Zhang Jingyi, Li Min, Pan Liying, Wang Ye, Yuan Hui, Zhang Zhiwei, Luo Chaochao, Zhang Runxiang
College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China.
College of Life Sciences, Shihezi University, Shihezi 832003, China.
Animals (Basel). 2025 Jun 26;15(13):1889. doi: 10.3390/ani15131889.
Fear is a critical welfare concern in laying hens. Fearful behaviors in domestic chickens are influenced by both genetic and environmental factors, contributing to individual differences in stress responses. Tonic immobility (TI) duration is widely recognized as a reliable indicator of fear levels. The hippocampus, a critical brain region for emotional states, plays a pivotal role in associating fearful experiences with specific stimuli, enabling adaptive behavioral responses. This study investigated hippocampal histological characteristics and transcriptomic profiles in laying hens with different fear responses categorized based on TI duration. A total of 80 native Lindian hens (75 weeks old) were individually housed in modified conventional cages. At 76 weeks of age, hens exhibiting the longest and shortest TI durations were classified into the high-fear (TH) and low-fear (TL) groups, respectively. Whole hemibrains were collected for histological and immunohistochemical analyses, while hippocampal tissues underwent transcriptome sequencing. The results showed a significant reduction in Nissl body counts in hippocampal neurons of high-fear hens ( < 0.05), suggesting potential neuronal damage or functional impairment. Transcriptomic analysis revealed 365 differentially expressed genes (DEGs) between two groups, with 277 upregulated and 88 downregulated genes in TH chickens. KEGG pathway enrichment analysis identified seven significantly associated pathways ( < 0.01), including retinol metabolism, vitamin B6 metabolism, and nicotinate and nicotinamide metabolism, all of which are crucial for neuronal function and immune regulation. In addition, a significant increase in DCX protein expression ( < 0.05) and a decrease in c-Fos protein expression ( < 0.05) was noted in in high-fear hens, whereas PCNA levels remained unchanged ( > 0.05) under immunohistochemical validation. The neuronal alterations observed in high fear individuals suggest neural damage, while transcriptomic variations point to potential disruptions in neurogenesis, synaptic signaling, and stress-related pathways. Collectively, these results provide novel insights into the neurobiological basis of fear regulation in laying hens and may have implications for poultry welfare and management strategies.
恐惧是蛋鸡的一个关键福利问题。家鸡的恐惧行为受遗传和环境因素的影响，导致个体对应激反应存在差异。强直静止（TI）持续时间被广泛认为是恐惧水平的可靠指标。海马体是情绪状态的关键脑区，在将恐惧经历与特定刺激联系起来以及实现适应性行为反应方面起着关键作用。本研究调查了根据TI持续时间分类的具有不同恐惧反应的蛋鸡的海马体组织学特征和转录组谱。总共80只本地林甸母鸡（75周龄）被单独饲养在改良的传统鸡笼中。在76周龄时，TI持续时间最长和最短的母鸡分别被归类为高恐惧（TH）组和低恐惧（TL）组。收集整个半脑进行组织学和免疫组织化学分析，同时对海马体组织进行转录组测序。结果显示，高恐惧母鸡海马体神经元中的尼氏体数量显著减少（<0.05），表明可能存在神经元损伤或功能障碍。转录组分析揭示两组之间有365个差异表达基因（DEG），TH组鸡中有277个基因上调，88个基因下调。KEGG通路富集分析确定了七个显著相关的通路（<0.01），包括视黄醇代谢、维生素B6代谢以及烟酸和烟酰胺代谢，所有这些对神经元功能和免疫调节都至关重要。此外，免疫组织化学验证显示，高恐惧母鸡中DCX蛋白表达显著增加（<0.05），c-Fos蛋白表达减少（<0.05），而PCNA水平保持不变（>0.05）。在高恐惧个体中观察到的神经元改变表明存在神经损伤，而转录组变化则表明神经发生、突触信号传导和应激相关通路可能受到破坏。总的来说，这些结果为蛋鸡恐惧调节的神经生物学基础提供了新的见解，可能对家禽福利和管理策略具有启示意义。
