Abstracts

The potential of using magnetic fields to control epilepctic episodes was evaluated in ICR mice. Intracerebroventricular (ICV) injection of NMDA (5 [mu]l, 200-400 [mu]g/kg) was used to trigger epileptic behavior in wild-type mice (ICR supplied by Charles River Laboratories, USA). The presence of the most severe of five types of behavior/outcomes was recorded for each mouse: wild running (WR), loss of righting (LOR), clonus (CLO), tonic hind-limb extension (THE), and death (DEA). Effects of exposure amplitude (0.44 mT, 2.6 mT, 6.6 mT nominal exposure), exposure duration (5 min, 15 min, 30 min and 60 min) and NMDA concentration (200, 300, and 400 [mu]g/kg) were examined in this study. Increasing field strenght tends to shift the distribution of observed behavior to less severe outcomes, significantly different from controls at 6.6 mT (mean over the head) with p[lt]0.01 by contingency table analysis, see Figure.[figure1]Figure: Distribution of seizure scores for controls (left bar in a pair) compared to field-exposed mice (right bar) for three field strengths (averaged over the head of the mouse). The numbers in parentheses indicate the number of animals in each group. The highest exposure level provided a shift not attributable to chance by a chi-square test for homogeniety on the resulting 6x2 contingency table.
Increasing duration of exposure also produced the same trends in shifting the observed behavior. The two higher doses of NMDA worsened the observed behavior slightly, but it also became gradually more difficult to control the seizure with the magnetic field at higher doses of NMDA, with no apparent difference between controls and field-exposed mice at 400 [mu]g/kg. Magnetic fields lessened the severity of NMDA-induced seizure manifestations in the ICR mouse. Higher fields (up to an average effective exposure of the head of 8 mT) provided stronger protection, as did longer exposures (studied up to 60 min). (Supported by Holcomb Medical Research Institute.)