Synaptic analysis of calretinin immunoreactive neurons in the rat olfactory glomerulus by electron microscopy

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K18825
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 56050:Otorhinolaryngology-related
• Research Institution: Kawasaki Medical School
• Principal Investigator: NOTSU EIJI 川崎医科大学, 医学部, 助教 (80388933)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 嗅球 / 神経回路 / シナプス結合 / 電子顕微鏡

Outline of Final Research Achievements

The olfactory bulb is the first processing center of odor information, and interneurons located there are thought to play an important role in information processing. Calretinin immunoreactive neurons (CR neurons) are one of the major subpopulations of olfactory bulb interneurons. However, the neural circuits underlying odor processing are not clear. The aim of this study is to characterize the morphological features of synapses, a major component of the neuronal circuit, in CR neurons by electron microscopy. Immunostaining and electron microscopic analysis of rat olfactory bulb CR neurons suggest that vesicles containing the inhibitory transmitter GABA are accumulated in several regions of the dendrites. On the other hand, no clearly identifiable synapses formed by CR neurons could be observed in the wide range of high-resolution images obtained by electron microscopy montage at present, suggesting that there are fewer output synapses compared to other periglomerular neurons.

Free Research Field

神経解剖学

Academic Significance and Societal Importance of the Research Achievements

本研究では、嗅球の主要な介在ニューロンの1つでありながら、未だその機能的基盤となる神経回路が明らかになっていないCRニューロンのシナプスを形態学的な観点から解析したものである。シナプス結合はナノメートルレベルの構造物であり、その存在や形態については電子顕微鏡を用いた解析が必要であるが、これまでにその報告は少数であった。今回得られた研究成果は、CRニューロンがこれまでに解析されているcalbindin免疫陽性ニューロン（CBニューロン）やtyrosine hydroxylase免疫陽性ニューロン（THニューロン）と異なる回路特性を有していることが示された。