Novel neuron-related regulatory mechanisms for astrocytic glutamate and GABA high affinity uptake

The effect of conditioned media from cultures of cerebral cortical neurons and cerebellar granule cells on high affinity uptake of glutamate and GABA into cerebellar astrocytes cultured from 7-day-old rats was studied. Granule cell-conditioned media selectively enhanced GABA uptake whereas cerebral cortex neuron-conditioned media selectively enhanced glutamate uptake into these astrocytes. This selectivity was apparently restricted to cerebellar astrocytes since astrocytes cultured from cerebral cortex of 7-day-old rats exhibited a slight increase in both GABA and glutamate uptake after culture in conditioned media from both types of neurons. The results point to as yet unknown regulatory mechanisms for the development of astrocytic uptake of transmitter amino acids which may be dependent upon the regional origin of the astrocytes as well as the surrounding neuronal cell type.