Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Anatomy and Cell Biology

Supervisor

Drs. Shawn N. Whitehead

2nd Supervisor

Gilles A. Lajoie

Joint Supervisor

Abstract

Neurons within different brain regions have varying levels of vulnerability to external stress and therefore respond differently to injury. A potential reason to explain this may lie within a key lipid class of the cell’s plasma membrane called gangliosides. These glycosphingolipid species have been shown to play various roles in the maintenance of neuronal viability. The purpose of this study is to use electrospray ionization mass spectrometry (ESI-MS) technique and immunohistochemistry to evaluate the temporal changes in the expression profiles of various ganglioside species during the course of neurodegeneration in rat primary cortical neurons exposed to glutamate toxicity. Primary embryonic (E18) rat cortical neurons were cultured to DIV14. Glutamate toxicity was induced for 1, 3, 6 and 24 h. Immunofluorescence was used to stain for GM1 and GM3 species and ESI-MS was used to quantify the ganglioside species expressed within these injured neurons, which were compared to expression profiles of healthy neurons. Neurons were also pretreated with GM1 24 h before glutamate exposure to assess the level of neuroprotection conferred by GM1. Microglia were also activated using amyloid-beta oligomer and stained for GM1 and GM3 expression. ESI-MS data revealed that d16:1 and d18:1 GM1 species were upregulated in neurons exposed to glutamate while no significant changes were observed for GM2 and GM3 expression. Furthermore, neurons that were pretreated with GM1 showed increased viability compared to untreated neurons when exposed to glutamate. Immunofluorescence revealed an elevated expression of GM3 in activated microglia compared to controls. These data suggests that different gangliosides and cells within the CNS play diverse roles in the process of neurodegeneration.

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