Ictal epileptiform events induced by removal of extracellular magnesium in slices of entorhinal cortex are blocked by baclofen.

Most manipulations employed to elicit epileptiform activity in brain slices result in brief, interictal-like events. In slices of the rat entorhinal cortex perfusion with a magnesium-depleted medium elicits prolonged seizure events which are more reminiscent of ictal activity. The interictal events in brain slice models are blocked by baclofen, but there is an indication from one study (H. S. Swartzwelder, D. V. Lewis, W. W. Anderson, and W. A. Wilson, 1987, Brain Res. 410: 362-366) that ictal events may not be affected by this drug. The present study examined the effects of baclofen on ictal events recorded in entorhinal cortex slices in magnesium-free medium. Simultaneous studies of effects of baclofen on interictal responses in the hippocampal region of the same slices were made on many occasions. The results show that both types of epileptiform activity are suppressed with a similar facility by baclofen.