Extremely low-frequency electromagnetic fields differentially regulate estrogen receptor-alpha and -beta expression in the rat olfactory bulb med./bio.

To study the effects of extremely low frequency electromagnetic fields on olfactory bulb estrogen receptor alpha and beta expression in adult female and male rats (in order to investigate the interaction between extremely low frequency electromagnetic fields and estrogens that underlies the improvement of sociaI recognition memory).

Estrogen receptors are located in many regions of the adult rat nervous system. In addition to their role in reproductive function, estrogens are implicated in nonreproductive functions such as learning, memory, and social recognition.
Animals were anaesthetized, then sacrificed (n =4-6/group) during proestrous, estrous, metestrous, diestrous phase. A further group of females were bilaterally ovariectomized (in order to avoid changes in 17-beta-estradiol concentrations), and 14 days later they received either 17-beta-estradiol replacement or an oil vehicle, administered daily (1 h prior to exposure) for 9 consecutive days. Additional males (n=9) were also studied.

• animal
• rat/Wistar
• whole body

Extremely low frequency electromagnetic field exposure exerted a biphasic effect on female olfactory bulb estrogen receptor beta gene expression, which increased during diestrous and decreased during estrous cycle. There was no influence of extremely low frequency electromagnetic fields on female estrogen receptor alpha expression.
The data demonstrated a fluctuating pattern of estrogen receptor alpha and beta gene expression in the female olfactory bulb throughout the phases of the estrous cycle in non-exposed animals.
The expression profile of estrogen recetor beta did not show any differences between ovariectomized- and "ovariectomized + 17-beta-estradiol"-electromagnetic field exposed rats. In the last-mentioned group, estrogen receptor beta expression was significantly different than the expression level in proestrous and estrous electromagnetic field exposed animals. The authors suggest that besides 17-beta-estradiol, there are other factors involved in electromagnetic field effects on estrogen receptor beta expression.
Estrogen receptor alpha and beta expression level in the male olfactory bulb did not exhibit any variation either in exposed or sham exposed animals.
In summary, extremely low frequency electromagnetic field exposure modulated estrogen receptor beta gene expression in the olfactory bulb of female adult rats but not in males. The authors suppose that mechanisms other than estrogenic are involved in social recognition in male rats.