Effect of glutathione depletion, hyperthermia, and a 100‐mT static magnetic field on an hsp70/luc reporter system

Abstract

Heat shock proteins, in particular hsp70, are induced under conditions of cellular stress. It has been reported that environmental stimuli such as hyperthermia, oxidative stress, and exposure to magnetic fields increase levels of hsp70. It has also been reported that hyperthermia in combination with magnetic field exposure results in a synergistic increase in hsp70 production. We tested the hypothesis that oxidative stress induced by glutathione (GSH) depletion in combination with static magnetic field (SMF) exposure will produce a similar synergistic increase in hsp70 production. We exposed cells to heat, SMF, and diethylmaleate (DEM), which depletes GSH levels alone and in combination with each other, and measured hsp70 production using an hsp70/luciferase reporter and mRNA levels using PCR. We found that treatment with DEM significantly reduced the rate of luciferase bioluminescence production, particularly in the presence of heat. There was no significant effect of a 100-mT SMF exposure either alone or in combination with heat, DEM, or both on bioluminescence, however there was a significant interaction between SMF and DEM on hsp70 mRNA levels. Therefore, under our exposure conditions, GSH depletion reduced hsp70 levels but a synergistic effect of combining this stress with other external stimuli was only observed at the level of mRNA.

Elevation of heat shock gene expression from static magnetic field exposure in vitro

“…The dependence on experimental conditions we observed is consistent with previous studies. Malagoli et al [2004] found the response of HSP70 and HSP90 to 50 Hz magnetic fields was dependent on flux density and time and in a similar experimental models to the one in this study, Belton et al [2011] found no response to 100 mT SMF exposure but a significant interaction between SMF and diethyl maleate (DEM) on HSP70 RNA levels.…”

“…Examinations of HSP70 responses to static magnetic fields (SMF) also suggest a dependence on experimental variables. For example, significant responses can be observed in [Potenza et al, ; Tenuzzo et al, ], whereas no significant response was observed in [Guisasola et al, ; Bodega et al, ; Belton et al, ; Abdelmelek et al, ]. However, non‐significant increases in heat shock were also reported by [Abdelmelek et al, ; Belton et al, ].…”

Non‐thermal extremely low frequency magnetic field effects on opioid related behaviors: Snails to humans, mechanisms to therapy

“…For example, advances in molecular biology have allowed the establishment that human cryptochrome exhibits light dependent magneto sensitivity by testing the human fluoroprotein cryptochrome using a transgenic approach in the magnetoreception system of Drosophila [Foley et al, ]. These advances have also allowed us to determine if effects occur during exposure, with an excellent example coming from the laboratory of Dr. Jeffrey Carson demonstrating that a 100 mT static magnetic field had no effect during or immediately after exposure on heat shock protein 70 using a hsp 70/luc reporter system [Belton et al, ].…”