[Rapamycin treatment starting at 24 h after cerebral ischemia/reperfusion exhibits protective effect on brain injury in rats].

Objective: To investigate whether rapamycin treatment starting at 24 h after cerebral ischemia/reperfusion(I/R) has protective effect on brain injury in rats.

Methods: The rat I/R model was established by middle cerebral artery occlusion according to Longa's method. A total of 104 Sprague Dawley rats were randomly divided into sham group, model group, and rapamycin-treated groups (6 h or 24 h after modeling). Neurological function was assessed with neurological severity score (NSS). Triphenyl tetrazolium chloride (TTC) staining and Fluoro-Jade B (FJB) staining were used to examine the infarct volume and neuronal apoptosis, respectively. The expression of p-S6 protein in mTOR signaling pathway was detected by Western blot analysis.

Results: Compared with sham group, NSS of the model group was significantly increased and TTC staining indicated obvious infarct area (all <0.01). Furthermore, significantly increased number of FJB-positive cells and p-S6 expression in the penumbra area were shown in the model group (all <0.01). Compared with the model group, both rapamycin-treated groups demonstrated decreased NSS, infarction volume and FJB positive cells as well as p-S6 expression in the penumbra area (<0.05 or <0.01). There was no significant difference between the groups of rapamycin administrated 6 h and 24 h after modeling (all >0.05).

Conclusions: Rapamycin treatment starting at 24 h after I/R exhibits protective effect on brain injury in rats.