title: Effect of pigment epithelium derived factor on the expression of glutamine synthetase in early phase of experimental diabetic retinopathy.
abstract: OBJECTIVE
  A predominant function of Müller cells is to regulate glutamate levels, but in diabetic retinopathy (DR) the function is compromised. The present study was performed to investigate the role of pigment epithelial-derived factor (PEDF) on the expression of glutamine synthetase (GS) in retina of diabetic rats.
  
  
  METHODS
  The levels of interleukin-1ß (IL-1ß), PEDF, and GS in the retina of diabetic rats were analyzed by Western blotting and real-time-RT-PCR, and glutamate concentrations in retina or vitreous body were determined by high-pressure liquid chromatography. After being treated with PEDF in diabetic rats, these proteins (IL-1ß and GS) and their mRNAs, as well as glutamate concentrations, were detected. To confirm the effect of PEDF on GS against the role of IL-1ß, treatments with IL-1ß companied with or without PEDF were performed in the eyes of normal rats.
  
  
  RESULTS
  Diabetes increased IL-1ß levels and decreased PEDF and GS levels in retina. Simultaneously, diabetes induced elevated glutamate concentrations in retina and vitreous body. Administration of PEDF ameliorated the characteristic changes in diabetic retinopathy. Moreover, the effect of IL-1ß on the expression of GS was inhibited by PEDF in retina of normal rats.
  
  
  CONCLUSIONS
  PEDF increases expression of GS against the effect of IL-1ß in early diabetic retinopathy. These findings suggest that PEDF may act as an anti-inflammatory factor against decrease of GS expression in retinal Müller cells in diabetic retinopathy.
authors.affiliation: Department of Ophthalmology, Ruijin Hospital, School of Medicine, The Jiaotong University, Shanghai, China. carl_shen2005@yahoo.com.cn
authors.forename: Xi
authors.initials: X
authors.lastname: Shen
authors.forename: Bing
authors.initials: B
authors.lastname: Xie
authors.forename: Yu
authors.initials: Y
authors.lastname: Cheng
authors.forename: Qin
authors.initials: Q
authors.lastname: Jiao
authors.forename: Yisheng
authors.initials: Y
authors.lastname: Zhong
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage* / Q000378:metabolism; D015153:Blotting, Western; D003930:Diabetic Retinopathy / Q000378:metabolism*; D005136:Eye Proteins / Q000008:administration & dosage* / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D007275:Injections, Intravenous; D053583:Interleukin-1beta / Q000008:administration & dosage / Q000378:metabolism; D008297:Male; D009414:Nerve Growth Factors / Q000008:administration & dosage* / Q000378:metabolism; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D015843:Serpins / Q000008:administration & dosage* / Q000378:metabolism; D014822:Vitreous Body / Q000187:drug effects / Q000378:metabolism; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D000893:Anti-Inflammatory Agents; D005136:Eye Proteins; D005974:Glutamate-Ammonia Ligase; D018698:Glutamic Acid; D053583:Interleukin-1beta; D009414:Nerve Growth Factors; D015843:Serpins; D000099174:Pigment Epithelium-Derived Factor