Abstract
Purpose: :
To determine whether the photoreceptor degeneration in transgenic (Tg) rabbits carrying the Pro347Leu rhodopsin mutation alters the neural activity of the middle and inner retinal neurons.
Methods: :
Multifocal electoretinograms (mfERG) were recorded from eight 12-week-old Tg rabbits before and after an intravitreal injection of tetrodotoxin citrate (TTX), N-methyl-DL- aspartic acid (NMDA), 2-amino-4-phosphonobutyric acid (APB), or cis-2, 3-piperidine-dicarboxylic acid (PDA). Digital subtraction of the mfERGs recorded before and after the drugs were used to extract the components that were abolished by these drugs. Eight age-matched, wild type (WT) rabbits were studied with the same protocol.
Results: :
There was no reduction in the amplitude of the cone photoreceptor response of the mfERGs in Tg rabbits. The first positive and first negative waves of the ON-bipolar cell responses were significantly larger in the Tg than in the WT rabbits. Late negative waves of the ON-bipolar cell response were recorded only in WT rabbits. The first negative wave of the inner retinal responses was larger in Tg than in Wt rabbits. The late positive waves were seen mainly in WT rabbits.
Conclusions: :
The ON-bipolar cell and inner retinal responses were altered at the early stage of photoreceptor degeneration in Tg rabbits despite the preservation of the cone photoreceptor responses.
Keywords: retinal degenerations: hereditary • electroretinography: non-clinical • photoreceptors