In this study we tested whether the prevalence or synaptic distribution of NMDA receptor subunits would be altered in the brain of the MeCP2-null mouse model of Rett syndrome. Detergent resistant membranes (DRMs) and post-synaptic densities (PSDs) were isolated from the synaptic membranes treated with TritonX-100, and resolved by sucrose density gradient centrifugation. Immunoblot analysis of the resulting density gradient fractions revealed that the relative distribution of the different NMDA receptor subunits between the DRM fractions, soluble fractions, and insoluble postsynaptic density fractions was preserved in the MeCP2-null brain. However, analysis of the overall NMDA receptor subunit prevalence within these fractions revealed a significant decrease in the expression of the NR1 and NR2A subunits, but not the NR2B subunit, in the MeCP2-null brain. The preservation of distribution of NMDAR subunits to the synaptic membranes, together with the decrease in NR1 and NR2A prevalence, suggest an imbalance in equilibrium between the mature and the immature synapses in a mouse model of Rett syndrome.

In this study we tested whether the prevalence or synaptic distribution of NMDA receptor subunits would be altered in the brain of the MeCP2-null mouse model of Rett syndrome. Detergent resistant membranes (DRMs) and post-synaptic densities (PSDs) were isolated from the synaptic membranes treated with TritonX-100, and resolved by sucrose density gradient centrifugation. Immunoblot analysis of the resulting density gradient fractions revealed that the relative distribution of the different NMDA receptor subunits between the DRM fractions, soluble fractions, and insoluble postsynaptic density fractions was preserved in the MeCP2-null brain. However, analysis of the overall NMDA receptor subunit prevalence within these fractions revealed a significant decrease in the expression of the NR1 and NR2A subunits, but not the NR2B subunit, in the MeCP2-null brain. The preservation of distribution of NMDAR subunits to the synaptic membranes, together with the decrease in NR1 and NR2A prevalence, suggest an imbalance in equilibrium between the mature and the immature synapses in a mouse model of Rett syndrome.