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Role of Dopamine D2 Receptor in Dopaminergic Neuronal Development and Emotional Behavior

  • 윤세현 (Sehyoun Yoon, 대학원 생명과학과 분자생물학전공)

초록/요약

The dopamine D2 receptor (D2R)-mediated ERK activation plays an important role in mesencephalic dopamine neuronal development. Previously, we have shown that Wnt5a-D2R interactions could regulate dopamine neuron development via EGFR and ERK pathway. We investigated the effect of EGFR inhibitor, AG1478 and metalloprotease inhibitor, GM6001, on D2R-mediated ERK activation and dopamine neuron development in mesencephalic primary cultures from wild-type (WT) and D2R knock-out (D2R-/-) mice. ERK activation and increase of the number and neurite length of dopamine neurons induced by D2R agonist were totally blocked by treatment with AG1478 and GM6001 in WT mice, but these effects were absent in D2R-/- mice. A disintegrase and metalloproteases (ADAMs) are well known mediators for EGFR transactivation by G protein-coupled receptors (GPCRs). The knockdown of ADAM10/17 expression using corresponding oligomeric siRNAs attenuated the effect of D2R agonist on ERK activation and increase of the number of dopaminergic neurons in WT mice, but not in D2R-/- mice. These results suggest that D2R-mediated transactivation of EGFR through ADAM10/17 plays a critical role in mesencephalic dopamine neuron development in association with ERK pathway.

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초록/요약

Mesolimbic dopaminergic pathway, begins from the ventral tegmental area (VTA) to the limbic system via the nucleus accumbens (NAc), the amygdala, the hippocampus and the medial prefrontal cortex, has been studied widely, however the function of neural subtypes remains poorly understood. We compared the responses of fear conditioning test and 5-choice serial time reaction task between wild-type (WT) and dopamine D2 receptor knockout (D2R-/-) mice. D2R-/- mice showed enhanced level of freezing response and impulsive behaviors, however, reduced attentional behaviors. Re-expression of D2R in the central amygdala of D2R-/- mice attenuated anxiety-like and impulsive behaviors, but not attentional behavior. Optogenetic activation of D2R positive neurons in the CeA increased the freezing response and impulsive behaviors. Our results suggest that D2R in the CeA has an important role for the control of anxiety-like and impulsive behaviors.

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목차

Chapter Ⅰ. Role of Dopamine D2 Receptor-mediated EGFR Transactivation in Dopaminergic Neuron Development 8
List of Figures 9
1. Abstract 10
2. Introduction 11
3. Material and Methods 14
3.1. Animal preparation and mesencephalic neuronal cell culture
3.2. Western blot analysis of p-ERK
3.3. Immunocytochemistry
3.4. Immunfluorescence histochemistry
3.5. Oligomeric siRNA Transfection
3.6. RNA isolation and RT-PCR
3.7. Enzyme immunoassay
3.8. Preparation of concentrated conditioned media
3.9. Statistical analysis
4. Results 19
4.1. D2R-mediated ERK activation via EGFRs in mesencephalic neuronal cells
4.2. Role of ADAMs in D2R-mediated dopaminergic neuron development
4.3. Activation of D2R induces the release of HB-EGF in mesencephalic neuronal cells
5. Discussion 48
6. References 51
Chapter Ⅱ. Role of Dopamine D2 Receptor for Anxiety and Impulsivity Behaviors in the Central Amygdala 56
List of Figures 57
1. Abstract 58
2. Introduction 59
3. Material and Methods 62
3.1. Mice
3.2. Virus preparation
3.3. Stereotaxic surgery
3.4. RT-PCR
3.5. Immunohistochemistry
3.6. Blue light delivery and protocol
3.7. Fear conditioning
3.8. Open-field test
3.9. Elevated plus-maze test
3.10. 5-choice serial reaction time task (5-CSRTT)
3.11. Statistical analysis
4. Results 69
4.1. The role of dopamine D2 receptor in central amygdala for behavioral responses.
4.2. Activation of D2R (+) neurons in the central amygdala enhances the anxiety and impulsive behaviors
4.3. D2R (+) neurons in the central amygdala project to BNST and VTA
5. Discussion 83
6. References 86
Acknowledgements 91

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