title: Effects of simvastatin on CAT-1-mediated arginine transport and NO level under high glucose conditions in conditionally immortalized rat inner blood-retinal barrier cell lines (TR-iBRB).
abstract: Hyperglycemia causes the breakdown of the blood-retinal barrier by impairing endothelial nitric oxide synthase (eNOS) function. Statins have many pleiotropic effects such as improving endothelial barrier permeability and increasing eNOS mRNA stability. The objective of this study was to determine effect of simvastatin on l-arginine transport and NO production under high-glucose conditions in conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB).
  
  
  
  Changes in l-arginine transport uptake and, expression levels of cationic amino acid transporter 1 (CAT-1) and eNOS mRNA were investigated after pre-treatment with simvastatin and NOS inhibitors (l-NMMA and l-NAME) under high-glucose conditions using TR-iBRB, an in vitro model of iBRB. The NO level released from TR-iBRB cells was examined using Griess reagents.
  
  
  
  Under high glucose conditions, [3H]l-arginine uptake was decreased in TR-iBRB cells. Simvastatin pretreatment elevated [3H]l-arginine uptake, the expression levels of CAT-1 and eNOS mRNA, and NO production under high-glucose conditions. Moreover, the co-treatment with simvastatin and NOS inhibitors reduced [3H]l-arginine uptake compared to pretreatment with simvastatin alone.
  
  
  
  Our results suggest that, in the presence of high-glucose levels, increased l-arginine uptake due to simvastatin treatment was associated with increased CAT-1 and eNOS mRNA levels, leading to higher NO production in TR-iBRB cells. Thus, simvastatin might be a good modulator for diabetic retinopathy therapy by increasing of the l-arginine uptake and improving endothelial function in retinal capillary endothelial cells.
authors.affiliation: College of Pharmacy and Research Center for Cell Fate Control, Sookmyung Women's University, Chungpa-dong 2-ga, Yongsan-gu, Seoul 140-742, Republic of Korea.
authors.forename: Temdara
authors.initials: T
authors.lastname: Tun
authors.affiliation: College of Pharmacy and Research Center for Cell Fate Control, Sookmyung Women's University, Chungpa-dong 2-ga, Yongsan-gu, Seoul 140-742, Republic of Korea. Electronic address: yskang@sm.ac.kr.
authors.forename: Young-Sook
authors.initials: YS
authors.lastname: Kang
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport; D001813:Blood-Retinal Barrier / Q000187:drug effects* / Q000378:metabolism; D027201:Cationic Amino Acid Transporter 1 / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003930:Diabetic Retinopathy / Q000188:drug therapy / Q000378:metabolism; D005947:Glucose / Q000633:toxicity*; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D019821:Simvastatin / Q000494:pharmacology*; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D027201:Cationic Amino Acid Transporter 1; D012333:RNA, Messenger; D009569:Nitric Oxide; D001120:Arginine; D019821:Simvastatin; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D005947:Glucose
keywords: Blood-retinal barrier; Endothelial nitric oxide synthase; Hyperglycemic condition; Simvastatin; l-Arginine