Rapid effects of estrogens on behavior: Environmental modulation and molecular mechanisms

• Estrogens can regulate behavior through rapid nongenomic mechanisms or through slower genomic mechanisms.
• Environmental cues such as photoperiod can modulate whether estrogens activate nongenomic or genomic pathways.
• This flexibility allows a single hormone molecule, such as estradiol, to have diverse effects on a range of social behaviors.

Estradiol can modulate neural activity and behavior via both genomic and nongenomic mechanisms. Environmental cues have a major impact on the relative importance of these signaling pathways with significant consequences for behavior. First we consider how photoperiod modulates nongenomic estrogen signaling on behavior. Intriguingly, short days permit rapid effects of estrogens on aggression in both rodents and song sparrows. This highlights the importance of considering photoperiod as a variable in laboratory research. Next we review evidence for rapid effects of estradiol on ecologically-relevant behaviors including aggression, copulation, communication, and learning. We also address the impact of endocrine disruptors on estrogen signaling, such as those found in corncob bedding used in rodent research. Finally, we examine the biochemical mechanisms that may mediate rapid estrogen action on behavior in males and females. A common theme across these topics is that the effects of estrogens on social behaviors vary across different environmental conditions.