title: Orexin-A promotes Glu uptake by OX1R/PKCα/ERK1/2/GLT-1 pathway in astrocytes and protects co-cultured astrocytes and neurons against apoptosis in anoxia/hypoglycemic injury in vitro.
abstract: Orexin-A, which is an endogenous neuropeptide, is reported to have a protective role in ischemic stroke. High-concentration glutamic acid (Glu) induced by hypoxia injury in ischemic stroke can be inhibited by glial glutamate transporter GLT-1 which is only expressed in astroglia cells. A previous study reported that Orexin-A may regulate GLT-1 expression. However, the role of orexin-A in the regulation of GLT-1 in ischemic stroke still remains unclear. In this study, we aimed to investigate the effect and the underlying mechanism of orexin-A on Glu uptake in astrocytes in vitro and this effect on protecting the neurons from anoxia/hypoglycemic injury. The expression of GLT-1 significantly increased in the astrocytes with orexin-A treatment under anoxia/hypoglycemic conditions, promoting the uptake of Glu and inhibiting the apoptosis of co-cultured cells of astrocytes and neurons. However, these effects were significantly weakened by treatment with orexin-A receptor 1 (OX1R) antagonist. Orexin-A significantly up-regulated the expressions of PKCα and ERK1/2 under anoxia/hypoglycemic conditions in astrocytes, whereas the OX1R antagonist markedly reversed the effect. Furthermore, PKCα or ERK1/2 inhibitor significantly constrained the GLT-1 expression in astrocytes and facilitated the apoptosis of co-cultured cells, and GLT-1 overexpression could reverse those effects of PKCα or ERK1/2 inhibitor. Taken together, orexin-A promoted the GLT-1 expression via OX1R/PKCα/ERK1/2 pathway in astrocytes and protected co-cultured cells against anoxia/hypoglycemic injury.
authors.affiliation: Department of Pharmacy, Ninth Hospital of Xi'an, No. 151 South Second Ring Road East, Xi'an, 710054, Shaanxi, China. qingshu9th@sohu.com.
authors.forename: Qing
authors.initials: Q
authors.lastname: Shu
authors.affiliation: Department of Pharmacy, Ninth Hospital of Xi'an, No. 151 South Second Ring Road East, Xi'an, 710054, Shaanxi, China.
authors.forename: Jianhuai
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Pharmacy, Ninth Hospital of Xi'an, No. 151 South Second Ring Road East, Xi'an, 710054, Shaanxi, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.affiliation: Department of Pharmacy, Ninth Hospital of Xi'an, No. 151 South Second Ring Road East, Xi'an, 710054, Shaanxi, China.
authors.forename: Youying
authors.initials: Y
authors.lastname: Lei
authors.affiliation: Department of Pharmacy, Ninth Hospital of Xi'an, No. 151 South Second Ring Road East, Xi'an, 710054, Shaanxi, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhou
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000378:metabolism*; D015687:Cell Hypoxia / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D027342:Excitatory Amino Acid Transporter 2 / Q000096:biosynthesis*; D005786:Gene Expression Regulation / Q000187:drug effects; D018698:Glutamic Acid / Q000378:metabolism*; D007003:Hypoglycemia / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D048052:Mitogen-Activated Protein Kinase 3 / Q000097:blood*; D009474:Neurons / Q000378:metabolism*; D064446:Orexin Receptors / Q000378:metabolism*; D000068797:Orexins / Q000494:pharmacology*; D051571:Protein Kinase C-alpha / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D027342:Excitatory Amino Acid Transporter 2; C578627:Hcrtr1 protein, rat; D064446:Orexin Receptors; D000068797:Orexins; C493395:Slc1a2 protein, rat; D018698:Glutamic Acid; D051571:Protein Kinase C-alpha; D048052:Mitogen-Activated Protein Kinase 3
keywords: GLT-1; Ischemic stroke; Neurons; Orexin-A; PKCα–ERK1/2 pathway