Department of Animal Science of the State, University of Maringá-Maringá, Paraná, Brazil 87020-900.
J Anim Sci. 2013 Feb;91(2):582-7. doi: 10.2527/jas.2012-5498. Epub 2012 Nov 12.
The aim of the present study was to evaluate the effect of acute heat stress on the production of mitochondrial reactive oxygen species (ROS), the gene expression of the avian uncoupling protein (avUCP) and glutathione peroxidase (GPX 7), and the activity of the enzyme GPX in the liver of meat quail. Two groups of 15 meat quail (Coturnix coturnix japonica) that were 23 d of age were initially housed individually in metallic cages. A period of 7 d was provided for the 2 bird groups to adapt to the cages and to a thermoneutral environment at 25°C with 60% relative humidity. At 30 d of age, 15 quail were exposed to a heat stress (HS) treatment of 34°C for 24 h, humidity 60%, whereas control quail (n = 15) were kept at 25°C. To analyze the production of ROS, 4 quail from each treatment group were slaughtered, and their livers were collected for mitochondrial isolation and to measure the subsequent production of ROS by the mitochondria. Additionally, the livers of 6 animals from each treatment group were collected for total RNA extraction. The cDNA was amplified using primers specific for the target genes, and expression was analyzed using the real-time PCR reaction (qRT-PCR). Five animals from each treatment group were slaughtered to analyze glutathione peroxidase (GPx) activity, which was determined by using of hydrogen peroxide (H2O2), and based on measuring the amount nicotinamide adenine dinucleotide phosphate oxidized. A greater amount of mitochondrial ROS was found in HS animals (0.34 vs. 0.22 nm of ROS produced min(-1) · mg(-1) of protein, P < 0.05) for the reactions that contained only rotenone and in the reactions that were performed with rotenone and antimycin (0.31 vs. 0.23 nm of ROS produced min(-1) · mg(-1) of protein, P < 0.05). Concomitantly, the birds that were subjected to acute heat stress and had a greater amount of ROS production expressed less avUCP mRNA [0.75 arbitrary units (AU) vs. 0.87 AU, P < 0.05] and more GPX 7 mRNA (2.37 AU vs. 1.17 AU, P < 0.01). The HS quail displayed significantly greater GPx activity in their hepatocytes (47.8 vs. 39.6 nmol of NADPH oxidized per mg of protein per minute, P < 0.05). Thus, acute heat stress at 34°C for 24 h affects the production of mitochondrial ROS, the expression of avUCP and GPX 7 mRNA, and the activity of the GPx enzyme in the liver of meat quail.
本研究旨在评估急性热应激对肉鹌鹑肝脏中线粒体活性氧（ROS）的产生、禽类解偶联蛋白（avUCP）和谷胱甘肽过氧化物酶（GPX 7）基因表达以及 GPX 酶活性的影响。将两组 23 日龄的 15 只肉鹌鹑（ Coturnix coturnix japonica ）分别单独饲养在金属笼中。为两组鸟类提供 7 天的时间以适应笼子和 25°C 下 60%相对湿度的热中性环境。30 日龄时，将 15 只鹌鹑暴露于 34°C 的热应激（HS）处理 24 小时，湿度为 60%，而对照组的 15 只鹌鹑则保持在 25°C。为分析 ROS 的产生，每组有 4 只禽类被屠宰，收集肝脏进行线粒体分离，并测量随后线粒体产生的 ROS。此外，每组有 6 只动物的肝脏被收集用于总 RNA 提取。使用针对靶基因的特异性引物扩增 cDNA，并使用实时 PCR 反应（qRT-PCR）分析表达。每组有 5 只动物被屠宰以分析谷胱甘肽过氧化物酶（GPx）活性，该活性通过使用过氧化氢（H2O2）并基于测量烟酰胺腺嘌呤二核苷酸磷酸氧化的量来确定。在仅含有鱼藤酮和进行鱼藤酮和抗霉素的反应中，HS 动物的线粒体 ROS 产生量更大（分别为 0.34 和 0.31 nm 的 ROS 产生 min(-1)·mg(-1) 蛋白质，P<0.05）。同时，暴露于急性热应激并产生更多 ROS 的鸟类 avUCP mRNA 表达量更低[0.75 个任意单位（AU）与 0.87 AU，P<0.05]，而 GPX 7 mRNA 表达量更高[2.37 AU 与 1.17 AU，P<0.01]。HS 鹌鹑的肝细胞中 GPx 活性显著升高（47.8 与 39.6 nmol NADPH 氧化/min·mg 蛋白质，P<0.05）。因此，34°C 下 24 小时的急性热应激会影响肉鹌鹑肝脏中线粒体 ROS 的产生、avUCP 和 GPX 7 mRNA 的表达以及 GPx 酶的活性。
