Protection of ischemic brain cells is dependent on astrocyte-derived growth factors and their receptors.
An in vitro ischemia model (oxygen, glucose, and serum deprivation) is used to investigate the possible cellular and molecular mechanisms responsible for cerebral ischemia. We have previously demonstrated that supernatants derived from ischemic microglia can protect ischemic brain cells by releasing GDNF and TGF-beta1. In the present study, we investigate whether products of ischemic astrocytes can also protect ischemic microglia, astrocytes, and neurons in a similar manner. Supernatants from ischemic astrocytes were collected after various periods of ischemia and incubated with microglia, astrocytes, or neurons individually, under in vitro ischemic conditions. The components responsible for the protective effects of astrocyte-derived supernatants were then identified by Western blot, ELISA, trypan blue dye exclusion, and immunoblocking assays. Results showed that under conditions of in vitro ischemia the number of surviving microglia, astrocytes, and neurons was significantly increased by the incorporation of the astrocyte-derived supernatants. Astrocyte supernatant-mediated protection of ischemic microglia was dependent on TGF-beta1 and NT-3, ischemic astrocytes were protected by GDNF, and ischemic neurons were protected by NT-3. In addition, protein expression of TGF-beta1 and NT-3 receptors in microglia, GDNF receptors in astrocytes, and NT-3 receptors in neurons was increased by in vitro ischemia. These results suggest that astrocyte-derived protection of ischemic brain cells is dependent not only on factors released from the ischemic astrocytes, but also on the type of receptor present on the responding cells. Therapeutic potential of TGF-beta1, GDNF, and NT-3 in the control of cerebral ischemia is further suggested.
Lin
Chi-Hsin
CH
Department of Life Sciences, National Chung Hsing University, Taichung 40227, Taiwan.
Cheng
Fu-Chou
FC
Lu
Yen-Zhen
YZ
Chu
Lan-Feng
LF
Wang
Chen-Hsuan
CH
Hsueh
Chi-Mei
CM
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015687:Cell Hypoxia; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000378:metabolism / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000494:pharmacology; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors / Q000378:metabolism; D006133:Growth Substances / Q000494:pharmacology*; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D020933:Neurotrophin 3 / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020812:Receptor, trkC / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D053773:Transforming Growth Factor beta1
D017077:Culture Media, Conditioned; D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D006133:Growth Substances; D020933:Neurotrophin 3; D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D020812:Receptor, trkC