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Somatosensory System

開催日 2014/9/12
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

末梢神経損傷による体性感覚視床内側毛体線維の再改編現象へのシナプス外 GABAA 受容体の役割
Role of extrasynaptic GABAA receptor on the remodeling of medial lemniscal fibers in the somatosensory thalamus by peripheral nerve injury

  • P2-168
  • 南雲 康行 / Yasuyuki Nagumo:1 宮田 麻理子 / Mariko Miyata:1,2 
  • 1:東京女子医大・医・第一生理 / Dept Physiol, Tokyo Women's Medical University, Tokyo, Japan 2:科学技術振興機構さきがけ / PRESTO, Japan Science and Technology Agency, Saitama, Japan 

Changes in excitatory and inhibitory synaptic inputs after the peripheral nerve injury are an initial step for reorganizing neural circuit and topographical map in the somatosensory system (Chen et al., Neuroscience, 2002). In the ventral posterior medial nucleus (VPM) of the somatosensory thalamus, the majority of VPM relay neurons are usually innervated by a single strong medial lemniscal fiber with GluA2 negative AMPA receptors after developmental synapse elimination. We previously reported that the infraorbital nerve cut (IONC) operation recruits additional medial lemniscal fibers with GluA2 positive AMPA receptors onto VPM relay neurons around 5 days after the operation (POD5) (Takeuchi et al., J Neurosci., 2012). However, little is known about the detail of the postoperative change in inhibitory GABA currents onto VPM relay neurons after the IONC. Here we report that the increase in tonic GABA currents after the IONC (from POD1-3) occurred much earlier than the remodeling of lemniscal fibers onto VPM relay neurons. Interestingly, potentiated tonic GABA current after the IONC was selectively observed in VPM relay neurons, which had multiple lemniscal fibers by the IONC, at POD7-9. Moreover, chronic treatment of extrasynaptic GABAA receptor agonist into the VPM of normal mice recruited newly lemniscal fibers with GluA2 positive AMPA receptors at postsynaptic sites. These results provide the possibility that enhancement of tonic GABA inhibition by the IONC drives the remodeling of lemniscal fibers with GluA2-positive AMPA receptors on a VPM neuron.

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