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젖산 탈수소 효수 B 결핍 마우스에서 신경세포의 변화

Neuronal Changes in Lactate Dehydrogenase B Deficiency Mice

초록/요약

Neuronal Changes in Lactate Dehydrogenase B Deficiency Mice The main energy source of the brain is glucose; however, it has been reported that neurons also metabolize lactate. Lactate is an anion that is supplied by astrocytes, as described by the astrocyte-to-neuron lactate shuttle hypothesis. Lactate dehydrogenase B (LDHB), contained within neurons, converts lactate to pyruvate to be utilized as an energy source. Accordingly, the utilization of lactate as energy source by neurons of LDHB knock-out (KO) mice may be limited. We hypothesized that a deficiency in LDHB would decrease neuronal function and induced histological changes in LDHB KO mice. Behavioral tests included an open field test, a Morris water maze test, and a Y maze test, which were performed at 15-18 months of age. We analyzed histological alterations in hippocampal neurons and glial cells using cresyl violet staining for quantification of cell numbers, and identified oxidative stress markers (e.g., nitrotyrosine and 8-hydroxy-deoxyguanosine). We also compared lactate peaks in the hippocampus using magnetic resonance spectroscopy. Histological tests and magnetic resonance spectroscopy were performed at 19-22 months of age. As results, the open field test revealed decreased locomotor motion LDHB KO mice compared to WT mice. Moreover, the Morris water maze test showed diminished spatial memory and non-spatial memory in LDHB KO mice compared to WT mice. The histological analyses showed that neuronal cells in LDHB KO mice appeared smaller and darker than that of WT mice. In addition, there were fewer astrocytes in the hippocampus of LDHB KO mice. Expression of the reactive oxygen species-related marker, 3-nitrotyrosine, tended to increase in the neurons of LDHB KO mice compared to WT mice. Magnetic resonance spectroscopy results showed increased ratio of hippocampal lactate/ N-acetyl aspartate ratio in LDHB KO mice compared to WT mice. The increase of reactive oxygen species found in hippocampal neurons might mediate the observed alterations in neuronal morphology and behavioral deterioration, and ultimately, could result in the acceleration of brain aging in aged LDHB KO mice.

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목차

ABSTRACT i
TABLE OF CONTENTS iii
LIST OF FIGURES v
I. INTRODUCTION 1
II. MATERIALS AND METHODS 8
A. Animal care and study time frame 8
B. Magnetic resonance spectroscopy 8
C. Behavior test 9
(1) Moriis water maze test 9
(2) Open field test 9
(3) Y maze test 10
(4) Novel object recognition test 10
D. Tissue processing 10
E. Cresyl violet staining 11
F. Immunohistochemistry 11
G. Statistical analysis 12
III. RESULTS 13
1. Behavior changes 13
2. Neuronal morphological change 16
3. Astrocyte and microglia 19
4. Oxidative stress 21
5. Glucose trnasporter 3 23
6. MR spectroscopic analysis 25
IV. DISCUSSION 27
V. REFFERENCES 32
국문요약 37

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