A sensitive method for determination 1,25-dihydroxyvitamin D3 in human brain using ultra-pressure liquid chromatography tandem mass spectrometry

Authors: XUAN, ANDREW - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; DOLNIKOWSKI, GREGORY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; BOOTH, SARAH - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; SHEA, KYLA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; SCHNEIDER, JULIE - Rush University; FU, XUEYAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Current Developments in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2024
Publication Date: 7/15/2024
Citation: Xuan, A., Dolnikowski, G.G., Booth, S.L., Shea, K., Schneider, J.A., Fu, X. 2024. A sensitive method for determination 1,25-dihydroxyvitamin D3 in human brain using ultra-pressure liquid chromatography tandem mass spectrometry. Current Developments in Nutrition. https://doi.org/10.1016/j.cdnut.2024.104418.
DOI: https://doi.org/10.1016/j.cdnut.2024.104418

Interpretive Summary: The active form of vitamin D has been associated with protective effects on brain aging. However, there are no studies that have directly measured this form in the human brain due to methodological challenges. We developed and validated a sensitive method using mass spectrometry to measure this form of vitamin D in human brain. This validated method of measuring the active vitamin D form can be applied to obtain information about its presence in various regions of the human brain and help elucidate its role in brain function.

Technical Abstract: 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3], the hormonally active form of vitamin D, has been associated with neuroprotective effects in the brain. Compared to its more abundant metabolites, like 25-hydroxyvitamin D3, 1,25(OH)2D3 has been more difficult to measure due to its low concentration in brain tissue. The aim of this study was to develop and validate a sensitive method to quantify 1,25(OH)2D3 in the human brain. Several extraction steps, including an additional solid phase extraction step with silica columns, were used in the homogenized samples (about 0.1 g each). Prior to analysis by the LC-MS/MS with electrospray ionization, the samples were derivatized with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD). The method showed good linearity of 1,25(OH)2D3 over the physiological concentration range (R2 = 0.9998). The limit of detection (LOD) for 1,25(OH)2D3 was 2.5 pg/g, over 10 times lower than the previously reported LOD. The developed method was used to detect 1,25(OH)2D3 concentrations of 153 postmortem brain samples, from the Rush Memory and Aging project (MAP), each with three distinct measurements in the respective regions: anterior watershed (AWS), middle temporal cortex (MT), and cerebellum (CR). 1,25(OH)2D3 was measured in these regions of the brain, with an average concentration of 30.7 pg/g, 19.2 pg/g, and 18.5 pg/g in AWS, MT and CR, respectively. In conclusion, this validated method of quantifying the hormonally active vitamin D metabolite can be applied to obtain information about its presence in various regions of the human brain associated with neurodegenerative diseases, and help elucidate its role in brain function.