Sodium-dependent proline and glutamate uptake by hippocampal synaptosomes during postnatal development

Na+-dependent uptake of proline and glutamate by hippocampal synaptosomes was studied during postnatal development. At all ages from 9 days to adulthood, hippocampal synaptosomes transported proline by both a high-affinity and a low-affinity process, whereas glutamate was always transported predominantly by a high-affinity process. During the period of rapid synaptogenesis, the K-T for high-affinity proline transport overshot the adult value, whereas the K-T for glutamate transport increased steadily toward the adult value. The ratio of K-T values for proline and glutamate was 2-3 times the adult value between 12 and 24 days of age. Although high-affinity transporters for proline and glutamate are expressed by nearly the same hippocampal pathways, they are differentially regulated during postnatal development.