Increasing methamphetamine doses inhibit glycogen synthase kinase 3β activity by stimulating the insulin signaling pathway in substantia nigra

2018 ◽  
Vol 119 (10) ◽  
pp. 8522-8530 ◽  
Author(s):  
Neda Valian ◽  
Abolhassan Ahmadiani ◽  
Leila Dargahi
Keyword(s):  
Substantia Nigra ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Glycogen Synthase ◽  
Insulin Signaling Pathway ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3Β

scholarly journals PTEN, but Not SHIP2, Suppresses Insulin Signaling through the Phosphatidylinositol 3-Kinase/Akt Pathway in 3T3-L1 Adipocytes

2005 ◽  
Vol 280 (23) ◽  
pp. 22523-22529 ◽  
Author(s):  
Xiaoqing Tang ◽  
Aimee M. Powelka ◽  
Neil A. Soriano ◽  
Michael P. Czech ◽  
Adilson Guilherme
Keyword(s):  
Signaling Pathway ◽  
Glucose Transport ◽  
Insulin Signaling ◽  
Glycogen Synthase ◽  
Sh2 Domain ◽  
Insulin Signaling Pathway ◽  
Dominant Negative ◽  
Tensin Homolog ◽  
Gene Ablation ◽  
Mitogen Activated Protein

Glucose homeostasis is controlled by insulin in part through the stimulation of glucose transport in muscle and fat cells. This insulin signaling pathway requires phosphatidylinositol (PI) 3-kinase-mediated 3′-polyphosphoinositide generation and activation of Akt/protein kinase B. Previous experiments using dominant negative constructs and gene ablation in mice suggested that two phosphoinositide phosphatases, SH2 domain-containing inositol 5′-phosphatase 2 (SHIP2) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) negatively regulate this insulin signaling pathway. Here we directly tested this hypothesis by selectively inhibiting the expression of SHIP2 or PTEN in intact cultured 3T3-L1 adipocytes through the use of short interfering RNA (siRNA). Attenuation of PTEN expression by RNAi markedly enhanced insulin-stimulated Akt and glycogen synthase kinase 3α (GSK-3α) phosphorylation, as well as deoxyglucose transport in 3T3-L1 adipocytes. In contrast, depletion of SHIP2 protein by about 90% surprisingly failed to modulate these insulin-regulated events under identical assay conditions. In control studies, no diminution of insulin signaling to the mitogen-activated protein kinases Erk1 and Erk2 was observed when either PTEN or SHIP2 were depleted. Taken together, these results demonstrate that endogenous PTEN functions as a suppressor of insulin signaling to glucose transport through the PI 3-kinase pathway in cultured 3T3-L1 adipocytes.

Defective insulin signaling in skeletal muscle of the hypertensive TG(mREN2)27 rat

2005 ◽  
Vol 288 (6) ◽  
pp. E1074-E1081 ◽  
Author(s):  
Julie A. Sloniger ◽  
Vitoon Saengsirisuwan ◽  
Cody J. Diehl ◽  
Betsy B. Dokken ◽  
Narissara Lailerd ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Angiotensin Ii ◽  
Insulin Receptor ◽  
Signaling Pathway ◽  
Glucose Transport ◽  
Insulin Signaling ◽  
Glycogen Synthase ◽  
Insulin Signaling Pathway ◽  
Whole Body

Essential hypertension is frequently associated with insulin resistance of skeletal muscle glucose transport, with a potential role of angiotensin II in the pathogenesis of both conditions. The male heterozygous TG(mREN2)27 rat harbors the mouse transgene for renin, exhibits local elevations in angiotensin II, and is an excellent model of both hypertension and insulin resistance. The present study was designed to investigate the potential cellular mechanisms for insulin resistance in this hypertensive animal model, including an assessment of elements of the insulin-signaling pathway. Compared with nontransgenic, normotensive Sprague-Dawley control rats, male heterozygous TG(mREN2)27 rats displayed elevated ( P < 0.05) fasting plasma insulin (74%), an exaggerated insulin response (108%) during an oral glucose tolerance test, and reduced whole body insulin sensitivity. TG(mREN2)27 rats also exhibited decreased insulin-mediated glucose transport and glycogen synthase activation in both the type IIb epitrochlearis (30 and 46%) and type I soleus (22 and 64%) muscles. Importantly, there were significant reductions (∼30–50%) in insulin stimulation of tyrosine phosphorylation of the insulin receptor β-subunit and insulin receptor substrate-1 (IRS-1), IRS-1 associated with the p85 subunit of phosphatidylinositol 3-kinase, Akt Ser473 phosphorylation, and Ser9 phosphorylation of glycogen synthase kinase-3β in epitrochlearis and soleus muscles of TG(mREN2)27 rats. Soleus muscle triglyceride concentration was 25% greater in the transgenic group compared with nontransgenic animals. Collectively, these data provide the first evidence that the insulin resistance of the hypertensive male heterozygous TG(mREN2)27 rat can be attributed to specific defects in the insulin-signaling pathway in skeletal muscle.

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