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X. Liu, L.M. McGuire, M.L. Robinson, M.M. LaVail, D.R. Copenhagen; Neurotrophin–3 Regulates the Development of Mouse Retinal Ganglion Cells . Invest. Ophthalmol. Vis. Sci. 2005;46(13):566.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To elucidate the possible role of neurotrophin 3 (NT–3) in the development and maturation of neural retina in mouse. In central nervous system, neurotrophins regulate the development and survival of different neuronal populations. In retina of Xenopus, BDNF regulates the arborization patterns of ganglion cells (Lom & Cohen–Cory, 1999). To search for potential neurotrophin actions on mouse retinal ganglion cells (RGCs), we examined RGC dendritic arborization patterns in transgenic mice that overexpress NT–3. Methods: Transgenic mice overexpressing NT–3 driven by the alphaA–crystallin promoter were crossed with transgenic mice carrying yellow fluorescent protein (YFP) driven by the Thy–1 promoter. Mice overexpressing NT–3 were identified by PCR of tail DNA and further confirmed by immunostaining with antibodies against NT–3. Animals were reared in 12h light/12h darkness (LD). Retinas were dissected at P12 (before eye–opening), and double immuno–stainings were performed with antibodies against GFP to enhance YFP signal and tyrosine hydroxylase (TH) as a marker for the outer margin of IPL. Z–stack images of YFP–expressing RGCs were collected using a Zeiss confocal laser–scanning microscope. The dendritic trees of RGCs were traced and analyzed using NIH ImageJ and NeuroJ. Results: NT–3 in the retina was localized by immunocytochemistry in highest concentration in the RGCs and inner retinal neurons. RGCs were grouped into mono–stratified ON or OFF cells, and bi–stratified ON–OFF cells based on the stratification depth of their dendrites in IPL. Fewer RGCs were bistratified in the NT–3 overexpressing mice at P12. Over–expression of NT–3 did not affect the soma size or total length of dendrites of RGCs at P12, but increased the number of branches and the dendritic density, which is defined as the total dendritic length in a dendritic tree divided by its dendritic field area. Conclusions: NT3 regulates the dynamic refinement of RGC dendrites. Given that the percentage of bi–stratified RGCs is decreasing during normal maturation of postnatal retina, these results suggest that NT–3 accelerates the rate at which bi–stratified arbors are converted into mono–stratified arbors.
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