title: Quercetin protects the retina by reducing apoptosis due to ischemia-reperfusion injury in a rat model.
abstract: OBJECTIVE
  This study aimed to investigate the effect of quercetin on apoptotic cell death induced by ischemia-reperfusion (I/R) injury in the rat retina.
  
  
  METHODS
  Twenty-four rats were divided into four equal groups: control, ischemic, solvent, and quercetin. I/R injury was achieved by elevating the intraocular pressure above the perfusion pressure. Intraperitoneal injections of 20 mg/kg of quercetin and dimethyl sulfoxide (DMSO) were performed in the quercetin and solvent groups, respectively, immediately prior to I/R injury, and the researchers allowed for the retinas to be reperfused. Forty-eight hours after injury, the thicknesses of the retinal ganglion cell layer (RGCL), inner nuclear layer (INL), inner plexiform layer (IPL), outer plexiform layer (OPL), and outer nuclear layer (ONL) were measured in all groups. Moreover, the numbers of terminal deoxynucleotidyl transferase dUTP nick-end-labeled [TUNEL (+)] cells and caspase-3 (+) cells in both INL and ONL were evaluated in all groups.
  
  
  RESULTS
  The administration of quercetin was found to reduce the thinning of all retinal layers. The mean thickness of INL in the quercetin and ischemic groups was 21 ± 5.6 µm and 16 ± 6.4 µm, respectively (P<0.05). Similarly, the mean thickness of ONL in the quercetin and ischemic groups was 50 ± 12.8 µm and 40 ± 8.7 µm, respectively (P<0.05). The antiapoptotic effect of quercetin in terms of reducing the numbers of both TUNEL (+) cells and caspase-3 (+) cells was significant in INL. The mean number of TUNEL (+) cells in INL in the ischemic and quercetin groups was 476.8 ± 45.6/mm2 and 238.72 ± 251/mm2, respectively (P<0.005). The mean number of caspase-3 (+) cells in INL of ischemic and quercetin groups was 633.6 ± 38.7/mm2 and 342.4 ± 36.1/mm2, respectively (P<0.001).
  
  
  CONCLUSIONS
  The use of quercetin may be beneficial in the treatment of retinal I/R injury because of its antiapoptotic effect on the retinal layers, particularly in INL.
authors.affiliation: Department of Ophthalmology, School of Medicine, Canakkale Onsekiz Mart University, Canakkale, Turkey.
authors.forename: Sedat
authors.initials: S
authors.lastname: Arikan
authors.affiliation: Department of Ophthalmology, School of Medicine, Canakkale Onsekiz Mart University, Canakkale, Turkey.
authors.forename: Ismail
authors.initials: I
authors.lastname: Ersan
authors.affiliation: Department of Histology and Embriyology, School of Medicine, Trakya University, Edirne, Turkey.
authors.forename: Turan
authors.initials: T
authors.lastname: Karaca
authors.affiliation: Department of Ophthalmology, School of Medicine, Canakkale Onsekiz Mart University, Canakkale, Turkey.
authors.forename: Selcuk
authors.initials: S
authors.lastname: Kara
authors.affiliation: Department of Ophthalmology, School of Medicine, Canakkale Onsekiz Mart University, Canakkale, Turkey.
authors.forename: Baran
authors.initials: B
authors.lastname: Gencer
authors.affiliation: Department of Histology and Embriyology, School of Medicine, Trakya University, Edirne, Turkey.
authors.forename: Ihsan
authors.initials: I
authors.lastname: Karaboga
authors.affiliation: Department of Ophthalmology, School of Medicine, Canakkale Onsekiz Mart University, Canakkale, Turkey.
authors.forename: Tufan
authors.initials: T
authors.lastname: Hasan Ali
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000187:drug effects; D002452:Cell Count; D004121:Dimethyl Sulfoxide / Q000627:therapeutic use; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007429:Intraocular Pressure; D008297:Male; D011794:Quercetin / Q000627:therapeutic use*; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000150:complications*; D015203:Reproducibility of Results; D012160:Retina / Q000187:drug effects* / Q000473:pathology; D012164:Retinal Diseases / Q000473:pathology / Q000517:prevention & control*; D012997:Solvents / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D000975:Antioxidants; D012997:Solvents; D011794:Quercetin; D053148:Caspase 3; D004121:Dimethyl Sulfoxide