Working with Nelson, Gammie showed last year that the genetic change had the opposite effect on females, decreasing their aggression when they were exposed to strange males after giving birth.
In the new experiments, funded by the National Institutes of Health and the National Institute of Mental Health, Gammie and Nelson exposed normal, non-altered mouse moms to strange males and tested their brains for transcription factors known as pCREB and cFOS. Both pCREB and cFOS have been linked to nerve cell activity by other labs.
Some of the regions highlighted in the new experiment have shown up before in experiments by Gammie and other researchers.
For example, the paraventricular nucleus has been linked to aggression in related research into the behavior of prairie voles. Voles are also rodents and look like a stout mouse or rat, but are more closely related to lemmings and muskrats than to mice. The paraventricular nucleus is located in the hypothalamus, a brain area where environmental stimuli are integrated with internal signals from the brain, and a response to the stimuli begins to be produced.
"We're not there yet, but the pieces of the puzzle are starting to come together," Gammie says. With a list of likely suspects based on the research of Gammie and others, neuroscientists can begin to consider more precise pharmacological manipulation of the brain to zero in on the brain circuitry that produces aggression.
"Maternal aggression occurs in almost all mammals. It is a highly adaptive behavior because it helps keep offspring aliv
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Contact: Michael Purdy
mcp@jhu.edu
410-516-7160
Johns Hopkins University
7-Nov-2000