OBJECTIVE: The objective of this study was to determine whether magnesium sulfate has central anticonvulsant effects.

STUDY DESIGN: In three experiments we investigated the anticonvulsant properties of magnesium sulfate on the hippocampus because of its high density of N-methyl-D-aspartate receptors and link to clinical epilepsy. Seizure activity was elicited in the hippocampus of rats or in in vitro hippocampal brain slices. The effects of magnesium on seizure activity were determined.

RESULTS: (1) Intraperitoneal magnesium sulfate (270 or 360 mg/kg) failed to block hippocampal seizures but reduced electroencephalographic amplitude and seizure duration. (2) Injection of magnesium sulfate directly into a seizure focus blocked seizures and elevated seizure thresholds. (3) Low magnesium levels produced epileptiform activity in an in vitro hippocampal brain slice preparation; the epileptiform activity was reversed by increasing the magnesium concentration.

CONCLUSIONS: Magnesium sulfate has central anticonvulsant activity on hippocampal seizures, implicating the N-methyl-D-aspartate receptor in eclamptic seizures and in the therapeutic efficacy of magnesium sulfate.

Cotton DB, Janusz CA, Berman RF
Am. J. Obstet. Gynecol. 1992 Apr;166(4):1127-34; discussion 1134-6
PMID: 1566765