Resveratrol pretreatment protects rat brain from cerebral ischemic damage via a sirtuin 1–uncoupling protein 2 pathway

Abstract

Resveratrol is a natural polyphenol found in grapes and wine and has been associated with protective effects against cardiovascular diseases. In vitro, both resveratrol preconditioning (RPC) and ischemic preconditioning (IPC) require activation of sirtuin 1 (SIRT1), an NAD+-dependent deacetylases, to induce neuroprotection against cerebral ischemia. In the present study, we tested two hypotheses: a) that neuroprotection against cerebral ischemia can be induced by RPC in vivo; and b) that RPC neuroprotection involves alterations in mitochondrial function via the SIRT1 target mitochondrial uncoupling protein 2 (UCP2). IPC was induced by two minutes of global ischemia (temporary bilateral carotid artery occlusion with hypotension), and RPC, by intraperitoneal injection of resveratrol at 10, 50 and 100 mg/Kg dosages. 48 hours later, we compared the neuroprotective efficacy of RPC and IPC in vulnerable CA1 hippocampal pyramidal neurons using a rat model of asphyxial cardiac arrest (ACA). SIRT1 activity was measured using a SIRT1-specific fluorescent enzyme activity assay. In hippocampal mitochondria isolated 48 hours after IPC or RPC, we measured UCP2 levels, membrane potential, respiration, and the mitochondrial ATP synthesis efficiency (ADP/O ratio). Both IPC and RPC induced tolerance against brain injury induced by cardiac arrest in this in vivo model. IPC increased SIRT1 activity at 48 hours, while RPC increased SIRT1 activity at 1 hour but not 48 hours after treatment in hippocampus. Resveratrol significantly decreased UCP2 levels by 35% compared to sham-treated rats. The SIRT1-specific inhibitor sirtinol abolished the neuroprotection afforded by RPC and the decrease in UCP2 levels. Finally, RPC significantly increased the ADP/O ratio in hippocampal mitochondria reflecting enhanced ATP synthesis effieciency. In conclusion, in vivo resveratrol pretreatment confers neuroprotection similar to IPC via the SIRT1-UCP2 pathway.

Ischemic Preconditioning Alters the Epigenetic Profile of the Brain from Ischemic Intolerance to Ischemic Tolerance

“…In contrast to ischemic neuroprotection by class I, II, and IV HDAC inhibitors (which do not inhibit sirtuins), our laboratory, and others, have demonstrated that SIRT1 activation is required for ischemic tolerance [38,39]. Our laboratory has demonstrated both in vivo and in organotypic hippocampal slices that nuclear SIRT1 activity is increased at 48 h following IPC and that blocking SIRT1 activation with sirtinol abrogated IPC-mediated ischemic neuroprotection [38,39]. We have also demonstrated that preconditioning could be induced, both in vivo and in hippocampal organotypic slices with the SIRT1 activator, resveratrol.…”

“…We have also demonstrated that preconditioning could be induced, both in vivo and in hippocampal organotypic slices with the SIRT1 activator, resveratrol. Resveratrol-mediated neuroprotection was lost in the presence of sirtinol, confirming a role for SIRT1 in resveratrolmediated ischemic neuroprotection [38,39]. Using a different model of preconditioning, Yan et al [40] demonstrated that hyperbaric oxygen preconditioning increased SIRT1 protein [38] expression and that inhibition of SIRT1 deacetylase activity with EX527 blocked hyperbaric oxygen preconditioning neuroprotection against MCAO-mediated damage.…”

“…Resveratrol-mediated neuroprotection was lost in the presence of sirtinol, confirming a role for SIRT1 in resveratrolmediated ischemic neuroprotection [38,39]. Using a different model of preconditioning, Yan et al [40] demonstrated that hyperbaric oxygen preconditioning increased SIRT1 protein [38] expression and that inhibition of SIRT1 deacetylase activity with EX527 blocked hyperbaric oxygen preconditioning neuroprotection against MCAO-mediated damage. It is interesting to note that transgenic mice overexpressing neuronalspecific SIRT1 are not protected against ischemic damage, suggesting that other signaling pathways may work in conjunction with SIRT1 for the induction of ischemic tolerance [41].…”

“…SIRT1 is a member of the sirtuin family of deacetylase and ADP-ribosylase enzymes, which are involved in numerous cellular activities, including the cellular stress response, genome stability, and energy metabolism [36,37]. In contrast to ischemic neuroprotection by class I, II, and IV HDAC inhibitors (which do not inhibit sirtuins), our laboratory, and others, have demonstrated that SIRT1 activation is required for ischemic tolerance [38,39]. Our laboratory has demonstrated both in vivo and in organotypic hippocampal slices that nuclear SIRT1 activity is increased at 48 h following IPC and that blocking SIRT1 activation with sirtinol abrogated IPC-mediated ischemic neuroprotection [38,39].…”

Redox Signaling Pathways Involved in Neuronal Ischemic Preconditioning

“…Furthermore, blocking SIRT1 with sirtinol abrogated IPC-induced neuroprotection against oxygen and glucose deprivation (OGD) induced cell death. Similarly, IPC increased SIRT1 enzymatic activity and neuroprotection in an in vivo rat model of cardiac arrest [114]. SIRT1 is also activated in the heart following IPC and provides cardioprotection from ischemia and coronary artery occlusion [115][116][117].…”