Abstract
In the present study we have examined the levels and phosphorylation state of the insulin receptor and insulin receptor substrate 1 (IRS-1) as well as the association between IRS-1 and phosphatidylinositol 3-kinase (PI 3-kinase) in the liver and muscle of rats treated with glucagon. There was a decrease in the insulin-stimulated receptor and IRS-1 phosphorylation levels which was paralleled by a reduced association between IRS-1 and PI 3-kinase in vivo in the liver and muscle of glucagon-treated rats. These observations suggest that glucagon, probably acting through cAMP, may impair insulin signaling in the three early steps in insulin action after binding.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Glucagon / pharmacology*
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Insulin / pharmacology*
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Insulin Receptor Substrate Proteins
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Liver / drug effects
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Liver / metabolism*
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Male
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Muscle, Skeletal / drug effects
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Muscle, Skeletal / metabolism*
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Phosphatidylinositol 3-Kinases
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Phosphoproteins / drug effects
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Phosphoproteins / isolation & purification
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Phosphoproteins / metabolism*
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Phosphorylation
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Phosphotransferases (Alcohol Group Acceptor) / drug effects
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Phosphotransferases (Alcohol Group Acceptor) / metabolism*
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Phosphotyrosine
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Rats
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Reference Values
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Tyrosine / analogs & derivatives
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Tyrosine / metabolism
Substances
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Insulin
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Insulin Receptor Substrate Proteins
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Irs1 protein, rat
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Phosphoproteins
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Phosphotyrosine
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Tyrosine
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Glucagon
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Phosphatidylinositol 3-Kinases
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Phosphotransferases (Alcohol Group Acceptor)