EXPRESSION OF GABA TRANSPORTER MESSENGER-RNAS IN THE DEVELOPING AND ADULT-RAT OPTIC-NERVE

There is electrophysiological evidence of a functional role for gamma- aminobutyric acid (GABA) and GABA transporters (GATs) in the neonatal rat optic nerve, and that they are down-regulated during development. The results of the present study demonstrate directly by reverse trans cription-polymerase chain reaction (RT-PCR) that the mRNAs encoding fo r GAT-1, -2 and -3 are expressed in the optic nerves of both neonatal (5 day old) and adult rats. The results support a role for GABA in the developing rat optic nerve, a typical white matter tract which contai ns axons and glia, but neither neuronal cell bodies nor synapses. Sign ificantly, the persistence of GAT mRNAs suggests an enduring function for both GABA and glial uptake mechanisms in the adult optic nerve. (C ) 1997 Elsevier Science Ireland Ltd.