Abstract
Purpose: :
To study functional changes in the retina after light-induced retinal degeneration
Methods: :
BALB/c albino mice were dark adapted overnight, their left pupil dilated with topical atropine and exposed to light (3,000 lux) for 24 hours (Montalbán-Soler et al., IOVS 2009;50: E-Abstract 3614). Three days before, and 1,3,7,14,30,90 or 180 days after light exposure (ALE), the Scotopic Threshold Response (STR) and the a- and b-waves of the electro-retinogram (ERG) were recorded from both eyes (Alarcón-Martínez et al., Mol. Vis. 2009;15:2373-2383; Vision Res. 2010;50:2176-87). Paraffin-embedded sagittal cross-sections of the retina were incubated with primary antibodies against α-Protein Kinase C (α-PKC) and Synaptophysin and secondary fluorescent antibodies. Fluorescence in the synaptic outer and inner retinal layers was quantitatively analyzed.
Results: :
One day ALE, the STR and the a- and b-wave amplitude decreased to values that represented approximately 40% of control values. Three days ALE, the STR and the a- and b-waves recovered and showed amplitudes that represented approximately 70% of control values. Fourteen days ALE, the STR had recovered completely, and the a- and b-waves showed amplitudes that represented approximately 65% an 80% of control values, respectively. One-hundred and eighty days ALE, the STR had normal values and the a- and b-waves showed amplitudes that represented 65% and 85% of control values, respectively. The fluorescent index for α-PKC and synaptophysin decreased significantly 1 day ALE (Kruskal-Wallis, p<0.001) and recovered with time, showing values close to normal in the outer retina (Kruskal-Wallis, p>0.05) and significantly increased values in the inner retina (Kruskal-Wallis, p<0.001) by 180 days ALE.
Conclusions: :
Light induced retinal degeneration induces a permanent decrease of photoreceptor functionality which is probably related to cell death and a transient decrease of bipolar cells and inner retina functionality. The functional recovery of the inner retina suggests that the retina is capable of compensatory functional changes after photoreceptor injury.
Keywords: electroretinography: non-clinical • retina: proximal (bipolar, amacrine, and ganglion cells) • plasticity