Abstract By using the method of microiontophoresis, the influence of sodium hydroxybutyrate (GHB) and dopamine (DA) on spontaneous, extracellularly recorded, electrical activity of frontal cortical neurones of the rabbit was studied. Both agents produced predominantly inhibitory effects on neuronal activity. The inhibitory effect of DA was potentiated during GHB applications to the neurones in doses which per se failed failed to induce neuronal depression. Sodium hydroxybutyrate prevented the ‘escape’ of neurones from the inhibitory effect of DA and increased the duration of recovery of cellular activity after the application of DA was stopped. It is suggested that γ-hydroxybutyrate prevents the process of DA inactivation.