Developmental study of [3H]TCP and [3H]glycine binding sites in the rat hippocampus

The postnatal development of [3H]thienylphencyclidine ([3H]TCP) sites in rat hippocampus has been studied autoradiographically and with membrane preparations. [3H]TCP binding increased progressively from birth to adulthood; this is due to a change in the maximal number of sites (Bmax) but not in the affinity (Kd). A different developmental pattern was found for strychnine-insensitive [3H]glycine binding which also increased after birth, but reached adult levels earlier than [3H]TCP binding. The ontogenesis of TCP or glycine sites also differed from that previously described for N-methyl-D-aspartate (NMDA) sites in the hippocampus. In neonatal, as in adult hippocampus, [3H]TCP binding was enhanced by NMDA or glycine and reduced by Mg2+. We suggest that TCP sites are functionally coupled to the NMDA receptor-ion channel complex in developing as in mature hippocampus, but that there are developmental changes in the receptor channel complex.