Basic Science and Pathogenesis

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• Alzheimer's disease (AD) is linked to altered neuronal plasticity, excitatory/inhibitory imbalance, and neuroinflammation.
• Autosomal dominant Alzheimer's disease (ADAD) mutations cause early neuronal connectivity changes, indicating a potential neurodevelopmental origin.
• The precise developmental stage of dysfunction in inhibitory neurons and glial cells in ADAD remains unclear.

Purpose of the Study:

• To investigate gene expression of inhibitory interneurons, astrocytes, and microglia during neurodevelopment in an ADAD rat model.
• To identify early molecular markers of ADAD-related neurodevelopmental alterations.

Main Methods:

• Gene expression of parvalbvalbumin (Pvalb), somatostatin (Sst), Slc1a3, glial fibrillary acidic protein (Gfap), and integrin subunit alpha M (Itgam) was quantified using RT-qPCR in wild-type (WT) and TgF344-AD (TG) rat embryos at gestational day 13.5.
• Statistical comparisons and correlation analyses (Pearson Correlation, linear regression) were performed between WT and TG groups.

Main Results:

• No significant differences in the expression levels of individual genes (Pvalb, Sst, Slc1a3, Gfap, Itgam) were found between WT and ADAD embryos.
• Significant correlations between gene pairs (Pvalb-Itgam, Sst-Slc1a3, Slc1a3-Gfap) were observed in WT embryos but were absent in ADAD embryos.
• Absence of these gene expression correlations in ADAD embryos suggests early disruptions in neural circuitry.

Conclusions:

• The study reveals that ADAD mutations abolish specific gene expression correlations during early neurodevelopment, indicating potential synaptic dysfunction.
• These findings suggest that ADAD-related neurodevelopmental alterations occur earlier than previously thought.
• Further research at later gestational stages is needed to fully elucidate the impact of ADAD mutations on the inhibitory neuron-microglia interplay.