To evaluate possible protective properties of repetitive daily exposure to static magnetic fields against the neurotoxicity of sustained blockade of N-methyl-D-aspartate (NMDA) receptor channels by dizocilpine (MK-801) in cultured rat hippocampal neurons.
The NMDA receptor antagonist MK-801 was added into culture medium at a concentration of 1-100 µM in hippocampal neurons cultured for up to 8 days in vitro.
Sustained exposure to static magnetic fields modulates cellular maturation and development, at least in part through the up-regulation of NMDA receptor channels.
|Setup||ferrite magnets with N pole upwards were placed on both sides of the culture dishes which were located at the center of the magnetic fields at a distance of 10 cm from each other. Control dishes were treated under the same environmental conditions as for the exposure groups in the absence of ferrite magnets.|
In hippocampal neuronal cultures treated with MK-801 a significant decrease was found in the expression of MAP2 (a major component of cross-bridges between microtubules in dendrites) as well as mRNA for both BDNF and GAP43 (a marker of neuronal maturity that is associated with neuronal development, axonal regeneration, and synaptogenesis). Additionally, a decreased viability was observed. MK-801 not only decreased the expression of the NR1 subunit of NMDA receptors, but also increased NR2A expression, without affecting NR2B expression.
Repetitive daily exposure to static magnetic fields led to a decrease in the expression of MAP2 (to approximately 50% of the control), without significantly affecting cell viability or the expression of neuronal nuclei and GAP43.
However, the exposure to repetitive magnetism prevented decreases in both BDNF mRNA and MAP2. In addition it increased the expression of NR2A subunit, without altering NR1 expression in neurons cultured in the presence of MK-801.
These data suggest that repetitive magnetism may at least in part counteract the neurotoxicity of MK-801 through modulation of the expression of particular NMDA receptor subunits in cultured rat hippocampal neurons.