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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.