Autophagy activation is associated with neuroprotection in a rat model of focal cerebral ischemic preconditioning.
Several recent studies have showed that autophagy is involved in ischemic brain damage, but it may also play a pro-survival role in ischemic preconditioning. This study was taken to determine the role of autophagy in an animal model of cerebral ischemic preconditioning (IPC). Focal cerebral IPC was produced in rats by a brief ischemic insult followed by permanent focal ischemia (PFI) 24 h later using the suture occlusion technique. The rats were pretreated with intracerebral ventricle infusion of the autophagy inhibitors 3-methyladenine (3-MA) and bafliomycin A1 (Baf A1) or the autophagy inducer rapamycin to evaluate the contribution of autophagy to IPC-induced neuroprotection. The results from electron microscopic examinations and immunofluorescence showed that both IPC and PFI induced autophagy activation, but the extent and persistence of autophagy activation were varied. IPC treatment significantly reduced infarct volume, brain edema and motor deficits after subsequent PFI, whereas 3-MA and Baf A1 suppressed the neuroprotection induced by IPC. 3-MA pretreatment also significantly attenuated upregulation of LC3-II, beclin 1 and HSP70 and downregulation of p62. To further determine if autophagy induction is responsible for IPC-induced neuroprotection, rats were treated with rapamycin 24 h before the onset of PFI. The results showed that rapamycin reduced infarct volume, brain edema and motor deficits induced by PFI. Rapamycin pretreatment also increased the protein levels of LC3-II and beclin 1. These results demonstrate that autophagy activation during IPC offers a remarkable tolerance to a subsequent fatal ischemic insult, and IPC's neuroprotective effects can be mimicked by autophagy inducers.
Sheng
Rui
R
Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Medicine, Suzhou, China.
Zhang
Li-Sha
LS
Han
Rong
R
Liu
Xiao-Qian
XQ
Gao
Bo
B
Qin
Zheng-Hong
ZH
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects; D000071186:Beclin-1; D002545:Brain Ischemia / Q000473:pathology*; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D019194:Ischemic Preconditioning; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism; D055495:Neurogenesis / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D018696:Neuroprotective Agents / Q000378:metabolism*; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D000071456:Sequestosome-1 Protein; D020123:Sirolimus / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
D000225:Adenine; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008869:Microtubule-Associated Proteins; D018696:Neuroprotective Agents; D000071456:Sequestosome-1 Protein; D020123:Sirolimus; C512829:Becn1 protein, rat; C526109:Anxa3 protein, rat; C491079:Sqstm1 protein, rat; C025946:3-methyladenine