Prenatal methotrexate exposure delays onset of low Mg2+-induced epileptiform discharges in the entorhinal cortex

We determined the effects of prenatal exposure to DNA synthesis inhibitor m ethotrexate (MTX) on: (a) the susceptibility to low Mg2+-induced epileptifo rm activity in deep layers (IV-V) of medial entorhinal cortex in vitro; and (b) neuronal counts in this area. Low Mg2+-induced discharges developed si gnificantly later in slices from prenatally MTX-exposed rats than in contro l slices. Neuronal counts were increased in the layer V of medial entorhina l cortex of prenatally MTX-exposed rats. Results indicate that: (a) MTX-ind uced prenatal brain DNA impairment is antiepileptogenic; and (b) simple inc reases in neuronal numbers may not be associated with epileptogenic effects . (C) 2000 Elsevier Science B.V. All rights reserved.