Electromagnetic fields enhance chemically-induced hyperploidy in mammalian oocytes

Epidemiological studies suggest that exposure to electromagnetic fields (EMFs) in the environment may be associated with mutagenic changes, but the relation between EMF exposure and aneuploidy has not previously been studied. Environmental EMFs apparently lack the energy necessary to function as aneugens, but the possibility exists that EMFs could influence the incidence of aneuploidy synergistically because EMFs can activate the neuroendocrine system, and ovulation and oocyte meiotic maturation are under neurohormonal control. This hypothesis was tested by examining the effect of EMF exposure on the occurrence of hyperploidy in mouse oocytes induced by vinblastine sulphate (VBS), which was employed as a surrogate for aneugens in the environment. The incidence of hyperploidy in metaphase II oocytes of individual mice following superovulation was determined, and statistical methods were developed to assess whether EMF exposure during oogenesis in the presence of VBS altered the rate of hyperploidy. A significant effect of EMF exposure on VBS-induced hyperploidy was found (P < 0.05). The data suggested that the EMF primarily affected the mice that exhibited a high incidence of VBS-induced hyperploidy. Exposure had no effect on the number of oocytes ovulated nor on the occurrence of hypoploidy. The results support the hypothesis that EMF exposure can promote the occurrence of aneuploidy caused by an aneugen via a mechanism involving the neuroendocrine system.