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Somatosensory System

開催日 2014/9/13
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Preferential inputs of cholecystokinin-positive neurons to the somatic compartment of parvalbumin-expressing neurons in the mouse primary somatosensory cortex

  • P3-154
  • 日置 寛之 / Hiroyuki Hioki:1 孫 在隣 / Jaerin Sohn:1,2 岡本 慎一郎 / Shinichiro Okamoto:1 亀田 浩司 / Hiroshi Kameda:3 金子 武嗣 / Takeshi Kaneko:1 
  • 1:京都大院・医・高次脳形態学 / Dept Morphol Brain Sci, Grad Sch of Med, Kyoto Univ, Kyoto, Japan 2:(独)日本学術振興会 特別研究員 DC2 / DC2 Research Fellow of Japan Society for Promotion of Science 3:帝京大・医・生理学講座 / Dept Physio, Teikyo Univ Sch of Med, Tokyo, Japan 

Neocortical GABAergic interneurons are divided into at least three distinct subgroups by chemical markers in the neocortex: 1) parvalbumin (PV)-expressing cells; 2) somatostatin (SOM)-producing cells; 3) the cells immunoreactive for other markers such as cholecystokinin (CCK) and vasoactive intestinal polypeptide (VIP). PV neurons are a major component of cortical GABAergic interneurons, and play a key role in higher-order brain functions including perception, recognition, attention and memory.
We previously investigated inhibitory inputs of PV, SOM or VIP neurons to PV neurons with the transgenic mice, which express somatodendritic membrane-targeted GFP specifically in PV-positive fast-spiking neurons (Kameda et al., 2012; Hioki et al., 2013). We revealed that their dendrites mainly received inhibitory inputs from PV neurons, and the cell bodies from vasoactive intestinal polypeptide (VIP)-producing interneurons.
In the present study, we first examined the distribution of CCK neurons. CCK neurons constituted 3.2% (169/5219) of GABAergic interneurons in entire layers of the primary somatosensory cortex. About 27% of CCK neurons were immunoreactive for VIP, and conversely, around 9% of VIP neurons were positive for CCK. We then analyzed the inhibitory inputs of CCK neurons to PV neurons by triple immunofluorescence staining for GFP, gephyrin and CCK. Gephyrin, a scaffold protein for GABAA and glycine receptors, is a reliable marker for postsynaptic inhibitory sites. We observed CCK inputs to PV neurons at the cell bodies and dendrites under a confocal microscope, and estimated the input density at each compartment. CCK inputs clearly preferred the cell bodies of PV neurons to the dendrites, like VIP inputs, and the amount of CCK inputs was about half of VIP inputs.
The previous and present results disclosed the compartmental organization of inhibitory inputs to PV neurons. The dendritic compartment principally received GABAergic inputs from PV neurons, and the somatic compartment from VIP and/or CCK neurons.

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