Elsevier

Neuroscience

Volume 67, Issue 4, August 1995, Pages 909-920
Neuroscience

In situ hybridization analysis of AMPA receptor subunit gene expression in the developing rat spinal cord

https://doi.org/10.1016/0306-4522(95)00094-YGet rights and content
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Abstract

In early postnatal life the acquisition of mature morphological and molecular features of motor neurons is influenced by synaptic activity within the spinal cord. Glutamatergic synaptic neurotransmission is believed to play a central role in this process. We hypothesize that the repertoire of glutamate receptors expressed by neurons in the young spinal cord differ from those expressed in adults and such receptors support activity-dependent developmental plasticity. To explore this idea, we used in situ hybridization histochemistry to determine the distribution, temporal expression, and potential subunit composition of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the developing rat spinal cord and compared these findings with those in adult rats.

We find qualitative and quantitative changes in α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor subunit gene expression over the first month of postnatal life. α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor subunit genes GluR1, 2 and 4 are expressed at greater levels throughout the spinal cord of the neonate versus the adult animals. The developmental down-regulation is most pronounced for GluR1 transcripts, less for GluR2 and GluR4 transcripts, and minimal for GluR3 transcripts. Analysis of flip and flop splice variants of each subunit show that receptors expressed by adult motor neurons are potentially composed of the subunits GluR1 flop, GluR2 flip, GLuR3 flip and flop, and GluR4 flip. In neonatal motor neuron all subunits are potentially expressed (except GluR2 flop) with quantitatively the dominent subunits being the flip splice variants of GluR1, 2 and 4. Receptors in the substantia gelatinosa undergo equally dramatic, developmentally independent changes.

Changes in the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit composition are likely to have an important effect on the electrophysiological properties of motor neurons and may form part of the molecular identity of neurons capable of undergoing activity-dependent developmental plasticity.

AMPA
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid
CNQX
6-cyano-7-nitroquinoxaline-2,3-dione
DH
dorsal horn
DTT
dithiothreitol
GluR
glutamate receptor subunit
KA
kainic acid
NMDA
N-methyl-d-aspartate
P
postnatal day
SG
substantia gelatinosa
SSC
standard saline citrate
VH
ventral horn

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