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Dhananjay Sakrikar, David Anderson, Jeffrey Spraggins, Wendi Lambert, Kevin Schey, David Calkins; Differential Distribution of Optic Nerve Lipids in the DBA/2J Mouse Model of Glaucoma. Invest. Ophthalmol. Vis. Sci. 2013;54(15):275.
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Glaucoma, a leading cause of irreversible blindness, is an age-related disease of visual system. The hallmark of glaucoma involves degeneration of retinal ganglion cell (RGC) neurons and their axons, which comprise the optic nerve. Here we examined optic nerves from a well-characterized DBA/2J mouse model of glaucoma. These mice experience an age dependent increase in intraocular pressure (IOP) and eventual RGC degeneration. Using Matrix Assisted Laser Desorption Ionization Imaging Mass Spectrometry (MALDI-IMS) we compared the relative abundance and distribution of lipids at different ages of DBA/2J mice.
3, 6, and 9-month-old DBA/2J mice were used in this study. Whole eyes including optic nerve were removed and rapidly frozen in carboxymethyl cellulose. A cryostat was used to collect 12 µ thick tissue sections that were then thaw mounted onto a gold-coated plate. The sections were desiccated and washed with 100 mM ammonium acetate before sublimating the MALDI matrix, 1,5-Diaminonaphthalene. Imaging was performed using a Bruker UltrafleXtreme II and lipid identification was performed using a 9.4T Bruker Apex Qe FT-ICR mass spectrometer. FlexImaging software was used to generate images.
MALDI imaging was performed in both positive and negative ion mode to identify different lipid species from the optic nerve. MALDI-IMS produced signals for a number of phosphocholine and ceramide species of lipids. As expected, a few lipids maintained similar spatial distributions across the age groups in DBA/2J mice. However, lipid species such as LPC (18:0/0:0), PC (18:1/18:0), PC (18:0/20:4), PC (18:0/22:6) in positive ion mode and sulphoHex-Cer (d18:1/18:0), sulphoHex-Cer (d18:1/22:0), sulphoHex-Cer (d18:1/22:0(2OH)) in negative ion mode showed differences in relative abundance and/or spatial distribution in the disease model with age.
Here we report alterations in relative abundance and differential localization of multiple lipid species in the DBA/2J mouse model of glaucoma with age. Some of these lipid species may be involved in cell signaling. Understanding the changes associated with lipid distributions in optic nerve tissue will further elucidate the underlying mechanism and signaling changes associated with glaucoma.
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