Apoptosis is induced by radiofrequency fields through the caspase-independent mitochondrial pathway in cortical neurons.
Joubert, V., Bourthoumieu, S., Leveque, P. and Yardin, C. Apoptosis is Induced by Radiofrequency Fields through the Caspase-Independent Mitochondrial Pathway in Cortical Neurons. Radiat. Res. 169, 38-45 (2008). In the present study, we investigated whether continuous-wave (CW) radiofrequency (RF) fields induce neuron apoptosis in vitro. Rat primary neuronal cultures were exposed to a CW 900 MHz RF field with a specific absorption rate (SAR) of 2 W/kg for 24 h. During exposure, an increase of 2 degrees C was measured in the medium; control experiments with neurons exposed to 39 degrees C were then performed. Apoptosis was assessed by condensation of nuclei with 4',6-diamino-2-phenylindole (DAPI) staining observed with an epifluorescence microscope and fragmentation of DNA with TdT-mediated dUTP nick-end labeling (TUNEL) analyzed by flow cytometry. A statistically significant difference in the rate of apoptosis was found in the RF-field-exposed neurons compared to the sham-, 37 degrees C- and 39 degrees C-exposed neurons either 0 or 24 h after exposure using both methods. To assess whether the observed apoptosis was caspase-dependent or -independent, assays measuring caspase 3 activity and apoptosis-inducing factor (AIF) labeling were performed. No increase in the caspase 3 activity was found, whereas the percentage of AIF-positive nuclei in RF-field-exposed neurons was increased by three- to sevenfold compared to other conditions. Our results show that, under the experimental conditions used, exposure of primary rat neurons to CW RF fields may induce a caspase-independent pathway to apoptosis that involves AIF.
Joubert
Vanessa
V
Department of Cell Biology, Histology and Cytogenetics, EA3842 Limoges University Hospital, Faculty of Medicine, 87025 Limoges Cedex, France.
Bourthoumieu
Sylvie
S
Leveque
Philippe
P
Yardin
Catherine
C
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D008928:Mitochondria / Q000378:metabolism* / Q000528:radiation effects*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects*; D011846:Radio Waves / Q000009:adverse effects*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000528:radiation effects*; D013696:Temperature
D051033:Apoptosis Inducing Factor; D053148:Caspase 3