Current Trends in Microdialysis, with Focus on the in vivo Study of Skeletal Muscle Glucose Metabolism

Author(s):  
J. Henriksson ◽  
R. C. Hickner ◽  
H. Rosdahl ◽  
T. Fuchi ◽  
Y. Oshida ◽  
...  
2000 ◽  
Vol 440 (2) ◽  
pp. 302-308 ◽  
Author(s):  
Tamás Ivanics ◽  
Zsuzsa Miklós ◽  
Zoltán Ruttner ◽  
Sándor Bátkai ◽  
Dick W. Slaaf ◽  
...  

2010 ◽  
Vol 299 (5) ◽  
pp. E832-E840 ◽  
Author(s):  
Emil Wolsk ◽  
Helene Mygind ◽  
Thomas S. Grøndahl ◽  
Bente K. Pedersen ◽  
Gerrit van Hall

Interleukin (IL)-6 is chronically elevated in type 2 diabetes but also during exercise. However, the exact metabolic role, and hence the physiological significance, has not been elucidated. The objective of this study was to investigate the in vivo effect of recombinant human (rh) IL-6 on human fat and glucose metabolism and signaling of both adipose tissue and skeletal muscle. Eight healthy postabsorptive males were infused with either rhIL-6 or saline for 4 h, eliciting IL-6 levels of ∼40 and ∼1 pg/ml, respectively. Systemic, skeletal muscle, and adipose tissue fat and glucose metabolism was assessed before, during, and 2 h after cessation of the infusion. Glucose metabolism was unaffected by rhIL-6. In contrast, rhIL-6 increased systemic fatty acid oxidation approximately twofold after 60 min, and it remained elevated even 2 h after the infusion. The increase in oxidation was followed by an increase in systemic lipolysis. Adipose tissue lipolysis and fatty acid kinetics were unchanged with rhIL-6 compared with saline infusion. Conversely, rhIL-6 infusion caused an increase in skeletal muscle unidirectional fatty acid and glycerol release, indicative of an increase in lipolysis. The increased lipolysis in muscle could account for the systemic changes. Skeletal muscle signaling increased after 1 h of rhIL-6 infusion, indicated by a fourfold increase in the phosphorylated signal transducer and activator of transcription (STAT) 3-to-STAT3 ratio, whereas no changes in phosphorylated AMP-activated protein kinase or acetyl-CoA carboxylase levels could be observed. Our findings suggest that an acute increase in IL-6 at a normophysiological level selectively stimulates lipolysis in skeletal muscle, whereas adipose tissue is unaffected.


2007 ◽  
Vol 21 (1) ◽  
pp. 215-228 ◽  
Author(s):  
Mark E. Cleasby ◽  
Tracie A. Reinten ◽  
Gregory J. Cooney ◽  
David E. James ◽  
Edward W. Kraegen

Abstract The phosphoinositide 3-kinase/Akt pathway is thought to be essential for normal insulin action and glucose metabolism in skeletal muscle and has been shown to be dysregulated in insulin resistance. However, the specific roles of and signaling pathways triggered by Akt isoforms have not been fully assessed in muscle in vivo. We overexpressed constitutively active (ca-) Akt-1 or Akt-2 constructs in muscle using in vivo electrotransfer and, after 1 wk, assessed the roles of each isoform on glucose metabolism and fiber growth. We achieved greater than 2.5-fold increases in total Ser473 phosphorylation in muscles expressing ca-Akt-1 and ca-Akt-2, respectively. Both isoforms caused hypertrophy of muscle fibers, consistent with increases in p70S6kinase phosphorylation, and a 60% increase in glycogen accumulation, although only Akt-1 increased glycogen synthase kinase-3β phosphorylation. Akt-2, but not Akt-1, increased basal glucose uptake (by 33%, P = 0.004) and incorporation into glycogen and lipids, suggesting a specific effect on glucose transport. Consistent with this, short hairpin RNA-mediated silencing of Akt-2 caused reductions in glycogen storage and glucose uptake. Consistent with Akt-mediated insulin receptor substrate 1 (IRS-1) degradation, we observed approximately 30% reductions in IRS-1 protein in muscle overexpressing ca-Akt-1 or ca-Akt-2. Despite this, we observed no decrease in insulin-stimulated glucose uptake. Furthermore, a 68% reduction in IRS-1 levels induced using short hairpin RNAs targeting IRS-1 also did not affect glucose disposal after a glucose load. These data indicate distinct roles for Akt-1 and Akt-2 in muscle glucose metabolism and that moderate reductions in IRS-1 expression do not result in the development of insulin resistance in skeletal muscle in vivo.


Cancer ◽  
1994 ◽  
Vol 73 (5) ◽  
pp. 1490-1498 ◽  
Author(s):  
Heikki Minn ◽  
Paula Lindholm ◽  
Pirjo Nuutila ◽  
Ulla Ruotsalainen ◽  
Mika Teräs ◽  
...  

2018 ◽  
Vol 48 (4) ◽  
pp. 1710-1722 ◽  
Author(s):  
Jianshu Ni ◽  
Hongchao Li ◽  
Yiwen Zhou ◽  
Baojun Gu ◽  
Yuemin Xu ◽  
...  

Background/Aims: To evaluate whether local injection of exosomes derived from human adipose-derived stem cells (hADSCs) facilitates recovery of stress urinary incontinence (SUI) in a rat model. Methods: For the in vitro study, a Cell Counting Kit-8 (CCK-8) array and proteomic analysis were performed. For the in vivo study, female rats were divided into four groups: sham, SUI, adipose-derived stem cell (ADSC), and exosomes (n = 12 each). The SUI model was generated by pudendal nerve transection and vaginal dilation. Vehicle, hADSCs, or exosomes were injected into the peripheral urethra. After 2, 4, and 8 weeks, the rats underwent cystometrography and leak point pressure (LPP) testing, and tissues were harvested for histochemical analyses. Results: The CCK-8 experiment demonstrated that ADSC-derived exosomes could enhance the growth of skeletal muscle and Schwann cell lines in a dose-dependent manner. Proteomic analysis revealed that ADSC-derived exosomes contained various proteins of different signaling pathways. Some of these proteins are associated with the PI3K-Akt, Jak-STAT, and Wnt pathways, which are related to skeletal muscle and nerve regeneration and proliferation. In vivo experiments illustrated that rats of the exosome group had higher bladder capacity and LPP, and had more striated muscle fibers and peripheral nerve fibers in the urethra than rats of the SUI group. Both urethral function and histology of rats in the exosome group were slightly better than those in the ADSC group. Conclusions: Local injection of hADSC-derived exosomes improved functional and histological recovery after SUI.


2014 ◽  
Vol 18 (5) ◽  
pp. 395-401 ◽  
Author(s):  
Natalia C. Rodrigues ◽  
Roberta Brunelli ◽  
Daniela C. C. Abreu ◽  
Kelly Fernandes ◽  
Nivaldo A. Parizotto ◽  
...  

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Linqin Ma ◽  
Jingchun Zhang ◽  
Yu Qiao ◽  
Xinli Sun ◽  
Ting Mao ◽  
...  

Objective. The aim of this study was to establish a 3T3-L1 adipocyte model and ApoE−/− mouse model of intermittent hypoxia (IH) composite abnormal glucose metabolism (AGM) in vitro and in vivo and explore their synergistic damage effect leading to atherosclerosis (AS) and the influence of SREBP-1 signaling molecule-related mechanisms. Methods. Mature 3T3-L1 adipocytes were cultured with complete culture medium containing DEX 1×106 mol/L for 96 h to establish an AGM-3T3-L1 adipocyte model. Then, AGM-3T3-L1 adipocytes were treated with IH for 0 cycles, 2 cycles, 4 cycles, 8 cycles, 16 cycles, and 32 cycles and sustained hypoxia (SH). ApoE−/− mice were treated with high-fat diet and injection of STZ solution to establish an AGM-ApoE−/− mouse model. A total of 16 AGM-ApoE−/− mice were randomly and averagely divided into the normoxic control group (NC) and model group (CIH). AGM-ApoE−/− mice of the CIH group were treated with IH, which meant that the oxygen concentration fell to 10±0.5% in the first 90 seconds of one cycle and then increased to 21±0.5% in the later 90 seconds, continuous for eight hours per day (09 : 00-17 : 00) with a total of eight weeks. Eight C57BL/6J mice were used as the blank control group (Con) which was fed with conventional diet. qPCR and Western blotting were used to detect the expression level of SREBP-1c, FAS, and IRS-1. Oil Red O staining was used to compare the plaque of the aorta among each mouse group. Results. As a result, within 32 cycles of IH, mRNA and protein expression levels of SREBP-1c and FAS in AGM-3T3-L1 adipocytes were elevated with the increase in IH cycles; the mRNA expression of IRS-1 was decreased after IH 32 cycles and lower than that of the SH group. For the study in vivo, Oil Red O staining showed a more obvious AS aortic plaque in the CIH group. After CIH treatment of 4 w and 8 w, fasting blood glucose (FBG) of the NC group and CIH group was higher than that of the Con group, and the insulin level of the CIH group was higher than that of the Con group after IH treatment of 8 w. The expressions of the IRS-1 mRNA level in the aorta, skeletal muscle, and liver of the CIH group were lower than those in the Con group. The mRNA and protein expression of SREBP-1c and its downstream molecule FAS in the aorta, skeletal muscle, and liver significantly enhanced in the CIH group in contrast with those in the Con group. Conclusion. The CIH composite AGM could promote the progress of AS, which might be related to the modulation of the expression of SREBP-1-related molecular pathways.


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