Ontogeny of glutamate accumulating activity in rat brain synaptic vesicles

The relationship between the ontogeny of the vesicular glutamate uptake system and synaptogenesis in rats was investigated. For this purpose we have developed a simplified procedure for the preparation of crude synaptic vesicles which are sufficiently pure to demonstrate a highly ATP-dependent glutamate uptake. ATP-dependent glutamate uptake into synaptic vesicles was found to increase dramatically starting on postnatal day 10 and reaching a maximum on day 30 (76 +/- 40 and 657 +/- 40 pmol/mg protein/10 min, respectively), correlating well with the active period of synaptogenesis. Stimulation of uptake by chloride also developed in parallel with the vesicular glutamate uptake. In contrast, combined non-ATP-dependent uptake and non-specific binding remained constant (21 +/- 6 pmol/mg protein/10 min). This development of vesicular glutamate uptake during the period of synaptogenesis supports the notion that synaptic vesicles play an important role in glutamate synaptic transmission.