Effects of 60 Hz electric and magnetic fields on maturation of the rat neopallium

Abstract

This study was undertaken to determine the effects of extremely low frequency (ELF; 60 Hz) electromagnetic (EM) fields on somatic growth and cortical development, as well as biochemical and morphological maturation, of the rat neopallium. On the fifth day of pregnancy, female rats were put in pairs into plastic cages that were housed in a specially constructed apparatus for irradiation under three separate sets of combination and intensity: 1) 1 kV/m and 10 gauss; 2) 100 kV/m and 1 gauss; and 3) 100 kV/m and 10 gauss. The dams were exposed for 23 h daily, from days 5 through 19 postconception, after which they were returned to cages outside the exposure apparatus until they littered. The neonates were culled to eight pups per litter. At 0 (birth), 5, 12, and 19 days postnatally, they were killed for biochemical and morphological studies. Another group of pregnant rats was sham-exposed in an identical apparatus, which was not energized, and the pups were used as controls. The irradiated rats exhibited no physical abnormalities, nor did they show brain deformities such as swelling or herniation following exposure to ELF-EM fields. There was no difference in somatic growth between control and exposed rats, but a small reduction in cortical weight was observed in rats exposed at 1 kV/m and 10 gauss, and 100 kV/m and 1 gauss, respectively. Biochemical measurements of DNA, RNA, protein, and cerebroside concentrations indicated that among the three separate exposures, only the neopallium of rats exposed at 1 kV/m and 10 gauss showed a small reduction in DNA level, as well as small reductions in RNA and protein levels. No changes were noticed in cerebroside levels in any exposed animals, and there were no differences in protein/DNA and cerebroside/DNA ratios between control and exposed rats. Morphological observations did not reveal any detectable alterations in the irradiated rats. These results indicate that exposure to ELF-EM fields caused minimal or no changes in somatic growth and cerebral development of the rat.

Developmental effects of electromagnetic fields

“…A few studies have been conducted to assess postnatal effects of in utero exposure to ELF fields. Although some changes have been reported in performing an operant task [Salzinger et al, 1990], territorial scent-marking behavior and accessory sex organ weights [McGivern et al, 1990], and brain DNA, RNA, and protein concentrations after combined electric and magnetic field exposures Yu et al, 1993], the results generally show no gross impairment of postnatal development or behavior. Effects of a 50 Hz, 20 mT magnetic field on postnatal development and behavior of prenatally exposed CD1 mice were studied by Sienkiewicz et al [1994].…”

Exposure to power frequency magnetic fields and X‐Rays induces GAP‐43 gene expression in human glioma MO54 cells

“…Therefore, GAP-43 may be a good biological marker for development and growth stimulation of cells in brain tissues. It has been reported that electromagnetic fields can alter biological cell proliferation [Heredia-Rojas et al, 2001], but exposure to electromagnetic fields does not seem to cause changes in somatic growth and cerebral development [Yu et al, 1993]. There has been only one article reporting the effect of exposure to an ELFMF on GAP-43 transcription, in which the magnetic field at a density of 2, 200, and 1000 mT did not affect the GAP-43 expression in rat brain tissues in vivo [Harry et al, 2000].…”

Neurodevelopmental anomalies of the hippocampus in rats exposed to weak intensity complex magnetic fields throughout gestation

“…Consistent with these findings, the application of simple invariant (“temporally symmetric”) field patterns, such as sinusoidal or rectangular pulses, are generally ineffective in altering prenatal development unless much higher intensities are used. This important distinction between the waveform pattern and field strength could account for some of the contradictory evidence presented in the literature concerning the teratogenic effects of magnetic field exposure on foetal CNS development (Juutilainen et al, 1986; Ubeda et al, 1983; Wiley et al, 1992; Yu et al, 1993).…”

“…presented in the literature concerning the teratogenic effects of magnetic field exposure on foetal CNS development (Juutilainen et al, 1986;Ubeda et al, 1983;Wiley et al, 1992;Yu et al, 1993).…”

“…Although minimal or nonsignificant teratogenic effects on the CNS have been reported (Hoyer et al, 2012; Wiley et al, 1992; Yu et al, 1993), it appears that the specific parameters of the applied field (i.e., waveform) may be one of the most important factors to consider in the study of teratogenesis. For instance, sinusoidal or square‐wave pulses can be harmful to CNS growth and development but typically require field strengths on the order of a millitesla or higher to produce reliable effects (Gona et al, 1993; Juutilainen et al, 1986; Lahijani et al, 2011; Sikov et al, 1984; Ubeda et al, 1983).…”