TY - JOUR
T1 - Comparison of in vivo and in situ detection of hippocampal metabolites in mouse brain using 1H-MRS
AU - Hsu, Chao Hsiung
AU - Lin, Stephen
AU - Ho, Ai Chen
AU - Johnson, T. Derek
AU - Wang, Paul C.
AU - Scafidi, Joseph
AU - Tu, Tsang Wei
N1 - Funding Information:
The authors thank Mr Ke‐Yi Wu and Mr Lian‐Jung Chen for assisting with the experiments. This study was supported by District of Columbia Intellectual and Developmental Disabilities Research Center (DC‐IDDRC) Award U54HD090257 by National Institute of Child Health and Human Development (V. Gallo, PCW), National Center for Advancing Translational Sciences Award UL1TR001409 (TWT), National Institute on Minority Health and Health Disparities Award U54MD007597 (PCW, TWT) and National Institute of Neurological Disorders and Stroke Award R01NS099461 (JS). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the above organizations or the National Institutes of Health
Funding Information:
The authors thank Mr Ke-Yi Wu and Mr Lian-Jung Chen for assisting with the experiments. This study was supported by District of Columbia Intellectual and Developmental Disabilities Research Center (DC-IDDRC) Award U54HD090257 by National Institute of Child Health and Human Development (V. Gallo, PCW), National Center for Advancing Translational Sciences Award UL1TR001409 (TWT), National Institute on Minority Health and Health Disparities Award U54MD007597 (PCW, TWT) and National Institute of Neurological Disorders and Stroke Award R01NS099461 (JS). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the above organizations or the National Institutes of Health
Publisher Copyright:
© 2020 John Wiley & Sons Ltd
PY - 2021/2
Y1 - 2021/2
N2 - The study of cerebral metabolites relies heavily on detection methods and sample preparation. Animal experiments in vivo require anesthetic agents that can alter brain metabolism, whereas ex vivo experiments demand appropriate fixation methods to preserve the tissue from rapid postmortem degradation. In this study, the metabolic profiles of mouse hippocampi using proton magnetic resonance spectroscopy (1H-MRS) were compared in vivo and in situ with or without focused beam microwave irradiation (FBMI) fixation. Ten major brain metabolites, including lactate (Lac), N-acetylaspartate (NAA), total choline (tCho), myo-inositol (mIns), glutamine (Gln), glutamate (Glu), aminobutyric acid (GABA), glutathione (GSH), total creatine (tCr) and taurine (Tau), were analyzed using LCModel. After FBMI fixation, the concentrations of Lac, tCho and mIns were comparable with those obtained in vivo under isoflurane, whereas other metabolites were significantly lower. Except for a decrease in NAA and an increase in Tau, all the other metabolites remained stable over 41 hours in FBMI-fixed brains. Without FBMI, the concentrations of mIns (before 2 hours), tCho and GABA were close to those measured in vivo. However, higher Lac (P <.01) and lower NAA, Gln, Glu, GSH, tCr and Tau were observed (P <.01). NAA, Gln, Glu, GSH, tCr and Tau exhibited good temporal stability for at least 20 hours in the unfixed brain, whereas a linear increase of tCho, mIns and GABA was observed. Possible mechanisms of postmortem degradation are discussed. Our results indicate that a proper fixation method is required for in situ detection depending on the targeted metabolites of specific interests in the brain.
AB - The study of cerebral metabolites relies heavily on detection methods and sample preparation. Animal experiments in vivo require anesthetic agents that can alter brain metabolism, whereas ex vivo experiments demand appropriate fixation methods to preserve the tissue from rapid postmortem degradation. In this study, the metabolic profiles of mouse hippocampi using proton magnetic resonance spectroscopy (1H-MRS) were compared in vivo and in situ with or without focused beam microwave irradiation (FBMI) fixation. Ten major brain metabolites, including lactate (Lac), N-acetylaspartate (NAA), total choline (tCho), myo-inositol (mIns), glutamine (Gln), glutamate (Glu), aminobutyric acid (GABA), glutathione (GSH), total creatine (tCr) and taurine (Tau), were analyzed using LCModel. After FBMI fixation, the concentrations of Lac, tCho and mIns were comparable with those obtained in vivo under isoflurane, whereas other metabolites were significantly lower. Except for a decrease in NAA and an increase in Tau, all the other metabolites remained stable over 41 hours in FBMI-fixed brains. Without FBMI, the concentrations of mIns (before 2 hours), tCho and GABA were close to those measured in vivo. However, higher Lac (P <.01) and lower NAA, Gln, Glu, GSH, tCr and Tau were observed (P <.01). NAA, Gln, Glu, GSH, tCr and Tau exhibited good temporal stability for at least 20 hours in the unfixed brain, whereas a linear increase of tCho, mIns and GABA was observed. Possible mechanisms of postmortem degradation are discussed. Our results indicate that a proper fixation method is required for in situ detection depending on the targeted metabolites of specific interests in the brain.
KW - FBMI
KW - H-MRS
KW - hippocampal metabolites
KW - microwave fixation
KW - mouse brain
KW - postmortem degradation
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U2 - 10.1002/nbm.4451
DO - 10.1002/nbm.4451
M3 - Article
C2 - 33258202
AN - SCOPUS:85096924283
SN - 0952-3480
VL - 34
JO - NMR in biomedicine
JF - NMR in biomedicine
IS - 2
M1 - e4451
ER -