To explore whether Radix Bupleuri extract (RBE) could protect lung injury of broilers under ammonia (NH3) exposure, 360 one-d-old male broilers were randomly allocated to four groups of six replicates each in a 2 × 2 factorial design with two diets (the basal diet [control; CON] and the basal diet supplemented with RBE [RB]) and two air conditions (normal condition [<2 ppm of NH3; NOR] and NH3 exposure [70 ppm of NH3; NH70]). The RB diet contained 80 mg saikosaponins/kg diet. On day 7, the lung tissues were collected and the lung epithelial cells (LEC) were isolated. Our experimental results showed that the NH3 exposure decreased body weight gain and feed intake irrespective of dietary treatments during days 1 to 7. However, the RBE addition decreased feed consumption to body weight gain ratio in broilers under NH70 conditions. In the LEC of CON-fed broilers under NH70 conditions, Golgi stacks showed the dilation of cisternaes and reduced secretory vesicles, mitochondria enlarged, the inner membrane of mitochondria became obscure, and the cristae of mitochondria ruptured, whereas only a mild enlargement of Golgi cisternaes and the part rupture of mitochondrial cristaes occurred in the LEC of RB-fed broilers under NH70 conditions. The NH3 exposure increased malondialdehyde (MDA) level, but decreased total antioxidant capacity (T-AOC) in the lungs of CON-fed broilers. However, the RBE addition decreased MDA level and increased T-AOC in the lungs of broilers under NH70 conditions. Simultaneously, the NH3 exposure increased apoptotic rate (AR), mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) level in the isolated LEC of CON-fed broilers. The RBE addition decreased AR, MMP, and ROS in the isolated LEC of broilers under NH70 condition. Besides, the NH3 exposure increased mRNA expression of B-cell lymphoma-2 associated X protein (BAX), caspase-3, and tumor necrosis factor α (TNF-α), but increased interferon γ (IFN-γ) mRNA abundance in the lungs of CON-fed broilers. The RBE supplement decreased mRNA levels of BAX, caspase-3, and TNF-α, but increased IFN-γ, interleukin (IL)-4, and IL-17 mRNA levels in the lungs of broilers under NH70 conditions. These results indicated that dietary RBE addition alleviated NH3 exposure-induced intercellular ultrastructural damage via mitochondrial apoptotic pathway, possibly due to RBE-induced increase of antioxidant capacity and immunomodulatory function in the lungs of broilers under NH3 exposure.

中文翻译：

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日粮添加柴胡提取物对大气氨暴露肉鸡生长性能、肺上皮细胞超微结构变化和凋亡的影响

为了探讨柴胡提取物 (RBE) 是否可以保护氨 (NH3) 暴露下的肉鸡肺损伤，将 360 只一龄雄性肉鸡随机分为四组，每组 6 个重复，采用 2 × 2 析因设计，采用两种日粮(基础饮食[对照；CON]和补充有RBE的基础饮食[RB])和两种空气条件(正常条件[＜2 ppm的NH 3 ；NOR]和NH 3 暴露[70 ppm的NH 3 ；NH70])。RB饮食含有80mg柴胡皂苷/kg饮食。第7天，收集肺组织并分离肺上皮细胞(LEC)。我们的实验结果表明，无论第 1 至 7 天的日粮处理如何，NH3 暴露都会降低体重增加和采食量。然而，在 NH70 条件下，添加 RBE 会降低肉鸡的饲料消耗与体重增加的比率。NH70条件下CON饲喂的肉鸡LEC中，高尔基体池扩张，分泌小泡减少，线粒体增大，线粒体内膜变得模糊，线粒体嵴破裂，而高尔基体池仅轻度增大。 NH70条件下RB饲喂肉鸡LEC发生线粒体嵴部分破裂。NH3 暴露增加了 CON 饲喂肉鸡的丙二醛 (MDA) 水平，但降低了肺部的总抗氧化能力 (T-AOC)。然而，在 NH70 条件下，添加 RBE 会降低肉鸡肺部的 MDA 水平并增加 T-AOC。同时，NH3 暴露增加了 CON 饲喂肉鸡分离 LEC 中的细胞凋亡率 (AR)、线粒体膜电位 (MMP) 和活性氧 (ROS) 水平。在 NH70 条件下，添加 RBE 可降低肉鸡分离 LEC 中的 AR、MMP 和 ROS。此外，NH3 暴露增加了 B 细胞淋巴瘤 2 相关 X 蛋白 (BAX)、caspase-3 和肿瘤坏死因子 α (TNF-α) 的 mRNA 表达，但增加了细胞中干扰素 γ (IFN-γ) mRNA 的丰度。 CON饲喂的肉鸡的肺。在 NH70 条件下，RBE 补充剂降低了肉鸡肺部 BAX、caspase-3 和 TNF-α 的 mRNA 水平，但增加了 IFN-γ、白介素 (IL)-4 和 IL-17 mRNA 水平。这些结果表明，日粮中添加 RBE 通过线粒体凋亡途径减轻了 NH3 暴露引起的细胞间超微结构损伤，这可能是由于 RBE 诱导 NH3 暴露下肉鸡肺部抗氧化能力和免疫调节功能的增加。