Parenteral magnesium sulfate fails to control electroshock and pentylenetetrazol seizures in mice

Abstract

Magnesium sulfate has been used as an anticonvulsant in the treatment of eclampsia, but efficacy of magnesium in other types of seizure disorders is poorly documented. We examined the effects of magnesium sulfate (MgSO 4) on seizures produced in mice by maximal electroshock (MES) and pentylenetetrazol (PTZ). MgSO 4 injection (6.7 mEq/kg i.p.) caused weakness in all animals. With supra-threshold electroshock, 10 10 controls and 11 12 treated animals had seizures with tonic hind limb extension ( P = NS). Electroshock threshold was unaltered by magnesium treatment ( n = 48; P = 0.47). PTZ induced clonic seizures in 12 12 controls and 5 14 treated animals ( P < 0.05). This difference was likely due to muscular weakness because frequency of EEG spikes was the same in PTZ and PTZ + MgSO 4 groups. Mean serum magnesium levels were 2.3 ± 0.3 mEq/1 in animals not given MgSO 4; 10.9 ± 1.4 mEq/1 and 12.8 ±2. mEq/1 in treated animals with and without seizures ( P = NS). We conclude that magnesium sulfate had no significant anticonvulsant activity in mouse MES and PTZ models for epilepsy. The relevance of these findings to the possible efficacy of magnesium sulfate in eclamptic seizures and other types of epilepsy remains to be determined.