['Increase in neuronal Ca(2+), activation of hippocampus N-methyl-D-aspartate receptor (NMDAR) and defects in enzymes such as brain cortex microsomal membrane Ca(2+)-ATPase (MMCA) are thought to play a role in epilepsy. Topiramate (TOP) is a novel drug with broad antiepileptic effect, and its effect on brain cortex MMCA is not known. We investigated effects of TOP on pentylentetrazol (PTZ)-induced MMCA activity and NMDAR subunits in rat brain.', 'Thirty-two rats were randomly divided into four equal groups. The first group and second groups were used for the control and PTZ groups, respectively. 50 and 100\u2009mg TOP were administered to rats constituting the third (TOP50) and fourth (TOP100) groups for 7 days, respectively. At the end of 7 days, all groups except the first received a single dose PTZ. Brain and hippocampus samples were taken at 3\u2009hrs after PTZ administration.', 'The microsomal MMCA activity was lower in the PTZ group than in control although the MMCA activities were higher in the treatment group than in PTZ group. Brain cortex total calcium levels, the hippocampus NMDAR 2A and 2B subunit concentrations were higher in the PTZ group than in control although their concentrations were decreased by TOP50 and TOP100 administration. Total brain cortex calcium and hippocampus NMDAR 2A and 2B subunit concentrations were higher in TOP100 group than in TOP50 group.'] Does topiramate modulate hippocampus NMDA receptors via brain Ca ( 2+ ) homeostasis in pentylentetrazol-induced epilepsy of rats?