Li Cong-Jun, Kahl Stanislaw, Carbaugh Donald, Elsasser Theodore H
Growth Biology Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Building 200, Room 209, Beltsville, MD 20705, USA.
Domest Anim Endocrinol. 2007 Feb;32(2):79-92. doi: 10.1016/j.domaniend.2006.01.001. Epub 2006 Jan 24.
We quantified the changes in abundance of inducible nitric oxide synthase (iNOS) and associated tissue signal transduction pathway elements (STPEs) in the bovine liver in response to lipopolysaccharide (LPS) challenge and further assessed the impact on the LPS-driven variable responses as affected by daily treatment with recombinant growth hormone (GH) prior to LPS challenge. Twenty-four cross-bred beef steers were divided into GH-treated (recombinant bovine GH, Monsanto Inc., St. Louis, MO; 0.1mg/kg BW, i.m., daily for 12 days) and non-GH-treatment (control) groups (n=12/group). Liver biopsy samples were obtained from all animals at 0, 3, 6, and 24h after LPS challenge (E. coli 055:B5, 2.5 microg/kg BW, i.v. bolus) for Western blot analyses of iNOS and STPEs. In response to LPS, tissue levels of iNOS increased significantly (P<0.001) in the first 3h and persisted at levels greater than those at time 0 until 24h. GH further augmented levels of iNOS at 0, 3, and 6h resulting in an overall significant increase in the iNOS protein level (P<0.01). AKT/protein kinase B (AKT/PKB) phosphorylation levels at time 0 were not different between GH-treated and control animals; LPS increased the phosphorylation of AKT/PKB with GH treatment stimulating a four-fold further increase of AKT/PKB phosphorylation. Effects similar to those on AKT/PKB were also observed on signal transducer and activator of transcription 5b (STAT5b). The family of mitogen-activated protein kinase (MAPK) showed different pattern of response. ERK1/2 phosphorylation increased 3h after LPS challenge but only in GH-treated group (P<0.01). Compared to 0 h, SAPK/JUN phosphorylation increased in both experimental groups 3, 6h (P<0.01), and 24h (P<0.05) after LPS. However, at 3h the increase was greater (P<0.01) in GH-treated than in control animals. No effect of LPS challenge or GH treatment on p38(MAPK) was observed. These results suggest that GH treatment has a significant impact on the differential activation of STPEs in the clinical response to LPS.
我们对牛肝脏中诱导型一氧化氮合酶（iNOS）及相关组织信号转导通路元件（STPEs）丰度的变化进行了定量分析，以研究其对脂多糖（LPS）刺激的反应，并进一步评估在LPS刺激前每日用重组生长激素（GH）处理对LPS驱动的可变反应的影响。将24头杂交肉牛分为GH处理组（重组牛GH，孟山都公司，密苏里州圣路易斯；0.1mg/kg体重，肌肉注射，每日12天）和非GH处理组（对照组）（每组n = 12）。在LPS刺激（大肠杆菌055:B5，2.5μg/kg体重，静脉推注）后0、3、6和24小时从所有动物获取肝脏活检样本，用于iNOS和STPEs的蛋白质印迹分析。对LPS的反应中，iNOS的组织水平在最初3小时显著增加（P < 0.001），并持续高于0小时水平直至24小时。GH进一步提高了0、3和6小时时iNOS的水平，导致iNOS蛋白水平总体显著增加（P < 0.01）。GH处理组和对照组动物在0小时时AKT/蛋白激酶B（AKT/PKB）的磷酸化水平无差异；LPS增加了AKT/PKB的磷酸化，GH处理则刺激AKT/PKB磷酸化进一步增加四倍。在信号转导和转录激活因子5b（STAT5b）上也观察到了与AKT/PKB类似的效应。丝裂原活化蛋白激酶（MAPK）家族表现出不同的反应模式。LPS刺激后3小时ERK1/2磷酸化增加，但仅在GH处理组中出现（P < 0.01）。与0小时相比，LPS刺激后3、6小时（P < 0.01）和24小时（P < 0.05）两个实验组中SAPK/JUN磷酸化均增加。然而，在3小时时，GH处理组的增加幅度大于对照组动物（P < 0.01）。未观察到LPS刺激或GH处理对p38（MAPK）有影响。这些结果表明，GH处理对LPS临床反应中STPEs的差异激活有显著影响。
