Role of hepatic STAT3 in brain-insulin action on hepatic glucose production

To investigate the role of sympathoadrenergic activity on glucose production (Ra) during exercise, eight healthy males bicycled 20 min at 41 +/- 2 and 74 +/- 4% maximal O2 uptake (VO2max; mean +/- SE) either without (control; Co) or with blockade of sympathetic nerve activity to liver and adrenal medulla by local anesthesia of the celiac ganglion (Bl). Epinephrine (Epi) was in some experiments infused during blockade to match (normal Epi) or exceed (high Epi) Epi levels during Co. A constant infusion of somatostatin and glucagon was given before and during exercise. At rest, insulin was infused at a rate maintaining euglycemia. During intense exercise, insulin infusion was halved to mimic physiological conditions. During exercise, Ra increased in Co from 14.4 +/- 1.0 to 27.8 +/- 3.0 mumol.min-1.kg-1 (41% VO2max) and to 42.3 +/- 5.2 (74% VO2max; P < 0.05). At 41% VO2max, plasma glucose decreased, whereas it increased during 74% VO2max. Ra was not influenced by Bl. In high Epi, Ra rose more markedly compared with control (P < 0.05), and plasma glucose did not fall during mild exercise and increased more during intense exercise (P < 0.05). Free fatty acid and glycerol concentrations were always lower during exercise with than without celiac blockade. We conclude that high physiological concentrations of Epi can enhance Ra in exercising humans, but normally Epi is not a major stimulus. The study suggests that neither sympathetic liver nerve activity is a major stimulus for Ra during exercise. The Ra response is enhanced by a decrease in insulin and probably by unknown stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

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Multiple metabolic effects of CGRP in conscious rats: role of glycogen synthase and phosphorylase

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1993.264.1.e1 ◽

1993 ◽

Vol 264 (1) ◽

pp. E1-E10 ◽

Cited By ~ 2

Author(s):

L. Rossetti ◽

S. Farrace ◽

S. B. Choi ◽

A. Giaccari ◽

L. Sloan ◽

...

Keyword(s):

Skeletal Muscle ◽

Glycogen Synthase ◽

Hepatic Glucose Production ◽

Glycogen Synthesis ◽

Plasma Concentrations ◽

Glucose Production ◽

Glucose Disposal ◽

Hepatic Glucose ◽

Intracellular Glucose

Calcitonin gene-related peptide (CGRP) is a neuropeptide that is released at the neuromuscular junction in response to nerve excitation. To examine the relationship between plasma CGRP concentration and intracellular glucose metabolism in conscious rats, we performed insulin (22 pmol.kg-1.min-1) clamp studies combined with the infusion of 0, 20, 50, 100, 200, and 500 pmol.kg-1.min-1 CGRP (plasma concentrations ranging from 2 x 10(-11) to 5 x 10(-9) M). CGRP antagonized insulin's suppression of hepatic glucose production at plasma concentrations (approximately 10(-10) M) that are only two- to fivefold its basal portal concentration. Insulin-mediated glucose disposal was decreased by 20-32% when CGRP was infused at 50 pmol.kg-1.min-1 (plasma concentration 3 x 10(-10) M) or more. The impairment in insulin-stimulated glycogen synthesis in skeletal muscle accounted for all of the CGRP-induced decrease in glucose disposal, while whole body glycolysis was increased despite the reduction in total glucose uptake. The muscle glucose 6-phosphate concentration progressively increased during the CGRP infusions. CGRP inhibited insulin-stimulated glycogen synthase in skeletal muscle with a 50% effective dose of 1.9 +/- 0.36 x 10(-10) M. This effect on glycogen synthase was due to a reduction in enzyme affinity for UDP-glucose, with no changes in the maximal velocity. In vitro CGRP stimulated both hepatic and skeletal muscle adenylate cyclase in a dose-dependent manner. These data suggest that 1) CGRP is a potent antagonist of insulin at the level of muscle glycogen synthesis and hepatic glucose production; 2) inhibition of glycogen synthase is its major biochemical action in skeletal muscle; and 3) these effects are present at concentrations of the peptide that may be in the physiological range for portal vein and skeletal muscle. These data underscore the potential role of CGRP in the physiological modulation of intracellular glucose metabolism.

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Arrestin domain-containing 3 (Arrdc3) modulates insulin action and glucose metabolism in liver

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1922370117 ◽

2020 ◽

Vol 117 (12) ◽

pp. 6733-6740 ◽

Cited By ~ 2

Author(s):

Thiago M. Batista ◽

Sezin Dagdeviren ◽

Shannon H. Carroll ◽

Weikang Cai ◽

Veronika Y. Melnik ◽

...

Keyword(s):

Messenger Rna ◽

Insulin Action ◽

Hepatic Glucose Production ◽

Glycogen Synthesis ◽

Glucose Production ◽

Hepatic Glycogen ◽

Glycogen Accumulation ◽

Hepatic Glucose ◽

Glucose Output

Insulin action in the liver is critical for glucose homeostasis through regulation of glycogen synthesis and glucose output. Arrestin domain-containing 3 (Arrdc3) is a member of the α-arrestin family previously linked to human obesity. Here, we show thatArrdc3is differentially regulated by insulin in vivo in mice undergoing euglycemic-hyperinsulinemic clamps, being highly up-regulated in liver and down-regulated in muscle and fat. Mice with liver-specific knockout (KO) of the insulin receptor (IR) have a 50% reduction inArrdc3messenger RNA, while, conversely, mice with liver-specific KO ofArrdc3(L-Arrdc3KO) have increased IR protein in plasma membrane. This leads to increased hepatic insulin sensitivity with increased phosphorylation of FOXO1, reduced expression of PEPCK, and increased glucokinase expression resulting in reduced hepatic glucose production and increased hepatic glycogen accumulation. These effects are due to interaction of ARRDC3 with IR resulting in phosphorylation of ARRDC3 on a conserved tyrosine (Y382) in the carboxyl-terminal domain. Thus,Arrdc3is an insulin target gene, and ARRDC3 protein directly interacts with IR to serve as a feedback regulator of insulin action in control of liver metabolism.

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Glucagon enhances the direct suppressive effect of insulin on hepatic glucose production in humans

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1997.272.3.e371 ◽

1997 ◽

Vol 272 (3) ◽

pp. E371-E378 ◽

Cited By ~ 4

Author(s):

G. F. Lewis ◽

M. Vranic ◽

A. Giacca

Keyword(s):

Type I Diabetes ◽

Hepatic Glucose Production ◽

Glucose Production ◽

Insulin Delivery ◽

Suppressive Effect ◽

Type I ◽

Constant Rate ◽

Hepatic Glucose ◽

Infusion Method

The present study examines the role of glucagon in modulating the hepatic and extrahepatic effects of insulin on hepatic glucose production (HGP). We infused glucagon at a constant rate (0.65 ng x kg(-1) x min(-1)) during equimolar portal and peripheral insulin delivery in seven healthy males by our previously published tolbutamide infusion method. In contrast to our previous study, in which glucagon fell by approximately 30% during hyperinsulinemia and suppression of HGP was significantly greater with equimolar peripheral than with portal insulin delivery, HGP was actually suppressed to a lesser extent with peripheral insulin delivery (69 +/- 10%) than when insulin was delivered portally (76 +/- 5%, P < 0.05). To further examine whether glucagon was enhancing the effect of portal insulin, in four additional individuals HGP was suppressed to a greater extent during a tolbutamide infusion when glucagon was administered continuously throughout the basal and hyperinsulinemic periods than when glucagon was infused during the basal period only; HGP suppressed by 63 +/- 3 vs. 52 +/- 3%, respectively, P = 0.02). Tolbutamide had no effect on HGP when infused into three C-peptide-negative individuals with type I diabetes during a low-dose insulin and glucagon infusion. These data suggest that glucagon levels are an important determinant of the balance between insulin's direct and indirect effects on HGP, with glucagon likely potentiating the direct hepatic effect of insulin.

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Predominant Role of Gluconeogenesis in Increased Hepatic Glucose Production in NIDDM

Diabetes ◽

10.2337/diab.38.5.550 ◽

1989 ◽

Vol 38 (5) ◽

pp. 550-557 ◽

Cited By ~ 186

Author(s):

A. Consoli ◽

N. Nurjhan ◽

F. Capani ◽

J. Gerich

Keyword(s):

Hepatic Glucose Production ◽

Glucose Production ◽

Predominant Role ◽

Hepatic Glucose

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THE ROLE OF iNOS FOR HEPATIC GLUCOSE PRODUCTION IN MURINE SEPTIC SHOCK

Shock ◽

10.1097/00024382-200610001-00010 ◽

2006 ◽

Vol 26 (Supplement 1) ◽

pp. 3-4

Author(s):

G. Albuszies ◽

J. Vogt ◽

P. Radermacher ◽

S. Weber ◽

U. Wachter ◽

...

Keyword(s):

Septic Shock ◽

Hepatic Glucose Production ◽

Glucose Production ◽

Hepatic Glucose

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Metformin improves peripheral but not hepatic insulin action in obese patients with type II diabetes

Acta Endocrinologica ◽

10.1530/acta.0.1200257 ◽

1989 ◽

Vol 120 (3) ◽

pp. 257-265 ◽

Cited By ~ 71

Author(s):

Ole Hother-Nielsen ◽

Ole Schmitz ◽

Per H. Andersen ◽

Henning Beck-Nielsen ◽

Oluf Pedersen

Keyword(s):

Type Ii Diabetes ◽

Insulin Action ◽

Glucose Utilization ◽

Hepatic Glucose Production ◽

Glucose Production ◽

Metformin Treatment ◽

Obese Patients ◽

Type Ii ◽

Plasma Lactate ◽

Hepatic Glucose

Abstract. Nine obese patients with Type II diabetes mellitus were examined in a double-blind cross-over study. Metformin 0.5 g trice daily or placebo were given for 4 weeks. At the end of each period fasting and day-time postprandial values of plasma glucose, insulin, C-peptide and lactate were determined, and in vivo insulin action was assessed using the euglycemic clamp in combination with [3-3H]glucose tracer technique. Metformin treatment significantly reduced mean day-time plasma glucose levels (10.2 ± 1.2 vs 11.4 ± 1.2 mmol/l, P< 0.01) without enhancing mean day-time plasma insulin (43 ± 4 vs 50 ± 7 mU/l, NS) or C-peptide levels (1.26 ± 0.12 vs 1.38 ± 0.18 nmol/l, NS). Fasting plasma lactate was unchanged (1.57 ± 0.16 vs 1.44 ± 0.11 mmol/l, NS), whereas mean day-time plasma lactate concentrations were slightly increased (1.78 ± 0.11 vs 1.38 ± 0.11 mmol/l, P< 0.01). The clamp study revealed that metformin treatment was associated with an enhanced insulin-mediated glucose utilization (370 ± 38 vs 313 ± 33 mg · m−2 · min−1, P< 0.01), whereas insulin-mediated suppression of hepatic glucose production was unchanged. Also basal glucose clearance was improved (61.0 ± 5.8 vs 50.6 ± 2.8 ml · n−2 · min−1,, P< 0.05), whereas basal hepatic glucose production was unchanged (81 ± 6 vs 77 ± 4 mg · m−2 · min−1, NS). Conclusions: 1) Metformin treatment in obese Type II diabetic patients reduces hyperglycemia without changing the insulin secretion. 2) The improved glycemic control during metformin treatment was associated with an enhanced insulin-mediated glucose utilization, presumably in skeletal muscle, whereas no effect could be demonstrated on hepatic glucose production.

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