Transport of G AB A, β-Alanine and Glutamate into Perikarya of Postnatal Rat Cerebellum

Abstract: Cells dissociated from the postnatally developing rat cerebellum retain their high-affinity carrier-mediated transport systems for ³H]GABA ( K _t=1.9 μM, V = 1.8 pmol/10⁶ cells/min) and ³H]glutamate ( K _t= 10 μM, V = 7.9 pmol/10⁶ cells/min). Using a unit gravity sedimentation technique it was demonstrated that 3H]GABA was taken principally into fractions that were enriched in inhibitory neurons (Purkinje, stellate and basket cells). ³H]β-alanine (which is taken up specifically by the glial GABA transport system) and ³H]glutamate were concentrated by glial-enriched fractions. However ³H]glutamate uptake was minimal in fractions enriched in precursors of granule cells, which may utilise this amino acid as their neurotransmitter. These results are discussed in relation to reports of high-affinity ³H]glutamate uptake by glia. The role of glutamate transport in glutamatergic cells is also considered. The data suggest that high-affinity glutamate transport is a property of glial cells but not granule neurons.