THE POSTNATAL-DEVELOPMENT OF AMPA RECEPTOR SUBUNITS IN THE BASAL GANGLIA OF THE RAT

In situ hybridization and immunohistochemistry were used to characteri ze the expression pattern of the lpha-amino-3-hydroxy-5-methyl-4-isoxa zolepropionic acid (AMPA) receptors during postnatal development in th e rat basal ganglia. All subunit transcripts showed some degree of dev elopmental regulation. GluR1 and GluR2 are expressed at high levels in the neonate with reduced expression in the adult. GluR3 and GluR4 are expressed at significantly lower levels in both neonates and adults a nd have much more modest degrees of reduced expression in adults as co mpared with GluR1 and GluR2. Analysis of the flip and flop transcript isoforms indicates that GluR1 flip and flop and GluR2 flip are the pre dominately expressed splice variants in adults. Observed changes in th e expression of the AMPA receptor transcripts indicate that there are fundamental differences in the expression of these receptor subunits i n adults and neonates. This phenomenon may play a significant role in the establishment of proper synaptic circuitry within the developing b asal ganglia in early postnatal life as well as contributing to differ ences in susceptibility to injury and disease in the aging brain.