The functional expression of NMDA receptors is independent of visual experience in the developing rabbit retina

[[abstract]]Purpose. Activation of the NMDA glutamate receptors is critical for the initiation of synaptic plasticity. In the developing rat retina, NMDA receptor function has been associated with visual experience, although the light-dependent regulation of the subunit composition of the NMDA receptors is controversial. In the present study, we characterized the functional expression of NMDA receptors in the developing rabbit retina, and examined the impact of light deprivation on how the subunit composition of the NMDA receptors is regulated. Methods. Antibodies against NR1 and NR2A/B were used to examine the neonatal expression patterns of the NMDA receptor subunits. Furthermore, the functional NMDA receptors were mapped using the agmatine (AGB) activation assay. Results. While NR1 and NR2A/B subunit immunoreactivity was only prominently detectable immediately after birth, the AGB activation assay showed that functional NMDA receptors could be identified as early as E21. No significant difference was observed between normal and dark reared animals in terms of their NR1 and NR2A/B expression. In addition, a comparison of AGB permeation between the normal and dark reared animals also showed no difference in the functional expression of the NMDA receptors. Conclusion. These results indicate that NMDA receptors participate in the synaptic maturation of the retinal circuits during the early stages of the development, but that the functional NMDA receptors, including their subunit composition, in the developing rabbit retina, are independent of the rabbit's visual experience.[[fileno]]2050130010021[[department]]生科