Maternal Choline Supplementation in a Mouse Model of Down Syndrome and Alzheimer's Disease Generates Unique Expression Profile Mosaics Within Three Hippocampal Excitatory Neuronal Populations.

Individuals with Down syndrome (DS) are at risk for early-onset Alzheimer's disease (AD), marked by neurodegeneration in hippocampal and basal forebrain circuits. Early-life interventions offer therapeutic potential, including maternal choline supplementation (MCS). MCS improves cognitive outcomes and neuroplasticity in rodent models of neurodevelopmental and neurodegenerative disorders, yet cell-type specific molecular effects remain unknown. We investigated the effect of MCS upon the onset of septohippocampal degeneration at 6 months of age in the Ts65Dn mouse model of DS/AD. Using laser capture microdissection and single population RNA-sequencing, transcriptomic changes were profiled within hippocampal CA1 and CA3 pyramidal neurons and dentate gyrus granule cells comparing trisomic and disomic offspring. Bioinformatic analysis revealed MCS-mediated downregulation of apoptotic pathways and upregulation of cognition-related functions across all populations, alongside cell-specific responses. These findings highlight MCS as a promising strategy for modulating disease-relevant pathways in a hippocampal cell-type-specific manner during early neurodegeneration in DS/AD.