GLUTAMATE TRANSPORT IN CULTURES FROM DEVELOPING AVIAN CEREBELLUM - PRESENCE OF GLT-1 IMMUNOREACTIVITY IN PURKINJE NEURONS

Immunocytochemical studies indicated that Purkinje cells cultured from chick embryonic cerebellum (embryonic day 8) strongly express a gluta mate transporter EAAT2 cloned from human brain (GLT-1 in rat brain). A t both 7 days and 14 days in culture, Purkinje neurons accumulated 1 m u M [H-3]L-glutamate via a potent ''high-affinity'' transport system t hat could be inhibited by D- and L-threo-3-hydroxyaspartate (D- and L- t-3OHA) and by L-trans-pyrrolidine-2,4-dicarboxylate (L-t-PDC). The or der of potency of the three inhibitors was L-t-PDC similar to L-t-3OHA > D-t-3OHA, Only the value of IC50 (concentration causing 50% inhibit ion) for D-t-3OHA significantly changed between 7 days (116 mu M) and 14 days in culture (40 mu M). All n(H) similar to 1, except in the cas e of the inhibition by D-t-3OHA at 14 days in culture (n(H) = 0.57), i ndicating the possible appearance of heterogeneity of the transport si tes at later stages of culturing, Chronic inhibition of L-glutamate tr ansport by L-t-PDC resulted in major changes in the morphology of Purk inje cells; particularly, the neurites almost completely regressed. (C ) 1998 Wiley-Liss, Inc.