title: Role of RhoA/MERK1/ERK1/2/iNOS signaling in ocular ischemic syndrome.
abstract: OBJECTIVE
  To determine the molecular mechanisms underlying ocular ischemic syndrome (OIS). This study uses a rat model to evaluate the role of the RhoA/MEK1/ ERK1/2/iNOS pathways in response to OIS-associated oxidative and nitrosative stress, with a long-term goal of identifying therapeutic targets for OIS.
  
  
  METHODS
  Rats were randomly allocated to one of three groups: bilateral occlusion of the common carotid artery (BOCCA), sham surgery control, or unoperated control (n = 8/group). Three months after the procedure, retinas were analyzed anatomically, using immunohistochemistry and by enzyme-linked immunosorbent assay for RhoA, MEK1, ERK1, ERK2, iNOS. Retinal injury was assessed using TUNEL. Levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by WST-1 and TBA methods, respectively.
  
  
  RESULTS
  In BOCCA rats, occlusion of the bilateral common carotid artery induced degeneration of retinal ganglion cells, which was not observed in either control group. Retinal levels of RhoA, MEK1, ERK1, ERK2, iNOS, NOX2, and MDA were elevated in the BOCCA group, but not in either control group. In comparison, retinal levels of SOD were reduced in SOD animals. By immunofluorescent staining, RhoA was elevated in all retinal layers, while the increased levels of MEK, ERK1/1, and NOX were restricted to the INL, and that of ERK1/2 and NOX inner nuclear layer; iNOS elevations were observed in both the inner and outer nuclear layers. TUNEL labeling results showed that BOCCA group is higher staining than sham and control group.
  
  
  CONCLUSIONS
  OIS elevates activity of the RhoA/MERK1/ERK1/2/iNOS pathways throughout the retina, likely reflecting a response to oxidative and nitrosative stress. Retinal thickness was reduced in BOCCA rats, reflecting a loss of retinal ganglion cells following the reduced blood flow to the eye. These results indicate that drugs that inhibit these pathways may be effective treatments for OIS.
authors.affiliation: Department of Ophthalmology, Beijing Friendship Hospital, Beijing, People's Republic of China.
authors.forename: Ran
authors.initials: R
authors.lastname: Du
authors.affiliation: Department of Ophthalmology, Beijing Friendship Hospital, Beijing, People's Republic of China. wangjialin@bjmu.edu.cn.|Department of Ophthalmology, Beijing Friendship hospital affiliated to Capital Medical University, 95 Yong'an Road, Xicheng District, Beijing, 100050, People's Republic of China. wangjialin@bjmu.edu.cn.
authors.forename: Jia-Lin
authors.initials: JL
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, Beijing Friendship Hospital, Beijing, People's Republic of China.
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D020287:In Situ Nick-End Labeling; D048369:MAP Kinase Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D018384:Oxidative Stress; D051381:Rats; D011914:Rats, Inbred BN; D015427:Reperfusion Injury / Q000150:complications; D012164:Retinal Diseases / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction / Q000502:physiology; D013577:Syndrome; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D020742:rhoA GTP-Binding Protein
keywords: Nitrosative; Ocular Ischemic Syndrome; Oxidative; Signaling pathway