The protective potential of
rapamycin has been reported in a few experimental models of
brain ischemia, both in vivo and in vitro. Although the precise cellular processes underlying the
neuroprotective effects of
rapamycin in experimental models of
stroke remain unknown, the current experimental data suggest that the mechanism of action of the drug may result from the mTOR-mediated autophagy induction. However, it is unclear whether the activation of autophagy acts as a pro-death or pro-survival factor in vascular endothelial cells in ischemic brain damage. It seems to be very important, since
stroke affects not only neurons and astrocytes but also microvessels. In the present study, we used human umbilical vein endothelial cells (HUVEC) subjected to
ischemia-simulating conditions (combined
oxygen and
glucose deprivation, OGD) for 6h to determine potential effect of
rapamycin-induced autophagy on HUVEC damage. The drug at concentrations of 100 and 1000nM increased the expression of
Beclin 1 and LC3-II together with a significant increase in the p62 degradation in ischemic HUVEC. Treatment with
rapamycin in OGD significantly increased the cell viability, indicating that the drug exerts cytoprotective effect. The inhibition of
Beclin 1 by siRNAs significantly attenuated the expression of
autophagy-related proteins and reduced HUVEC viability following OGD and
rapamycin treatment. Our findings demonstrated that toxicity of simulated
ischemia conditions were enhanced in HUVEC when autophagy was blocked, and that
rapamycin effectively prevented OGD-evoked damage by induction of protective autophagy via inhibition of the mTOR pathway.