Circularly polarised MF (500 μT 50 Hz) does not acutely suppress melatonin secretion from cultured Wistar rat pineal glands

Abstract

Magnetic fields (MF, 50 Hz) have been proposed to affect melatonin production in mammals; however, there is very little data about the mechanism by which this possible interaction may occur. Here we describe results from the first study in which circularly polarised 50 Hz MF have been administered to isolated pineals in highly controlled conditions. Melatonin release from isolated Wistar rat pineal glands, dissected 2 h after light onset ZT 2, was measured in a flow through culture system, during and after exposure to a 4 h MF similar in nature and magnitude to that produced in extremely close proximity to a high voltage power line (500 micro T 50 Hz circularly polarised). Melatonin release from isolated pineals was comparable to that observed in previous studies, plateauing to approximately 100 pg/ml/30 min. No significant alterations in pineal melatonin release were caused by exposure to the MF when compared to sham exposure (< 1 micro T). These results suggest that if the circadian system is acutely responsive to MF exposure of this nature, an intact circadian axis may be necessary in order to observe an effect on the production on melatonin from the pineal gland

Comparing performances of logistic regression and neural networks for predicting melatonin excretion patterns in the rat exposed to ELF magnetic fields

“…The value of the cutoff should be optimized using a trial-and-error procedure. In our study, we used LR with variable selection method to predict melatonin excretion Tripp et al [2003] patterns in the rat exposed to ELF-MF. A tolerance filter of 0.5 was also used to avoid multicollinearity, and thus avoid the mutually correlated variables being incorporated into the final regression equation.…”

Influence of Electric, Magnetic, and Electromagnetic Fields on the Circadian System: Current Stage of Knowledge

“…A reduction in isoproterenol-stimulated melatonin secretion and activity of arylalkylamine N-acetyltransferase has also been found in studies of rat pinealocytes after exposure to ELF-MF [96, 97]. On the contrary, Lewy et al [98] noted increased activity of melatonin-synthetizing enzymes, while Tripp et al [99] found no changes in melatonin secretion in rat pinealocytes in response to ELF-MF.…”

“…In vitro studies concerning the effect of electromagnetic fields on melatonin secretion were conducted on the pineal glands of Djungarian hamsters [95, 100] and rats [96–99]. The results of experiments with hamster pineals in the superfusion organ culture demonstrated that ELF-MF with an intensity of 86  μ T and a frequency of 16.67 or 50 Hz caused a decrease in melatonin secretion, activated by isoproterenol [95].…”

Effect of extremely low frequency electromagnetic fields on brain activity

“…Various in vivo, in vitro, human experimental and epidemiological studies carried out to identify effects of electromagnetic fields on melatonin are reviewed in as shown in table 1 and 2. [12] REVIEW ARTICLE Table-1: Studies of the effects of magnetic fields on melatonin production Exposure Effect 'Ion-cyclotron resonance' for calcium [13] NA stimulation of melatonin production and release reduced 50 μT, 60Hz for 12 h [14] NA stimulation of melatonin release reduced 1 mT, 50Hz for 1 h [15] NAT activity decreased 86 μT, 50Hz or 16.67 Hz for 8 h [16] Isoproterenol stimulation of melatonin production reduced 1 mT, 50Hz for 4h [17] NA stimulation of melatonin release increased 0.5 mT, 50 Hz for 4h [18] No effect on melatonin release [19,20] EMF exposure partially blocked melatonin (10 -9 M) inhibition in MCF-7 cells, Similar result with tamoxifen (10 -7 M) 1.2 μT, 60Hz for 7 days [21] EMF exposure partially blocked temoxifen (2.5 10 -8 M) inhibition of MCF-7 cells 1.2 or 100 μT, 50Hz for 7 days [22] Inhibition of DNA synthesis by melatonin (10 -11 M) partially blocked by 1.2 µT EMF exposure. 100 µT blocked cAMP inhibition by melatonin (10 -9 M) in MCF-7 celss 0.3 mT pulsed for 20ms at 2 Hz for 1 h repeated over 3 days [23] Growth of MCF-7 cells unaffected…”