Suspect list shortens for maternal aggression's brain origins

November 07, 2000

Scientists studying the origins of aggression have highlighted areas in the brains of mouse mothers that may generate fierce attacks on males who pose a potential threat to their pups.

The findings will be presented by Johns Hopkins University postdoctoral researcher Stephen Gammie at this week's annual meeting of the Society for Neuroscience in New Orleans. Gammie says the results are an important step towards pinning down the origins of this type of aggressive behavior in the mouse brain, an accomplishment that could help scientists better probe aggression's origins in humans.

To prevent strange male mice from harming their offspring, female mice with pups normally attack any such mouse who comes into their area. A few mouse moms, however, fail to show this response. Gammie divided mice into groups based on this distinction, compared the two groups for presence of compounds related to brain activity, and was able to identify four brain areas that were active in the aggressive moms but not in the non-aggressives.

Given the mouse brain's small size, cutting down the list of suspects for production of aggression might seem an unlikely or unimportant step. But even the humble mouse brain has sufficient structural and biochemical complexity to resist giving up its secrets easily, Gammie says.

"By taking advantage of natural variation in aggression, our study decreased the odds of confusing aggression control mechanisms with other areas of the brain activated when a strange male mouse approaches," says Gammie. "For example, areas of the brain that are involved in seeing and smelling the males become active in both groups of mouse moms. Areas that become active only in the aggressive moms have a good chance of being linked to production of the primary difference in behavior, the aggression."

Gammie's postdoctoral mentor, Hopkins psychology and neuroscience professor Randy Nelson, was one of a group of several Hopkins scientists who discovered a link five years ago between the brain neurotransmitter nitric oxide and aggression in male mice. In an attempt to greatly reduce or eliminate nitric oxide in the mice's brains, scientists had given them a defective copy of a gene involved in nitric oxide production. They found that this led to a dramatic increase in aggression levels among the male mice.

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 alive," Gammie says, noting that highly adaptive characteristics tend to be preserved by evolution. "If we gain a detailed understanding of the neural circuitry underlying maternal aggression in rodents, then it may be possible later on to use that information to help understand how maternal aggression is controlled in humans."
-end-
THE JOHNS HOPKINS UNIVERSITY
OFFICE OF NEWS AND INFORMATION
3003 N. Charles Street, Suite 100
Baltimore, Maryland 21218-3843
Phone: (410) 516-7160 / Fax (410) 516-5251


Johns Hopkins University

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.