Data_Sheet_1_Neuronal Nitric Oxide Synthase Knockdown Within Basolateral Amygdala Induces Autistic-Related Phenotypes and Decreases Excitatory Synaptic Transmission in Mice.pdf

Autism spectrum disorder (ASD) is a heterogeneous group of neurodevelopmental disorders characterized by deficits in communication, impaired social interaction, and repetitive or restricted interests and behaviors. We have recently shown that neuronal nitric oxide synthase (nNOS) expression was reduced in the basolateral amygdala of mice after postnatal valproic acid exposure. However, the specific role of nNOS downregulation in mice remains to be elucidated. Herein, we investigated the behavioral alternations of naive mice with a recombinant adeno-associated virus (rAAV)-mediated knockdown of nNOS in a comprehensive test battery, including the social interaction, marble burying, self-grooming, and open field tests. Further, the electrophysiological and surface expression changes induced by nNOS deficiency of the basolateral amygdala in these animals were examined. Our results show that nNOS knockdown displayed typical symptoms of ASD-like behaviors, such as reduced social interaction and communication, elevated stereotypes, and anxiety in mice. Surprisingly, we found that nNOS knockdown exhibited greatly reduced excitatory synaptic transmission concomitant with the lower surface expression of GluN2B-containing N-methyl-D-aspartate receptors and postsynaptic density protein 95 in mice. These findings support a notion that dysregulation of nNOS might contribute to ASD-associated phenotypes, with disease pathogenesis most likely resulting from deficits in excitatory synaptic transmission.

孤独症谱系障碍（Autism spectrum disorder, ASD）是一类异质性神经发育障碍，以社交沟通缺陷、社交互动障碍以及重复或局限的兴趣与行为为核心临床特征。本团队此前研究证实，新生小鼠经出生后丙戊酸暴露后，其基底外侧杏仁核内的神经元型一氧化氮合酶（neuronal nitric oxide synthase, nNOS）表达水平显著降低。然而，nNOS表达下调在小鼠体内的具体生物学作用仍有待阐明。本研究中，我们通过包含社交互动实验、埋珠实验、自我梳理行为实验与旷场实验在内的综合行为测试组合，探究了重组腺相关病毒（recombinant adeno-associated virus, rAAV）介导的nNOS敲低对野生型小鼠的行为表型改变；同时检测了该模型小鼠基底外侧杏仁核中，nNOS缺乏所诱导的电生理变化与表面蛋白表达改变。结果显示，nNOS敲低小鼠呈现出典型的类孤独症样行为表型，包括社交与沟通能力减退、刻板行为增多以及焦虑样行为。令人意外的是，我们发现nNOS敲低小鼠的兴奋性突触传递显著受损，同时其大脑内含GluN2B亚基的N-甲基-D-天冬氨酸（N-methyl-D-aspartate, NMDA）受体以及突触后致密蛋白95（postsynaptic density protein 95, PSD-95）的表面表达水平均出现显著下降。上述研究结果支持“nNOS表达失调可能参与ASD相关表型的发生，其致病机制大概率与兴奋性突触传递缺陷相关”这一学术观点。