Autophagy was activated in injured astrocytes and mildly decreased cell survival following glucose and oxygen deprivation and focal cerebral ischemia.
The present study evaluated autophagy activation in astrocytes and its contribution to astrocyte injury induced by cerebral ischemia and hypoxia. Focal cerebral ischemia was induced by permanent middle cerebral artery occlusion (pMCAO) in rats. In vitro hypoxia in cultured primary astrocytes was induced by the oxygen-glucose deprivation (OGD). Alterations of astrocytes were evaluated with astroglia markers glial fibrillary acidic protein (GFAP). The formation of autophagosomes in astrocytes was examined with transmission electron microscopy (TEM). The expression of autophagy-related proteins were examined with immunoblotting. The role of autophagy in OGD or focal cerebral ischemia-induced death of astrocytes was assessed by pharmacological inhibition of autophagy with 3-methyladenine (3-MA) or bafilomycin A(1) (Baf). The results showed that GFAP staining was reduced in the infarct brain areas 3-12 h following pMCAO. Cerebral ischemia or OGD induced activation of autophagy in astrocytes as evidenced by the increased formation of autophagosomes and autolysosomes and monodansylcadaverine (MDC)-labeled vesicles; the increased production of microtubule-associated protein 1 light chain 3 (LC3-II ); the upregulation of Beclin 1, lysosome-associated membrane protein 2 (LAMP2) and lysosomal cathepsin B expression; and the decreased levels of cytoprotective Bcl-2 protein in primary astrocytes. 3-MA inhibited OGD-induced the increase in LC3-II and the decline in Bcl-2. Furthermore, 3-MA and Baf slightly but significantly attenuated OGD-induced death of astrocytes. 3-MA also significantly increased the number of GFAP-positive cells and the protein levels of GFAP in the ischemic cortex core 12 h following pMCAO. These results suggest that ischemia or hypoxia-induced autophagic/lysosomal pathway activation may at least partly contribute to ischemic injury of astrocytes.
Qin
Ai-Ping
AP
Department of Pharmacology, Laboratory of Aging and Nervous Diseases, Soochow University School of Medicine, Suzhou, China.
Liu
Chun-Feng
CF
Qin
Yuan-Yuan
YY
Hong
Li-Zhi
LZ
Xu
Min
M
Yang
Lei
L
Liu
Jianqing
J
Qin
Zheng-Hong
ZH
Zhang
Hui-Ling
HL
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology / Q000473:pathology* / Q000648:ultrastructure; D001343:Autophagy / Q000187:drug effects*; D000071186:Beclin-1; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology*; D002401:Cathepsin B / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000473:pathology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005947:Glucose / Q000172:deficiency* / Q000494:pharmacology; D020244:Infarction, Middle Cerebral Artery; D052119:Lysosomal-Associated Membrane Protein 2 / Q000378:metabolism; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism
D000225:Adenine; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; D002401:Cathepsin B; D005904:Glial Fibrillary Acidic Protein; D005947:Glucose; D052119:Lysosomal-Associated Membrane Protein 2; D008869:Microtubule-Associated Proteins; D010100:Oxygen; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; C512829:Becn1 protein, rat; C526109:Anxa3 protein, rat; C018589:lysosomal proteins; C025946:3-methyladenine