畜牧兽医学报  2023, Vol. 54 Issue (11): 4766-4776. DOI: 10.11843/j.issn.0366-6964.2023.11.030    PDF    
AA肉鸡和如皋黄鸡海马和下丘脑GR和FKBP5的表达及其与应激敏感性的关系
刘杰1,2, 丛玮1,2, 赵敏蝶1,2, 赵茹茜1,2     
1. 南京农业大学动物医学院, 南京 210095;
2. 农业农村部动物生理生化重点实验室, 南京 210095
摘要:旨在探究肉鸡海马和下丘脑糖皮质激素受体(glucocorticoid receptor, GR)及其负反馈因子FK-506结合蛋白5(FK-506 binding protein, FKBP5)的表达是否与应激敏感性有关。选用35日龄的AA肉鸡和如皋黄鸡, 连续10 d皮下注射皮质酮(corticosterone, CORT), 建立慢性应激模型。对应激后AA肉鸡和如皋黄鸡的体重、采食量、行为、血浆生化指标等进行检测, 比较应激敏感性的差异。通过qPCR和Western blot检测海马和下丘脑GR和FKBP5的表达, 并与血浆CORT水平进行相关分析。结果表明: 1)AA肉鸡在CORT处理后体重显著降低, 紧张性不动持续时间和血浆CORT水平均显著增加, 但如皋黄鸡变化均不显著; AA肉鸡和如皋黄鸡血液异嗜性粒细胞/淋巴细胞比率在CORT处理后均显著上调, 但AA肉鸡显著高于如皋黄鸡。2)基础状态下, 如皋黄鸡海马和下丘脑GR蛋白表达量显著高于AA肉鸡; CORT处理导致AA肉鸡和如皋黄鸡海马和下丘脑GR蛋白表达显著下调, 但应激后如皋黄鸡GR蛋白表达量仍显著高于AA肉鸡。3)CORT诱导AA肉鸡海马和下丘脑FKBP5 mRNA和蛋白表达均显著上调, 而如皋黄鸡海马和下丘脑FKBP5的上调只发生在蛋白水平, mRNA的表达量没有变化; 应激后AA肉鸡FKBP5的蛋白表达量显著高于如皋黄鸡。4)血浆CORT水平与海马和下丘脑中GR蛋白表达量呈负相关, 与FKBP5蛋白表达量呈正相关; 海马和下丘脑中GR与FKBP5的蛋白表达量呈负相关。以上结果表明, AA肉鸡和如皋黄鸡应激敏感性的差异与海马和下丘脑GR和FKBP5的表达及其调控有关。
关键词肉鸡    应激    海马    下丘脑    糖皮质激素受体    FK-506结合蛋白5    
Expression of GR and FKBP5 in Hippocampus and Hypothalamus of Arbor Acres and Rugao Yellow Broiler Chickens and Its Relationship with Stress Sensitivity
LIU Jie1,2, CONG Wei1,2, ZHAO Mindie1,2, ZHAO Ruqian1,2     
1. College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China;
2. Key Laboratory of Animal Physiology and Biochemistry, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
Abstract: This study was conducted to investigate whether the expression of glucocorticoid receptor (GR) and FK-506 binding protein 5 (FKBP5) in hippocampus and hypothalamus of broiler chickens is related to stress sensitivity. Arbor Acres (AA) and Rugao yellow (Rugao) broiler chickens at 35 days of age were injected subcutaneously with corticosterone (CORT) for 10 consecutive days to establish a chronic stress model. The body weight, feed intake, behavior and plasma biochemical indexes of the two lines of chickens were detected, and the differences in stress sensitivity were compared. The expression of GR and FKBP5 in hippocampus and hypothalamus were detected by qPCR and Western blot, and their correlation with plasma CORT levels was analyzed. The results showed as follows: 1) After CORT treatment, the body weight of AA decreased significantly, the tonic immobility (TI) duration and plasma CORT level increased significantly, but there was no significant change in Rugao. CORT treatment resulted in increased heterophil/lymphocyte (H/L) ratio in blood of both AA and Rugao, yet H/L ratio was significantly higher in AA than in Rugao. 2) The basal level of GR protein expression in hippocampus and hypothalamus was significantly higher in Rugao than that in AA; The protein expression of GR was significantly down-regulated after CORT treatment, but Rugao still showed significantly higher GR protein than AA after stress. 3) CORT significantly up-regulated FKBP5 expression at both mRNA and protein levels in hippocampus and hypothalamus of AA, while the FKBP5 up-regulation in hippocampus and hypothalamus of Rugao only occurred at the protein level. FKBP5 protein expression was significantly in AA than in Rugao after stress. 4) Plasma CORT level was negatively correlated with GR protein expression in hippocampus and hypothalamus, and positively correlated with FKBP5 protein expression. GR was negatively correlated with FKBP5 protein expression in hippocampus and hypothalamus. These results indicate that AA and Rugao have different stress sensitivity, and the expression levels of GR and FKBP5 in hippocampus and hypothalamus are related to stress sensitivity.
Key words: broiler chicken    stress    hippocampus    hypothalamus    glucocorticoid receptor    FK-506 binding protein 5    

在规模化养殖中,应激会影响肉鸡的健康,并造成巨大的经济损失。品种的选育提高了肉鸡的生长性能,也改变了肉鸡对环境的适应能力和应激敏感性。不同品种的鸡对各种急性和慢性应激的抵抗能力不同,包括急性或慢性热应激[1-2]、慢性冷应激[3]、约束应激[4]等。应激反应由下丘脑-垂体-肾上腺轴(hypothalamic-pituitary-adrenal axis,HPA)调节[5]。应激会激活HPA轴释放糖皮质激素(glucocorticoid,GC),而海马和下丘脑中的糖皮质激素受体(glucocorticoid receptor,GR)通过与GC结合[6],负反馈调节HPA轴来终止应激反应。慢性应激可引起HPA轴过度激活和GCs水平持续升高,导致中枢GR表达下调,HPA轴的负反馈调节机制受损。与白来航鸡相比,红原鸡对急性应激表现出更强的行为和生理反应,但能够更快地恢复正常水平,说明红原鸡可以更好地应对环境应激[7]。因此,HPA轴的负反馈能力在调节鸡的应激反应中至关重要。

FK506结合蛋白5(FK-506 binding protein 5,FKBP5)是GR的分子伴侣,通过减少GR与GC结合和阻碍GC/GR复合物向细胞核的转运来调节GR的功能[8-9]。GR作为FKBP5的转录因子,其激活会诱导FKBP5转录增加,FKBP5与热休克蛋白90(heat shock protein 90,HSP90)相互作用阻止GC/GR复合物向核的易位,在细胞中形成超短负反馈环路[10-11]。通过这一过程,FKBP5降低了应激后GR对GC的敏感性。海马和下丘脑在HPA轴的反馈抑制中起着重要作用。FKBP5在多种应激性精神疾病患者或动物模型的外周血、海马和下丘脑表达增加[12-15]。体外研究发现,抑制FKBP5可以促进海马神经元的生长、分化和增殖[16-17]。FKBP5在小鼠下丘脑的基础表达水平较低,但在地塞米松暴露或应激原刺激后,FKBP5显著增加[18]。鸟类的大脑中也发现了同样的变化,并且FKBP5表达与HPA轴的灵敏度呈负相关,下丘脑FKBP5表达越高,对GR的抑制作用越强,导致GR对HPA轴的负反馈功能受损,使得应激后升高的血浆CORT水平不能及时恢复,从而导致持续应激和行为异常[19]。因此,FKBP5作为治疗应激相关疾病的潜在药物靶点而备受关注,而肉鸡应激敏感性的品种差异是否与海马和下丘脑FKBP5表达有关尚不清楚。

本研究选取AA肉鸡和如皋黄鸡,通过皮下注射皮质酮建立慢性应激模型,分析海马和下丘脑GR和FKBP5的表达是否与应激敏感性有关。研究发现,AA肉鸡抗应激能力较差,这与海马和下丘脑GR和FKBP5表达的差异有关。研究结果为抗应激肉鸡品种选育和肉鸡应激调控提供了新的靶点。

1 材料与方法 1.1 动物模型和样品采集

选用1日龄(d)雄性AA肉鸡(购自江苏京海禽业集团有限公司)和如皋黄鸡各40只(购自江苏省家禽科学研究所)。肉鸡在密闭鸡舍内3层叠层笼养,每笼3只鸡,自由采食和饮水,肉鸡配合饲料购自新希望六和。每天光照16 h,黑暗8 h。35 d时,分别将AA肉鸡和如皋黄鸡随机分为对照组(n=20)和CORT组(n=20)。CORT组连续10 d每天两次皮下注射CORT(C104537,阿拉丁)建立慢性应激模型[20-21],剂量为4.0 mg·(kg·d)-1。每天记录采食量,每7 d称量体重。45 d屠宰,采集抗凝血用于血浆分离。参考鸡脑部图谱[22-23]对海马和下丘脑组织进行采集,置于液氮速冻,并保存于-80 ℃。

1.2 紧张性不动(tonic immobility, TI)测试

TI测试通常用于评估动物的恐惧和应激反应程度。在CORT处理前和处理后进行TI检测。在一个安静的房间里,将鸡背部朝下平放在桌面上,用手轻轻地固定住鸡的胸部和头部。若10 s内鸡没有翻身,则诱导成功,开始记录时间,直到鸡翻身站起。如果鸡平躺时间超过4 min,停止计时,记录时间240 s。

1.3 血浆生化指标测定

将采集的抗凝血置于冰上,3 500 r·min-1 离心10 min,收集血浆。使用生化分析仪(Hitachi,日本)检测血浆三酰甘油(TG)(H201)、葡萄糖(GLU)(H108)、丙氨酸氨基转移酶(ALT)(H001)和天门冬氨酸氨基转移酶(AST)(H002),试剂盒均购自美康生物科技股份有限公司。采用ELISA检测血浆CORT含量,按照鸡皮质酮检测试剂盒(0160c,Elbscience)说明书上的操作步骤测定。

1.4 异嗜性粒细胞/淋巴细胞比率

异嗜性粒细胞/淋巴细胞(heterophil/lymphocyte, H/L)比率的变化反映肉鸡的应激程度,可以作为检测肉鸡应激程度的指标。从翅静脉采集血液制备血涂片,用瑞氏染液(G1040,索莱宝)和姬姆萨染液(G1010,索莱宝)染色。显微镜下随机选择视野,共计数100个白细胞,包括淋巴细胞和异嗜性粒细胞,计算异嗜性粒细胞与淋巴细胞的比值。

1.5 总RNA提取和qPCR

采用Trizol法提取总RNA,使用逆转录试剂盒(AE341,全式金)合成cDNA。参考GenBank设计相关引物(表 1)。使用ABI快速实时PCR系统(QuantStudioTM 6 Flex,Applied Biosystems,美国)进行实时荧光定量PCR,检测相关基因的mRNA表达水平。相对基因表达量采用2-ΔΔCt法计算。

表 1 引物序列 Table 1 Nucleotide sequences of primers
1.6 蛋白提取和Western blot检测

RIPA裂解液配制:1% Triton-100,0.5%脱氧胆酸钠,150 mmol·L-1 NaCl,0.1% SDS,50 mmol·L-1 Tris以及1%蛋白酶抑制剂(B14001,Bimake)。用RIPA裂解液提取组织蛋白,用BCA蛋白检测试剂盒(DQ11,全式金)测定蛋白浓度。用20 μg蛋白进行SDS-PAGE凝胶电泳。鸡GR抗体(本实验室自制,1∶2 000)或FKBP5抗体(ab46002,Abcam,1∶250)4 ℃孵育过夜。次日,使用二抗(bl003a,Biosharp,1∶100 000)室温孵育1 h后,使用ECL化学发光试剂盒(bl523,Biosharp)进行孵育显影。使用ImageJ进行条带灰度定量分析。

1.7 统计分析

采用SPSS软件对数据进行双因素方差分析,若主效应显著,采用单因素方差分析(LSD法)进行组间比较。所有试验数据均以“x±s”表示,P<0.05认为有显著性差异。

2 结果 2.1 AA肉鸡和如皋黄鸡应激敏感性的差异

为了比较不同品种肉鸡的应激敏感性,使用CORT处理AA肉鸡和如皋黄鸡模拟慢性应激。结果显示,AA肉鸡的生长速度比如皋黄鸡快(图 1A)。CORT处理后,AA肉鸡的体重显著下降(P<0.001),而如皋黄鸡的体重没有变化(图 1B)。CORT处理没有改变AA肉鸡和如皋黄鸡的采食量(图 1C)。行为学试验结果显示,正常情况下如皋黄鸡的TI持续时间显著高于AA肉鸡(P<0.05),CORT可显著提高AA肉鸡的TI持续时间(P<0.01),而如皋黄鸡则无明显变化(图 1D)。

A. 1~35 d体重;B. 45 d体重;C. 36~45 d采食量;D. TI静止时间;E. 血浆皮质酮含量;F. 血液中H/L;G. 血涂片染色(标尺=20 μm)。图中所标字母相异表示差异显著(P<0.05),所标字母相同表示差异不显著(P>0.05)。下同 A. Body weight from 1 day to 35 days of age; B. Body weight at 45 days of age; C. Feed intake from 36 to 45 days of age; D. Tonic immobility time; E. Corticosterone content in plasma; F. Heterophil/Lymphocyte ratio in blood; G. Blood smear staining (bar=20 μm). Different letters mean significant difference (P < 0.05), same letter means not significant difference (P > 0.05). The same as below 图 1 AA肉鸡和如皋黄鸡体重、TI持续时间和血液指标 Fig. 1 Body weight, TI duration and blood indexes of AA and Rugao broiler chickens

血浆CORT水平和H/L比值是反映机体应激水平的重要指标。AA肉鸡和如皋黄鸡血浆CORT的基础水平无差异,但CORT处理后AA肉鸡血浆CORT水平显著升高(P<0.01,图 1E),如皋黄鸡没有变化。品种间H/L的基础水平无差异,CORT处理后,AA肉鸡和如皋黄鸡血液中异嗜性粒细胞增加,H/L均显著升高(P<0.001),但AA肉鸡明显高于如皋黄鸡(P<0.05)(图 1FG)。

对下丘脑和海马中谷胱甘肽过氧化物酶(glutathione peroxidase,GPX)和超氧化物歧化酶(superoxide dismutase,SOD)的mRNA表达进行检测,发现CORT导致AA肉鸡下丘脑GPX3和SOD1表达上调(P<0.05)(图 2A~D),以及海马中GPX1、GPX3、SOD1、SOD3表达上调(P<0.05)(图 2E~H),但如皋黄鸡没有变化,说明CORT导致AA肉鸡下丘脑和海马发生氧化损伤,激活抗氧化酶表达。

A~D. 下丘脑GPX1、GPX3、SOD1、SOD3 mRNA表达;E~H. 海马GPX1、GPX3、SOD1、SOD3 mRNA表达 A-D. GPX1, GPX3, SOD1 and SOD3 mRNA expression in hypothalamus; E-H. GPX1, GPX3, SOD1 and SOD3 mRNA expression in hippocampus 图 2 AA肉鸡和如皋黄鸡下丘脑和海马中抗氧化相关基因mRNA表达 Fig. 2 mRNA expression of antioxidant genes in hypothalamus and hippocampus of AA and Rugao chickens
2.2 CORT对AA肉鸡和如皋黄鸡血浆中TG、ALT和AST的影响

对AA肉鸡和如皋黄鸡血浆TG和GLU浓度,以及ALT和AST活性进行检测(表 2)。结果显示,CORT处理后AA肉鸡和如皋黄鸡TG水平均显著升高(P<0.01)。AA肉鸡和如皋黄鸡GLU在基础水平和CORT处理后均没有差异。AA肉鸡ALT和AST的基础水平显著高于如皋黄鸡(P<0.01)。CORT处理后,AA肉鸡的ALT显著降低(P<0.001),AST显著升高(P<0.01),从而导致AST/ALT显著升高(P<0.001),而如皋黄鸡没有变化。结果表明CORT引起AA肉鸡的肝损伤更严重。

表 2 AA肉鸡和如皋黄鸡血浆生化指标(x±s) Table 2 Plasma biochemical parameters of AA and Rugao chickens(x±s)
2.3 CORT对AA肉鸡和如皋黄鸡海马及下丘脑GR与FKBP5表达的影响

中枢的GR和FKBP5在应激反应中起着重要作用,为了探究在品种间是否存在差异,作者对海马、下丘脑中GR和FKBP5在mRNA、蛋白水平的表达进行了检测。结果表明,海马中GRFKBP5 mRNA的基础表达水平在两个品种间没有差异。CORT处理后AA肉鸡海马中GR mRNA显著下降(P<0.05,图 3A),FKBP5 mRNA显著上调(P<0.01,图 2B),而如皋黄鸡GRFKBP5 mRNA没有变化(图 3AB)。如皋黄鸡海马中GR蛋白的基础表达量显著高于AA肉鸡(P<0.001),CORT处理导致AA肉鸡和如皋黄鸡海马的GR蛋白表达均显著下调(P<0.001),但应激后如皋黄鸡的GR蛋白表达量仍显著高于AA肉鸡(P<0.001)(图 3C)。AA肉鸡和如皋黄鸡海马中FKBP5蛋白表达的基础水平没有差异,在CORT处理后均显著增加(P<0.001),但应激后AA肉鸡FKBP5蛋白表达量仍显著高于如皋黄鸡(P<0.001)(图 3D)。

A. GR mRNA表达;B. FKBP5 mRNA表达;C. GR蛋白表达;D. FKBP5蛋白表达 A. GR mRNA expression; B. FKBP5 mRNA expression; C. GR protein expression; D. FKBP5 protein expression 图 3 AA肉鸡和如皋黄鸡海马中GR和FKBP5 mRNA和蛋白表达 Fig. 3 mRNA and protein expression of GR and FKBP5 in hippocampus of AA and Rugao chickens

下丘脑中GR mRNA在两个品种和处理之间没有变化(图 4A)。CORT处理后AA肉鸡下丘脑中FKBP5 mRNA显著上调(P<0.01),而如皋黄鸡没有变化(图 4B)。如皋黄鸡下丘脑GR蛋白的基础表达量显著高于AA肉鸡(P<0.05,图 4C),CORT处理导致AA肉鸡和如皋黄鸡下丘脑的GR蛋白表达均显著下调(P<0.01),但应激后如皋黄鸡的GR蛋白表达量仍显著高于AA肉鸡(P<0.05)(图 4C)。AA肉鸡和如皋黄鸡下丘脑中FKBP5蛋白表达的基础水平没有差异,在CORT处理后均显著增加(P<0.001),但应激后AA肉鸡FKBP5蛋白表达量仍显著高于如皋黄鸡(P<0.001)(图 4D)。

A. GR mRNA表达;B. FKBP5 mRNA表达;C. GR蛋白表达;D. FKBP5蛋白表达 A. GR mRNA expression; B. FKBP5 mRNA expression; C. GR protein expression; D. FKBP5 protein expression 图 4 AA肉鸡和如皋黄鸡下丘脑中GR和FKBP5 mRNA和蛋白表达 Fig. 4 mRNA and protein expression of GR and FKBP5 in hypothalamus of AA and Rugao chickens
2.4 GR和FKBP5蛋白表达水平与血浆皮质酮含量的相关性分析

血浆皮质酮含量与应激反应有关,作者对海马和下丘脑中GR和FKBP5的蛋白表达水平与血浆皮质酮含量进行相关性分析,结果表明,海马(r=-0.535 5,P=0.007 0,图 5A)和下丘脑(r=-0.555 3,P=0.004 8,图 5B)中GR的蛋白表达与血浆皮质酮含量呈负相关,海马(r=0.593 9,P=0.002 2,图 5C)和下丘脑(r=0.694 7,P=0.000 2,图 5D)中FKBP5的蛋白表达与血浆皮质酮含量呈正相关。表明GR与FKBP5的表达水平能够反映肉鸡的应激程度。海马(r=-0.713 0,P<0.000 1,图 5E)和下丘脑(r=-0.666 7,P=0.000 4,图 5F)中GR与FKBP5的蛋白表达呈负相关,表明CORT导致GR表达的降低与FKBP5增加有关。

A. 海马中GR表达与血浆皮质酮含量的相关性;B. 下丘脑中GR表达与血浆皮质酮含量的相关性;C. 海马中FKBP5表达与血浆皮质酮含量的相关性;D. 下丘脑中FKBP5表达与血浆皮质酮含量的相关性;E. 海马中FKBP5表达与GR表达的相关性;F. 下丘脑中FKBP5表达与GR表达的相关性 A. Correlation between GR expression in hippocampus and plasma corticosterone content; B. Correlation between GR expression in hypothalamus and plasma corticosterone content; C. Correlation between FKBP5 expression in hippocampus and plasma corticosterone content; D. Correlation between FKBP5 expression in hypothalamus and plasma corticosterone content; E. Correlation between FKBP5 expression and GR expression in hippocampus; F. Correlation between FKBP5 expression and GR expression in hypothalamus 图 5 AA肉鸡和如皋黄鸡海马和下丘脑中血浆皮质酮含量、GR和FKBP5蛋白表达水平的相关性分析 Fig. 5 Correlation analysis of plasma corticosterone content, GR and FKBP5 protein expression levels in hippocampus and hypothalamus of AA and Rugao chickens
3 讨论

增强抗应激能力有利于肉鸡的生长,提高肉鸡生产的经济效益。因此,提高肉鸡的抗应激能力对生产极为重要。已有研究发现不同品种肉鸡的应激敏感性存在差异[1, 24-25]。本研究证明如皋黄鸡比AA肉鸡抗应激能力更强。AA肉鸡和如皋黄鸡的海马和下丘脑中GR的基础表达水平和CORT诱导的FKBP5表达存在差异,与应激敏感性有关。

为了满足对畜禽肉产品日益增长的需求,经过近几十年的人工选育,肉鸡的生长速度不断增加,同时应激敏感性也发生改变[26-27]。AA肉鸡为我国白羽肉鸡工厂化生产的主要品种之一,特点为体型大、生长发育快、饲料转化率高。如皋黄鸡生长较慢,属肉蛋兼用型地方品种。已有研究发现,生长缓慢的品种对应激有更好的抵抗力。在急性热应激试验中,科宝500肉鸡的体温、H/L、血浆CORT含量和脑中HSP70表达均有升高,而红原鸡和土种鸡没有变化[28]。慢性热应激试验中也得到相似的结果[29]。限饲引起的慢性应激使血浆CORT含量增加,应激后快速型肉鸡血浆中的CORT含量增加了2.48倍,而慢速型肉鸡仅增加了1.30倍[24]。作者的研究结果与以上研究结果一致,通过皮下注射CORT模拟慢性应激,AA肉鸡体重显著降低,H/L比率和血浆CORT含量显著升高,说明AA肉鸡的应激反应比如皋黄鸡更强烈。TI测试和循环皮质酮水平通常用于评估恐惧和应激反应。在本研究中,AA肉鸡的TI时间在基线时低于如皋黄鸡,在CORT处理后升高,此外,AA肉鸡血浆CORT含量也显著升高,而如皋黄鸡的TI时间和血浆CORT含量没有改变。研究发现,选育可以改变鸡对应激源的恐惧程度,红原鸡比家养鸡表现出更多的恐惧行为,以及不同的应激恢复模式[30]。在急性应激后,红原鸡的行为反应迅速,CORT变化更为显著,并更快地恢复到基础水平[7, 31]。和AA肉鸡相比,如皋黄鸡选育程度可能较低,其应激反应与红原鸡相似,在自然状态下高度警惕,但在受到应激时能够迅速恢复。

HPA轴能够调节机体的适应能力。GR是机体应激反应系统的关键组成部分,也是GC结合的主要受体。GR在大脑中大量表达,负反馈抑制GC诱导的HPA轴激活,在应激和精神活动中起着重要的调节作用。研究发现,在红原鸡和白来航鸡的海马中GR mRNA没有差异,而白来航鸡下丘脑中GR mRNA高于红原鸡[4]。也有研究发现科宝肉鸡下丘脑中GR mRNA和蛋白表达高于白来航鸡[32]。在作者的试验中,GR mRNA的基础表达水平在两个品种间没有差异,但在蛋白水平,如皋黄鸡海马和下丘脑中GR的基础水平高于AA肉鸡,说明如皋黄鸡中枢的GR对HPA具有更强的负反馈调节作用。PTSD和抑郁模型小鼠的海马和下丘脑中GR表达降低[33-34]。CORT处理也会导致鸡下丘脑GR蛋白表达下调[35],在本研究中观察到相同的结果。

GR主要以复合物的形式存在于细胞质中,FKBP5是其分子伴侣之一。FKBP5可以调节GR敏感性和HPA轴功能,并与许多应激相关的精神疾病有关。FKBP5是GR的负反馈调节因子,高水平的FKBP5会减少GR入核,引起糖皮质激素抵抗[36]。GR-FKBP5蛋白复合物在PTSD患者和小鼠模型中增加。破坏GR-FKBP5结合可促进GR核易位,降低小鼠恐惧记忆的巩固和回忆[37]。应激后麻雀下丘脑中FKBP5表达越低,HPA轴越灵活[19]。本研究中,GR与FKBP5的表达呈负相关,并且CORT使AA肉鸡海马和下丘脑FKBP5蛋白比如皋黄鸡增加更多,表明AA肉鸡FKBP5可能与GR结合更多,形成GR-FKBP5蛋白复合物,阻止GR进入细胞核,使GR不能发挥对HPA轴的抑制作用。

GC含量反映机体的应激水平,可以作为应激反应的生物标志物。GC高分泌与应激相关精神疾病有关,通常伴随着GR低表达和FKBP5高表达[38]。作者发现肉鸡循环皮质酮与海马和下丘脑中GR的表达呈负相关,与FKBP5的表达正相关,表明海马和下丘脑中GR和FKBP5的表达水平可以反映肉鸡的应激程度,并与应激敏感性有关。因此,GR和FKBP5可以作为肉鸡育种筛选的候选基因。在应激相关精神疾病中GR和FKBP5表达变化与单核苷酸多态性(single nucleotide polymorphisms,SNPs)有关[39-40]。在畜禽养殖中SNPs被应用于育种筛选。已有研究发现猪肝和皮肤中GR SNPs与应激反应和攻击行为有关,可以作为育种标记[41]。本研究结果中,AA肉鸡和如皋黄鸡下丘脑和海马中GR和FKBP5在应激反应中的表达差异可能与SNPs有关,需要进一步探究。

4 结论

作者对采用CORT处理AA肉鸡和如皋黄鸡建立慢性应激模型,比较应激敏感性的差异。结果表明,不同品种肉鸡海马和下丘脑中GR和FKBP5的表达与应激敏感性有关。因此,GR和FKBP5可作为调控肉鸡抗逆性和遗传改良的靶点。

参考文献
[1]
ADU-ASIAMAH P, ZHANG Y, AMOAH K, et al. Evaluation of physiological and molecular responses to acute heat stress in two chicken breeds[J]. Animal, 2021, 15(2): 100106. DOI:10.1016/j.animal.2020.100106
[2]
RIMOLDI S, LASAGNA E, SARTI F M, et al. Expression profile of six stress-related genes and productive performances of fast and slow growing broiler strains reared under heat stress conditions[J]. Meta Gene, 2015, 6: 17-25. DOI:10.1016/j.mgene.2015.08.003
[3]
XIE S, YANG X, GAO Y, et al. Performance differences of Rhode Island Red, Bashang Long-tail chicken, and their reciprocal crossbreds under natural cold stress[J]. Asian-Australas J Anim Sci, 2017, 30(10): 1507-1514. DOI:10.5713/ajas.16.0957
[4]
LØTVEDT P, FALLAHSHAHROUDI A, BEKTIC L, et al. Chicken domestication changes expression of stress-related genes in brain, pituitary and adrenals[J]. Neurobiol Stress, 2017, 7: 113-121. DOI:10.1016/j.ynstr.2017.08.002
[5]
MCEWEN B S. Protective and damaging effects of stress mediators[J]. N Engl J Med, 1998, 338(3): 171-179. DOI:10.1056/NEJM199801153380307
[6]
SMITH S M, VALE W W. The role of the hypothalamic-pituitary-adrenal axis in neuroendocrine responses to stress[J]. Dialogues Clin Neurosci, 2006, 8(4): 383-395. DOI:10.31887/DCNS.2006.8.4/ssmith
[7]
ERICSSON M, FALLAHSHAROUDI A, BERGQUIST J, et al. Domestication effects on behavioural and hormonal responses to acute stress in chickens[J]. Physiol Behav, 2014, 133: 161-169. DOI:10.1016/j.physbeh.2014.05.024
[8]
GRAD I, PICARD D. The glucocorticoid responses are shaped by molecular chaperones[J]. Mol Cell Endocrinol, 2007, 275(1-2): 2-12. DOI:10.1016/j.mce.2007.05.018
[9]
WOCHNIK G M, RVEGG J, ABEL G A, et al. FK506-binding proteins 51 and 52 differentially regulate dynein interaction and nuclear translocation of the glucocorticoid receptor in mammalian cells[J]. J Biol Chem, 2005, 280(6): 4609-4616. DOI:10.1074/jbc.M407498200
[10]
DENNY W B, VALENTINE D L, REYNOLDS P D, et al. Squirrel monkey immunophilin FKBP51 is a potent inhibitor of glucocorticoid receptor binding[J]. Endocrinology, 2000, 141(11): 4107-4113. DOI:10.1210/endo.141.11.7785
[11]
HUBLER T R, SCAMMELL J G. Intronic hormone response elements mediate regulation of FKBP5 by progestins and glucocorticoids[J]. Cell Stress Chaperones, 2004, 9(3): 243-252. DOI:10.1379/CSC-32R.1
[12]
BINDER E B. The role of FKBP5, a co-chaperone of the glucocorticoid receptor in the pathogenesis and therapy of affective and anxiety disorders[J]. Psychoneuroendocrinology, 2009, 34: S186-S195. DOI:10.1016/j.psyneuen.2009.05.021
[13]
KLENGEL T, MEHTA D, ANACKER C, et al. Allele-specific FKBP5 DNA demethylation mediates gene-childhood trauma interactions[J]. Nat Neurosci, 2013, 16(1): 33-41. DOI:10.1038/nn.3275
[14]
GERRITSEN L, MILANESCHI Y, VINKERS C H, et al. HPA axis genes, and their interaction with childhood maltreatment, are related to cortisol levels and stress-related phenotypes[J]. Neuropsychopharmacology, 2017, 42(12): 2446-2455. DOI:10.1038/npp.2017.118
[15]
GUIDOTTI G, CALABRESE F, ANACKER C, et al. Glucocorticoid receptor and FKBP5 expression is altered following exposure to chronic stress: modulation by antidepressant treatment[J]. Neuropsychopharmacology, 2013, 38(4): 616-627. DOI:10.1038/npp.2012.225
[16]
QIU B, ZHONG Z, RIGHTER S, et al. FKBP51 modulates hippocampal size and function in post-translational regulation of Parkin[J]. Cell Mol Life Sci, 2022, 79(3): 175. DOI:10.1007/s00018-022-04167-8
[17]
CODAGNONE M G, KARA N, RATSIKA A, et al. Inhibition of FKBP51 induces stress resilience and alters hippocampal neurogenesis[J]. Mol Psychiatry, 2022, 27(12): 4928-4938. DOI:10.1038/s41380-022-01755-9
[18]
SCHARF S H, LIEBL C, BINDER E B, et al. Expression and regulation of the Fkbp5 gene in the adult mouse brain[J]. PLoS One, 2011, 6(2): e16883. DOI:10.1371/journal.pone.0016883
[19]
ZIMMER C, HANSON H E, MARTIN L B. FKBP5 expression is related to HPA flexibility and the capacity to cope with stressors in female and male house sparrows[J]. Horm Behav, 2021, 135: 105038. DOI:10.1016/j.yhbeh.2021.105038
[20]
DUAN Y, FU W, WANG S, et al. Cholesterol deregulation induced by chronic corticosterone (CORT) stress in pectoralis major of broiler chickens[J]. Comp Biochem Physiol A Mol Integr Physiol, 2014, 176: 59-64. DOI:10.1016/j.cbpa.2014.07.010
[21]
HU Y, FENG Y, ZHANG L, et al. GR-mediated FTO transactivation induces lipid accumulation in hepatocytes via demethylation of m(6)A on lipogenic mRNAs[J]. RNA Biol, 2020, 17(7): 930-942. DOI:10.1080/15476286.2020.1736868
[22]
GRIFFIN C, FLOURIOT G, SHARP P, et al. Distribution analysis of the two chicken estrogen receptor-alpha isoforms and their transcripts in the hypothalamus and anterior pituitary gland[J]. Biol Reprod, 2001, 65(4): 1156-1163. DOI:10.1095/biolreprod65.4.1156
[23]
GUPTA S K, BEHERA K, PRADHAN C R, et al. Studies of the macroscopic and microscopic morphology (hippocampus) of brain in Vencobb broiler[J]. Vet World, 2016, 9(5): 507-511. DOI:10.14202/vetworld.2016.507-511
[24]
YAN C, XIAO J, CHEN D, et al. Feed restriction induced changes in behavior, corticosterone, and microbial programming in slow- and fast-growing chicken breeds[J]. Animals (Basel), 2021, 11(1): 141.
[25]
VACCARO L A, PORTER T E, ELLESTAD L E. Effects of genetic selection on activity of corticotropic and thyrotropic axes in modern broiler chickens[J]. Domest Anim Endocrinol, 2022, 78: 106649. DOI:10.1016/j.domaniend.2021.106649
[26]
FANATICO A C, PILLAI P B, EMMERT J L, et al. Meat quality of slow- and fast-growing chicken genotypes fed low-nutrient or standard diets and raised indoors or with outdoor access[J]. Poult Sci, 2007, 86(10): 2245-2255. DOI:10.1093/ps/86.10.2245
[27]
FANATICO A C, PILLAI P B, HESTER P Y, et al. Performance, livability, and carcass yield of slow- and fast-growing chicken genotypes fed low-nutrient or standard diets and raised indoors or with outdoor access[J]. Poult Sci, 2008, 87(6): 1012-1021. DOI:10.3382/ps.2006-00424
[28]
SOLEIMANI A F, ZULKIFLI I, OMAR A R, et al. Physiological responses of 3 chicken breeds to acute heat stress[J]. Poult Sci, 2011, 90(7): 1435-1440. DOI:10.3382/ps.2011-01381
[29]
XU Y, LAI X, LI Z, et al. Effect of chronic heat stress on some physiological and immunological parameters in different breed of broilers[J]. Poult Sci, 2018, 97(11): 4073-4082. DOI:10.3382/ps/pey256
[30]
CAMPLER M, JöNGREN M, JENSEN P. Fearfulness in red junglefowl and domesticated White Leghorn chickens[J]. Behav Processes, 2009, 81(1): 39-43. DOI:10.1016/j.beproc.2008.12.018
[31]
KHAN M S, SHIGEOKA C, TAKAHARA Y, et al. Ontogeny of the corticotrophin-releasing hormone system in slow- and fast-growing chicks (Gallus gallus)[J]. Physiol Behav, 2015, 151: 38-45. DOI:10.1016/j.physbeh.2015.06.033
[32]
YUAN L, NI Y, BARTH S, et al. Layer and broiler chicks exhibit similar hypothalamic expression of orexigenic neuropeptides but distinct expression of genes related to energy homeostasis and obesity[J]. Brain Res, 2009, 1273: 18-28. DOI:10.1016/j.brainres.2009.03.052
[33]
PRAJAPATI S K, DANGI D S, KRISHNAMURTHY S. Repeated caffeine administration aggravates post-traumatic stress disorder-like symptoms in rats[J]. Physiol Behav, 2019, 211: 112666. DOI:10.1016/j.physbeh.2019.112666
[34]
DANAN D, TODDER D, ZOHAR J, et al. Is PTSD-phenotype associated with HPA-axis sensitivity? Feedback inhibition and other modulating factors of glucocorticoid signaling dynamics[J]. Int J Mol Sci, 2021, 22(11): 6050. DOI:10.3390/ijms22116050
[35]
AHMED A A, MA W, NI Y, et al. Embryonic exposure to corticosterone modifies aggressive behavior through alterations of the hypothalamic pituitary adrenal axis and the serotonergic system in the chicken[J]. Horm Behav, 2014, 65(2): 97-105. DOI:10.1016/j.yhbeh.2013.12.002
[36]
CRIADO-MARRERO M, REIN T, BINDER E B, et al. Hsp90 and FKBP51: complex regulators of psychiatric diseases[J]. Philos Trans R Soc Lond B Biol Sci, 2018, 373(1738): 20160532. DOI:10.1098/rstb.2016.0532
[37]
LI H, SU P, LAI T K, et al. The glucocorticoid receptor-FKBP51 complex contributes to fear conditioning and posttraumatic stress disorder[J]. J Clin Invest, 2020, 130(2): 877-889. DOI:10.1172/JCI130363
[38]
MERKULOV V M, MERKULOVA T I, BONDAR N P. Mechanisms of brain glucocorticoid resistance in stress-induced psychopathologies[J]. Biochemistry (Mosc), 2017, 82(3): 351-365. DOI:10.1134/S0006297917030142
[39]
CASTRO-VALE I, VAN ROSSUM E F, MACHADO J C, et al. Genetics of glucocorticoid regulation and posttraumatic stress disorder--What do we know?[J]. Neurosci Biobehav Rev, 2016, 63: 143-157. DOI:10.1016/j.neubiorev.2016.02.005
[40]
MENDONÇA M S, MANGIAVACCHI P M, RIOS Á F L. Regulatory functions of FKBP5 intronic regions associated with psychiatric disorders[J]. J Psychiatr Res, 2021, 143: 1-8. DOI:10.1016/j.jpsychires.2021.08.014
[41]
REYER H, PONSUKSILI S, WIMMERS K, et al. Association of N-terminal domain polymorphisms of the porcine glucocorticoid receptor with carcass composition and meat quality traits[J]. Anim Genet, 2014, 45(1): 125-129. DOI:10.1111/age.12083

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