DIFFERING ACTIONS OF BACLOFEN AND 3-AMINO-PROPYLPHOSPHINIC ACID IN RAT NEOCORTICAL SLICES

Rat neocortical slices maintained in Mg2+-free Krebs medium developed spontaneous paroxysmal discharges which were attenuated or suppressed by the γ-aminobutyric acid-B (GABAB) receptor agonist baclofen, occasionally accompanied by a slight hyperpolarisation, and antagonised by the specific GABAB-receptor antagonist, 2-OH-saclofen. Over the same dose range, the GABA-analogue 3-amino-propylphosphinic acid (3-APA) caused a marked, prompt hyperpolarisation with little or no effect on the frequency of the discharges, although their amplitude was attenuated. In the presence of 2-OH-saclofen, 3-APA still induced a hyperpolarisation but the amplitude of the discharges was no longer affected. This marked difference in action between baclofen and 3-APA in the rat neocortical slices suggests there may be a heterogeneity of GABAB-receptors. © 1990.