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 Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>