Poster Topical Area: Neurobiology
Location: Hall D
Poster Board Number: 701
Objective: Low serum total 25-hydroxyvitamin D3 [25(OH)D] concentrations have been associated with cognitive impairment. However, it is unclear if serum 25(OH)D concentrations are a valid indicator of the concentrations of vitamin D and its metabolites in the human brain. The objective of this study was to develop and validate a method to quantify vitamin D and its metabolites in mammalian brain.
Methods: (1) The validation experiments were performed using unstripped porcine brains (Pel-Freez Biologicals). Liquid-lipid extraction was used in homogenized samples (about 0.1 g each) prior to analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization following derivatization with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD). (2) This method was used to characterize vitamin D and its metabolites in a whole human brain obtained from a 54 year old female donor through the National Development and Research Institutes and dissected by trained neuroscientist.
Results: The method showed good linearity of vitamin D3, 25(OH)D, and 1,25(OH)2D over the physiological range (R2=0.9995, 0.9968 and 0.9970, respectively). The lowest detection limit for vitamin D3, 25(OH)D, and 1,25(OH)2D in porcine brain was 0.25, 0.12 and 0.12 ng/g, respectively. The method was successfully applied to the determination of vitamin D3 and its metabolites in the prefrontal cortex, middle frontal cortex, middle temporal cortex, cerebellum, corpus callosum, medulla and pons of human brain. There was wide variation in 1,25(OH)2D concentration across analyzed human brain sections, with medulla containing 3.1 ng/g compared to 0.3 ng/g in prefrontal cortex. All analyzed human brain regions contained similar 25(OH)D concentrations. There was no vitamin D3 detected in any examined areas of this single human brain.
Conclusions: To the best of our knowledge, this study is the first report of the measurement of concentrations of vitamin D metabolites in human brain. This validated method can be applied to post-mortem studies to obtain accurate information about the presence and role of vitamin D and metabolites in human brain and neurodegenerative diseases.