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P. A. Williams, J. E. Morgan, M. Votruba; OPA1 Deficiency in a Mouse Model of Dominant Optic Atrophy Leads to Dendritic Pruning in Retinal Ganglion Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2344.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify and evaluate the dendritic morphology of retinal ganglion cells (RGCs) in the OPA1+/- mutant mouse, a model of autosomal dominant optic atrophy (ADOA). The heterozygous mutation, B6;C3-Opa1Q285STOP (exon 8) leads to 50% reduction in opa1 transcript and protein in retina and neural tissues. Visual dysfunction and structural changes in optic nerve have been previously observed.
Retinas of OPA1+/- mutant mice (n=9) and accompanying age and sex matched controls (n=7) (age ranges of <10, 10-15 and 20< months) were flat-mounted and stained using a Diolistic method (DiI) to label retinal ganglion cells. Retinas were fixed with 4% PFA and imaged at 20x using a Zeiss LSM510 confocal microscope. Image stacks of ON-Centre RGCs were collected allowing the specific dendritic morphologies to be analysed using ImageJ. Sholl analyses were undertaken using Matlab running a custom macro.
Analysis of the dendritic trees shows a decrease in the average dendritic field area in 10-15 month mice (-35.1%; CV=0.83; p < 0.05) and 20< month mice (-43.8%; CV=0.66; p < 0.05) as well as a decrease in the average total dendritic length in 10-15 month mice (-44.9%; CV=0.78; p < 0.05) and 20< month mice (-56.1%; CV=0.59; p < 0.05).Results of the Sholl analysis showed a marked difference in the dendritic arborisation of the 10-15 month group and of the 20< month group compared to the control group. Bars of SE were all non-overlapping. There was no apparent change in dendritic morphology of <10 month mice compared to controls (p > 0.05). There was also no marked difference in dendritic density implying pruning of secondary and tertiary dendrites rather than of primary dendrites.
Results show dendritic pruning in the RGCs of the OPA1+/- mouse model of ADOA from as early as 10 months. These results highlight the importance of normal mitochondrial fusion balance, as influenced by the OPA1 protein in the dendritic morphology of RGCs. The presence of active dendritic pruning preceeding the onset of clinical visual loss and structural changes in optic nerve on EM, indicate the key role that mitochondrial morphology has to play in neural cells.
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