Role of insulin during exercise-induced glycogenesis in muscle: effect on cyclic AMP.

1977 ◽  
Vol 233 (6) ◽  
pp. E509 ◽  
Author(s):  
J L Ivy
Keyword(s):  
Skeletal Muscle ◽  
Cyclic Amp ◽  
Glycogen Synthesis ◽  
Male Rats ◽  
Control Treatment ◽  
Glycogen Depletion ◽  
Camp Content ◽  
Glucose Administration ◽  
Exercise Induced

Skeletal muscle cyclic AMP (cAMP) content and glycogen synthesis were investigated in male rats subjected to exhaustive exercise, alloxan diabetes, and combinations of these conditions. After an exhaustive swim or control treatment of wading, randomly selected animals were administered 500 mg glucose via stomach tube. Two hours after glucose administration, gastrocnemius glycogen levels rose from 1.31 to 10.67 mg/g wet wt in fatigued nondiabetics (FND), producing a 94% supercompensation above control values. Glycogen of fatigued diabetics (FD) increased from 0.88 to 4.21 mg/g wet wt during the first 2 hr after glucose administration and did not reach control values for 24 h. In conjunction with these glycogen changes, cAMP increased from 1.23 to 2.59 and 1.47 to 2.81 pmol/mg wet wt for FND and FD, respectively (P less than 0.05). No difference in cAMP levels between diabetics and nondiabetics was found. These in vivo data suggest that insulin may not be essential for muscle glycogen synthesis, but that after glycogen depletion it plays a prominent role in supercompensation. Also, this hormone's mechanism of action in skeletal muscle does not appear to be mediated through alteration in the tissue cAMP concentration.

Regulation of glucose transporter GLUT-4 and hexokinase II gene transcription by insulin and epinephrine

1997 ◽  
Vol 273 (4) ◽  
pp. E682-E687 ◽  
Author(s):  
Jared P. Jones ◽  
G. Lynis Dohm
Keyword(s):  
Skeletal Muscle ◽  
Gene Transcription ◽  
Glucose Transporter ◽  
Male Rats ◽  
Rat Skeletal Muscle ◽  
Hexokinase Ii ◽  
Epinephrine Infusion ◽  
Glut 4 ◽  
Gastrocnemius Muscles

Transport of glucose across the plasma membrane by GLUT-4 and subsequent phosphorylation of glucose by hexokinase II (HKII) constitute the first two steps of glucose utilization in skeletal muscle. This study was undertaken to determine whether epinephrine and/or insulin regulates in vivo GLUT-4 and HKII gene transcription in rat skeletal muscle. In the first experiment, adrenodemedullated male rats were fasted 24 h and killed in the control condition or after being infused for 1.5 h with epinephrine (30 μg/ml at 1.68 ml/h). In the second experiment, male rats were fasted 24 h and killed after being infused for 2.5 h at 1.68 ml/h with saline or glucose (625 mg/ml) or insulin (39.9 μg/ml) plus glucose (625 mg/ml). Nuclei were isolated from pooled quadriceps, tibialis anterior, and gastrocnemius muscles. Transcriptional run-on analysis indicated that epinephrine infusion decreased GLUT-4 and increased HKII transcription compared with fasted controls. Both glucose and insulin plus glucose infusion induced increases in GLUT-4 and HKII transcription of twofold and three- to fourfold, respectively, compared with saline-infused rats. In conclusion, epinephrine and insulin may regulate GLUT-4 and HKII genes at the level of transcription in rat skeletal muscle.

Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle

2008 ◽  
Vol 294 (1) ◽  
pp. E28-E35 ◽  
Author(s):  
Michale Bouskila ◽  
Michael F. Hirshman ◽  
Jørgen Jensen ◽  
Laurie J. Goodyear ◽  
Kei Sakamoto
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Wild Type ◽  
Muscle Glycogen Synthesis ◽  
Mutant Forms

Insulin promotes dephosphorylation and activation of glycogen synthase (GS) by inactivating glycogen synthase kinase (GSK) 3 through phosphorylation. Insulin also promotes glucose uptake and glucose 6-phosphate (G-6- P) production, which allosterically activates GS. The relative importance of these two regulatory mechanisms in the activation of GS in vivo is unknown. The aim of this study was to investigate if dephosphorylation of GS mediated via GSK3 is required for normal glycogen synthesis in skeletal muscle with insulin. We employed GSK3 knockin mice in which wild-type GSK3α and -β genes are replaced with mutant forms (GSK3α/βS21A/S21A/S9A/S9A), which are nonresponsive to insulin. Although insulin failed to promote dephosphorylation and activation of GS in GSK3α/βS21A/S21A/S9A/S9Amice, glycogen content in different muscles from these mice was similar compared with wild-type mice. Basal and epinephrine-stimulated activity of muscle glycogen phosphorylase was comparable between wild-type and GSK3 knockin mice. Incubation of isolated soleus muscle in Krebs buffer containing 5.5 mM glucose in the presence or absence of insulin revealed that the levels of G-6- P, the rate of [14C]glucose incorporation into glycogen, and an increase in total glycogen content were similar between wild-type and GSK3 knockin mice. Injection of glucose containing 2-deoxy-[3H]glucose and [14C]glucose also resulted in similar rates of muscle glucose uptake and glycogen synthesis in vivo between wild-type and GSK3 knockin mice. These results suggest that insulin-mediated inhibition of GSK3 is not a rate-limiting step in muscle glycogen synthesis in mice. This suggests that allosteric regulation of GS by G-6- P may play a key role in insulin-stimulated muscle glycogen synthesis in vivo.

Physical exercise increases autophagic signaling through ULK1 in human skeletal muscle

2015 ◽  
Vol 118 (8) ◽  
pp. 971-979 ◽  
Author(s):  
Andreas Buch Møller ◽  
Mikkel Holm Vendelbo ◽  
Britt Christensen ◽  
Berthil Forrest Clasen ◽  
Ann Mosegaard Bak ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Physical Exercise ◽  
Light Chain ◽  
Human Skeletal Muscle ◽  
Transgenic Animal ◽  
Dependent Manner ◽  
Healthy Humans ◽  
Transgenic Animal Models ◽  
Exercise Induced

Data from transgenic animal models suggest that exercise-induced autophagy is critical for adaptation to physical training, and that Unc-51 like kinase-1 (ULK1) serves as an important regulator of autophagy. Phosphorylation of ULK1 at Ser555 stimulates autophagy, whereas phosphorylation at Ser757 is inhibitory. To determine whether exercise regulates ULK1 phosphorylation in humans in vivo in a nutrient-dependent manner, we examined skeletal muscle biopsies from healthy humans after 1-h cycling exercise at 50% maximal O2 uptake on two occasions: 1) during a 36-h fast, and 2) during continuous glucose infusion at 0.2 kg/h. Physical exercise increased ULK1 phosphorylation at Ser555 and decreased lipidation of light chain 3B. ULK1 phosphorylation at Ser555 correlated positively with AMP-activated protein kinase-α Thr172 phosphorylation and negatively with light chain 3B lipidation. ULK1 phosphorylation at Ser757 was not affected by exercise. Fasting increased ULK1 and p62 protein expression, but did not affect exercise-induced ULK1 phosphorylation. These data demonstrate that autophagy signaling is activated in human skeletal muscle after 60 min of exercise, independently of nutritional status, and suggest that initiation of autophagy constitutes an important physiological response to exercise in humans.

Exercise-enhanced satellite cell proliferation and new myonuclear accretion in rat skeletal muscle

2001 ◽  
Vol 90 (4) ◽  
pp. 1407-1414 ◽  
Author(s):  
Heather K. Smith ◽  
Linda Maxwell ◽  
Carol D. Rodgers ◽  
Nancy H. McKee ◽  
Michael J. Plyley
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Satellite Cell ◽  
Normal Activity ◽  
Adult Skeletal Muscle ◽  
Vastus Intermedius ◽  
Muscle Loading ◽  
Satellite Cell Proliferation ◽  
Exercise Induced

The effects of increased functional loading on early cellular regenerative events after exercise-induced injury in adult skeletal muscle were examined with the use of in vivo labeling of replicating myofiber nuclei and immunocyto- and histochemical techniques. Satellite cell proliferation in the soleus (Sol) of nonexercised rats (0.4 ± 0.2% of fibers) was unchanged after an initial bout of declined treadmill exercise but was elevated after two (1.0 ± 0.2%, P ≤ 0.01), but not four or seven, daily bouts of the same task. Myonuclei produced over the 7-day period comprised 0.9–1.9% of myonuclei in isolated fibers of Sol, tibialis anterior, and vastus intermedius of nonexercised rats. The accretion of new myonuclei was enhanced ( P ≤ 0.05) in Sol and vastus intermedius by the initial exercise followed by normal activity (to 3.1–3.4% of myonuclei) and more so by continued daily exercise (4.2–5.3%). Observed coincident with a lower incidence of histological fiber injury and unchanged fiber diameter and myonuclei per millimeter, the greater new myonuclear accretion induced by continued muscle loading may contribute to an enhanced fiber repair and regeneration after exercise-induced injury.

scholarly journals In vivo uptake of [14C]leucine by skeletal muscle ribosomes after injury in rats fed two levels of protein

1969 ◽  
Vol 23 (2) ◽  
pp. 271-280 ◽  
Author(s):  
V. R. Young ◽  
P. C. Huang
Keyword(s):  
Skeletal Muscle ◽  
Specific Activity ◽  
Male Rats ◽  
Thigh Muscle ◽  
Left Femur ◽  
The Right ◽  
And Control ◽  
The Relationship ◽  
In Vivo Uptake

1. After 14 days on a diet containing 5 or 25% casein male rats received a fracture of the left femur. Four hours before they were killed the injured and control rats were injected with [1-14C]leucine; the incorporation of radioactivity into an isolated fraction of skeletal muscle ribosomes was studied 6, 12, 24, 48, 72, 96 and 228 h after injury.2. The incorporation of [14C]leucine into the ribosome fraction in right thigh muscles dropped to 40% of control values 72 h after fracture in well-nourished rats and after 96 h with diets containing 5 or 25%, casein.3. The specific activity of the trichloroacetic acid-soluble fraction of muscle from injured rats was equal to or higher than that of the controls during the first 72 h but lower at 96 h.4. These results suggest that a reduced incorporation of amino acids by ribosomes from the right thigh muscle occurred on day 3 after fracture in the group receiving 25% casein but not in the group receiving 5% casein.5. Muscle RNA and DNA concentrations were not affected by the injury.6. The relationship between these findings and the loss of muscle N after injury is discussed.

Reversal of the exercise-induced increase in muscle permeability to glucose

1987 ◽  
Vol 253 (4) ◽  
pp. E331-E335 ◽  
Author(s):  
D. A. Young ◽  
H. Wallberg-Henriksson ◽  
M. D. Sleeper ◽  
J. O. Holloszy
Keyword(s):  
Protein Synthesis ◽  
Glucose Transport ◽  
Glycogen Synthesis ◽  
Carbohydrate Restriction ◽  
Rat Serum ◽  
Low Concentration ◽  
Carbohydrate Feeding ◽  
Exercise Induced

Exercise is associated with an increase in permeability of muscle to glucose that reverses slowly (h) in fasting rats during recovery. Previous studies showed that carbohydrate feeding speeds and carbohydrate restriction slows reversal of the exercise-induced increase in glucose uptake. This study was designed to evaluate the roles of glucose transport, glycogen synthesis, and protein synthesis in the reversal process in rat epitrochlearis muscle. In contrast to recovery in vivo, when muscles were incubated without insulin in vitro, the exercise-induced increase in muscle permeability to sugar reversed rapidly regardless of whether glucose transport or glycogen synthesis occurred. Inhibition of protein synthesis did not prevent the reversal. Addition of 33% rat serum or a low concentration of insulin to the incubation medium markedly slowed reversal in vitro. We conclude that 1) prolonged persistence of the increased permeability of mammalian muscle to glucose after exercise requires a low concentration of insulin, and 2) reversal of the increase in permeability does not require glucose transport, glycogen synthesis, or protein synthesis.

Effect of estradiol on the temporal pattern of exercise-induced tissue glycogen depletion in male rats

1993 ◽  
Vol 75 (4) ◽  
pp. 1502-1506 ◽  
Author(s):  
T. P. Rooney ◽  
Z. V. Kendrick ◽  
J. Carlson ◽  
G. S. Ellis ◽  
B. Matakevich ◽  
...  
Keyword(s):  
Temporal Pattern ◽  
Vastus Lateralis ◽  
Treadmill Running ◽  
Male Rats ◽  
Vastus Lateralis Muscle ◽  
Glycogen Depletion ◽  
Muscle Tissues ◽  
Triacylglycerol Content ◽  
Exercise Induced ◽  
Glycogen Sparing

The effect of 17 beta-estradiol 3-benzoate (10 micrograms.01 ml of sunflower oil-1 x 100 g body wt-1) on the temporal pattern of exercise-induced tissue glycogen depletion and tissue lipid availability during submaximal treadmill running was determined in male rats. Animal were administered estradiol or oil for 5 days and were then time matched for motorized treadmill running for 30, 60, 90, or 120 min. Significant depletion of liver, soleus muscle, and red and white vastus lateralis muscle tissue glycogen occurred in oil-administered animals run between 30 and 120 min. The greatest extent of tissue glycogen depletion occurred during the first 30 min of exercise with the rate of glycogen depletion slowing between 30 and 120 min of exercise. Administration of estradiol attenuated the temporal pattern of glycogen depletion in both liver and muscle tissues. Significant depletion of red and white vastus glycogen of estradiol-administered animals did not occur until 90 and 120 min of exercise, respectively. Administration of estradiol significantly increased resting plasma free fatty acids and red and white vastus triacylglycerol content. These data indicate that estradiol administration for 5 days resulted in significant glycogen sparing of liver and muscle tissues during submaximal treadmill running for up to 120 min by altering the temporal pattern of glycogen depletion of male rats secondary to an estradiol-mediated increase in availability of lipid substrate during exercise.

IL-6 is not essential for exercise-induced increases in glucose uptake

2013 ◽  
Vol 114 (9) ◽  
pp. 1151-1157 ◽  
Author(s):  
Hayley M. O'Neill ◽  
Rengasamy Palanivel ◽  
David C. Wright ◽  
Tara MacDonald ◽  
James S. Lally ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Glucose Uptake ◽  
Substrate Utilization ◽  
Treadmill Running ◽  
Glucose Clearance ◽  
Skeletal Muscle Glucose Uptake ◽  
Exercise Induced ◽  
Similar Body

Interleukin-6 (IL-6) increases glucose uptake in resting skeletal muscle. IL-6 is released from skeletal muscle during exercise; however; it is not known whether this IL-6 response is important for exercise-induced increases in skeletal muscle glucose uptake. We report that IL-6 knockout (KO) mice, 4 mo of age, have similar body weight to wild-type (WT), and, under resting conditions, oxygen consumption, food intake, substrate utilization, glucose tolerance, and insulin sensitivity are not different. Maximal exercise capacity is also similar to WT. We investigated substrate utilization and glucose clearance in vivo during steady-state treadmill running at 70% of maximal running speed and found that WT and IL-6 KO mice had similar rates of substrate utilization, muscle glucose clearance, and phosphorylation of AMP-activated protein kinase T172. These data provide evidence that IL-6 does not play a major role in regulating substrate utilization or skeletal muscle glucose uptake during steady-state endurance exercise.

Glucose feeding and exercise in trained rats: mechanisms for glycogen sparing

1986 ◽  
Vol 61 (3) ◽  
pp. 859-863 ◽  
Author(s):  
H. Kuipers ◽  
D. L. Costill ◽  
D. A. Porter ◽  
W. J. Fink ◽  
W. M. Morse
Keyword(s):  
Skeletal Muscle ◽  
Glucose Solution ◽  
Glycogen Synthesis ◽  
Oral Glucose ◽  
Glycogen Depletion ◽  
Stomach Tube ◽  
Glucose Feeding ◽  
Per Se ◽  
Glycogen Stores ◽  
Glycogen Sparing

This investigation studied the effect of an oral glucose feeding on glycogen sparing during exercise in non-glycogen-depleted and glycogen-depleted endurance-trained rats. The non-glycogen-depleted rats received via a stomach tube 2 ml of a 20% glucose solution labeled with [U-14C]glucose just prior to exercise (1 h at 25 m/min). Another group of rats ran for 40 min at higher intensity to deplete glycogen stores, after which they received the same glucose feeding and continued running for 1 h at 25 m/min. The initial 40-min run depleted glycogen in heart, skeletal muscle, and liver. In the non-glycogen-depleted rats the glucose feeding spared glycogen in the liver, primarily from the oxidation of blood-borne glucose in muscle. In the glycogen-depleted rats, muscle glycogen was repleted after the feeding, but sources other than the administered glucose also contributed to glycogen synthesis. The results suggest that glycogen depletion rather than the glucose feeding per se stimulates glycogen resynthesis in muscle during exercise in endurance-trained rats.

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