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Isolation of Primary Murine Retinal Ganglion Cells RGCs by Flow Cytometry
Published on: July 5, 2017
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NMDA Receptor Expression by Retinal Ganglion Cells Is Not Required for Retinofugal Map Formation nor Eye-Specific
Kristy O Johnson1,2, Nathan A Smith1,3,4, Evan Z Goldstein1
1Center for Neuroscience Research, Children's National Research Institute, Washington, DC 20010.
Eneuro
|July 1, 2021
Summary
NMDA receptors (NMDARs) in retinal ganglion cells (RGCs) are not essential for forming topographic maps in the brain. Genetic deletion of NMDARs in RGCs did not alter map formation or eye-specific segregation in the superior colliculus and dLGN.
Area of Science:
- Neuroscience
- Developmental Biology
- Visual System Research
Background:
- Retinal ganglion cells (RGCs) form topographic maps in the superior colliculus (SC) and dorsal lateral geniculate nucleus (dLGN).
- Spontaneous activity is crucial for retinotopic mapping, with NMDA receptors (NMDARs) implicated in this process.
- The specific roles of presynaptic versus postsynaptic NMDARs in retinotectal development are not fully understood.
Purpose of the Study:
- To investigate the necessity of NMDARs specifically expressed by RGCs for retinofugal topographic map formation.
- To determine if RGC-specific NMDARs are required for eye-specific segregation of visual inputs.
Main Methods:
- Utilized a conditional genetic knockout (pre-cKO) approach to delete the GluN1 subunit of NMDARs exclusively in RGCs (Chrnb3-Cre;GluN1flox/flox mice).
- Assessed RGC-specific GluN1 expression and NMDAR expression in target brain regions (SC).
- Employed anatomical tracing to analyze termination zone size and eye-specific organization in the SC and dLGN.
- Used GCaMP5 imaging in RGCs to confirm NMDA-induced activity in RGC terminals.
Main Results:
- Confirmed reduced GluN1 expression in the retina of pre-cKO mice, with no change in SC NMDAR expression.
- Anatomical tracing revealed no significant alterations in the size of termination zones in the SC and dLGN.
- Observed no changes in the eye-specific organization of retinal inputs to the SC and dLGN.
- Verified that NMDA stimulation induces calcium transients in RGC terminals.
Conclusions:
- NMDARs located on retinal ganglion cells are not required for the establishment of topographic maps in the SC and dLGN.
- RGC-specific NMDARs do not play a critical role in the eye-specific segregation of visual inputs.
- These findings clarify the molecular mechanisms of retinotopic map development, highlighting that RGC-intrinsic NMDAR function is dispensable for these processes.
