# Investigating Microtubule-Associated Protein 2 in the Study of Postoperative Delirium

## TL;DR

This study investigates the link between microtubule-associated protein 2 (MAP2) and postoperative delirium in older adults undergoing cardiac surgery.

## Contribution

The study introduces MAP2 as a potential biomarker for postoperative delirium and explores its secretion in response to neuronal stress.

## Key findings

- Patients with postoperative delirium had elevated MAP2 levels on postoperative day 1.
- MAP2 levels increased during cardiopulmonary bypass and remained elevated in delirium patients.
- Glutamate exposure increased MAP2 secretion in SH-SY5Y cells without cell rupture.

## Abstract

This study explored potential associations between microtubule-associated protein 2 (MAP2), as a marker of neuronal stress, and postoperative delirium.

Custom single-molecule immunoassays were used to measure MAP2 in serum collected from two small cohorts of older adults undergoing major cardiac surgery. An in vitro study of differentiated SH-SY5Y cells derived from a neuroblastoma cell line was performed to assess MAP2 secretion following exposure to acute glutamate stimulation.

Patients who experienced postoperative delirium within 3 days of surgery had increased MAP2 serum levels on postoperative day 1. Perioperative blood sampling revealed an increase in circulating MAP2 at the end of cardiopulmonary bypass that was sustained up to postoperative day 3 in patients who developed delirium. Differentiated SH-SY5Y cells exposed to high-dose glutamate showed increased MAP2 in conditioned media independent of changes in total cytosolic protein levels suggesting that extracellular stimuli may promote acute secretion of MAP2 without inducing cell rupture.

Further studies exploring the MAP family as biomarkers of cognitive changes following surgery are warranted.