EFFECTS OF 60 HZ ELECTRIC AND MAGNETIC-FIELDS ON THE DEVELOPMENT OF THE RAT CEREBELLUM

The effects of extremely low frequency (ELF) electromagnetic (EM) fiel ds on the maturation of the rat cerebellum were studied. Newborn rats were exposed to 60 Hz electric and magnetic fields under three differe nt combinations in a specially constructed apparatus. The pups were ir radiated for 7-8 h daily, with a 30-min interruption for nursing. Pups were kept with their mothers for the remainder of the time. After app roximately 1, 2, or 3 weeks of exposure, the pups were killed. Control pups were sham exposed. The somatic growth of the irradiated rats did not show any significant difference from sham-exposed controls. At 1 kV/m and 10 gauss exposure, there was a small but statistically signif icant decrease in cerebellar mass. In rats exposed at 1 kV/m and 10 ga uss, DNA and RNA levels were significantly higher than those in sham-e xposed controls at 6 and 13 days of age, but at 20 days, these two bio chemical constituents were similar in both groups of rats. The ELF-EM treatment had no effect on protein and cerebroside concentrations. In terms of age effects, DNA and RNA exhibited increases from 6 to 13 day s of age, and declined from 13 to 20 days. Protein and cerebroside lev els exhibited increases during the 6-20-day periods. In rats exposed a t 100 kV/m and 1 gauss, the DNA levels were initially less than those of sham-exposed controls at 8 days of age, reached approximately the s ame levels at 14 days, and then were higher than those of controls at 22 days. There was, therefore, a significant ELF-EM effect as well as a significant interaction between age and ELF-EM exposure. In terms of age effects, DNA levels for both control and exposed animals increase d from 8 to 14 days. From 14 to 22 days, DNA levels of exposed rats co ntinued to increase while those of the controls decreased. This age ef fect was significant. RNA levels in both groups of animals showed incr eases from 8 to 14 days of age but the increase was less for the irrad iated animals than for the controls. From days 14 to 22, RNA levels fo r both groups showed a reduction, but the decrease was greater in the irradiated than in control rats. ELF-EM treatment significantly reduce d protein levels at S days of age but at 14 to 22 days, protein levels of exposed rats were higher than those of controls. The cerebroside l evels were not affected by exposure treatments but increased with the age of the animals. Exposure to 100 kV/m and 10 gauss did not exert an y effect on the concentrations of DNA, RNA, protein, and cerebroside a t all three time points examined. Both DNA and RNA exhibited increases with age from 6 to 13 days, and leveled off from 13 to 20 days. Prote in and cerebroside levels also showed corresponding increases with the age of the animals. Morphological observations revealed no detectable changes in the irradiated animals in any experimental group. Thus, on ly biochemical studies indicate that exposure at certain ELF-EM field combinations induces alterations in cerebellar maturation. These chang es were clearly detectable in the early postnatal period but gradually diminished with time. (C)1993 Wiley-Liss, Inc.