Hippocampal Neural Dynamics and Postoperative Delirium-like Behavior in Aged Mice.

Summary

Using high-density electrophysiology and two-photon imaging, aged mice showed transient hippocampal pyramidal hyperactivity and interneuron suppression at 9 hours post-op that paralleled emergence of delirium-like behavior, normalizing by 24 hours. Indole-3-propionic acid pretreatment dampened these circuit imbalances and mitigated behavioral deficits.

Key Findings

• Aged mice displayed significant delirium-like behavior after anesthesia/surgery compared to adult mice.
• At 9 hours post-op, hippocampal pyramidal cell activity increased and interneuron activity decreased; both normalized by 24 hours alongside behavioral improvement.
• Indole-3-propionic acid pretreatment attenuated pyramidal hyperactivity, partially restored interneuron function, and mitigated delirium-like behavior.

Clinical Implications

Suggests targets for neuromodulatory or metabolic interventions to prevent POD in older adults; supports timing-sensitive monitoring and interventions within the first 24 hours post-op.

Limitations

• Animal model limits direct clinical translatability; small behavioral cohort (N=10) and species differences.
• IPA effects demonstrated as pretreatment; therapeutic efficacy post-insult remains to be determined.

Future Directions

Test post-operative IPA or related metabolic interventions; translate circuit biomarkers to human EEG/MEG; evaluate interactions with anesthetic agents and inflammatory mediators.