# Exploration of the Therapeutic Time Window for Thrombectomy in Rat Models of Middle Cerebral Artery Ischemia‐Reperfusion

## TL;DR

This study finds that reperfusion after 4 hours of stroke in rats is the optimal time window for thrombectomy, as later reperfusion causes more brain damage and inflammation.

## Contribution

The study identifies a specific therapeutic time window for thrombectomy in rat stroke models and explores the mechanisms of reperfusion injury beyond this window.

## Key findings

- Reperfusion at 4 hours post-stroke in rats showed peak infarct size and lowest neurological function.
- Reperfusion beyond 4 hours caused more BBB disruption and higher levels of inflammatory markers like IL-6, IL1-β, and TNF-α.
- Neurological function scores declined significantly in the 5-hour reperfusion group compared to earlier groups.

## Abstract

To investigate the therapeutic time window of middle cerebral artery occlusion (MCAO) reperfusion in rats and the potential mechanism of injury beyond the time window.

Male Sprague Dawley (SD) rats were randomly divided into eight groups: a sham operation group, six ischemia‐reperfusion groups (reperfusion initiated 1, 2, 3, 4, 5, and 6 h after infarction, respectively), and a 24‐h infarction group without reperfusion therapy. Neurological function scores were assessed 24 h after reperfusion, and then brain samples were collected to explore the mechanisms.

After 4 h of MCAO reperfusion for 24 h, the infarct area reached its peak, while the neurological function score reached its bottom, and both indicators exhibited a trend toward stabilization. Additionally, a significant increase in the mortality rate was observed in the 5‐h group. Compared to the MCAO 2‐h group, the 5‐h group exhibited a significant increase in the number of dead neurons, more serious disruption of the blood–brain barrier (BBB), and elevated expression levels of IL‐6, IL1‐β, and TNF‐α.

Taken together, our study indicates that MCAO 4 h is likely to be the therapeutic time window for thrombectomy in rat models of middle cerebral artery ischemia‐reperfusion. Reperfusion injury beyond the time window leads to more severe disruption of the BBB, a significant increase in inflammatory products, and may ultimately result in a significant decline in neural function scores.

MCAO 4 hours is likely to be the therapeutic time window for thrombectomy in rat models of MCA ischemia‐reperfusion. Reperfusion injury beyond the time window leads to more severe disruption of BBB, an significant increase in inflammatory products, and may ultimately result to a significant decline in neurological function.