Early Reversible Changes on ERG in Pharmaceutically Induced Retinal Degeneration in Rats.
- Author:
Kyu Hwa ROH
1
;
Tae Kwann PARK
;
Young Hoon OHN
Author Information
1. Department of Ophthalmology, Soonchunhyang University, College of Medicine, Korea. tkpark@sch.ac.kr
- Publication Type:Original Article
- Keywords:
Electroretinogram;
Guanylate cyclase;
MNU;
Phototransduction;
TUNEL
- MeSH:
Animals;
Guanylate Cyclase;
Humans;
In Situ Nick-End Labeling;
Light Signal Transduction;
Male;
Methylnitrosourea;
Photoreceptor Cells;
Rats*;
Retinal Degeneration*;
Retinaldehyde*
- From:Journal of the Korean Ophthalmological Society
2006;47(7):1117-1125
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
PURPOSE: To evaluate the early ERG (electroretinogram) changes in N-methyl-N-nitrosourea (MNU)-induced retinal degeneration in rats. METHODS: Thirty-six 6-week-old male rats were injected intraperitoneally with 60mg/kg MNU and divided into 6 groups. Histology and ERG were recorded for the rats of each group before treatment and at 3, 6, 12, 18, and 24 hours after MNU injection. Promptly after the ERG recording, rats were sacrificed and the eyeballs prepared for histologic sectioning. The Tdt-mediated dUTP-digoxigenin nick end labeling (TUNEL) method was used to detect photoreceptor cell death. RESULTS: The first decreases of ERG responses were noticed maximally at 3 hours after the treatment. Thereafter, the amplitude of the responses was partially recovered at 12 hours post-treatment. The second decrease of ERG amplitudes was observed in the 18-hour recordings, and those changes progressed to 24 hours after the treatment. In the histologic findings, TUNEL (+) cells in the Outer Nuclear Layer (ONL) were not detected at 3 hours after MNU injection, but were initially noticed at 6 hours post-injection. CONCLUSIONS: The first decreases of ERG amplitudes proceeded the appearance of TUNEL (+) cells in ONL, and these electrophysiological changes seemed to not be related to photoreceptor cell death. We propose that electrophysiological changes observed might be related to the MNU-induced activity enhancement of guanylate cyclase in the phototransduction pathway. We also show that photoreceptor cell death in the MNU-induced retinal degeneration model occurs at 6 hours after the treatment, which is earlier than the results of previous reports.
