Induction of immunoreactive proliferating cell nuclear antigen (PCNA) in goldfish retina following intravitreal injection with tunicamycin.
Effects of a photoreceptor-specific biotoxin, tunicamycin (TM), injected intravitreally into the goldfish eye at one side, were explored on electroretinograms (ERGs) and proliferating cell nuclear antigen-immunoreactive (PCNA-ir) nuclei, representing the mitotic activity of rod precursors, in the retina at both sides. The eye-cup preparations were made for ERG recording, and the retinas were isolated and processed as cryosections or wholemounts by a routine immunohistochemical method for visinin (cones), opsin (rods), tyrosine hydroxylase (dopaminergic cells) and proliferating cell nuclear antigen (PCNA), at various intervals after intravitreal injection with TM (1.0 micrograms/eye). On some thin sections, autoradiographic study was combined following intravitreal injection with [3H]thymidine (TdR, 0.1 microCi/eye). The dose of TM used heavily destroyed cones and rods only in the treated retinas 2-15 days after injection, the photoreceptors being renewed for further 15-20 days. Approximately in parallel, ERGs were largely impaired 2-10 days after TM injection and recovered for 10-20 days. However, intravitreal TM altered the distribution and density of PCNA-ir nuclei in both treated and untreated retinas. The density of PCNA-ir nuclei reduced at first (on days 1 and 2), and then clustered and rapidly increased on days 3-5 and maintained at high levels with diffuse distribution over the whole area, particularly in the treated retinas, up to 60 days after TM injection; the maximum peak of 3.7 and 20 times the initial level was seen on day 20 in the outer nuclear layer (ONL) and inner nuclear layer (INL), respectively. PCNA-ir nuclei were found to be abundant in the ONL even after the photoreceptors and ERGs had been restored in the treated retinas on day 20, suggesting a kind of overproduction of retinal cells. The autoradiographic study provided comparable results to those obtained with PCNA immunohistochemistry. The mechanism by which damage to the treated retina causes rod precursor cells to proliferate in the untreated retina remains unresolved.
Department of Neurophysiology, University of Kanazawa School of Medicine, Japan.
K
K
Negishi
K
K
Sugawara
S
S
Shinagawa
T
T
Teranishi
C H
CH
Kuo
Y
Y
Takasaki
D000818:Animals; D001324:Autoantigens / Q000096:biosynthesis*; D001345:Autoradiography; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects; D004596:Electroretinography; D006054:Goldfish / Q000276:immunology*; D007150:Immunohistochemistry; D007267:Injections; D009687:Nuclear Proteins / Q000096:biosynthesis*; D010786:Photoreceptor Cells / Q000166:cytology / Q000187:drug effects; D018809:Proliferating Cell Nuclear Antigen; D012160:Retina / Q000276:immunology*; D014415:Tunicamycin / Q000008:administration & dosage*; D014822:Vitreous Body
D001324:Autoantigens; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D014415:Tunicamycin