Abstract
Abstract: :
Purpose: Senescence-accelerated mouse (SAM) strains show general senescence acceleration. In the senescence-prone mouse strain SAM P8 age-associated degenerative changes of the retinal pigment epithelium and Bruch´s membrane, but not of the photoreceptors have been shown by light and electron microscopy (Majji et al. 2000). In contrast, in the senescence-resistant mouse strain SAM R1 a marked loss of photoreceptor and ganglion cells have been described (Masato et al. 1998). Therefore in the current study electroretinograms (ERG) were performed in both strains to elucidate their retinal function. Methods: Age-matched SAM R1 (n=8) and SAM P8 (n=5) mice were anaesthetised for corneal ERG recordings. Scotopic and photopic Ganzfeld ERGs were then recorded using a range of flash intensities (scotopic: 0.4, 1, 4, 10, 100 and 1000 mcds/m² and photopic: 15 cds/m² and 2,5 cds/m², 1/20 Hz Flicker). A green light stimulus at three different intensities (84, 163 and 252 cds/m²) of 250 ms duration was used to record the c-wave. Statistic evaluation was performed using a permutation test. Results: SAM R1 mice had significantly lower amplitudes of the scotopic b-wave (54-66%, p<0,04), oscillatory potential (55%, <0,02) and c-wave (42-45%, p<0,009) compared to SAM P8 mice. Mean photopic b-wave amplitudes were also lower in the SAM R1 group, but without statistic significance. Conclusion: According to the morphological findings a moderate reduction of retinal function could be demonstrated in SAM R1 mice. In contrast, the retinal function of SAM P8 mice, known to have morphological changes of the retinal pigment epithelium, seems to be less compromised.
Keywords: 554 retina • 396 electroretinography: non-clinical • 309 aging