Abstract T P85: Mammalian Target of Rapamycin (mTOR) Signaling Pathway Mediates Cerebral Ischemic Brain Damage
BACKGROUND: Mammalian target of rapamycin (mTOR) signaling regulates cell energy metabolism and cell proliferation. Recent studies have demonstrated that mTOR activation is associated with increased cardiac infarct volume and necroptosis. The role of mTOR in cerebral ischemia has not been studied. The aim of this study is to explore how mTOR pathway behavior after cerebral ischemia and whether inhibition of mTOR reduces or increases ischemic brain damage.
METHODS: Ten minutes of global ischemia was induced in Wistar rats (2-3 months old). Animals were either treatment with mTOR inhibitor rapamycin (6 mg/kg) or its vehicle. Animal brains were harvested after 3 hrs, 16 hrs and 7 days for histopathology and protein analyses. Sham-operated non-ischemic rats were used as control. Rapamycin was i.p. injected 1 hr after reperfusion in 7-day subgroups and injected 7 days prior to ischemia in 3 and 16 hrs subgroups.
RESULTS: 10 minutes of global ischemia caused neuronal damage to the striatum, hippocampal CA1, and neocortical regions at 7 days of reperfusion. Levels of p-mTOR, p-S6K were increased significantly after 3 and 16 hrs in both the hippocampus and cortex. In addition, p-Akt and cytochrome c were elevated in the hippocampi after 3 hrs, peaked at 16 hrs and remained elevated after 7 days of reperfusion. Post-ischemic treatment with rapamycin 1 hrs after reperfusion significantly reduced brain damage in the CA1 and cortical areas at 7 days of reperfusion. Levels of p-mTOR, p-S6K, p-Akt and cytochrome c were significantly suppressed by rapamycin in non-ischemic and ischemic animals.
CONCLUSION: Cerebral ischemia activates mTOR signaling pathway and inhibition of mTOR activativity reduces ischemic brain damage.
Author Disclosures: C. Hei: None. X. Yang: None. P. Liu: None. Y. Meli: None. H. Li: None. E. Yap: None. W. Ma: None. P. Li: None.
- © 2015 by American Heart Association, Inc.