Hamal K R, Wideman R, Anthony N, Erf G F
Department of Poultry Science, University of Arkansas, Fayetteville 72701, USA.
Poult Sci. 2008 Apr;87(4):636-44. doi: 10.3382/ps.2007-00468.
Intravenous microparticle (MP) injection is a patented method used to select broilers with a robust pulmonary capacity and improved resistance to pulmonary hypertension syndrome (PHS, ascites). Injected MP become entrapped in the terminal pulmonary arterioles where they elicit an increase in pulmonary arterial pressure attributable to vascular occlusion and focal thrombocyte aggregation. Within 2 to 48 h postinjection perivascular mononuclear cell aggregates begin to form around MP-occluded vessels. Nitric oxide (NO) has been shown to modulate the pulmonary arterial pressure response to MP entrapment, but a role of NO during the more chronic (2 to 48 h) focal inflammatory response has not been evaluated. In this study we determined the time-course of inducible nitric oxide synthase (iNOS) expression in the lungs of MP-injected broilers from PHS-resistant (RES) and PHS-susceptible (SUS) lines. Four-week-old broilers (10 broilers/line per time point) were injected i.v. with a minimally lethal dose of MP, and the right lung was collected at 0 h (no MP) and 2, 24, and 48 h postinjection. Immunohistochemistry revealed that macrophage infiltration increased over time in both lines and was higher in the RES line than the SUS line (P<0.0001) at all time points. Nicotinamide adenine dinucleotide phosphate diaphorase staining showed nitric oxide synthase activity around MP-occluded vessels and in the perivascular mononuclear cell aggregates. Relative iNOS expression in lung tissue was examined by 2-step reverse transcription PCR. Lines differed in relative iNOS mRNA expression only at 24 h (P<0.001; RES > SUS line). For the RES line iNOS mRNA expression increased consistently from 0 to 48 h, but for the SUS line iNOS mRNA expression increased at 2 h, decreased to baseline at 24 h, and increased again by 48 h. The decline in iNOS expression in the SUS line between 2 and 24 h coincides with the interval when most of the MP-induced mortality occurs, which suggests that NO synthesized by iNOS may contribute to lower MP-induced mortality in the RES line when compared with the SUS line.
静脉注射微粒（MP）是一种获得专利的方法，用于筛选具有强大肺功能且对肺动脉高压综合征（PHS，腹水症）抵抗力增强的肉鸡。注射的MP会滞留在终末肺小动脉中，在那里它们会因血管阻塞和局部血小板聚集而导致肺动脉压升高。注射后2至48小时内，血管周围单核细胞聚集物开始在MP阻塞的血管周围形成。一氧化氮（NO）已被证明可调节肺动脉压对MP滞留的反应，但尚未评估NO在更慢性（2至48小时）的局部炎症反应中的作用。在本研究中，我们确定了来自抗PHS（RES）和易感PHS（SUS）品系的MP注射肉鸡肺中诱导型一氧化氮合酶（iNOS）表达的时间进程。4周龄的肉鸡（每个时间点每个品系10只肉鸡）静脉注射最小致死剂量的MP，并在注射后0小时（未注射MP）、2小时、24小时和48小时收集右肺。免疫组织化学显示，两个品系中巨噬细胞浸润均随时间增加，并且在所有时间点RES品系中的巨噬细胞浸润均高于SUS品系（P<0.0001）。烟酰胺腺嘌呤二核苷酸磷酸黄递酶染色显示MP阻塞血管周围和血管周围单核细胞聚集物中有一氧化氮合酶活性通过两步逆转录PCR检测肺组织中相对iNOS表达。品系仅在24小时时相对iNOS mRNA表达存在差异（P<0.001；RES品系>SUS品系）。对于RES品系，iNOS mRNA表达从0至48小时持续增加，但对于SUS品系，iNOS mRNA表达在2小时时增加，在24小时时降至基线，并在48小时时再次增加。SUS品系在2至24小时之间iNOS表达的下降与大多数MP诱导的死亡发生的时间段一致，这表明与SUS品系相比，RES品系中由iNOS合成的NO可能有助于降低MP诱导的死亡率。
