Iron-induced apoptosis in the photoreceptor cells of rats.
OBJECTIVE
To determine whether apoptosis is involved in retinal degeneration induced by intravitreal implantation of 5 iron particles in rat eyes.


METHODS
Autoclaved iron particles were implanted in the vitreous cavities of the experimental eyes. Glass chips were implanted in the control eyes. The experimental eyes were enucleated at various time intervals from days 1 to 15. Retinal degeneration was examined using the TdT-mediated, dUTP-biotin nick-end labeling (TUNEL) method. Electrophoresis on agarose gel was used to detect internucleosomal DNA fragmentation.


RESULTS
TUNEL-positive nuclei were observed only in the outer nuclear layer beginning on day 2. The nuclei spread throughout the outer nuclear layer by the end of day 3. No TUNEL-positive nuclei were observed in other layers throughout the experimental period. Analysis of DNA, extracted from the retinas by electrophoresis on agarose gel, revealed a typical ladder pattern of internucleosomal DNA cleavage in the experimental eyes.


CONCLUSIONS
Apoptosis occurred during photoreceptor cell death at the early phase of iron-induced retinopathy in these rats. Like photic injury, iron-induced apoptosis was limited to the outer nuclear layer.
Wang
Z J
ZJ
Department of Ophthalmology, General Hospital of Chinese PLA, Chinese University of Hong Kong, Shatin, Hong Kong.
Lam
K W
KW
Lam
T T
TT
Tso
M O
MO
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D004247:DNA / Q000032:analysis; D053938:DNA Fragmentation / Q000187:drug effects; D004587:Electrophoresis, Agar Gel; D007501:Iron / Q000633:toxicity*; D008297:Male; D010786:Photoreceptor Cells / Q000187:drug effects / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012162:Retinal Degeneration / Q000139:chemically induced / Q000473:pathology*; D012806:Siderosis / Q000209:etiology / Q000473:pathology*
D004247:DNA; D007501:Iron