A high-fructose diet induces changes in pp185 phosphorylation in muscle and liver of rats
Carregando...
Data
2000
Título da Revista
ISSN da Revista
Título de Volume
Editor
Resumo
Insulin stimulates the tyrosine kinase activity of its receptor resulting
in the tyrosine phosphorylation of pp185, which contains insulin
receptor substrates IRS-1 and IRS-2. These early steps in insulin
action are essential for the metabolic effects of insulin. Feeding
animals a high-fructose diet results in insulin resistance. However, the
exact molecular mechanism underlying this effect is unknown. In the
present study, we determined the levels and phosphorylation status of
the insulin receptor and pp185 (IRS-1/2) in liver and muscle of rats
submitted to a high-fructose diet evaluated by immunoblotting with
specific antibodies. Feeding fructose (28 days) induced a discrete
insulin resistance, as demonstrated by the insulin tolerance test. Plasma
glucose and serum insulin and cholesterol levels of the two groups of
rats, fructose-fed and control, were similar, whereas plasma triacyl-
glycerol concentration was significantly increased in the rats submit-
ted to the fructose diet (P<0.05). There were no changes in insulin
receptor concentration in the liver or muscle of either group. However,
insulin-stimulated receptor autophosphorylation was reduced to 72 ±
4% (P<0.05) in the liver of high-fructose rats. The IRS-1 protein levels
were similar in both liver and muscle of the two groups of rats. In
contrast, there was a significant decrease in insulin-induced pp185
(IRS-1/2) phosphorylation, to 83 ± 5% (P<0.05) in liver and to 77 ±
4% (P<0.05) in muscle of the high-fructose rats. These data suggest
that changes in the early steps of insulin signal transduction may have
an important role in the insulin resistance induced by high-fructose
feeding.
Descrição
Palavras-chave
Fructose, Phosphorylation, Insulin receptor pp185
Citação
UENO, M.; BEZERRA, R. M. N.; SILVA, M. S. ; TAVARES, D. Q.; CARVALHO, C. R. ; SAAD, M. J. A. A high-fructose diet induces changes in pp185 phosphorylation in muscle and liver of rats. Brazilian Journal of Medical and Biological Research, Ribeirão Preto, v. 33, n. 12, p. 1421-1427, 2000.