• Top page
  • Timetable
  • Per session
  • Per presentation
  • How to
  • Meeting Planner



Axonal/Dendritic Growth and Circuit Formation

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

Developmental change in GluN2B and critical period for corticospinal synapse

  • P3-060
  • 磯脇 睦美 / Mutsumi Isowaki:1 大野 孝恵 / Takae Ohno:1 磯尾 紀子 / Noriko Isoo:1 福田 諭 / Satoshi Fukuda:1 三品 昌美 / Masayoshi Mishina:2 桜井 正樹 / Masaki Sakurai:1 
  • 1:帝京大・医・生理 / Dept Physiol, Teikyo Univ Sch Med 2:東京大院・薬理・分子神経生物 / Dept Mol Neurobiol & Pharmacol, Grad Sch Med, Univ Tokyo 

In in vitro model system of CS projection using slice co-cultures of mice cerebral cortex and spinal cord, CS synapses are once formed throughout spinal cord and then eliminated from the ventral side. This elimination is dependent on NMDA receptor (NMDAR) and its subunit, GluN2B, and have critical period from 6 to 11 days in vitro (DIV). It is known that 2B is abundantly expressed at a juvenile age, but replaced by GluN2A later. Because 2B-containing NMDAR (2B) has much slower channel kinetics with higher Ca2+ influx than 2A containing-NMDAR (2A), it could support outstanding plasticity only seen during early development.
We investigated 2B component of CS-EPSCs during development by stimulating CS axons electrically. 2B gradually decreased to the end of the critical period and plateaued around 12 DIV. We confirmed spermine (7 μM) and proBDNF (1 ng/ml), which are known to increase 2B, both recovered 2B to comparable level of 6-8 DIV at this time. To examine whether 2B upregulation reopen the critical period, we used these two pharmacological agents. We evaluated spatial distribution of CS synaptic response visualized with voltage-sensitive dye, RH1691. CS neurons were selectively activated by optogenetic method using ChR2-EYFP. First APV was applied during the critical period to block synapse elimination and thereafter removed. To increase 2B expression, spermine or proBDNF were added for three days from one day after removal of APV. Although synapse elimination was no longer seen on 16 DIV, treatment with spermine or proBDNF induced reduction of synaptic signals on the ventral side. These suggest that developmental decline of 2B is crucially important for closing the critical period for CS synapse elimination.

Copyright © Neuroscience2014. All Right Reserved.