title: N-methyl-N-nitrosourea induces retinal degeneration in the rat via the inhibition of NF-κB activation.
abstract: Retinitis pigmentosa (RP) is a group of inherited neurodegenerative diseases characterized by the loss of photoreceptor cells through apoptosis. N-methyl-N-nitrosourea (MNU) is an alkylating toxicant that induces photoreceptor cell death resembling hereditary RP. This study aimed to investigate the role of nuclear factor κB (NF-κB) in MNU-induced photoreceptor degeneration. Adult rats received a single intraperitoneal injection of MNU (60 mg/kg bodyweight). Hematoxylin and eosin staining demonstrated progressive outer nuclear layer (ONL) loss after MNU treatment. Transmission electron microscopy revealed nuclear pyknosis, chromatin margination in the photoreceptors, increased secondary lysosomes, and lobulated retinal-pigmented epithelial cells in MNU-treated rats. Numerous photoreceptor cells in the ONL showed positive TUNEL staining and apoptosis rate peaked at 24 hours. Enhanced depth imaging spectral-domain optical coherence tomography showed ONL thinning and decreased choroid thickness. Electroretinograms showed decreased A wave amplitude that predominated in scotopic conditions. Western blot analysis showed that nuclear IκBα level increased, whereas nuclear NF-κB p65 decreased significantly in the retinas of MNU-treated rats. These findings indicate that MNU leads to selective photoreceptor degradation, and this is associated with the inhibition of NF-κB activation.
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Hong-Pei
authors.initials: HP
authors.lastname: Ji
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Wei-Tao
authors.initials: WT
authors.lastname: Song
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Ye-Wei
authors.initials: YW
authors.lastname: Yin
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Chao-Hua
authors.initials: CH
authors.lastname: Xia
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Ophthalmology Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Xia
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000187:drug effects / Q000473:pathology; D002829:Choroid / Q000187:drug effects / Q000473:pathology; D004596:Electroretinography; D005260:Female; D020287:In Situ Nick-End Labeling; D008770:Methylnitrosourea / Q000633:toxicity*; D016328:NF-kappa B / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D017207:Rats, Sprague-Dawley; D012162:Retinal Degeneration / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014057:Tomography, X-Ray Computed
chemical_list: D016328:NF-kappa B; D008770:Methylnitrosourea
keywords: N-methyl-N-nitrosourea; NF-κB; choroid thickness; retinal degeneration; retinitis pigmentosa