凝结芽孢杆菌下调肾上腺皮质激素改善断奶仔猪应激的作用及机理研究

weaning stress imposes a severe challenge to the young piglets and often leads to growth retardation in the swine production. On the work of the several finished experiments supported by Yunnan natural science foundation, It had been established that the supplementation of 1.0× 107cfu/g Bacillus coagulans down-regulated plasma adrenocortical hormone and improve weanling stress and performance of piglets. According to these interesting findings, the hypothesis or mechanism of probiotics Bacillus coagulans improving the weanling stress and growth performance of piglets by adrenocortical hormone is worth to study in the field of neuroendocrinology. According to the difference of stress factors in actual production, three stress test models in wealing piglets were desigen in this project, including on maternal isolation physiological stress model, LPS immune stimulation stress model, and E.coli k88 attack stress model. The hypothalamic-pituitary-adrenal axis (HPA) hormones CRH, ACTH, and cortisol, the neurotransmitters 5-HT and P substance, and the cytokines IL-1, IL-2, IL-6, TNF-α, and IFN-γ were analyzed and detected. Furthermove, by these data statistics, the mechanism of probiotics Bacillus coagulans improving weanling stress and young piglet performance were clarified through the intestinal neurotransmitters and/or cytokines down-regulation of adrenocorticotropic hormone in HPA axis pathway. The research and these findings should be benefit for the advancement of neuroendocrinology, and also be valuable to be applied in the swine production.

断奶应激迟滞仔猪生长性能是当前我国养猪业生产难题之一。申请人前期在云南省自然科学基金资助下首次发现：饲粮添加1.0×107cfu/g凝结芽孢杆菌具有下调肾上腺皮质激素而改善仔猪断奶应激及生产性能的效果。据此，本项目借助神经内分泌学这一新兴交叉学科的创新研究思路，依据实际养殖生产应激类型的不同，设计母仔隔离生理应激模型、LPS免疫刺激应激模型、大肠杆菌K88攻毒应激模型等3个试验。重点分析血液“下丘脑－垂体－肾上腺”轴CRH、ACTH、cortisol激素；肠粘膜神经递质5-HT、P物质以及IL-1、IL-2、IL-6、TNF-α、IFN-γ等5个细胞因子，来揭示不同应激模式下饲粮添加凝结芽孢杆菌通过肠神经递质和（或）细胞因子，影响“下丘脑－垂体－肾上腺”轴通路，下调肾上腺糖皮质激素，进而改善仔猪断奶应激及生产性能的机理。项目成果不仅丰富神经内分泌学科的内涵，并在养猪业有实际的应用价值。

断奶应激迟滞仔猪生长性能是当前我国养猪业生产难题之一，本项目借助神经内分泌学这一新兴交叉学科的创新研究思路，依据仔猪养殖生产应激类型的不同，设计母仔隔离生理应激模型、大肠杆菌K88攻毒应激模型、LPS免疫刺激应激模型等3个试验，重点分析多个细胞因子与神经递质对“下丘脑－垂体－肾上腺”轴激素的调控作用，以揭示不同应激模式下饲粮添加凝结芽孢杆菌下调肾上腺糖皮质激素，进而改善仔猪断奶应激及生产性能的机制。结果显示：（1）采用母仔隔离生理应激试验研究发现，凝结芽孢杆菌通过神经递质P物质的下调，抑制了肾上腺糖皮质激素，改善了断奶隔离生理应激仔猪的生长性能；（2）采用大肠杆菌感染应激试验模型研究发现，凝结芽孢杆菌通过细胞因子IL-1、IL-6的下调与IFN-γ、TNF-α的上调，以及神经递质P物质、5-HT的下调，抑制了肾上腺糖皮质激素，改善了肠致病菌感染应激仔猪的生长性能；（3）采用LPS免疫刺激应激试验模型研究发现，凝结芽孢杆菌通过细胞因子IL-1、IL-6的下调与TNF-α的上调，以及神经递质P物质、5-HT的下调，抑制了肾上腺糖皮质激素，改善了免疫刺激应激仔猪的生长性能。以上研究表明，饲用凝结芽孢杆菌通过调控多个细胞因子及神经递质，抑制了不同应激条件下仔猪的肾上腺皮质激素分泌，进而改善仔猪断奶应激及生产性能。本项目成果不仅丰富神经内分泌学科的内涵，并在养猪业有实际的应用价值。