Navigation Links
Scripps research scientists discover chemical triggers for aggression in mice
Date:12/6/2007

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.


'/>"/>

Contact: Keith McKeown
kmckeown@scripps.edu
858-784-8134
Scripps Research Institute
Source:Eurekalert

Related medicine news :

1. Scripps Research scientists shed new light on how antibodies fight HIV
2. Scripps Health Treats More Than 160 Fire Victims at Emergency Departments Across San Diego County
3. Stanford researchers find culprit in aging muscles that heal poorly
4. Children of depressed moms do better when dad is involved, SLU researcher finds
5. UCLA researchers identify markers that may predict diabetes in still-healthy people
6. Mayo Clinic researchers discover new diagnostic test for detecting infection in prosthetic joints
7. New research shows how chronic stress worsens neurodegenerative disease course
8. New research explores newborn in-hospital weight loss
9. Research may unlock mystery of autisms origin in the brain
10. Bipolar disorder relapses halved by Melbourne researchers
11. HIVs impact in Zimbabwe explored in new research
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/16/2017)... ... January 16, 2017 , ... ... Dental Center, is currently offering complimentary consultations and financing for orthodontics for a ... for bite irregularities and learn about their orthodontic options. Walk-in, late-evening, Saturday, and ...
(Date:1/16/2017)... ... 2017 , ... Permobil has just completed the acquisition of ... systems has a well-earned reputation for premium quality, with a focus on fit ... in the custom seating business, which enjoys strong demand, and it complements Permobil’s ...
(Date:1/16/2017)... ... 16, 2017 , ... Atlanta-based incentive company Incentive Solutions ... wheelchair accessibility industry, BraunAbility . Incentive Solutions will provide BraunAbility a debit ... With this new incentive plan, BraunAbility plans to continue their tradition of excelling ...
(Date:1/16/2017)... (PRWEB) , ... January 16, 2017 , ... ... editor, attorney, science teacher, http://www.ageofautism.com/legal , Sharon Kleyne, America’s leading water ... Heckenlively to her nationally syndicated radio program, The Sharon Kleyne Hour Power of ...
(Date:1/16/2017)... ... 2017 , ... In 1985, the International Association of Eating ... an international multidisciplinary group of healthcare treatment providers and helping professions who treat ... mission at the grassroots level, iaedp launched MemberSHARE, an online peer community solely ...
Breaking Medicine News(10 mins):
(Date:1/16/2017)...  This report by Persistence Market Research examines ... the period 2016–2024. The primary objective of the ... to market opportunities in the global peripherally inserted ... the various dynamics that are expected to influence ... global peripherally inserted central catheters market over the ...
(Date:1/16/2017)... 16, 2017 Derek H. Potts , ... was recently appointed Liaison Counsel in California,s ... Xarelto cases. In this role, Potts was assigned to ... actively assist the Court and Co Lead Plaintiff,s Counsel. ... Adelman Jackson Fairchild & Wade and Ruth ...
(Date:1/16/2017)... ROCKVILLE, Md. , Jan. 16, 2017 /PRNewswire/ ... tomography (CT) systems market is valued at $4.9 ... applications for CT, coupled with an aging population ... incidence of chronic disease, is propelling the market ... report, Computed Tomography Markets , focuses on ...
Breaking Medicine Technology: