Title Page
Contents
ABSTRACT 12
Chapter 1. Introduction 15
1.1. Major depressive disorder 15
1.1.1. Monoamine hypothesis of depression 15
1.1.2. Neuroplasticity on depression 17
1.2. Stress and depression 18
1.2.1. Divers stress protocols in depression studies 18
1.2.2. Neuroendocrine mechanisms of the stress response 26
1.2.3. Epigenetic changes to stress response 27
1.2.4. Sex differences in stress 30
1.3. The habenula complex 31
1.3.1. The medial habenula 31
1.3.2. The lateral habenula 33
1.4. Character of the lateral habenula 35
1.4.1. Circuit-specific various functions of the LHb 35
1.4.2. Heterogeneous of LHb neuronal subpopulations and their functions 37
1.4.3. Molecular mediators of hyperactivity of LHb neurons 38
1.4.4. Transcriptome diversity of LHb neurons 41
1.5. Phospho-TRAP technique to capture translating mRNA 42
1.6. Purpose of study 43
Chapter 2. Stress-induced translational of KCNB1 contributes to the enhanced synaptic transmission of the Lateral habenula 45
2.1. Introduction 45
2.2. Materials and Methods 47
2.2.1. Animals 47
2.2.2. Translating phosphorylated ribosome affinity purification (phospho- TRAP) 47
2.2.3. Tissue sampling and Western blot 49
2.2.4. Virus information 49
2.2.5. Surgery and virus injection 49
2.2.6. Stress paradigm 50
2.2.7. Slice preparation 50
2.2.8. Electrophysiological recording 50
2.2.9. Active Avoidance Task (AAT) 51
2.2.10. Data Analysis and Statistics 52
2.3. Results 53
2.3.1. KCNB1 is readily translated in the LHb during stress 53
2.3.2. KCNB1 reduction alters firing patterns of LHb neurons 53
2.3.3. Knockdown of KCNB1 reverses enhanced synaptic potentiation of LHb neurons after stress exposure 55
2.4. Discussion 65
Chapter 3. Caspr1-mediated AMPA receptor trafficking in the Lateral Habenula 70
3.1. Introduction 70
3.2. Materials and Methods 72
3.2.1. Animals 72
3.2.2. Virus information 72
3.2.3. Surgery and virus injection 72
3.2.4. Stress paradigm 72
3.2.5. The LHb tissue sampling for Western blot 72
3.2.6. Slice preparation 72
3.2.7. Electrophysiological recording 72
3.2.8. Behavior test 73
3.2.9. Data Analysis and Statistics 74
3.3. Results 75
3.3.1. Acute stress exposure regulates expression of Caspr1 75
3.3.2. Caspr1 has no impact on spontaneous synaptic activity 75
3.3.3. Caspr1 increases AMPA receptor-mediated currents without compositional changes of AMPA receptor 76
3.3.4. Caspr1 knockdown improved anhedonia and anxiety-like behavior in aLH animal 77
3.4. Discussion 84
Chapter 4. Nat8l-mediated synaptic modulation in the Lateral habenula 87
4.1. Introduction 87
4.2. Materials and Methods 89
4.2.1. Animals 89
4.2.2. Virus information 89
4.2.3. Surgery and virus injection 89
4.2.4. aLH stress protocol 89
4.2.5. The LHb tissue sampling for Western blot 89
4.2.6. Slice preparation 89
4.2.7. Electrophysiological recording 89
4.2.8. Behavior test 90
4.2.9. Data Analysis and Statistics 90
4.3. Results 91
4.3.1. The impacts of stress exposure on expression of Nat8l 91
4.3.2. Nat8l regulates the basal synaptic transmission of LHb neuron 91
4.3.3. The impact of Nat8l on BDNF expression in the LHb 92
4.3.4. Nat8l has no effects on depressive-like behavior 92
4.3. Discussion 98
Chapter 5. Extended analysis of stress-responsive genes in the Lateral habenula 101
5.1. Introduction 101
5.2. Materials and Methods 104
5.2.1. GO data analysis 104
5.3. Results 105
5.3.1. Extended analysis using LPEseq 105
5.3.2. Gene Ontology analysis of stress-responsive genes in the LHb 105
5.3.3. Gene-to-gene interaction map using STRING 106
5.4. Discussion 121
Chapter 6. Conclusion 125
References 130
Appendices 163
[Appendix 1] Gene list that up-regulated during stress exposure 163
[Appendix 2] Gene list that down-regulated during stress exposure 177
[Appendix 3] A gene list obtained by using LPEseq 182
[Appendix 4] List of Abbreviations 190
[Appendix 5] List of publication 193
Abstract (in Korean) 194
Table 2.1. The fundamental electrophysiological properties are based on the presence or absence of stress and KCNB1. 57
Table 2.2. The molecular profile of up- or down- regulated genes during exposure to stress. 58
Table 5.1. A list of genes with increased or decreased translation levels when exposed to stress was re-analyzed using LPEseq 109
Figure 2.1. Expression Regulation of KCNB1 in the LHb Under Stress 59
Figure 2.2. Impact of KCNB1 knockdown on basal neuronal properties. 60
Figure 2.3. Distribution of firing types with and without acute stress. 61
Figure 2.4. Impact of KCNB1 knockdown on synaptic transmission 63
Figure 2.5. The impacts of KCNB1 on despair behaviors 64
Figure 3.1. Increased expression of Caspr1 during stress exposure 79
Figure 3.2. Caspr1 could not mediate spontaneous synaptic activity during stress exposure 80
Figure 3.3. Caspr1 increased AMPA receptor-mediated synaptic activity without subunit regulation 81
Figure 3.4. Caspr1 mediates stress-induced anhedonia and anxiety-like behaviors in aLH animal 82
Figure 4.1. Nat8l reduces basal synaptic transmission independent of exposure to stress 94
Figure 4.2. Nat8l regulates presynaptic release probability at synaptic neurons 95
Figure 4.3. The presence of stress and Nat8l can not yield significant differences in BDNF expression 96
Figure 4.4. Nat8l cannot mediate depressive behavioral changes induced by stress 97
Figure 5.1. Scatter plot graph depicting gene expression changes after using LPEseq. 110
Figure 5.2. Categorization of genes using DAVID analysis (cellular component). 111
Figure 5.3. Categorization of genes using DAVID analysis (Molecular function). 112
Figure 5.4. Categorization of genes using DAVID analysis (Biological pathway). 113
Figure 5.5. STRING analysis map of genes with the "cytoplasm" involved in cellular component. 114
Figure 5.6. STRING analysis map of genes with the "cytoplasmic vesicle" involved in cellular component. 115
Figure 5.7. Gene-to-gene interaction map connected around the Hck 116
Figure 5.8. Gene-to-gene interaction map connected around the Egfr 117
Figure 5.9. Gene-to-gene interaction map connected around the Dok3 118
Figure 5.10. Gene-to-gene interaction map connected around the Penk 119
Figure 5.11. Gene-to-gene interaction map connected around the Glp1r 120