Cruz-Morales Sara Eugenia, García-Saldívar Norma Laura, González-López María Reyes, Castillo-Roberto Georgina, Monroy Juana, Domínguez Roberto
Psychopharmacology, FES-Iztacala, UNAM, P.O. Box 314, Tlalnepantla, México, Zip Code 54090, Mexico.
Behav Brain Res. 2008 Dec 16;195(1):187-91. doi: 10.1016/j.bbr.2008.02.022. Epub 2008 Feb 20.
Serotonin (5-HT) is involved in behaviors such as sleep, eating, memory, in mental disorders like anxiety and depression and plays an important role in the modulation of stress. On the other hand, exposure to stress influence learning as well as declarative and non-declarative memory. These effects are dependent on the type of stressor, their magnitude, and the type of memory. The striatum has been associated with non-declarative procedural memory, while the information about stress effects on procedural memory and their relation with striatal serotonin is scarce. The objective of this study was to evaluate the effects of stress on the modifications of the striatal serotonergic system. In Experiment 1, the effects of either 60 min of restraint (R) or exposure to the elevated T-maze (ETM) was assessed. Exposure to ETM decreased 5-HT concentration and to R increased 5-HT activity ([metabolite]/[neurotransmitter]). In Experiment 2, we evaluated the effects of restraint on ETM trained immediately, 24 or 48 h after restraint. No effects were detected in acquisition or escape latencies, while retention latencies were lower in all groups compared with the non-restrained group, although significant effects were detected immediately and 24h after restraint. The memory impairment seems to be associated with changes in striatal serotonergic system, given that 5-HT concentration increased, while serotonergic activity decreased. The differences in the activity of 5-HT detected in each experiment could be explained by the effects of different stressors on the serotonergic neurons ability to synthesize the neurotransmitter. Thus, we suggest that exposure to stress impairs procedural memory and that striatal serotonin modulates this effect.
血清素（5-羟色胺，5-HT）参与睡眠、进食、记忆等行为，在焦虑和抑郁等精神障碍中也有涉及，并且在应激调节中发挥重要作用。另一方面，暴露于应激会影响学习以及陈述性和非陈述性记忆。这些影响取决于应激源的类型、其强度以及记忆的类型。纹状体与非陈述性程序记忆有关，而关于应激对程序记忆的影响及其与纹状体血清素的关系的信息却很少。本研究的目的是评估应激对纹状体血清素能系统改变的影响。在实验1中，评估了60分钟束缚（R）或暴露于高架T迷宫（ETM）的影响。暴露于ETM会降低5-HT浓度，而束缚则会增加5-HT活性（[代谢物]/[神经递质]）。在实验2中，我们评估了束缚对在束缚后立即、24或48小时进行ETM训练的影响。在习得或逃避潜伏期未检测到影响，而与未束缚组相比，所有组的保持潜伏期均较低，尽管在束缚后立即和24小时检测到了显著影响。记忆损害似乎与纹状体血清素能系统的变化有关，因为5-HT浓度增加，而血清素能活性降低。每个实验中检测到的5-HT活性差异可以通过不同应激源对血清素能神经元合成神经递质能力的影响来解释。因此，我们认为暴露于应激会损害程序记忆，并且纹状体血清素会调节这种作用。
