The molecular basis of dopaminergic transmission: Identifying and Characterizing Cellular Adhesion Sites

Research Project

Project/Area Number	22KF0335
Project/Area Number (Other)	22F22386 (2022)
Research Category	Grant-in-Aid for JSPS Fellows
Allocation Type	Multi-year Fund (2023) Single-year Grants (2022)
Section	外国
Review Section	Basic Section 46010:Neuroscience-general-related
Research Institution	Keio University
Principal Investigator	柚崎通介慶應義塾大学, 医学部(信濃町), 教授 (40365226)
Co-Investigator(Kenkyū-buntansha)	DILINA TUERDE 慶應義塾大学, 医学部(信濃町), 外国人特別研究員
Project Period (FY)	2023-03-08 – 2025-03-31
Project Status	Granted (Fiscal Year 2023)
Budget Amount *help	¥2,300,000 (Direct Cost: ¥2,300,000) Fiscal Year 2024: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 2023: ¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 2022: ¥500,000 (Direct Cost: ¥500,000)
Keywords	ドーパミン / シナプス / 側坐核 / 背側被蓋野
Outline of Research at the Start	In the present study, I will investigate how dopaminergic pathways are formed to achieve their neurotransmission, focusing on the VTA-NAc mesolimbic dopaminergic pathway. I will accomplish three specific goals. First, I will characterize synaptic and non-synaptic contact sites along dopaminergic axons. Second, I will identify molecules involved in these contact sites. Finally, I will elucidate how synaptic and non-synaptic contact sites regulate dopaminergic functions. I expect to accomplish these goals and address long-standing questions in the mesolimbic dopaminergic pathway.
Outline of Annual Research Achievements	In this study, I investigated how dopaminergic pathways are formed to achieve their neurotransmission focusing on the mesolimbic VTA-NAc pathway. To achieve this, I outlined three specific aims: Firstly, I aim to visualize and characterize cell-cell contact sites along the mesolimbic pathway using the GRAPHIC method. Secondly, I intend to identify the cell adhesion molecules involved in these contact sites. Finally, I aim to elucidate how these cell adhesion molecules regulate dopaminergic functions. Through these aims, my goal is to gain deeper insights into the intricate mechanisms underlying dopaminergic pathway formation and functions.
Current Status of Research Progress	Current Status of Research Progress 2: Research has progressed on the whole more than it was originally planned. Reason In 2023, I successfully visualized cell-cell contact sites along the mesolimbic pathway using the GRAPHIC method, employing both immunofluorescence and electron microscopy techniques. Through these approaches, I identified the cell adhesion molecules involved in the mesolimbic VTA-NAc pathway. These molecules were found at the contact sites between dopamine fibers and medium spiny neurons. Notably, their absence resulted in a reduced number of dopamine varicosities and VMAT2 expression. Additionally, I identified the receptors for these cell adhesion molecules on the medium spiny neurons. Knockout of the receptors revealed a similar dysfunction of dopamine fibers and a reduction in such cell adhesions. These findings provide significant insights into the role of these molecules in regulating dopamine transmission in the VTA-NAc pathway.
Strategy for Future Research Activity	To deepen our comprehension of the functional significance of these cell adhesion molecules within the VTA-NAc pathway, I intend to conduct conditional knockout experiments targeting these molecules to evaluate their impact on dopamine transmission and reward behaviors. Consequently, this study is expected to offer a comprehensive understanding of the molecular mechanisms governing the regulation of the dopaminergic system. Additionally, I intend to summarize the findings and submit them for publication in 2024.