scholarly journals Lithium enhances exercise-induced glycogen breakdown and insulin-induced AKT activation to facilitate glucose uptake in rodent skeletal muscle

Author(s):  
Su-Ryun Jung ◽  
Sol-Yi Park ◽  
Jin-Ho Koh ◽  
Jong-Yeon Kim

AbstractThe purpose of this study was to investigate the effect of lithium on glucose disposal in a high-fat diet-induced type 2 diabetes mellitus (T2DM) and streptozotocin-induced type 1 diabetes mellitus (T1DM) animal model along with low-volume exercise and low-dose insulin. Lithium decreased body weight, fasting plasma glucose, and insulin levels when to treat with low-volume exercise training; however, there were no adaptive responses like an increase in GLUT4 content and translocation factor levels. We discovered that lithium enhanced glucose uptake by acute low-volume exercise-induced glycogen breakdown, which was facilitated by the dephosphorylation of serine 473-AKT (Ser473-AKT) and serine 9-GSK3β. In streptozotocin-induced T1DM mice, Li/low-dose insulin facilitates glucose uptake through increase the level of exocyst complex component 7 (Exoc7) and Ser473-AKT. Thus, lithium enhances acute exercise-induced glycogen breakdown and insulin-induced AKT activation and could serve as a candidate therapeutic target to regulate glucose level of DM patients.

1987 ◽  
Vol 63 (4) ◽  
pp. 1319-1323 ◽  
Author(s):  
V. A. Koivisto ◽  
H. Yki-Jarvinen

Acute exercise increases insulin binding to its receptors on blood cells. Whether the enhanced insulin binding explains the exercise-induced increase in glucose uptake is unclear, since insulin binding and glucose uptake have not been measured simultaneously in a target tissue of insulin. In this study, we determined insulin binding and the rate of glucose transport in adipocytes obtained by needle biopsy from 10 healthy men before and after 3 h of cycle-ergometric exercise. During the exercise, plasma glucose (P less than 0.01) and insulin (P less than 0.001) fell and serum free fatty acid level rose 4.3-fold (P less than 0.001). 125I-insulin binding to adipocytes remained unchanged during exercise. The rate of basal glucose transport clearance fell from 28.1 +/- 5.7 fl.cell-1.s-1 to 22.9 +/- 5.6 fl.cell-1.s-1 (P less than 0.005), and the insulin-stimulated increase in glucose transport rate rose from 196 +/- 26 to 279 +/- 33% (P less than 0.025) during the exercise. Thus, in the adipocytes during exercise, the basal glucose transport rate and the responsiveness of glucose transport to insulin changed in the absence of alterations in insulin binding. These data indicate that the exercise-induced changes in insulin binding show tissue specificity and do not always parallel alterations in glucose transport.


2015 ◽  
Vol 308 (7) ◽  
pp. E603-E612 ◽  
Author(s):  
Naveen Sharma ◽  
Haiyan Wang ◽  
Edward B. Arias ◽  
Carlos M. Castorena ◽  
Gregory D. Cartee

Either calorie restriction [CR; consuming 60–65% of ad libitum (AL) intake] or acute exercise can independently improve insulin sensitivity in old age, but their combined effects on muscle insulin signaling and glucose uptake have previously been unknown. Accordingly, we assessed the independent and combined effects of CR (beginning at 14 wk old) and acute exercise (3–4 h postexercise) on insulin signaling and glucose uptake in insulin-stimulated epitrochlearis muscles from 30-mo-old rats. Either CR alone or exercise alone vs. AL sedentary controls induced greater insulin-stimulated glucose uptake. Combined CR and exercise vs. either treatment alone caused an additional increase in insulin-stimulated glucose uptake. Either CR or exercise alone vs. AL sedentary controls increased Akt Ser473and Akt Thr308phosphorylation. Combined CR and exercise further elevated Akt phosphorylation on both sites. CR alone, but not exercise alone, vs. AL sedentary controls significantly increased Akt substrate of 160 kDa (AS160) Ser588and Thr642phosphorylation. Combined CR and exercise did not further enhance AS160 phosphorylation. Exercise alone, but not CR alone, modestly increased GLUT4 abundance. Combined CR and exercise did not further elevate GLUT4 content. These results suggest that CR or acute exercise independently increases insulin-stimulated glucose uptake via overlapping (greater Akt phosphorylation) and distinct (greater AS160 phosphorylation for CR, greater GLUT4 for exercise) mechanisms. Our working hypothesis is that greater insulin-stimulated glucose uptake in the combined CR and exercise group vs. CR or exercise alone relies on greater Akt activation, leading to greater phosphorylation of one or more Akt substrates other than AS160.


Metabolism ◽  
2000 ◽  
Vol 49 (7) ◽  
pp. 920-930 ◽  
Author(s):  
Tetsuya Taguchi ◽  
Hideki Kishikawa ◽  
Hiroyuki Motoshima ◽  
Kohji Sakai ◽  
Toshihiko Nishiyama ◽  
...  

2004 ◽  
Vol 287 (6) ◽  
pp. E1049-E1056 ◽  
Author(s):  
Christian Meyer ◽  
Hans J. Woerle ◽  
Jean M. Dostou ◽  
Stephen L. Welle ◽  
John E. Gerich

Recent studies indicate an important role of the kidney in postprandial glucose homeostasis in normal humans. To determine its role in the abnormal postprandial glucose metabolism in type 2 diabetes mellitus (T2DM), we used a combination of the dual-isotope technique and net balance measurements across kidney and skeletal muscle in 10 subjects with T2DM and 10 age-, weight-, and sex-matched nondiabetic volunteers after ingestion of 75 g of glucose. Over the 4.5-h postprandial period, diabetic subjects had increased mean blood glucose levels (14.1 ± 1.1 vs. 6.2 ± 0.2 mM, P < 0.001) and increased systemic glucose appearance (100.0 ± 6.3 vs. 70.0 ± 3.3 g, P < 0.001). The latter was mainly due to ∼23 g greater endogenous glucose release (39.8 ± 5.9 vs. 17.0 ± 1.8 g, P < 0.002), since systemic appearance of the ingested glucose was increased by only ∼7 g (60.2 ± 1.4 vs. 53.0 ± 2.2 g, P < 0.02). Approximately 40% of the diabetic subjects’ increased endogenous glucose release was due to increased renal glucose release (19.6 ± 3.1 vs. 10.6 ± 2.4 g, P < 0.05). Postprandial systemic tissue glucose uptake was also increased in the diabetic subjects (82.3 ± 4.7 vs. 69.8 ± 3.5 g, P < 0.05), and its distribution was altered; renal glucose uptake was increased (21.0 ± 3.5 vs. 9.8 ± 2.3 g, P < 0.03), whereas muscle glucose uptake was normal (18.5 ± 1.8 vs. 25.9 ± 3.3 g, P = 0.16). We conclude that, in T2DM, 1) both liver and kidney contribute to postprandial overproduction of glucose, and 2) postprandial renal glucose uptake is increased, resulting in a shift in the relative importance of muscle and kidney for glucose disposal. The latter may provide an explanation for the renal glycogen accumulation characteristic of diabetes mellitus as well as a mechanism by which hyperglycemia may lead to diabetic nephropathy.


2015 ◽  
Vol 40 (3) ◽  
pp. 251-262 ◽  
Author(s):  
Carlos M. Castorena ◽  
Edward B. Arias ◽  
Naveen Sharma ◽  
Gregory D. Cartee

One exercise session can improve subsequent insulin-stimulated glucose uptake by skeletal muscle in healthy and insulin-resistant individuals. Our first aim was to determine whether a brief (2 weeks) high-fat diet (HFD) that caused muscle insulin resistance would activate the mammalian target of rapamycin complex 1 (mTORC1) and/or inhibitor of κB kinase/nuclear factor κB (IKK/NF-κB) pathways, which are potentially linked to induction of insulin resistance. Our second aim was to determine whether acute exercise that improved insulin-stimulated glucose uptake by muscles would attenuate activation of these pathways. We compared HFD-fed rats with rats fed a low-fat diet (LFD). Some animals from each diet group were sedentary and others were studied 3 h postexercise, when insulin-stimulated glucose uptake was increased. The results did not provide evidence that brief HFD activated either the mTORC1 (including phosphorylation of mTORSer2448, TSC2Ser939, p70S6KThr412, and RPS6Ser235/236) or the IKK/NF-κB (including abundance of IκBα or phosphorylation of NF-κBSer536, IKKα/βSer177/181, and IκBSer32) pathway in insulin-resistant muscles. Exercise did not oppose the activation of either pathway, as evidenced by no attenuation of phosphorylation of key proteins in the IKK/NF-κB pathway (NF-κBSer536, IKKα/βSer177/181, and IκBSer32), unaltered IκBα abundance, and no attenuation of phosphorylation of key proteins in the mTORC1 pathway (mTORSer2448, TSC2Ser939, and RPS6Ser235/236). Instead, exercise induced greater phosphorylation of 2 proteins of the mTORC1 pathway (PRAS40Thr246 and p70S6KThr412) in insulin-stimulated muscles, regardless of diet. Insulin resistance induced by a brief HFD was not attributable to greater activation of the mTORC1 or the IKK/NF-κB pathway in muscle, and exercise-induced improvement in insulin sensitivity was not attributable to attenuated activation of these pathways in muscle.


2010 ◽  
Vol 298 (2) ◽  
pp. E179-E192 ◽  
Author(s):  
M. P. Sajan ◽  
G. Bandyopadhyay ◽  
A. Miura ◽  
M. L. Standaert ◽  
S. Nimal ◽  
...  

Activators of 5′-AMP-activated protein kinase (AMPK) 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), metformin, and exercise activate atypical protein kinase C (aPKC) and ERK and stimulate glucose transport in muscle by uncertain mechanisms. Here, in cultured L6 myotubes: AICAR- and metformin-induced activation of AMPK was required for activation of aPKC and ERK; aPKC activation involved and required phosphoinositide-dependent kinase 1 (PDK1) phosphorylation of Thr410-PKC-ζ; aPKC Thr410 phosphorylation and activation also required MEK1-dependent ERK; and glucose transport effects of AICAR and metformin were inhibited by expression of dominant-negative AMPK, kinase-inactive PDK1, MEK1 inhibitors, kinase-inactive PKC-ζ, and RNA interference (RNAi)-mediated knockdown of PKC-ζ. In mice, muscle-specific aPKC (PKC-λ) depletion by conditional gene targeting impaired AICAR-stimulated glucose disposal and stimulatory effects of both AICAR and metformin on 2-deoxyglucose/glucose uptake in muscle in vivo and AICAR stimulation of 2-[3H]deoxyglucose uptake in isolated extensor digitorum longus muscle; however, AMPK activation was unimpaired. In marked contrast to AICAR and metformin, treadmill exercise-induced stimulation of 2-deoxyglucose/glucose uptake was not inhibited in aPKC-knockout mice. Finally, in intact rodents, AICAR and metformin activated aPKC in muscle, but not in liver, despite activating AMPK in both tissues. The findings demonstrate that in muscle AICAR and metformin activate aPKC via sequential activation of AMPK, ERK, and PDK1 and the AMPK/ERK/PDK1/aPKC pathway is required for metformin- and AICAR-stimulated increases in glucose transport. On the other hand, although aPKC is activated by treadmill exercise, this activation is not required for exercise-induced increases in glucose transport, and therefore may be a redundant mechanism.


1986 ◽  
Vol 113 (1_Suppl) ◽  
pp. S120-S121
Author(s):  
TH. LINN ◽  
H. GERMANN ◽  
B. HERING ◽  
R. BRETZEL ◽  
K. FEDERLIN

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