Effects of the vitamin derivatives of GABA on inhibitory postsynaptic responses of the rat cortical neurons

With the use of an intracellular recording technique, in experiments on immobilized anesthetized rats, we studied intracortical stimulation (ICS)-evoked responses of the motor cortex neurons before and after applications of pantogam (PG) and GABA ascorbinate (A-GABA) on the cortical surface. Application of PG prolonged the IPSP, suppressed the background spike activity (BA), and increased the membrane potential level of the neurons studied. Applications of A-GABA in low and medium concentrations (below 50 μM) increased the amplitude and duration of inhibitory responses, while that in high concentrations (50 μM and more) evoked depolarization of the neuronal membrane with concurrent intensification of the BA. Probable cellular mechanisms of the effects of the above drugs are discussed.