SHANK3 gene is a highly replicated causative gene for autism spectrum disorder and has been well characterized in multiple Shank3 mutant rodent models. When compared to rodents, domestic dogs are excellent animal models in which to study social cognition as they closely interact with humans and exhibit similar social behaviors. Using CRISPR/Cas9 editing, we recently generated a dog model carrying Shank3 mutations, which displayed a spectrum of autism-like behaviors, such as social impairment and heightened anxiety. However, the neural mechanism underlying these abnormal behaviors remains to be identified. We used Shank3 mutant dog models to examine possible relationships between Shank3 mutations and neuronal dysfunction. We studied electrophysiological properties and the synaptic transmission of pyramidal neurons from acute brain slices of the prefrontal cortex (PFC). We also examined dendrite elaboration and dendritic spine morphology in the PFC using biocytin staining and Golgi staining. We analyzed the postsynaptic density using electron microscopy. We established a protocol for the electrophysiological recording of canine brain slices and revealed that excitatory synaptic transmission onto PFC layer 2/3 pyramidal neurons in Shank3 heterozygote dogs was impaired, and this was accompanied by reduced dendrite complexity and spine density when compared to wild-type dogs. Postsynaptic density structures were also impaired in Shank3 mutants; however, pyramidal neurons exhibited hyperexcitability. Causal links between impaired PFC pyramidal neuron function and behavioral alterations remain unclear. Further experiments such as manipulating PFC neuronal activity or restoring synaptic transmission in Shank3 mutant dogs are required to assess PFC roles in altered social behaviors. Our study demonstrated the feasibility of using canine brain slices as a model system to study neuronal circuitry and disease. Shank3 haploinsufficiency causes morphological and functional abnormalities in PFC pyramidal neurons, supporting the notion that Shank3 mutant dogs are new and valid animal models for autism research.

中文翻译：

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自闭症相关 Shank3 突变狗前额皮质锥体神经元的突触功能受损和过度兴奋

SHANK3 基因是一种高度复制的自闭症谱系障碍致病基因，并在多种 Shank3 突变啮齿动物模型中得到了很好的表征。与啮齿类动物相比，家犬是研究社会认知的优秀动物模型，因为它们与人类密切互动并表现出类似的社会行为。使用 CRISPR/Cas9 编辑，我们最近生成了一个携带 Shank3 突变的狗模型，该模型表现出一系列类似自闭症的行为，例如社交障碍和高度焦虑。然而，这些异常行为背后的神经机制仍有待确定。我们使用 Shank3 突变狗模型来研究 Shank3 突变与神经元功能障碍之间的可能关系。我们研究了前额皮质 (PFC) 急性脑切片中锥体神经元的电生理特性和突触传递。我们还使用生物胞素染色和高尔基体染色检查了 PFC 中的树突精细化和树突棘形态。我们使用电子显微镜分析了突触后密度。我们建立了犬脑切片电生理记录协议，并发现 Shank3 杂合子狗的 PFC 层 2/3 锥体神经元上的兴奋性突触传递受损，并且与野生型相比，伴随着树突复杂性和脊柱密度的降低小狗。Shank3 突变体的突触后密度结构也受到损害；然而，锥体神经元表现出过度兴奋。PFC 锥体神经元功能受损与行为改变之间的因果关系仍不清楚。需要进行进一步的实验，例如操纵 PFC 神经元活动或恢复 Shank3 突变狗的突触传递，以评估 PFC 在改变社会行为中的作用。我们的研究证明了使用犬脑切片作为模型系统来研究神经元回路和疾病的可行性。Shank3单倍体不足会导致PFC锥体神经元的形态和功能异常，这支持了Shank3突变狗是用于自闭症研究的新的有效动物模型的观点。