60 Hz magnetic field exposure and urinary 6-sulphatoxymelatonin levels in the rat

Abstract

Four separate experiments were carried out to investigate the effect of extremely low frequency magnetic field (MF) exposure (60 Hz, 1 mT rms) on urinary 6‐sulphatoxymelatonin (aMT6s) levels in Sprague‐Dawley rats. In the first experiment, immature male rats maintained under a regular 12 h daily photoperiod (white fluorescent light) were exposed to a 20 h daily MF exposure for 6 weeks. The second experiment was similar to the first, except that the MF exposure was limited to 10 days. In the third experiment, adult male rats acclimated to a combination of continuous dim red light and regular 12 h daily photoperiod (white fluorescent) were subjected to a single 1 h exposure to intermittent MF (1 min on and 1 min off cycles), 2 h before fluorescent lights went off. The fourth experiment was similar to the third, except that the animals received 2 consecutive days of 20 h daily exposure to intermittent MF, beginning 1 h before the fluorescent lights went off each day. In all four experiments, the circadian profile of urinary aMT6s was examined before, during, and after the MF exposure. No significant effect of 1 mT MF on indoleamine metabolism was observed in any of the above experiments. However, in one of the experiments (no. 4), both the control and the MF groups showed a lower aMT6s level during the exposure days, when compared with that of pre‐ and post‐exposure days, suggesting that the existence of possible effects with lower field strengths at the range of stray field cannot be ruled out. Bioelectromagnetics 19:172–180, 1998. © 1998 Wiley‐Liss, Inc.

Blood melatonin and prolactin concentrations in dairy cows exposed to 60 Hz electric and magnetic fields during 8 h photoperiods

“…In rodents, the evidence for suppression of MLT by EMF exposure is inconsistent. Whereas, some studies show suppression [Grota et al, 1994;Kato et al, 1994;Mevissen et al, 1996;Picazo et al, 1998], others show no effects [John et al, 1998;Bakos et al, 2002]. In humans, several studies have demonstrated an EMF induced suppression of MLT [Wood et al, 1998;Graham et al, 2000;Griefahn et al, 2001].…”

Direct suppressive effects of weak magnetic fields (50 Hz and 162/3 Hz) on melatonin synthesis in the pineal gland of Djungarian hamsters (Phodopus sungorus)

“…In fact, it has been frequently demonstrated that low-frequency magnetic fields are able to affect the function of the pineal gland in animals and humans [Lerchl et al, 1990;Grota et al, 1994;Kato et al, 1994;Selmaoui and Touitou, 1995;Mevissen et al, 1996;Pfluger and Minder, 1996;John et al, 1998;Karasek et al, 1998;Lerchl et al, 1998;Wood et al, 1998;Burch et al, 1999;Wilson et al, 1999]. However, these studies often yielded inconsistent results, even when the conditions of exposure seemed to be identical [Truong and Yellon, 1997;Lö scher et al, 1998;Reiter et al, 1998;Yellon and Truong, 1998].…”

Melatonin Levels and Low‐Frequency Magnetic Fields in Humans and Rats: New Insights From a Bayesian Logistic Regression

“…Jahandideh et al [] compiled various laboratory studies on the putative effect of ELF‐MF on rat MLT, whose list is reproduced in Table . We removed the entries that were not consistent with the original study, e.g., the entries with ID 13, 14, and 15 from John et al []. In addition, we added the study of Löscher et al [].…”