title: Green tea extract suppresses N-methyl-N-nitrosourea-induced photoreceptor apoptosis in Sprague-Dawley rats.
abstract: BACKGROUND
  Retinitis pigmentosa (RP) is a group of inherited neurodegenerative human diseases characterized by the loss of photoreceptor cells by apoptosis and eventual blindness. A single intraperitoneal (ip) injection of N-methyl-N-nitrosourea (MNU) causes photoreceptor cell apoptosis within 7 days in rats. Green tea extract (THEA-FLAN 90S; GTE) is a common herbal supplement with pluripotent properties including antioxidant activity. The purpose of the present study was to evaluate the efficacy of GTE against photoreceptor apoptosis in 7-week-old female Sprague-Dawley rats that received a single ip injection of 40 mg/kg MNU.
  
  
  METHODS
  The oral administration of 250 mg/kg/day GTE was initiated 3 days prior to MNU injection and continued once daily throughout the experiment. Rats were sacrificed at 12, 24, and 72 h and 7 days after MNU injection, and the eyes were examined morphologically and morphometrically. The photoreceptor cell ratio, retinal damage ratio, and retinal preservation ratio were used to determine the structural and functional alterations. The number of apoptotic photoreceptor cells per mm(2) was determined in situ by TdT-mediated dUTP-digoxigenin nick end labeling (TUNEL). Our results indicated that oral administration of GTE significantly suppressed the loss of photoreceptor cells morphometrically 7 days after MNU injection. The number of TUNEL-positive cells per mm(2) in MNU-exposed rat central retina with or without GTE administration was 981 vs. 2056 at 24 h after MNU injection.
  
  
  CONCLUSIONS
  GTE structurally and functionally suppressed MNU-induced photoreceptor cell apoptosis. These findings indicate that GTE may help to ameliorate the onset and progression of human RP.
authors.affiliation: Department of Pathology II, Kansai Medical University, Shinmachi 2-5-1, Hirakata, Osaka, 573-1010, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Emoto
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yoshizawa
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kinoshita
authors.forename: Takashi
authors.initials: T
authors.lastname: Yuri
authors.forename: Michiko
authors.initials: M
authors.lastname: Yuki
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Sayama
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Shikata
authors.forename: Airo
authors.initials: A
authors.lastname: Tsubura
mesh_terms: D000284:Administration, Oral; D000477:Alkylating Agents / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002392:Catechin / Q000031:analogs & derivatives / Q000097:blood; D002853:Chromatography, Liquid; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6 / Q000378:metabolism; D005260:Female; D020287:In Situ Nick-End Labeling; D007274:Injections, Intraperitoneal; D008770:Methylnitrosourea / Q000633:toxicity*; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008517:Phytotherapy; D010936:Plant Extracts; D051381:Rats; D017207:Rats, Sprague-Dawley; D012162:Retinal Degeneration / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D012243:Rhodopsin / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D013662:Tea
chemical_list: D000477:Alkylating Agents; D010936:Plant Extracts; D013662:Tea; D008770:Methylnitrosourea; D002392:Catechin; D012243:Rhodopsin; C045651:epigallocatechin gallate; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6