Filiz, K. D. | Search bioRxiv

bioRxiv2026

Maternal separation remodels Purkinje cell circuits and impairs cerebellar synaptic plasticity

Introduction: Early-life adversity has been associated with cerebellar abnormalities, but the cellular and circuit-level changes involved and their persistence across development remain poorly understood. We examined whether maternal separation (MS) disrupts cerebellar circuit maturation and whether these changes are accompanied by alterations in synaptic function and behavior. Methods: CD1 mice underwent daily maternal separation from postnatal day 2 to 18, whereas control litters remained undisturbed. Cerebellar alterations were assessed using transcriptomic and DNA methylation profiling, RT-qPCR, immunoblotting, Purkinje-cell morphometric analysis, and VGLUT1/VGLUT2 immunofluorescence. Patch-clamp electrophysiology was used to examine synaptic transmission and plasticity. Motor coordination, spontaneous locomotion, social approach, and stress-coping behavior were also evaluated. Results: RNA sequencing of whole cerebellar tissue revealed early transcriptional remodeling, involving synaptic transmission, neuronal architecture, and plasticity-related pathways. Consistent with this profile, we found that MS altered Purkinje cell dendritic arborization and excitatory input remodeling, together with deficits in cerebellar long-term synaptic plasticity and reduced BDNF-related signaling. In parallel, methylation analysis revealed hypermethylation of the glucocorticoid receptor promoter and reduced cerebellar receptor expression, indicating that early-life stress also engages stress-related epigenetic mechanisms in this region. Importantly, these neurobiological changes were associated with motor coordination deficits, altered stress-coping behavior, and impaired social interaction. Discussion: These findings identify the developing cerebellum as a target of early-life adversity and suggest that disrupted cerebellar maturation may contribute to lasting functional consequences. This study extends our understanding of the effects of maternal separation beyond the brain regions traditionally associated with stress responses.

neuroscience↗

bioRxiv2022

Combined DiI and antibody labeling reveals complex dysgenesis of hippocampal spine synapses in a mouse model of Fragile X Syndrome.

Structural, functional, and molecular alterations in excitatory spine synapses are a common hall-mark of many neurodevelopmental disorders including intellectual disability and autism. Here, we describe an optimized methodology, based on combined use of DiI and immunofluorescence, for rapid and sensitive characterization of the structure and composition of spine synapses in native brain tissue. We successfully demonstrate the applicability of this approach by examining the properties of hippocampal spine synapses in juvenile Fmr1 KO mice, a mouse model of Fragile X Syndrome. We find that mutant mice display pervasive dysgenesis of spine synapses evidenced by an overabundance of both abnormally elongated thin spines and cup-shaped spines, in combination with reduced density of mushroom spines. We further find that mushroom spines expressing the actin-binding protein Synaptopodin - a marker for spine apparatus - are more prevalent in mutant mice. Previous work identified spines with Synaptopodin/spine apparatus as the locus of mGluR-LTD, which is abnormally elevated in Fmr1 KO mice. Altogether, our data suggest this enhancement may be linked to the preponderance of this subset of spines in the mutant. Overall, these findings demonstrate the sensitivity and versatility of the optimized methodology by uncovering a novel facet of spine dysgenesis in Fmr1 KO mice.

neuroscience↗