title: Glutamate-induced retinal lipid and protein damage: the protective effects of catechin.
abstract: Glutamate toxicity has been implicated in various retinal diseases. Green tea leaf extract catechin has protective effects against cellular toxicity. This study investigated the effects of catechin on the glutamate-treated retina. Porcine retinal homogenates were incubated with glutamate (20 nmol) at 37 degrees C for 60 min. Catechin was co-incubated with the glutamate-treated retina in the same condition. The malondialdehyde (MDA) levels were determined as an index of lipid peroxidation (LPO). Differential protein expressions were derived from two-dimensional gel electrophoresis. Mass spectrometry was conducted to identify the proteins. Glutamate increased the retinal MDA (p<0.0001) and catechin reversed the effect (p<0.0001). There were significant changes in seven proteins after the glutamate treatment (p<0.05), namely, heterogeneous ribonucleoprotein, thioredoxin peroxidase, 5-hydroxytryptamine receptor, pyruvate dehydrogenase, ARHA protein, peroxiredoxin 6 and proteasome. Catechin significantly reversed the changes in thioredoxin peroxidase, 5-hydroxytryptamine receptor, peroxiredoxin 6 and pyruvate dehydrogenase (p<0.05). Our study shows that (a) retinal glutamate toxicity is mediated by LPO and protein modification, and (b) catechin ameliorates the toxicity.
authors.affiliation: School of Optometry, The Hong Kong Polytechnic University, Yuk Choi Road, Hunghom, Hong Kong, China. siuanz@gmail.com
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Siu
authors.forename: Mick K
authors.initials: MK
authors.lastname: Lau
authors.forename: John S
authors.initials: JS
authors.lastname: Cheng
authors.forename: Catherine K
authors.initials: CK
authors.lastname: Chow
authors.forename: Wai C
authors.initials: WC
authors.lastname: Tam
authors.forename: K K
authors.initials: KK
authors.lastname: Li
authors.forename: Daniel K L
authors.initials: DK
authors.lastname: Lee
authors.forename: Tony S S
authors.initials: TS
authors.lastname: To
authors.forename: Chi H
authors.initials: CH
authors.lastname: To
authors.forename: Chi W
authors.initials: CW
authors.lastname: Do
mesh_terms: D000818:Animals; D002392:Catechin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D018698:Glutamic Acid / Q000633:toxicity*; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects*; D008315:Malondialdehyde / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D011506:Proteins / Q000378:metabolism; D012160:Retina / Q000187:drug effects*; D013552:Swine
chemical_list: D011506:Proteins; D018698:Glutamic Acid; D008315:Malondialdehyde; D002392:Catechin