Ingested d-Aspartate Facilitates the Functional Connectivity and Modifies Dendritic Spine Morphology in Rat...

Area of Science:

• Neuroscience
• Neurochemistry
• Cognitive Science

Background:

• d-Aspartate (d-Asp), a stereoisomer of l-aspartate, is implicated in memory function in rodents.
• The precise mechanism underlying d-Asp's cognitive effects remains incompletely understood.

Purpose of the Study:

• To investigate if ingested d-Asp reaches hippocampal tissue and modulates neural network connectivity.
• To explore the role of spinogenesis in hippocampal CA1 neurons as a mechanism for d-Asp's effects.

Main Methods:

• Acute rat hippocampal slices were used to assess d-Asp-induced spinogenesis.
• Functional magnetic resonance imaging (fMRI) in awake rats monitored brain activation post-d-Asp administration.
• d-Asp concentrations in blood serum and hippocampus were measured after oral administration.

Main Results:

• d-Asp application increased the density of CA1 spines, involving the LIM kinase pathway.
• Oral d-Asp administration significantly elevated d-Asp levels in blood and hippocampus within 15 minutes.
• fMRI revealed increased slow-frequency synchronization between the hippocampus and other brain regions (somatosensory cortex, striatum, nucleus accumbens) post-d-Asp.

Conclusions:

• Ingested d-Asp successfully crosses the blood-brain barrier to reach the hippocampus.
• d-Asp modulates hippocampal neural networks by promoting spinogenesis.
• These findings support d-Asp's role in regulating brain network functional connectivity relevant to cognitive processes.