To study the influence of pulsed magnetic fields on the release (during exposure) and uptake (after exposure) of glutamate in the hippocampal tissue.
The release was examined by using hippocampal slices (of mice), the uptake process was characterized by the use of synaptosomes obtained from hippocampal slices.
Patterns of magnetic fields were applied, which induced seizures in hippocampal tissue in vitro and epileptic episodes in preclinical trials.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
25 mHz
Exposure duration:
640 s
Paradigm 1
|
|
|
Exposure 2:
25–100 mHz
Exposure duration:
3340 s
Paradigm 1+2
|
|
|
Exposure 3:
25–250 mHz
Exposure duration:
6095 s
Paradigm 1+2+3
|
|
| Frequency | 25 mHz |
|---|---|
| Type | |
| Waveform |
|
| Exposure duration | 640 s |
| Additional info | Paradigm 1 |
| Additional info | Paradigm 1(0.025 Hz) is given as: 9 mT, 12 mT and 15 mT MF with 20 s on/off cycle applied 4, 4 and 8 times, respectively. The exposure time pattern of E1 is calculated as follows: 20 s pulse on + 20 s pulse off multiplied by the number of repetitions which was 4 + 4 + 8. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 12 mT | unspecified | unspecified | - | - |
| magnetic flux density | 15 mT | unspecified | unspecified | - | - |
| magnetic flux density | 9 mT | unspecified | unspecified | - | - |
| Frequency | 25–100 mHz |
|---|---|
| Type | |
| Waveform |
|
| Exposure duration | 3340 s |
| Additional info | Paradigm 1+2 |
| Additional info | Paradigm 1 (0.025 Hz) + Paradigm 2 (0.1 Hz) were applied. Paradigm 2 is given: 15 mT and another 15 mT MF with 5 s on/off cycle applied 9 and 6 times, respectively. The exposure time pattern of E2 is calculated as follows: Exposure time pattern of E1 + (5 s on + 5 s off + 20 s pause + 5 s on + 5 s off + 220 s multiplied by # of repetitions which was 9 + 6). |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 9 mT | unspecified | unspecified | - | - |
| magnetic flux density | 12 mT | unspecified | unspecified | - | - |
| magnetic flux density | 15 mT | unspecified | unspecified | - | - |
| Frequency | 25–250 mHz |
|---|---|
| Type | |
| Waveform |
|
| Exposure duration | 6095 s |
| Additional info | Paradigm 1+2+3 |
| Additional info | Paradigm 1 (0.025 Hz) + Paradigm 2 (0.1 Hz) + Paradigm 3(0.25 Hz) were applied. Paradigm 3 is given as: 15 mT with 2 s on/off cycle applied 12, 4, 3, 5 and 6 times. The exposure time pattern of E3 is calculated as follows: Exposure time pattern of E2 + (2 s on + 2 s off + 30 s pause + 2 s on + 2 s off + 10 s pause + 2 s on + 2 s off + 25 s pause + 2 s on + 2 s off + 10 pause + 2 s on + 2 s off multiplied by # of repetitions which was 12+4+3+5+6). |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 9 mT | unspecified | unspecified | - | - |
| magnetic flux density | 12 mT | unspecified | unspecified | - | - |
| magnetic flux density | 15 mT | unspecified | unspecified | - | - |
The pulsed magnetic fields (9-15 mT) amplified and attenuated the release and uptake of glutamate, respectively. However, the magnetic fields which induced an increase in neuronal excitability without concomitant seizures amplified both processes.
These data indicate that the glutamergic synapses are the target of magnetic fields action. The results show that modulation of glutamate turnover by magnetic fields correlates with overexcitability of hippocampal neurons and with epileptic episodes observed in the hippocampus of the patients exposed to magnetic fields. Pulsed magnetic field stimulation has the potential to be used as a diagnostic procedure which could help to localize the seizure-generating part of the brain.
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