Dendritic spines are the main postsynaptic neuronal targets of excitatory inputs in cortical neurons, and both spine density and shape possess a well known adaptive synaptic-stimulation-dependent plastic capacity. Eighteen Sprague-Dawley adult male rats were used. Monosodium glutamate-treated rats (4 g/kg of body weight, i.p.) showed tonic and clonic epileptic seizures, as well as less dendritic spines in the apical arborization of their hippocampal CA1 pyramidal cells, compared to both control groups. No changes were seen in the proportional density of thin, stubby, mushroom-shaped, wide, or ramified spines between groups. Excessive glutamate-mediated excitatory activity on receptors could have led dendritic spines to shrink until they disappeared, while the spine-type proportion may be kept balanced as an adaptive response.