LPS Pretreatment Blunts Subsequent GH-Induced STAT5 Tyrosine Phosphorylation and Nuclear Accumulation in C3H/HeJ Mice
As detailed in Materials and Methods, mice were pretreated with LPS or PBS for the indicated durations and then with GH or PBS for 15 min. Livers were homogenized and separated into nuclear and cytoplasmic fractions, and these were immunoblotted to detect tyrosine-phosphorylated and total nuclear STAT5 and total and tyrosine-phosphorylated cytoplasmic STAT5. Densitometric analysis revealed the following relative abundances of tyrosine-phosphorylated nuclear STAT5 (expressed as a percentage of maximum): 0 min GH, 0%; 15 min GH, 100%; 15 min GH with 30 min LPS pretreatment, 85.3%; 15 min GH with 60 min LPS pretreatment, 38.3%; and 15 min GH with 120 min LPS, 25.2%.