Autism spectrum disorders (ASDs) are among the most common neurodevelopmental diseases. These disorders are characterized by lack of social interaction, by repetitive behavior, and often anxiety and learning disabilities. The brain serotonin (5-HT) system is known to be crucially implicated in a wide range of physiological functions and in the control of different kinds of normal and pathological behavior. A growing number of studies indicate the involvement of the brain 5-HT system in the mechanisms underlying both ASD development and ASD-related behavioral disorders. There are some review papers describing the role of separate key players of the 5-HT system in an ASD and/or autistic-like behavior. In this review, we summarize existing data on the participation of all members of the brain 5-HT system, namely, 5-HT transporter, tryptophan hydroxylase 2, MAOA, and 5-HT receptors, in autism in human and various animal models. Additionally, we describe the most recent studies involving modern techniques for in vivo regulation of gene expression that are aimed at identifying exact roles of 5-HT receptors, MAOA, and 5-HT transporter in the mechanisms underlying autistic-like behavior. Altogether, results of multiple research articles show that the brain 5-HT system intimately partakes in the control of some types of ASD-related behavior, and that specific changes in a function of a certain 5-HT receptor, transporter, and/or enzyme may normalize this aberrant behavior. These data give hope that some of clinically used 5-HT–related drugs have potential for ASD treatment.

中文翻译：

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自闭症患者的大脑血清素系统

自闭症谱系障碍（ASD）是最常见的神经发育疾病之一。这些疾病的特点是缺乏社交互动、重复性行为，通常还伴有焦虑和学习障碍。众所周知，大脑血清素 (5-HT) 系统与多种生理功能以及不同类型的正常和病理行为的控制密切相关。越来越多的研究表明，大脑 5-HT 系统参与 ASD 发展和 ASD 相关行为障碍的机制。有一些评论论文描述了 5-HT 系统的各个关键参与者在自闭症谱系障碍和/或自闭症样行为中的作用。在这篇综述中，我们总结了大脑 5-HT 系统所有成员（即 5-HT 转运蛋白）参与的现有数据，色氨酸羟化酶 2、MAOA 和 5-HT 受体在人类和各种动物模型的自闭症中的作用。此外，我们描述了涉及现代技术的最新研究体内基因表达的调控，旨在确定 5-HT 受体、MAOA 和 5-HT 转运蛋白在自闭症样行为机制中的确切作用。总之，多篇研究文章的结果表明，大脑 5-HT 系统密切参与某些类型的 ASD 相关行为的控制，并且某些 5-HT 受体、转运蛋白和/或酶的功能发生特定变化可能会使这种异常行为正常化。这些数据给临床使用的一些 5-HT 相关药物带来了治疗 ASD 的潜力。