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Effect of fasting on insulin signaling in the aorta of intact rats.

Authors
Type
Published Article
Journal
Brazilian Journal of Medical and Biological Research
0100-879X
Publisher
SciELO
Publication Date
Volume
29
Issue
12
Pages
1611–1615
Identifiers
PMID: 9222420
Source
Medline
License
Unknown

Abstract

Insulin stimulates the tyrosine kinase activity of its receptor, resulting in the phosphorylation of its cytosolic substrate, insulin receptor substrate 1 (IRS-1). Previous studies have demonstrated a tissue-specific regulation of IRS-1. In the present study we investigated the levels and phosphorylation state of IRS-1 after insulin stimulation in the rat aorta in vivo, and the modulation of this protein after 72 h of fasting, using immunoprecipitation and immunoblotting with anti-insulin receptor, anti-IRS-1 and antiphosphotyrosine antibodies. We show that IRS-1 is present in rat aorta, and is tyrosine phosphorylated after insulin stimulation. After insulin stimulation, rats fasted for 72 h showed an increase in insulin receptor (100 +/- 45%, P < 0.05) and IRS-1 phosphorylation (68 +/- 24%, P < 0.05) in aorta, compared to fed rats. There was no change in insulin receptor of IRS-1 protein levels in fasted rats. In summary, the present study demonstrated that proteins involved in the early steps of insulin signal transduction are present in the rat aorta and can be modulated by fasting. It will be of interest to study the regulation of these proteins in the aorta of animal models of hypertension and/or atherosclerosis.

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