A Model to Study NMDA Receptors in Early Nervous System Development

Abstract

N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels that play critical roles in neuronal development and nervous system function. Here, we developed a model to study NMDARs in early development in zebrafish, by generating CRISPR-mediated lesions in the NMDAR genes, grin1a and grin1b, which encode the obligatory GluN1 subunits. While receptors containing grin1a or grin1b show high Ca 21 permeability, like their mammalian counterpart, grin1a is expressed earlier and more broadly in development than grin1b. Both grin1a 2/2 and grin1b 2/2 zebrafish are viable. Unlike in rodents, where the grin1 knockout is embryonic lethal, grin1 double-mutant fish (grin1a 2/2 ; grin1b 2/2), which lack all NMDAR-mediated synaptic transmission, survive until ;10 d dpf (days post fertilization), providing a unique opportunity to explore NMDAR function during development and in generating behaviors. Many behavioral defects in the grin1 double-mutant larvae, including abnormal evoked responses to light and acoustic stimuli, prey-capture deficits, and a failure to habituate to acoustic stimuli, are replicated by short-term treatment with the NMDAR antagonist MK-801, suggesting that they arise from acute effects of compromised NMDAR-mediated transmission. Other defects, however, such as periods of hyperactivity and alterations in place preference, are not phenocopied by MK-801, suggesting a developmental origin. Together, we have developed a unique model to study NMDARs in the developing vertebrate nervous system.

NMDARs Drive the Expression of Neuropsychiatric Disorder Risk Genes Within GABAergic Interneuron Subtypes in the Juvenile Brain

“…Immature interneurons express different glutamate receptor subunits including the NMDA-type iGluR (NMDAR) and AMPA/Kainate-type iGluR (AMPAR/KAR) (Monyer et al, 1994;Soria, 2002;Manent, 2006), prior to the expression of any functional synapses. Multiple evidence indicates a critical role for neuronal activity, particularly through ionotropic glutamate receptors (iGluRs), in driving the development of MGE-derived interneurons (Matta et al, 2013;De Marco García et al, 2015;Pelkey et al, 2017;Priya et al, 2018;Zoodsma et al, 2020). But unlike the mature interneurons, where iGluRs are established to mediate synaptic transmission and plasticity, the precise roles for the iGluR subunits within developing interneurons are only emerging.…”

Bisphenol A Exposure Induces Sensory Processing Deficits in Larval Zebrafish during Neurodevelopment

“…5 , 6 ). Because the neural circuitry and molecules underlying these two behavioral phenomena are well-described in larval zebrafish ( Liu and Fetcho, 1999 ; Burgess and Granato, 2007 ; Kohashi and Oda, 2008 ; Roberts et al, 2011 , 2019 ; Wolman et al, 2011 ; Kohashi et al, 2012 ; Bergeron et al, 2015 ; Marsden and Granato, 2015 ; Wolman et al, 2015 ; Tabor et al, 2018 ; Nelson et al, 2020 ; Zoodsma et al, 2020 ), elucidation of the BPA-induced pathology should be relatively straightforward. Furthermore, habituation and PPI of the C-start reflex are behaviors that are well-suited for high-throughput drug screening, which should facilitate the development of novel treatments to mitigate the effects of BPA ( Rihel et al, 2010 ; Thyme et al, 2019 ).…”

Disruption of grin2B, an ASD-associated gene, produces social deficits in zebrafish.

“…3) Prey-capture Feeding Assay Prey-capture assays using paramecia were performed as previously reported (Zoodsma et al, 2020). Larval prey capture learning assays were adapted from (Geng et al, 2021).…”

“…Feedings occurred for 6 hours each day; food was refreshed and media washed after 3 hours. Prey-capture paramecia feeding experiments were run at 7 dpf, as previously reported (Zoodsma et al, 2020), aside for substituting Paramecia Multimicronucleatum for Paramecia Caudatum. qPCR cDNA was generated from RNA extracted from pools of either 4 larvae at 3 dpf or 2 larvae at 5 dpf as outlined above.…”