Featured Research

from universities, journals, and other organizations

Brain Compound's Anti-Aggression Effects Appear To Reverse In Monogamous Male Rodents

Date:
October 26, 1999
Source:
Johns Hopkins University
Summary:
The latest results from a line of Johns Hopkins research on the role of nitric oxide in the brain show that the chemical, which dampens aggression in male mice, has the reverse impact in a monogamous species of rodent.

EMBARGOED FOR RELEASE ON TUESDAY, OCT. 26

Related Articles


The male prairie vole's interest in defending his pups, an oddity in male rodents, may come in part from his brain's production of a compound linked to aggressive behavior in mice, according to new results from researchers at The Johns Hopkins University.

Scientists found evidence suggesting that the male vole's brain chemistry more closely resembles nursing mouse females than it does his feckless male mouse counterparts, an intriguing possibility that could help researchers begin to tease apart some of the complex biochemical roots of mating-related behaviors.

"By focusing on these specialized behaviors, we're starting to pick up on some important similarities in the ways they may be triggered," says Stephen Gammie, a postdoctoral fellow in the Psychology Department at Hopkins. "When they and their pups are approached by a stranger, both the male vole and the female mouse with pups experience increased production of a compound called citrulline in the brain."

Citrulline is a byproduct of the reaction brain cells use to produce the messenger compound nitric oxide, which suggests that nitric oxide plays a role in turning on these forms of aggression.

Hopkins scientists began to investigate nitric oxide's relationship to aggressive behavior four years ago, when they found that a line of genetically engineered mice produced to study brain damage from stroke had suffered an unexpected side effect. The males among the mice were unusually aggressive, relentlessly attacking other males and ignoring female rejection of attempts to mate.

Researchers had given the mice a damaged form of the gene for a protein known as nitric oxide synthase, theoretically leaving the mice with little or no nitric oxide in their brains.

Earlier this year, researchers studied the effects of the modification on female mice. Instead of gaining increased aggressiveness like the males, the females lost their aggressive behavior in the one context where it normally showed up, when they were nursing pups and a strange male mouse came around, putting the pups in danger of an attack.

For the new study, scientists switched over to voles, which are also rodents and look like a stout mouse or rat, but are more closely related to lemmings and muskrats than to mice.

"Voles were interesting to us because, as in humans, the males are monogamous, and help take care of the pups they produce," says Gammie. "Also, while voles are relatively non-aggressive, previous research had shown that males experience a dramatic increase in aggression toward intruders after mating."

For the new study, Gammie and co-author Randy Nelson, a Hopkins professor of psychology and neuroscience, exposed mated and non-mated male voles and female voles with pups to intruders, and then examined the levels of citrulline in their brains.

They found consistently higher levels of citrulline in the mated males and females with pups, the animals that would aggressively confront a stranger. The increase was focused on an area of the brain known as the paraventricular nucleus.

"That area is located in the hypothalamus, a part of the brain where environmental stimuli are integrated with internal signals from the brain, and a response begins to be produced," Gammie says..

Researchers plan to see if they can suppress nitric oxide production in the voles with a drug. If so, they'll test to see if using this drug in mated male voles reduces their aggression levels. Scientists may also test the possibility of links between nitric oxide and the monogamous behavior of the voles.

Gammie and Nelson's research was funded by grants from the National Institutes of Health and the National Institute of Mental Health. It is being presented at the annual meeting of the Society for Neuroscience in Miami Beach.


Story Source:

The above story is based on materials provided by Johns Hopkins University. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins University. "Brain Compound's Anti-Aggression Effects Appear To Reverse In Monogamous Male Rodents." ScienceDaily. ScienceDaily, 26 October 1999. <www.sciencedaily.com/releases/1999/10/991022100223.htm>.
Johns Hopkins University. (1999, October 26). Brain Compound's Anti-Aggression Effects Appear To Reverse In Monogamous Male Rodents. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/1999/10/991022100223.htm
Johns Hopkins University. "Brain Compound's Anti-Aggression Effects Appear To Reverse In Monogamous Male Rodents." ScienceDaily. www.sciencedaily.com/releases/1999/10/991022100223.htm (accessed October 25, 2014).

Share This



More Plants & Animals News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins