Dextromethorphan alters gene expression in rat brain hippocampus and cortex.

Area of Science:

• Neuroscience
• Pharmacology
• Molecular Biology

Background:

• Dextromethorphan is a common antitussive medication.
• It acts as a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors.
• Understanding its effects on gene expression is crucial for its therapeutic applications.

Purpose of the Study:

• To investigate the impact of daily dextromethorphan administration on gene expression in rat brain.
• To identify specific genes and pathways affected by dextromethorphan in the hippocampus and cortex.
• To determine the role of NMDA receptors in mediating these gene expression changes.

Main Methods:

• Utilized Rat 5K cDNA microarrays to analyze gene expression profiles.
• Administered dextromethorphan daily to rats for 1, 3, and 10 days.
• Confirmed microarray findings using semi-quantitative RT-PCR.

Main Results:

• Dextromethorphan administration significantly altered gene expression in rat brain, primarily mediated by NMDA receptors.
• The hippocampus exhibited more gene expression changes than the cerebral cortex.
• Down-regulation of glutamate-induced and NO-dependent apoptosis-related genes was observed.
• Upregulation of anti-apoptotic genes (e.g., nucleophosmin/B23, Rab2, MAP kinase kinase, CREB binding protein) and some SNARE genes occurred.
• Down-regulation of VEGF-associated genes suggests potential inhibition of angiogenesis.

Conclusions:

• Dextromethorphan modulates gene expression in a time-dependent manner in rat brain regions.
• The observed changes involve critical pathways such as apoptosis and angiogenesis.
• NMDA receptor antagonism is a key mechanism underlying dextromethorphan's effects on gene expression.