Effects of Heat Stress on the Development of GABAergic Neurons in the HPG Axis of Wenchang Chicks

ABSTRACT This study conducted an in-depth investigation on the development of GABAergic neurons and their receptors in HPG axis-related target organs of Wenchang chicks under heat stress. One-day-old healthy Wenchang chicks were randomly divided into control (CK) and heat stress (HS) groups. Chicks in the HS group were placed in a 40±0.5°C climatic chamber for HS treatment from 13:00 to 15:00 daily. By immunohistochemistry and Western blotting, GABA and GABAA receptor (GABAAR) expression in the hypothalamus of the HS group was significantly higher (p<0.05), but GABAB receptor (GABABR) expression was significantly lower than that of the CK group (p<0.05). Expression of GABA and its two receptors in the pituitary tissues of the HS group was significantly lower than in the CK group (p<0.05). Expression of GABA and GABABR in ovaries in the HS group was significantly higher, but expression of GABAAR in the testes of the HS group was lower than that of the CK group (p<0.05). In the male chicks, expression of GABA and its two receptors in the hypothalamus, pituitary, and testicular tissues of the HS group was significantly higher than that of the CK group (p<0.05). Western blotting showed that the GABAAR and GABABR expression of the HS group was significantly higher than that of the CK group at 3 and 5 weeks of age. Thus, HS caused GABAergic nervous system disorder in the HPG axis of Wenchang chicks and seriously hindered the normal development of GABAergic neurons in chicks, leading to the disorder of the expression of GABA and its receptors in tissues.

摘要 本研究针对热应激条件下文昌鸡下丘脑-垂体-性腺（HPG）轴相关靶器官内γ-氨基丁酸能神经元（GABAergic neurons）及其受体的发育特征展开深入探究。选取1日龄健康文昌鸡，随机分为对照组（CK）与热应激组（HS）。热应激组雏鸡每日13:00至15:00被置于40±0.5℃的人工气候箱中进行热应激处理。通过免疫组织化学与蛋白质免疫印迹（Western blotting）技术检测，结果显示：热应激组雏鸡下丘脑组织中γ-氨基丁酸（GABA）与GABAA受体（GABAA receptor）的表达水平显著升高（p<0.05），而GABAB受体（GABAB receptor）的表达水平则显著低于对照组（p<0.05）。热应激组雏鸡垂体组织中GABA及其两种受体的表达水平均显著低于对照组（p<0.05）。热应激组雏鸡卵巢组织中GABA与GABAB受体的表达水平显著升高，而睾丸组织中GABAA受体的表达水平则显著低于对照组（p<0.05）。针对雄性雏鸡的亚组分析显示，热应激组雏鸡下丘脑、垂体及睾丸组织中GABA及其两种受体的表达水平均显著高于对照组（p<0.05）。蛋白质免疫印迹实验结果表明，热应激组雏鸡在3周龄与5周龄时，其GABAA受体与GABAB受体的表达水平均显著高于对照组。综上，热应激可引发文昌鸡HPG轴的γ-氨基丁酸能神经系统紊乱，严重阻碍雏鸡体内γ-氨基丁酸能神经元的正常发育，最终导致各组织中GABA及其受体的表达失衡。