Selective time-dependent changes in activity and cell-specific gene expression in human postmortem brain

Area of Science:

• Neuroscience
• Genomics
• Molecular Biology

Background:

• Human brain research often relies on postmortem samples, which may not accurately reflect the in vivo state.
• Understanding transcriptional changes during the postmortem interval is critical for accurate interpretation of disease-associated gene expression.

Purpose of the Study:

• To compare transcriptional patterns and histological features between fresh surgical human neocortex and postmortem brain tissue.
• To investigate genome-wide transcription changes over time after tissue removal to mimic the postmortem interval.
• To elucidate the dynamic cellular and molecular alterations occurring during the postmortem interval in the human brain.

Main Methods:

• Genome-wide transcription profiling of fresh human neocortex and postmortem brain tissue.
• Time-course analysis of gene expression following surgical tissue resection.
• Histological examination of tissue to correlate with transcriptional changes.

Main Results:

• Fresh human brain transcriptome shows unique patterns compared to postmortem samples.
• Rapid reduction in neuronal activity-dependent transcripts within hours of tissue removal.
• Reciprocal time-dependent increase in astroglial and microglial gene expression over 24 hours.
• Histological confirmation of neuronal degeneration and glial process outgrowth.

Conclusions:

• The postmortem interval induces rapid and significant dynamic transcriptional and cellular changes in the human brain.
• Neuronal gene expression declines rapidly, while glial gene expression increases, affecting sample integrity.
• Accurate interpretation of human brain disorder research requires consideration of postmortem interval-induced gene expression alterations.