Viral-fMOST Reveals Region-Specific and Lateralized Remodeling of Whole-Brain GABAergic Neurons in Shank3 KO Mice

Background: Shank3 knockout (KO) mice recapitulate core autism spectrum disorder (ASD)-like behaviors and are widely regarded as a reliable model for autism. Although dysfunction of GABAergic neurons is closely associated with ASD-like phenotypes, it remains unclear how Shank3 deficiency leads to whole-brain structural remodeling of GABAergic neurons. Furthermore, there is currently a lack of systematic methodologies for the comprehensive statistical analysis of GABAergic neurons across the entire brain. Methods: By combining rAAV/B10-mGAD65-EGFP virus labeling with fluorescence Micro-Optical Sectioning Tomography (fMOST), we constructed a mesoscopic whole-brain atlas of GABAergic neurons in Shank3 KO mice, enabling systematic quantification of soma numbers and comprehensive morphological profiling across multiple brain regions. Results: We systematically analyzed soma counts and morphology across multiple brain regions in Shank3 KO and WT mice. Soma counts did not differ significantly between the two groups in any of the analyzed brain regions. However, morphological changes were region-specific, exhibiting increased neurite complexity in the anterior cingulate cortex (ACC) and entorhinal cortex (ENT), but reduced neurite complexity in the retrosplenial cortex (RSP). Conclusions: Viral-fMOST enables whole-brain quantification of GABAergic neurons and provides a reference for imaging other neuronal subtypes. In Shank3 KO mice, neurite changes reveal a mesoscopic map of GABAergic alterations relevant to ASD research.