WEDNESDAY, Oct. 18, 2006 (HealthDay News) -- A study in mice suggests a connection between sunlight, estrogen and aggression in male mammals.
During short winter days, estrogen prompts male Oldfield mice to be more aggressive, but the hormone decreases aggression during long summer days, says a team from Ohio State University.
Oldfield mice are commonly found in the southeastern United States.
"We found that estrogen has totally opposite effects on behavior in these mice, depending only on how much light they got each day. It was quite a surprising finding," study co-author Brian Trainor, a postdoctoral fellow in psychology and neuroscience, said in a prepared statement.
The study is one of only a few that have shown how hormones other than testosterone influence aggression in mammals.
"This goes against the common belief that testosterone is the hormone that regulates aggression. There are now several studies showing that, in some species, estrogen plays a key role in aggressiveness as well," study co-author Randy Nelson, a professor of psychology and neuroscience, said in a prepared statement.
The study was presented Wednesday at the Society for Neuroscience annual meeting, in Atlanta.
This line of research could help scientists better understand a number of human issues, including aggression and the role of estrogen in promoting cancer.
The Hormone Foundation explains the endocrine system.