FIG. 4.

Increased hepatic STAT3 and PI3K/Akt signaling in fasted Ptpn2+/− mice. 8- to 10-week-old Ptpn2+/− and +/+ male mice were fed a high-fat diet for 15 weeks. A: Livers were harvested from 4-h fasted mice, and processed for immunoblot analysis with antibodies to the phosphorylated (Ser-473) and activated Akt (p-Akt), phosphorylated (Y705) STAT3 (p-STAT3) and phosphorylated (Y1162/Y1163) IR-β subunit (p-IR) or the corresponding proteins. Representative blots and quantified results (arbitrary units: AU) are shown (means ± SE); *P < 0.05, **P < 0.01 by a two-tailed Student t test. B: Plasma IL-6 levels were determined using an ELISA kit (eBiosciences, San Diego, CA) according to the manufacturer's instructions. C: Livers were harvested from 4-h fasted mice and processed for quantitative (ΔΔCt) RT-PCR to measure the expression of Il6. Results shown are means ± SE. D: Mice were fasted overnight for 8 h, and at the beginning of the light cycle, refed for 4 h, or refed and refasted for 4 h. Livers were harvested from fasted, refed, and fasted/refed and refasted mice and processed for immunoblot analysis as indicated. Representative blots and quantified results are shown (means ± SE); ***P < 0.005 by a two-tailed Student t test. AU, arbitrary units.