Neuronal injury in rat model of permanent focal cerebral ischemia is associated with activation of autophagic and lysosomal pathways.
It has been reported that ischemic insult increases the formation of autophagosomes and activates autophagy. However, the role of autophagy in ischemic neuronal damage remains elusive. This study was taken to assess the role of autophagy in ischemic brain damage. Focal cerebral ischemia was introduced by permanent middle cerebral artery occlusion (pMCAO). Activation of autophagy was assessed by morphological and biochemical examinations. To determine the contribution of autophagy/lysosome to ischemic neuronal death, rats were pretreated with a single intracerebral ventricle injection of the autophagy inhibitors 3-methyl-adenine (3-MA) and bafliomycin A1 (BFA) or the cathepsin B inhibitor Z-FA-fmk after pMCAO. The effects of 3-MA and Z-FA-fmk on brain damage, expression of proteins involved in regulation of autophagy and apoptosis were assessed with 2,3,5-triphenyltetrazolium chloride (TTC) staining and immunoblotting. The results showed that pMACO increased the formation of autophagosomes and autolysosomes, the mRNA and protein levels of LC3-II and the protein levels of cathepsin B. 3-MA, BFA and Z-FA-fmk significantly reduced infarct volume, brain edema and motor deficits. The neuroprotective effects of 3-MA and Z-FA-fmk were associated with an inhibition on ischemia-induced upregulation of LC3-II and cathepsin B and a partial reversion of ischemia-induced downregulation of cytoprotective Bcl-2. These results demonstrate that ischemic insult activates autophagy and an autophagic mechanism may contribute to ischemic neuronal injury. Thus, autophagy may be a potential target for developing a novel therapy for stroke.
Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Medicine, Suzhou, China.
Ya-Dan
YD
Wen
Rui
R
Sheng
Li-Sha
LS
Zhang
Rong
R
Han
Xuan
X
Zhang
Xing-Ding
XD
Zhang
Feng
F
Han
Kohji
K
Fukunaga
Zheng-Hong
ZH
Qin
D000225:Adenine / Q000031:analogs & derivatives / Q000378:metabolism; D000590:Amino Acid Chloromethyl Ketones / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology; D002401:Cathepsin B / Q000235:genetics / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D006801:Humans; D020244:Infarction, Middle Cerebral Artery; D008247:Lysosomes / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D018696:Neuroprotective Agents / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology
D000590:Amino Acid Chloromethyl Ketones; D015415:Biomarkers; D015853:Cysteine Proteinase Inhibitors; D018696:Neuroprotective Agents; D019253:Proto-Oncogene Proteins c-bcl-2; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C025946:3-methyladenine; D002401:Cathepsin B; D000225:Adenine