Abstract
Abstract: :
Purpose: Accumulation of autofluorescent storage material in the brain has been documented in both human patients and in mouse models of neuronal ceroid lipofuscinosis (Batten Disease). Since the retina is generally the first CNS target affected in Batten Disease and could serve as a convenient means to assess the early progression of the disease as well as potential therapeutic responses, we measured autofluorescence intensity and retinal pathology in tissues from the mnd mouse, along with appropriate controls. Methods: A developmental series of eyes from mnd (CLN8) mice and age–matched control littermates (ages P0, P2, P4, P7, P14, P21, 1 month and 2 months) were fixed in 4% paraformaldehyde, processed into 4 micron histological sections and analyzed for autofluorescence at 410 nm excitation wavelength. Retinal sections were stained for periodic acid schiff to identify cytoplasmic inclusions, congo red to determine the presence of amyloid–like deposits and TUNEL to quantitate and localize regions of cell death. Results: Significant retinal autofluorescence was evident in mnd mice at P0 (our earliest timepoint), prior to eye–opening. Cytoplasmic inclusions in the retinal ganglion cell layer were shown by periodic acid schiff and congo red stains by P7. TUNEL reactivity indicative of cell death became significant at P21 (p<0.001) with most cell death occuring in the photoreceptor layer. Conclusions:1) Retinal autofluorescence occurs prior to eye opening and precedes significant cell death in mnd retina. 2) For the first time, we have shown congophilic deposits in mnd retinal ganglion cells that correspond with the timing and ganglion cell location of PAS–reactive cytoplasmic inclusions. 3) Despite retinal ganglion cell pathologies, cell death occurs predominantly in the photoreceptor layer. An increased understanding of the timing, location and characteristic retinal pathologies of Batten Disease may lead to diagnostic and therapeutic advances in the clinical setting.
Keywords: retinal degenerations: cell biology • pathology: experimental • cell death/apoptosis