The results showed that the alpha receptor played a key role in increasing aggression in short days and decreasing aggression in long days.
"So the differences in how estrogen affected behavior in long days compared to short days could not be explained by the hormone using different receptors in different times of year," Trainor said.
So how did estrogen have opposite behavioral effects depending on seasonal light conditions?
The researchers generated another hypothesis by using microarrays, small chips that examine thousands of genes at a time to see which ones are active. They compared genes from mice living in winter-like short days with those living under longer day lengths. The results showed that certain genes associated with estrogen were more active in the long-day mice than in the short-day mice.
That suggested estrogen works in mice living in long days through these specific genes, creating a genomic pathway leading to less aggressive behaviors, Trainor said.
The flip side of this finding is that estrogen increases aggression in short-day mice through different cellular mechanisms not involving genomic pathways.
While it would be difficult to test that hypothesis directly, neuroscientists know that when hormones work through genomic pathways, behavioral effects can take hours, days or even weeks to occur. But neuroscientists believe that when hormones send messages to cells outside of this gene-controlled network, behavior can change in minutes.
So in another study, the researchers injected short-day and long-day mice with estradiol, a type of estrogen. The findings showed that the injection increased aggression in mice in winter-like short days almost immediately. It had no noticeable immediate behavioral effect on the mice living in longer day lengths.
Overall, then, these studies showed estrog
Source:Ohio State University