epinephrine or glucagon on HGP, the effect of NE is, on a molar basis, less potent but nore sustained over time.

scholarly journals Adropin reduces blood glucose levels in mice by limiting hepatic glucose production

2019 ◽  
Vol 7 (8) ◽  
pp. e14043 ◽  
Author(s):  
Dharendra Thapa ◽  
Bingxian Xie ◽  
Janet R. Manning ◽  
Manling Zhang ◽  
Michael W. Stoner ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Hepatic Glucose

scholarly journals Glucagon Deficiency Reduces Hepatic Glucose Production and Improves Glucose Tolerance In Adult Mice

2010 ◽  
Vol 31 (4) ◽  
pp. 606-606
Author(s):  
Aidan S. Hancock ◽  
Aiping Du ◽  
Jingxuan Liu ◽  
Mayumi Miller ◽  
Catherine L. May
Keyword(s):  
Glucose Homeostasis ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Postprandial Glucose ◽  
Glucagon Receptor ◽  
Glucose Levels ◽  
Adult Mice ◽  
Hepatic Glucose ◽  
Knockout Animals

Abstract The major role of glucagon is to promote hepatic gluconeogenesis and glycogenolysis to raise blood glucose levels during hypoglycemic conditions. Several animal models have been established to examine the in vivo function of glucagon in the liver through attenuation of glucagon via glucagon receptor knockout animals and pharmacological interventions. To investigate the consequences of glucagon loss to hepatic glucose production and glucose homeostasis, we derived mice with a pancreas specific ablation of the α-cell transcription factor, Arx, resulting in a complete loss of the glucagon-producing pancreatic α-cell. Using this model, we found that glucagon is not required for the general health of mice but is essential for total hepatic glucose production. Our data clarifies the importance of glucagon during the regulation of fasting and postprandial glucose homeostasis.

Hypoglycemia counterregulation in elderly humans: relationship to glucose levels

1994 ◽  
Vol 267 (4) ◽  
pp. E497-E506 ◽  
Author(s):  
F. J. Ortiz-Alonso ◽  
A. Galecki ◽  
W. H. Herman ◽  
M. J. Smith ◽  
J. A. Jacquez ◽  
...  
Keyword(s):  
Glucose Utilization ◽  
Hepatic Glucose Production ◽  
Severe Hypoglycemia ◽  
Glucose Production ◽  
Counterregulatory Hormones ◽  
Glucose Levels ◽  
Hepatic Glucose ◽  
Consistent Increase ◽  
Step Study ◽  
Elderly Humans

This study was designed to define the effect of human aging on hypoglycemia counterregulatory mechanisms. A hyperinsulinemic (2 mU.kg-1.min-1) glucose clamp procedure was used to control glucose and insulin levels during stepwise lowering of plasma glucose. Counterregulatory hormones, hepatic glucose production (HGP), glucose utilization, and symptoms of hypoglycemia were studied in 13 healthy young [age 24 +/- 1 (SE) yr] and 11 healthy old (age 65 +/- 1 yr) nondiabetic volunteers on two occasions: 1) at matched euglycemia and 70 and 60 mg/dl (study 1) and 2) at matched euglycemia and 60 and 50 mg/dl (study 2). The old had consistently lower epinephrine (P < 0.005), glucagon (P < 0.02), cortisol (P < 0.05), and pancreatic polypeptide (P < 0.02) responses at the 60-mg/dl glucose step in study 1. However, these differences were no longer detectable at the more severe hypoglycemic stimulus of 50 mg/dl in study 2. A consistent increase in HGP occurred in both groups only at the 50-mg/dl glucose step (study 2) and was not different between young and old. There were also no differences in symptom responses between young and old. In summary, we found that elderly individuals have a subtle impairment of the glucose counterregulatory response during moderate hypoglycemia, but this impairment is no longer detectable during more severe hypoglycemia.

scholarly journals Prevention of Diabetes in db/db Mice by Dietary Soy Is Independent of Isoflavone Levels

Endocrinology ◽  
2012 ◽  
Vol 153 (11) ◽  
pp. 5200-5211 ◽  
Author(s):  
Céline Zimmermann ◽  
Christopher R. Cederroth ◽  
Lucie Bourgoin ◽  
Michelangelo Foti ◽  
Serge Nef
Keyword(s):  
Glucose Homeostasis ◽  
Cell Function ◽  
Hepatic Glucose Production ◽  
Cell Mass ◽  
Glucose Production ◽  
Metabolic Effects ◽  
Pancreatic Β Cell ◽  
Β Cell ◽  
Glucose Levels ◽  
Hepatic Glucose

Abstract Recent evidence points towards the beneficial use of soy proteins and isoflavones to improve glucose control and slow the progression of type 2 diabetes. Here, we used diabetic db/db mice fed a high soy-containing diet (SD) or a casein soy-free diet to investigate the metabolic effects of soy and isoflavones consumption on glucose homeostasis, hepatic glucose production, and pancreatic islet function. Male db/db mice fed with a SD exhibited a robust reduction in hyperglycemia (50%), correlating with a reduction in hepatic glucose production and preserved pancreatic β-cell function. The rapid decrease in fasting glucose levels resulted from an inhibition of gluconeogenesis and an increase in glycolysis in the liver of db/db mice. Soy consumption also prevented the loss of pancreatic β-cell mass and thus improved glucose-stimulated insulin secretion (3-fold), which partly accounted for the overall improvements in glucose homeostasis. Comparison of SD effects on hyperglycemia with differing levels of isoflavones or with purified isoflavones indicate that the beneficial physiological effects of soy are not related to differences in their isoflavone content. Overall, these findings suggest that consumption of soy is beneficial for improving glucose homeostasis and delaying the progression of diabetes in the db/db mice but act independently of isoflavone concentration.

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