Short-term in vivo inhibition of insulin receptor substrate-1 expression leads to insulin resistance, hyperinsulinemia, and increased adiposity

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOInsulin receptor substrate-1 (IRS-1) has an important role as an early intermediary between the insulin and IGF receptors and downstream molecules that participate in insulin and IGF-I signal transduction. Here we employed an antisense oligonucleotide (IRS-1AS) to inhibit whole-body expression of IRS-1 in vivo and evaluate the consequences of short-term inhibition of IRS-1 in Wistar rats. Four days of treatment with IRS-1AS reduced the expression of IRS-1 by 80, 75, and 65% (P < 0.05) in liver, skeletal muscle, and adipose tissue, respectively. This was accompanied by a 40% ( P < 0.05) reduction in the constant of glucose decay during an insulin tolerance test, a 78% ( P < 0.05) reduction in glucose consumption during a hyperinsulinemic-euglycemic clamp, and a 90% ( P < 0.05) increase in basal plasma insulin level. The metabolic effects produced by IRS-1AS were accompanied by a significant reduction in insulin-induced [Ser (473)] Akt phosphorylation in liver (85%, P < 0.05), skeletal muscle (40%, P < 0.05), and adipose tissue ( 85%, P < 0.05) and a significant reduction in insulin-induced tyrosine phosphorylation of ERK in liver (20%, P < 0.05) and skeletal muscle (30%, P < 0.05). However, insulin-induced tyrosine phosphorylation of ERK was significantly increased (60%, P < 0.05) in adipose tissue of IRS-1AS-treated rats. In rats treated with IRS-1AS for 8 d, a 100% increase (P < 0.05) in relative epididymal fat weight and a 120% (P < 0.05) increase in nuclear expression of peroxisome proliferator-activated receptor-gamma were observed. Thus, acute inhibition of IRS-1 expression in rats leads to insulin resistance accompanied by activation of a growth-related pathway exclusively in white adipose tissueo TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.146314281437FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informaçã

Long-term disruption of maternal glucose homeostasis induced by prenatal glucocorticoid treatment correlates with miR-29 upregulation

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO CIENTÍFICO E TECNOLOGICOExcess of glucocorticoids (GCs) during pregnancy is strongly associated with the programming of glucose intolerance in the offspring. However, the impact of high GC levels on maternal metabolism is not clearly documented. This study aimed to test the hypothesis that mothers exposed to elevated levels of GCs might also display long-term disturbances in glucose homeostasis. Dexamethasone (DEX) was administered noninvasively to the mothers via drinking water between the 14th and the 19th days of pregnancy. Mothers were subjected to glucose and insulin tolerance tests at 1, 2, 3, 6, and 12 mo post-weaning. Pregnant rats not treated with DEX and age-matched virgin rats were used as controls. Pancreatic islets were isolated at the 20th day of pregnancy and 12 mo postweaning in order to evaluate glucose-stimulated insulin secretion. The expression of the miR-29 family was also studied due to its responsiveness to GCs and its well-documented role in the regulation of pancreatic beta-cell function. Rats treated with DEX during pregnancy presented long-term glucose intolerance and impaired insulin secretion. These changes correlated with 1) increased expression of miR-29 and its regulator p53, 2) reduced expression of syntaxin-1a, a direct target of miR-29, and 3) altered expression of genes related to cellular senescence. Our data demonstrate that the use of DEX during pregnancy results in deleterious outcomes to the maternal metabolism, hallmarked by reduced insulin secretion and glucose intolerance. This maternal metabolic programming might be a consequence of time-sustained upregulation of miR-29s in maternal pancreatic isletso TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.3061E109E120FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO CIENTÍFICO E TECNOLOGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ – CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO CIENTÍFICO E TECNOLOGICOsem informaçãosem informaçã