Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scripps research scientists discover chemical triggers for aggression in mice

10.12.2007
Work could help unravel general neurological basis for behaviors

The work, reported in an advance, online issue of the journal Nature on December 6, 2007, furthers the broad and important goal of elucidating how the neurological system can detect and respond to specific cues in of a sea of potential triggers.

“These results are a really exciting starting place for us to understand how pheromones and the brain can shape behavior,” says team leader Lisa Stowers of the Scripps Research Department of Cell Biology.

Pheromones are chemical cues that are released into the air, secreted from glands, or excreted in urine and picked up by animals of the same species, initiating various social and reproductive behaviors.

“Although the pheromones identified in this research are not produced by humans, the regions of the brain that are tied to behavior are the same for mice and people,” says James F. Battey, Jr., director of the National Institute on Deafness and Other Communication Disorders (NIDCD) of the National Institutes of Health, which provided funding for the study. “Consequently, this research may one day contribute to our understanding of the neural pathways that play a role in human behavior. Much is known about how pheromones work in the insect world, but we know very little about how these chemicals can influence behavior in mammals and other vertebrates.”

The Complex Puzzle of Brain Function

Identifying the chemical pathway of signals that make their way through the neurological system is not easy. One of the challenges for scientists studying brain circuits is that the brain is constantly changing. How a brain detects and then responds to the scent of a particular food, for instance, evolves as the animal learns about that food.

But certain behaviors such as aggression responses between male mice tend to be the same each time they are triggered, suggesting a steady pathway through neurological circuits. So, the Stowers group has focused a research program on understanding the aggression pathway as a general model for brain response.

As a first step in the current study, the group sought to identify specific chemical triggers for aggression in mice, which other researchers had shown involved urine. The Stowers group separated out several classes of chemicals within the urine, then individually swabbed each class onto the backs of castrated mice to determine which could spark an aggressive response by another male. Castrated males lose the ability to elicit aggression on their own, so any such response could be attributed to the added chemicals.

Using this experimental setup, the researchers were able to show specific compounds triggered aggression. Upon examination, the scientists found that these compounds fell into two distinct chemical groups-low molecular weight and high molecular weight proteins.

Particularly intriguing were the high molecular weight compounds, as few high molecular weight compounds exist in urine and none had ever before been shown to act as pheromones. The Stowers group focused on these for the remainder of the study.

Tracing Phermones’ Path

Next, the Stowers lab sought to discover the effect of these high molecular weight compounds on two neurological organs that could potentially convey the pheromone signals to the brain. The first, called the vomeronasal organ (VNO), is located above the roof of the mouth in the nasal cavity. The second is the main olfactory epithelium (MOE), found under the eyeball at the top back portion of the nasal cavity.

Which of these two organs is the main starting point for the aggression pathway is somewhat controversial. Stowers' group had shown in past work that mice genetically altered to lack the VNO did not have aggression responses, suggesting this organ plays a key role, but other researchers had made similar findings with knockout mice lacking the MOE.

To further explore this aspect of signal processing, the Stowers team used an assay of their own design that allows the isolation of individual VNO neurons and MOE neurons and measurement of their firing in response to a given chemical cue. The researchers found that, when exposed to high molecular weight compounds, VNO neurons fired indicating that these are the sensory neurons that mediate aggressive behavior. Moreover, the group was able to provide details about both specific neurons and compounds, and further, identify the subset of VNO neurons that fired in response to four specific high molecular weight proteins acting together.

Stowers adds that while the work elucidates the VNO vs. MOE debate, the current study does not settle it, because the yet-to-be-tested low molecular weight compound class could function via the MOE instead of the VNO. This could make sense because the smaller compounds are more easily volatilized, making it easier for them to reach the MOE, which resides much farther back in the nasal cavity than the VNO.

Interestingly, the four high molecular weight pheromone compounds isolated are from a much larger class of proteins, but an individual mouse only produces four, and the combinations produced differs among individuals. In the past, this four-protein signature was thought to be random, but Stowers says it is possible that different combinations of the proteins could code for different responses.

Keith McKeown | EurekAlert!
Further information:
http://www.scripps.edu

Further reports about: Aggression Chemical MOE Pheromone Stowers VNO neurological neurons triggers urine

More articles from Life Sciences:

nachricht Nonstop Tranport of Cargo in Nanomachines
20.11.2018 | Max-Planck-Institut für molekulare Zellbiologie und Genetik

nachricht Researchers find social cultures in chimpanzees
20.11.2018 | Universität Leipzig

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

When AI and optoelectronics meet: Researchers take control of light properties

20.11.2018 | Physics and Astronomy

Researchers use MRI to predict Alzheimer's disease

20.11.2018 | Medical Engineering

How to melt gold at room temperature

20.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>