热应激对文昌鸡HPG轴GABA能神经元和生殖激素细胞生长发育的影响及其机制

Due to the frequent and intense occurrence of heat waves caused by the global climate warming, the heat stress has become a key issue in animal production and reproduction as the high temperature environment has seriously impeded the productivity of domestic animals. In this study, experiments were conducted to investigate the effect of heat stress on the growth of one-day-old Wenchang chicken, under a hot environment with a temperature of 40°C and a humidity of 80%, by using various methods including morphological anatomy, immunocytochemistry, flow cytometry and molecule biology so as to reveal the impact of heat stress on the growth and development process of GABAergic neuron and main reproductive cells in the hypothalamic-pituitary-gonad (HPG) axis of Wenchang chicken, to understand the natural law of GABAergic neuron and its receptor, reproductive hormone cells and their receptors, reproductive hormone receptors of main reproductive organs of HPG axis in Wenchang chicken, to illuminate the damage to the development process of the HPG axis, to expound the time-space relationship between heat stress and the growth of GABAergic neuron and reproductive hormone cells, and to clarify the mechanism in relieving the damage to the development of HPG axis in Wenchang chicken under heat stress. .New evidences were obtained on the development of the HPG axis of Wenchang chicken under heat stress and its mechanism so as to further understand the relationship between the development of the HPG axis and heat stress and to provide fresh ideas and data for effective precautions as well as easing the impact of the hot environment on the development of the HPG axis in Wenchang chicken.

由于全球气候变暖,热浪袭击的频率和强度在逐年增加,高温环境严重地阻碍畜禽生产力发展,因此，热应激是动物生产繁殖过程中十分重要的问题。本项目拟选用1日龄文昌鸡为实验对象,采用温度40℃,湿度80%的热环境对雏鸡进行热应激，运用形态组织解剖学、免疫细胞化学、流式细胞术和分子生物学等手段,研究热环境下文昌鸡下丘脑-垂体-性腺（HPG）轴GABA能神经元和主要生殖激素细胞的生长发育过程，揭示文昌鸡HPG轴GABA能神经元及其受体、生殖激素细胞及其受体以及主要靶器官生殖激素受体发育的自然规律；弄清热应激对文昌鸡HPG轴上这些细胞及其受体生长发育过程的损伤, 厘清热应激文昌鸡HPG轴GABA能神经元与生殖激素细胞发育的时空关系，阐明热应激影响文昌鸡HPG轴GABA能神经元和生殖激素细胞发育的可能机制，为理解热应激生理机制增添新的证据,为减轻热应激对鸡HPG轴神经内分泌系统发育损伤及预防提供新思路和资料

随着全球极端高温天气频发，动物的热应激时常发生,严重地影响雏鸡下丘脑-垂体-性腺（HPG）轴功能的发育。本项目通过组织解剖学、免疫细胞化学 、蛋白质印迹技术（WB）和分子生物学等手段,研究热应激影响文昌鸡雏鸡HPG轴GABA能神经元和主要生殖激素细胞的生长发育及其可能机制，结果显示：.1/.与对照组(CK)相比，HS组雌鸡下丘脑组织中GABA, GABA A 受体的表达均显著增加，而GABA B 受体的表达则显著降低; 垂体组织中GABA及两种受体的表达均显著降低；卵巢组织中GABA及GABA B受体的表达显著高于CK组, 而GABA A 受体的表达则显著降低；而HS组雄鸡下丘脑、垂体、睾丸组织中GABA及其两种受体的表达均显著增加；雏鸡HPG轴组织样品中均检测出GABA A受体β3亚基和GABA B受体GB2亚基mRNA的存在；随着周龄增加，GABA受体基因在雏鸡的不同组织中的表达具有波动性和差异性；GABA A和GABA B受体mRNA在垂体、睾丸、卵巢组织中表达量峰值均出现在第3周龄。.2/. HS组雄鸡雏鸡血清T、LH激素含量显著偏低，FSH激素含量显著偏高，组织中GnRH，FSH、LH和T细胞的表达均在3周龄后降低，并在6周龄时具有显著性差异；而雌鸡的GnRH 、垂体LH、FSH和卵巢E2的表达随着发育的进行均呈现波动的趋势。HS组雏鸡垂体TR、LHR、FSHR的受体表达呈波动性变化,第2、4、5、6周龄FSHR表达显著偏低；第2、3、6 周龄TR表达显著偏高；睾丸LHR和FSHR表达随着周龄的增长先增加后降低,分别在第2和第3-5周达到高峰，而TR的表达随着周龄的增长逐渐增加。.3/. HS组的雌鸡下丘脑ERK在第1、2周上调，JNK和p38反之；垂体MAPKs在第3周均下调，而在第4周p38出现上调，卵巢MAPKs在第5周均上调，第6周ERK下调。HS组雄鸡下丘脑MAPKs的ERK在第1、2、5周与雌鸡完全相反，在p38和JNK在第2、3周与热应激雌鸡同为下调；垂体、睾丸的MAPKs在第5周与热应激雌鸡相反，均为下调。因此，雏鸡HPG轴MAPKs信号通路存在性别差异，并具有可塑性。这些结果表明：热应激影响了文昌鸡雏鸡HPG轴GABA 能神经元和生殖激素细胞的正常发育，其可能机制是通过MAPKs通路的介导。