The effects of exposure of rat cerebellar granule neurons to 50 Hz magnetic fields on gamma aminobutyric acid (GABA) type A receptor ion channel activity and associated signal pathways should be investigated.
|Exposure duration||continuous for up to 120 min|
|Setup||a pair of horizontal Helmholtz coils (20 cm in height and 20 cm in radius, each coil consisting of 150 turns of copper wire) was placed parallel to each other; the surfaces of the culture plates were perpendicular to the force lines of the alternating magnetic field; the magnetic field was homogeneous in exposure area|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||0.2 mT||-||measured||-||-|
Cells exposed to a magnetic field of 0.2 mT (group 1) for 120 min or of 1 mT (group 1) for 60 min showed significantly increased GABA type A receptor ion channel currents compared to sham exposed cells. No significant differences were obeserved at the respective earlier points in time. An activation of protein kinase A led to a slight decrease of the ion channel current, however, whereas a protein kinase C activation led to an increase of the currents comparable to the magnetic field exposure and the inhibition of protein kinase C blocked the current.
Western blot analysis indicated that the protein expression of phosphorylated protein kinase C was significantly increased in cells after 60 minutes of 1 mT exposure in comparison to sham exposed cells, which could subsequently be blocked by the addition of the prostaglandin E receptor inhibitor SC19220. SC19220 also significantly inhibited the magnetic field-induced elevation of the GABA type A receptors ion channel currents.
The authors conclude that exposure of rat cerebellar granule neurons to a 50 Hz magnetic field could increase the GABA type A receptor ion channel activity and that these effects might be mediated via prostaglandin E receptor 1-protein kinase C pathway.