Impaired insulin secretion and decreased expression of the nutritionally responsive ribosomal kinase protein S6K-1 in pancreatic islets from malnourished rats

Low-protein diet disrupts the crosstalk between the PKA and PKC signaling pathways in isolated pancreatic islets

“…2 These values were obtained from fed rats. [7,8,54,66], LP islets showed a higher level of hepatic glycogen compared with NP islets (Pb.05). The increase in hepatic glycogen may be explained by the up-regulation of insulin signaling and subsequent inhibition of gluconeogenesis in the rat liver [59].…”

Chronic supplementation of beta-hydroxy-beta methylbutyrate (HMβ) increases the activity of the GH/IGF-I axis and induces hyperinsulinemia in rats

“…The hyperinsulinemia also might account for the apparent insulin resistance, since chronic exposure to insulin was shown to provoke serine phosphorylation of IRS1 and inhibit PI3-K activity, proteins that are essential in signaling mechanisms involved in insulin action [40,41]. It is interesting to stress that some amino acids, like leucine, are able to increase insulin secretion, as pointed beforehand [42], and it is possible that its metabolite HMβ could also exert this action, which remains to be addressed.…”

Short-term low-protein diet during pregnancy alters islet area and protein content of phosphatidylinositol 3-kinase pathway in rats

“…Some studies have attempted to identify the molecular mechanisms underlying these adaptations in response to pregnancy and protein deprivation. Long-term exposure to a low-protein diet during the growth phase produces an increase in IR, IRS2 and PI3K levels and a reduction in IRS1 and p70 S6K expression (Araujo et al 2004, Filiputti et al 2008. In this study, a short-term, low-protein diet did not alter the IR, IRS1, IRS2 or PI3K-p85 levels but did increase the expression of AKT1 and p70 S6K in the pancreatic islets of non-pregnant rats.…”

“…The control nonpregnant (CNP) and pregnant (CP) groups were fed a 17% protein diet, and the low-protein nonpregnant (LPNP) and pregnant (LPP) groups were fed a 6% protein diet from days 1 to 15 of pregnancy. The diets were isocaloric, as previously described (Filiputti et al 2008). During the experimental period, rats had free access to food and water and were housed at 22°C with a 12h light:dark cycle.…”