Increased dexamethasone-induced apoptosis of thymocytes from mice exposed to long-term extremely low frequency magnetic fields

Abstract

To address the effect of extremely low frequency electromagnetic fields on programmed cell death we assessed both the spontaneous and dexamethasone (Dex)‐induced apoptosis of thymocytes and spleen cells from mice submitted to a long‐term continuous exposure of a 0.4–1.0 μT 60 Hz magnetic field or an 8–20 μT direct current (DC) magnetic field. Dex‐induced apoptosis but not spontaneous apoptosis was substantially increased in thymocytes from 0.4 to 1.0 μT 60 Hz field‐exposed animals. Spontaneous apoptosis and Dex‐induced apoptosis of spleen cells were not affected by the 0.4–1.0 μT 60 Hz field exposure. In addition, spontaneous apoptosis and Dex‐induced apoptosis of thymocytes and spleen cells from mice exposed to an 8–20 μT DC field were similar to the controls. These findings represent the first demonstration that thymocytes from mice exposed to a long‐term 0.4–1.0 μT 60 Hz field may show abnormal response to Dex apoptotic stimuli. Bioelectromagnetics 19:131–135, 1998. © 1998 Wiley‐Liss, Inc.

Decreased DNA repair rates and protection from heat induced apoptosis mediated by electromagnetic field exposure

“…Recent studies investigating changes in susceptibility to apoptosis with regard to EMF exposure have reported both decreased [Fanelli et al, 1999] and increased susceptibility [Flipo et al, 1998;Ismael et al, 1998]. Interestingly, previous studies involving DNA repair and EMF exposure have reported no effect [Cossarizza et al, 1989a;Frazier et al, 1990;Cantoni et al, 1995Cantoni et al, , 1996.…”

Magnetic-field-induced DNA strand breaks in brain cells of the rat.

“…Both hydroxy radical and nitric oxide have been shown to cause apoptotic and necrotic cell death, especially in brain cells (Simonian and Coyle 1996). In addition to the present study, others have shown apoptosis in various other cell types after exposure to extremely lowfrequency electromagnetic fields (Blumenthal et al 1997;Ismael et al 1998;Phillips et al 1997;Simko et al 1998;Singh et al 1994).…”

Extremely low frequency magnetic fields and the promotion of H2O2‐induced cell death in HL‐60 cells

“…In addition, the effects of exposure to ELF magnetic fields on previously induced apoptosis have also been investigated, but the results are inconsistent. The observations are as follows: (1) an increase of dexamethasone-induced apoptosis of thymocytes from mice exposed to long-term ELF magnetic field (Ismael et al 1998); (2) a transient suppression of X-ray-induced apoptosis by exposure to power frequency magnetic fields in MCF-7 cells (Ding et al 2001); and (3) protection from heatinduced apoptosis mediated by magnetic fields in HL-60, HL-6R and Raji cells (Robison et al 2002).…”