Stracke Jenny, Otten Winfried, Tuchscherer Armin, Puppe Birger, Düpjan Sandra
Institute of Behavioral Physiology, Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany.
Institute of Genetics and Biometry, Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany.
Physiol Behav. 2017 May 15;174:18-26. doi: 10.1016/j.physbeh.2017.02.036. Epub 2017 Feb 28.
Cognitive and affective processes are highly interrelated. This has implications for neuropsychiatric disorders such as major depressive disorder in humans but also for the welfare of non-human animals. The brain serotonergic system might play a key role in mediating the relationship between cognitive functions and affective regulation. The aim of our study was to examine the influence of serotonin depletion on the affective state and cognitive processing in pigs, an important farm animal species but also a potential model species for biomedical research in humans. For this purpose, we modified a serotonin depletion model using para-chlorophenylalanine (pCPA) to decrease serotonin levels in brain areas involved in cognitive and affective processing (part 1). The consequences of serotonin depletion were then measured in two behavioral tests (part 2): the spatial judgement task (SJT), providing information about the effects of the affective state on cognitive processing, and the open field/novel object (OFNO) test, which measures behavioral reactions to novelty that are assumed to reflect affective state. In part 1, 40 pigs were treated with either pCPA or saline for six consecutive days. Serotonin levels were assessed in seven different brain regions 4, 5, 6, 11 and 13days after the first injection. Serotonin was significantly depleted in all analyzed brain regions up to 13days after the first application. In part 2, the pCPA model was applied to 48 animals in behavioral testing. Behavioral tests, the OFNO test and the SJT, were conducted both before and after pCPA/saline injections. While results from the OFNO tests were inconclusive, an effect of treatment as well as an effect of the phase (before and after treatment) was observed in the SJT. Animals treated with pCPA showed more pessimistic-like behavior, suggesting a more negative affective state due to serotonin depletion. Thus, our results confirm that the serotonergic system is a key player in cognitive-emotional processing. Hence, the serotonin depletion model and the spatial judgement task can increase our understanding of the basic mechanisms underlying both human neuropsychiatric disorders and animal welfare.
认知过程和情感过程高度相关。这不仅对人类的神经精神疾病如重度抑郁症有影响，对非人类动物的福利也有影响。大脑血清素能系统可能在介导认知功能与情感调节之间的关系中起关键作用。我们研究的目的是检验血清素耗竭对猪的情感状态和认知加工的影响，猪是一种重要的农场动物物种，也是人类生物医学研究的潜在模型物种。为此，我们改良了一种使用对氯苯丙氨酸（pCPA）的血清素耗竭模型，以降低参与认知和情感加工的脑区中的血清素水平（第1部分）。然后在两项行为测试中测量血清素耗竭的后果（第2部分）：空间判断任务（SJT），提供有关情感状态对认知加工影响的信息；旷场/新物体（OFNO）测试，该测试测量对新奇事物的行为反应，假定其反映情感状态。在第1部分中，40头猪连续6天接受pCPA或生理盐水治疗。在首次注射后的第4、5、6、11和13天，在七个不同的脑区评估血清素水平。在首次应用后的13天内，所有分析的脑区中的血清素均显著耗竭。在第2部分中，将pCPA模型应用于48只动物进行行为测试。在注射pCPA/生理盐水之前和之后都进行了行为测试，即OFNO测试和SJT。虽然OFNO测试的结果尚无定论，但在SJT中观察到了治疗效果以及阶段（治疗前后）效果。用pCPA治疗的动物表现出更类似悲观的行为，表明由于血清素耗竭导致更消极的情感状态。因此，我们的结果证实血清素能系统是认知-情感加工中的关键因素。因此，血清素耗竭模型和空间判断任务可以增进我们对人类神经精神疾病和动物福利背后基本机制的理解。
