Introduction: Huntington disease (HD) is a neurodegenerative disease, whose key pathological signature is the formation of intracellular inclusions [1]. The exact role of inclusions in driving HD pathology, however, remains to be clearly understood. Our lab has previously shown that the formation of huntingtin inclusions in cell culture models correlates with the cells becoming functionally quiescent and undergoing a slow death by necrosis [2]. We hypothesize that inclusion formation establishes cellular quiescence in vivo. Our goal is to assess the extent to which neurons in vivo are metabolically quiescent and how this relates to the presence of inclusions in a transgenic mouse model of HD.
Methods: We have conducted a metabolic flux analysis of neuronal membrane lipids by feeding wild-type (WT) and R6/1, a mouse model of HD, with deuterated water to track membrane lipid turnover. The left hemisphere of the brain was reserved for determining the spatial distribution and the abundance of the brain metabolites using MALDI-TOF imaging mass spectrometry (MALDI-IMS). The right hemisphere was dissected, and the frontal cortex, striatum and hippocampus reserved for Liquid Chromatography-Mass spectrometry analysis.
Results: Our preliminary data points towards a change in deuterium incorporation rate in neuronal membrane lipids in different brain regions of WT and HD mice, in particular, the pyramidal neuronal cell layer of the hippocampus, an area that has been found to have a dense population of inclusions using EM48-immunohistochemistry directed to the inclusions.
Novel Aspect
Use of Stable Isotope Labelling (Deuterium) to study in vivo kinetics in spatial and traditional analytic approaches