Ontogeny of ionotropic glutamate receptor expression in human fetal brain.

Glutamate receptors have multiple roles in the central nervous system. Recent evidence suggests that the iontropic glutamate receptors are critical during brain development, particularly for corticogenesis, neuronal migration, and synaptogenesis. In this study, we examined subunit mRNA expression and binding sites of the NMDA, AMPA, and kainate receptors from gestational weeks 8-20 in human fetal brain. Expression of glutamate receptors was high during several periods in these brains. Different levels of expression of each NMDA, AMPA, and kainate receptor subunit transcripts were present during development, with a greater abundance of NR1, NR2B, NR2D, GluR7, and KA1 mRNA at most gestational ages. Binding sites for NMDA, AMPA, and kainate receptors were all detected, but each had a unique pattern of expression. These results demonstrate that glutamate receptors are expressed early in human brain development, and undergo complex changes over time consistent with their role in normal development.