Effects of 17 b-estradiol and extremely low-frequency electromagnetic fields on social recognition memory in female rats: a possible interaction?

We have investigated a potential memory-enhancing effect of exposure to extremely low-frequency electromagnetic fields (ELF EMF) in female rats and its dependence on estrogen, using a social recognition task. A juvenile social recognition paradigm was used and memory retention tested at 30 and 300 min after an adult was exposed to a juvenile during two 4-min trials. Results showed that an intact social recognition memory was present at 30 min in both gonadally intact and ovariectomized rats with, or without, ELF-EMF. However, whereas gonadally intact control females failed to show retention of the recognition memory at 300 min, those additionally exposed to ELF EMF did. This shows that the enhanced duration effect of ELF EMF on social recognition memory occurs in gonadally intact females as well as in males. In addition, results showed that the ELF EMF facilitation of memory retention was prevented by ovariectomy but restored by exogenous treatment with estrogen. This suggests that this ELF EMF effect on social recognition memory is estrogen-dependent.