Fig. 2. Oxidative stress promotes insulin-induced STAT-5.

(a) 8 week-old male C57BL/6 mice were chow- or HFF for 24 weeks, fasted, injected with PBS or insulin and livers processed for immunoblotting. (b) 20 week-old male C57BL/6 mice were subjected to hyperinsulinemic euglycemic clamps. Plasma GH levels were measured and livers processed for immunoblotting or quantitative real-time PCR to measure Igf-1. (c-g) Hepatocytes from chow-fed mice were treated with vehicle or 0.5 mM palmitate. (c, e-g) Hepatocytes were serum-starved, stimulated with 100 nM insulin and processed for immunoblotting. (d) H₂O₂ production was measured. Where indicated hepatocytes were pre-treated with vehicle, the JAK inhibitor CMP6 (10 µM), mitoTempol (10 µM) or SS31 (50 µM) for 2 h. In (f) hepatocytes were transfected with GFP control or Jak-2-specific siRNAs prior to palmitate treatment. (h) H₂O₂ production and (i) insulin (100 nM)-induced p-STAT-5 signaling in Gpx1+/+ and −/− hepatocytes. (j) 8 week-old male C57BL/6 mice were HFF for 12 weeks and treated with vehicle or SS31 for 10 days. Mice were fasted and injected with PBS or insulin (0.5 mU/g, 10 min) and livers extracted for immunoblotting. (k-l) Gpx1+/+ and −/− male mice were HFF for 24 weeks, fasted and livers processed for immunoblotting. Representative and quantified (means ± SEM) results are shown.