Pieces of fetal rat lumbar spinal cord were transplanted into the anterior eye chamber of adult rat hosts. At least seven months later, extracellular single-unit recordings of spontaneously active graft neurons were made prior to
and during the superfusion of either glutamate or γ-aminobutyric acid (GABA). Superfusion of glutamate produced an increase (five cells),
decrease (three cells), or had no effect (two cells) on the firing rate of neurons tested. Superfusion
of GABA decreased the firing rate of all twelve neurons tested, while superfusion of the GABA receptor
antagonist bicuculline increased the firing rates of all eight neurons tested. The latency and magnitude
of the responses to glutamate and GABA were not related to depth of the recording electrode below the graft
surface. Together, these data suggest that the intraocular spinal cord graft is suitable for
the in vivo study of GABA and glutamate neuropharmacology