Jenkins N L, Turner J L, Dritz S S, Durham S K, Minton J E
Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506, USA.
Domest Anim Endocrinol. 2004 Jan;26(1):49-60. doi: 10.1016/j.domaniend.2003.09.001.
One of the hallmarks of the pathophysiology of enteric disease in young pigs is reduced growth performance. This reduction in growth is associated with changes in the endocrine somatotropic growth axis. Our laboratory previously demonstrated that circulating insulin-like growth factor-I (IGF-I) was reduced in pigs infected with Salmonella enterica serovar Typhimurium (S. typhimurium) while circulating growth hormone remained unchanged. The objective of the current study was to determine if infection with S. typhimurium also was associated with changes in circulating IGF binding proteins (IGFBP). In addition, pigs experiencing active enteric disease have reduced feed intake. Because this inappetence may be related to systemic appetite reduction signals, we also evaluated circulating leptin in pigs undergoing active S. typhimurium-induced enteric disease. Crossbred pigs were penned in environmentally controlled rooms with free access to feed and water. Following an acclimation period, pigs were gavaged with 10(10) cfu of S. typhimurium (SAL; n=6) or were given a similar volume of sterile growth media (CON; n=6). Rectal temperatures and feed intakes were measured daily through 168 h to track the time course of the response to S. typhimurium infection. Samples of serum were obtained by jugular venipuncture at 0, 24, 48, 96 and 168 h after infection. Sera were frozen until evaluation for IGF-I by immunoradiometric assay (IRMA). In addition, sera were subjected to western ligand blotting utilizing 125I-IGF-I and 125I-IGF-II. Images were evaluated for total IGFBP and IGFBP-3 by densitometric analyses. Rectal temperature was increased in SAL pigs 24h post-infection (P<0.001) but not at other times. Feed intake was reduced in SAL pigs during the intervals 24-72 h (P<0.001) and 96-144 h (P<0.05) after infection. Serum IGF-I, expressed as a percentage of the 0 h concentration, was reduced in SAL pigs versus CON pigs at 48 h (28.1+/-18.7% versus 102.2+/-17.1%; P<0.01) and 96 h (20.0+/-18.7% versus 128.4+/-17.0%; P<0.0001) post-infection. Both total IGFBP and IGFBP-3, as estimated by ligand blotting, also were reduced in infected pigs at 48 h postchallenge (P<0.05). IGFBPs were similar between the two treatments at other sampling times. Concentrations of IGFBP-3 also were estimated utilizing an IRMA for human IGFBP-3. Serum IGFBP-3 was reduced in S. typhimurium-infected pigs at 24 h (P<0.01), 48 h (P<0.001), 96 h (P<0.001), and 168 h (P<0.05). Serum leptin levels were similar between SAL and CON pigs. The data suggest that swine enteric disease is associated with reduced circulating IGF-I and reductions in total IGFBP and IGFBP-3. However, serum leptin was not affected by enteric disease challenge.
幼猪肠道疾病病理生理学的一个标志是生长性能下降。这种生长减缓与内分泌生长激素轴的变化有关。我们实验室先前证明，感染鼠伤寒沙门氏菌的猪循环胰岛素样生长因子-I（IGF-I）减少，而循环生长激素保持不变。本研究的目的是确定感染鼠伤寒沙门氏菌是否也与循环IGF结合蛋白（IGFBP）的变化有关。此外，患有活动性肠道疾病的猪采食量减少。由于这种食欲不振可能与全身性食欲降低信号有关，我们还评估了患有活动性鼠伤寒沙门氏菌诱导的肠道疾病的猪的循环瘦素。将杂交猪饲养在环境可控的房间内，自由采食和饮水。适应期后，给猪灌胃10(10) cfu的鼠伤寒沙门氏菌（SAL；n=6），或给予相同体积的无菌生长培养基（CON；n=6）。每天测量直肠温度和采食量，持续168小时，以追踪对鼠伤寒沙门氏菌感染的反应时间进程。在感染后0、24、48、96和168小时通过颈静脉穿刺采集血清样本。血清冷冻保存，直至通过免疫放射分析（IRMA）评估IGF-I。此外，利用125I-IGF-I和125I-IGF-II对血清进行Western配体印迹分析。通过密度分析评估图像中的总IGFBP和IGFBP-3。感染后24小时，SAL猪的直肠温度升高（P<0.001），但其他时间没有升高。感染后24-72小时（P<0.001）和96-144小时（P<0.05），SAL猪的采食量减少。感染后48小时（28.1±18.7%对102.2±17.1%；P<0.01）和96小时（20.0±18.7%对128.4±17.0%；P<0.0001），与CON猪相比，SAL猪血清IGF-I以0小时浓度的百分比表示降低。通过配体印迹估计，感染猪在攻毒后48小时总IGFBP和IGFBP-3也降低（P<0.05）。在其他采样时间，两种处理之间的IGFBP相似。还利用人IGFBP-3的IRMA估计IGFBP-3的浓度。鼠伤寒沙门氏菌感染的猪在24小时（P<0.01）、48小时（P<0.001）、96小时（P<0.001）和168小时（P<0.05）血清IGFBP-3降低。SAL猪和CON猪的血清瘦素水平相似。数据表明，猪肠道疾病与循环IGF-I降低以及总IGFBP和IGFBP-3降低有关。然而，血清瘦素不受肠道疾病攻击的影响。
