ZFIN ID: ZDB-PUB-191024-3
Glutamate receptor subtypes differentially contribute to optogenetically-activated swimming in spinally-transected zebrafish larvae
Wahlstrom-Helgren, S., Montgomery, J.E., Vanpelt, K.T., Biltz, S.L., Peck, J.H., Masino, M.A.
Date: 2019
Source: Journal of neurophysiology   122(6): 2414-2426 (Journal)
Registered Authors: Masino, Mark A., Montgomery, Jacob, Peck, Jack, Vanpelt, Kayce, Wahlstrom-Helgren, Sarah
Keywords: NMDA, locomotion, optogenetics, spinal cord, zebrafish
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Behavior, Animal/physiology*
  • Larva
  • Nerve Net/physiology*
  • Optogenetics*
  • Receptors, AMPA/antagonists & inhibitors
  • Receptors, AMPA/physiology*
  • Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate/physiology*
  • Signal Transduction/physiology*
  • Spinal Cord*
  • Swimming*
  • Zebrafish
PubMed: 31642404 Full text @ J. Neurophysiol.
ABSTRACT
The spinal cord (SC) contains neural networks that are capable of producing organized locomotor activity autonomously from the brain. Locomotor activity can be induced in spinally-transected (spinalized) animals by adding a source of tonic excitation to activate spinal networks. This is commonly accomplished by activating N-methyl-D-aspartate (NMDA) glutamate receptors through bath application of NMDA. More recently, optogenetic approaches have enabled both activation and inactivation of neuronal cell populations to control the activity of locomotor networks. Larval zebrafish are exceptionally amenable to optogenetic techniques due to their transparency, which permits noninvasive light delivery. Here, we induced locomotor activity in spinalized transgenic zebrafish larvae that expressed channelrhodopsin-2 in all subtypes of spinal vesicular glutamate transporter 2a (vglut2a)-expressing neurons by applying 10 s of constant blue light to the preparations. The resultant locomotor activity possessed all of the characteristics of swimming: bilateral alternation, rostrocaudal progression, and organization into discrete swimming episodes. Spatially-restricted light application revealed that illumination of the rostral SC produced more robust activity than illumination of the caudal SC. Moreover, illumination of only three body segments was sufficient to produce fictive swimming. Intriguingly, organized swimming activity persisted during NMDA receptor antagonism but was disrupted by AMPA receptor antagonism. Hence, AMPA receptor signaling is required for episodically-organized swimming while NMDA receptor signaling is not necessary.
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