College of Veterinary Medicine, China Agricultural University , Beijing , China.
Institute of Microbiology, Chinese Academy of Sciences , Beijing , China.
Stress. 2019 Nov;22(6):707-717. doi: 10.1080/10253890.2019.1625328. Epub 2019 Jun 11.
Transport stress causes not only physiological changes but also behavioral responses, including anxiety-like and depression-like behaviors in animals. The serotonergic system in the brain plays a pivotal role in processing anxiety. This study aimed to explore changes in concentrations of 5-hydroxytryptamine (serotonin), and the expression changes of tryptophan hydroxylase 2 (TPH2) mRNA and protein associated with anxiety-related behavioral responses under transport stress. A model of simulated transport stress was established in 40 adult male Sprague-Dawley rats, including a control group ( = 20) and a transport stress (TS) group ( = 20). The results showed that the rats in the TS group exhibited an increased feeding latency in the novelty-suppressed feeding test and a reduced frequency and dwelling time in the central area in the open-field test (OFT). Two hours following the final behavioral test, blood samples were collected. Creatine kinase (CK) activities and glucose and corticosterone concentrations in serum were significantly higher in the rats in the TS group than in the control group. Transport stress also significantly reduced the concentrations of 5-hydroxytryptamine in the hippocampus, striatum, and raphe nuclei and also reduced the expression levels of mRNA and protein for TPH2 in the raphe nuclei. Notably, the number of Fos-immunoreactive neurons was higher in the dorsal raphe nucleus under transport stress, whereas the number of 5-hydroxytryptamine-positive neurons was significantly lower. These findings are consistent with the hypothesis that the 5-hydroxytryptamine transmitter in the hippocampus, striatum, and raphe nuclei is involved in processing anxiety-related behavioral responses under transport stress. Lay summary Physiological and psychological stress responses were induced in a rat model of simulated transport stress. We examined whether serotonin in the brain may be involved in mediating behavioral responses following exposure to transport stress. Tissue concentrations of serotonin in rat brain regions, including the hippocampus, striatum, and raphe nuclei, were reduced following exposure to transport stress. Expression of tryptophan hydroxylase 2 mRNA and protein, which catalyses serotonin synthesis, as well as numbers of serotonin-immunoreactive neurons, were decreased in the brainstem raphe nuclei.
运输应激不仅会引起生理变化，还会引起动物的行为反应，包括焦虑样和抑郁样行为。大脑中的 5-羟色胺能系统在处理焦虑中起着关键作用。本研究旨在探讨在运输应激下，与焦虑相关的行为反应中，5-羟色胺（血清素）浓度的变化，以及与焦虑相关行为反应相关的色氨酸羟化酶 2（TPH2）mRNA 和蛋白质的表达变化。在 40 只成年雄性 Sprague-Dawley 大鼠中建立了模拟运输应激的模型，包括对照组（n=20）和运输应激组（n=20）。结果显示，在新异抑制进食试验中，TS 组大鼠的摄食潜伏期增加，在旷场试验（OFT）中中央区域的活动频率和停留时间减少。最后一次行为测试后 2 小时，采集血样。与对照组相比，TS 组大鼠血清肌酸激酶（CK）活性、血糖和皮质酮浓度明显升高。运输应激还显著降低了海马、纹状体和中缝核中 5-羟色胺的浓度，以及中缝核中 TPH2 的 mRNA 和蛋白质的表达水平。值得注意的是，在运输应激下，背侧中缝核中的 Fos-免疫反应性神经元数量增加，而 5-羟色胺阳性神经元的数量明显减少。这些发现与以下假设一致，即在运输应激下，海马、纹状体和中缝核中的 5-羟色胺递质参与处理与焦虑相关的行为反应。
运输应激会引起动物的生理和心理应激反应，包括焦虑样和抑郁样行为。大脑中的 5-羟色胺（5-HT）能系统在处理焦虑中起着关键作用。本研究旨在探讨在运输应激下，与焦虑相关的行为反应中，5-HT 浓度的变化，以及与焦虑相关行为反应相关的色氨酸羟化酶 2（TPH2）mRNA 和蛋白质的表达变化。
在 40 只成年雄性 Sprague-Dawley 大鼠中建立了模拟运输应激的模型，包括对照组（n=20）和运输应激组（n=20）。结果显示，在新异抑制进食试验中，TS 组大鼠的摄食潜伏期增加，在旷场试验（OFT）中中央区域的活动频率和停留时间减少。最后一次行为测试后 2 小时，采集血样。与对照组相比，TS 组大鼠血清肌酸激酶（CK）活性、血糖和皮质酮浓度明显升高。运输应激还显著降低了海马、纹状体和中缝核中 5-HT 的浓度，以及中缝核中 TPH2 的 mRNA 和蛋白质的表达水平。
值得注意的是，在运输应激下，背侧中缝核中的 Fos-免疫反应性神经元数量增加，而 5-HT 阳性神经元的数量明显减少。这些发现与以下假设一致，即在运输应激下，海马、纹状体和中缝核中的 5-HT 递质参与处理与焦虑相关的行为反应。
