title: Pigment epithelium-derived factor regulates glutamine synthetase and l-glutamate/l-aspartate transporter in retinas with oxygen-induced retinopathy.
abstract: OBJECTIVE
  A predominant function of Müller cells is to regulate glutamate levels, but these cells are compromised in oxygen-induced retinopathy. The aim of this study was to investigate the role of pigment epithelium-derived factor (PEDF) in regulating glutamate levels in retina under hypoxia.
  
  
  METHODS
  One-week-old C57BL/6J mice were exposed to 75% oxygen for 5 days and then kept in room air for another 5 days to establish the oxygen-induced retinopathy (OIR) mouse model. Mice received intravitreous injections of 2 μg PEDF or vehicle on postnatal (P)12 and P14, respectively. Antibody against interleukin-1Beta (IL-1β) (IL-1ab) was used to neutralize the activity of IL-1β, mice received intravitreous injections of 500 ng IL-1ab or vehicle on P12 and P14, respectively, too. At P17, the mice were euthanized and their eyes were enucleated. The expression levels of IL-1β, glutamine synthetase (GS) and l-glutamate/l-aspartate transporter (GLAST) in retinas with different treatments were detected. In addition, wild-type C57BL/6J mice received intravitreous injections of IL-1β or PEDF. After 24 h, the expression of GS and GLAST in the retinas was also detected. Furthermore, high-performance liquid chromatography (HPLC) was performed to determine the glutamate concentrations in retinas with different treatments.
  
  
  RESULTS
  The expression of IL-1β and levels of glutamate were increased in retinas with OIR, while the expression of GS and GLAST was decreased. Administration of PEDF ameliorated the characteristic changes in retinas of OIR mice. And neutralization of IL-1β by administration of IL-1ab increased GS and GLAST expression in retinas with OIR. Moreover, the effects of IL-1β on GS and GLAST expression and unbalanced glutamate levels were inhibited after receiving intravitreous injections of PEDF in retinas of normal mice.
  
  
  CONCLUSIONS
  These results suggested that PEDF might up-regulate GS and GLAST expression and decrease glutamate levels by suppressing the role of IL-1β as an anti-inflammatory factor under hypoxia, and these functions may underlie the neuroprotective effects of PEDF.
authors.affiliation: a Department of Ophthalmology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.
authors.forename: Yanuo
authors.initials: Y
authors.lastname: Wang
authors.affiliation: a Department of Ophthalmology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lu
authors.affiliation: a Department of Ophthalmology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.
authors.forename: Sha
authors.initials: S
authors.lastname: Gao
authors.affiliation: a Department of Ophthalmology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.
authors.forename: Yanji
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: a Department of Ophthalmology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.
authors.forename: Yushuo
authors.initials: Y
authors.lastname: Gao
authors.affiliation: a Department of Ophthalmology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.
authors.forename: Bing
authors.initials: B
authors.lastname: Xie
authors.affiliation: a Department of Ophthalmology , Ruijin Hospital, Shanghai Jiaotong University School of Medicine , Shanghai , China.
authors.forename: Xi
authors.initials: X
authors.lastname: Shen
mesh_terms: D027322:Amino Acid Transport System X-AG / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D004195:Disease Models, Animal; D063928:Ependymoglial Cells / Q000187:drug effects* / Q000378:metabolism; D005136:Eye Proteins / Q000494:pharmacology*; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation / Q000502:physiology; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D053583:Interleukin-1beta / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D058449:Intravitreal Injections; D051379:Mice; D008810:Mice, Inbred C57BL; D009414:Nerve Growth Factors / Q000494:pharmacology*; D010100:Oxygen / Q000633:toxicity; D011480:Protease Inhibitors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012178:Retinopathy of Prematurity / Q000188:drug therapy* / Q000209:etiology / Q000235:genetics / Q000378:metabolism; D015843:Serpins / Q000494:pharmacology*; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D027322:Amino Acid Transport System X-AG; D005136:Eye Proteins; D005974:Glutamate-Ammonia Ligase; D018698:Glutamic Acid; D053583:Interleukin-1beta; D009414:Nerve Growth Factors; D010100:Oxygen; D011480:Protease Inhibitors; D012333:RNA, Messenger; D015843:Serpins; D000099174:Pigment Epithelium-Derived Factor
keywords: Glutamine synthetase; Müller cells; interleukin-1Beta; l-glutamate/l-aspartate transporter; pigment epithelium-derived factor