Featured Research

from universities, journals, and other organizations

Fat sand rats are SAD like us: Research shines a light on a mood disorder

Date:
November 9, 2010
Source:
American Friends of Tel Aviv University
Summary:
With her work on the Israeli desert inhabitant gerbil called the fat sand rat, a researcher has found new hope for the study of seasonal affective disorder and similar conditions. Her research indicates that her new test subjects are a more suitable model animal for the study of SAD than the rats and mice used previously.

New research suggests that the Fat Sand Rat (Psammomys obesus) is a more suitable model animal for the study of SAD than the rats and mice used previously.
Credit: Image courtesy of American Friends of Tel Aviv University

Saying goodbye to summer can be difficult for everybody. In some people the onset of winter triggers Seasonal Affective Disorder, or SAD, a mood disorder in which sufferers experience symptoms of depression. Happily, a special kind of gerbil exhibits remarkably similar reactions to SAD treatments as humans, opening a promising new channel for study and treatment of the common complaint.

With her work on the Israeli desert inhabitant gerbil called the Fat Sand Rat (Psammomys obesus), Prof. Noga Kronfeld-Schor of Tel Aviv University's Department of Zoology and her fellow researcher, Prof. Haim Einat of the University of Minnesota, have found new hope for the study of these and similar disorders. Her results, recently published in the International Journal of Neuropsychopharmacology, indicate that her new test subjects are more suitable model animal for the study of SAD than the rats and mice used previously.

Until now, Prof. Kronfeld-Schor explains, most research on the mechanisms of affective disorders was carried out on mice and rats. But this has been problematic in applying the research results to humans -- mice are nocturnal, while humans are diurnal. Clearly, when we conduct research of disorders like SAD which affect our circadian system, she says, our model animals should be diurnal as well.

Different as night and day

Most laboratory mice don't produce melatonin, a natural hormone produced by humans and other mammals during the night. Moreover, as nocturnal animals, mice and rats become more active at night, when melatonin levels are high, while humans are active during the day, when melatonin levels are now. For most biomedical research, Prof. Kronfeld-Schor explains, mice are excellent model subjects. But for affective disorders, which rely heavily on the human circadian system, she hypothesized that a diurnal mammal would provide a superior animal model.

To test this theory, Prof. Kronfeld-Schor and her fellow researcher put two groups of Fat Sand Rats through several experiments. First, to test the effect of the length of light exposure on the rats' emotional state, one group was exposed to long hours of light similar to that of the summer season, and the other to shorter hours of the winter length daylight. In several tests, the sand rats of the second group behaved in ways similar to depressed humans, exhibiting despair, reduced social interactions and increased anxiety.

Once the researchers established that Fat Sand Rats and humans had a similar reaction to light, the team explored whether common medications or other SAD therapies would be as effective in their rat population. These studies included a variety of medications commonly used to treat the disorder in humans, as well as a program of exposing the depressed sand rats to brighter light for one hour every morning or evening.

More than a placebo

According to Prof. Kronfeld-Schor, the results were surprising. The medications were effective in treating the sand rats' depression, but even more effective was the daily exposure to bright light in the mornings, a common treatment for human SAD. "Humans have been using this treatment for a long time," she explains, "but many of us thought that a large part of its success was based on the placebo effect. For the first time, we've found it to be effective in animals as well, which weakens the possibility of the placebo effect."

The breakthrough, says Prof. Kronfeld-Schor, is the discovery of a superior and viable animal model for studying affective disorders. Though several biological mechanisms for SAD have been proposed, they have not been scientifically proven. A good animal model to study the mechanisms of SAD will advance understanding of the disorder, help screen for effective treatments and allow for the development of new therapies.


Story Source:

The above story is based on materials provided by American Friends of Tel Aviv University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Tal Ashkenazy, Haim Einat, Noga Kronfeld-Schor. We are in the dark here: induction of depression- and anxiety-like behaviours in the diurnal fat sand rat, by short daylight or melatonin injections. The International Journal of Neuropsychopharmacology, 2008; 12 (01): 83 DOI: 10.1017/S1461145708009115

Cite This Page:

American Friends of Tel Aviv University. "Fat sand rats are SAD like us: Research shines a light on a mood disorder." ScienceDaily. ScienceDaily, 9 November 2010. <www.sciencedaily.com/releases/2010/11/101108140921.htm>.
American Friends of Tel Aviv University. (2010, November 9). Fat sand rats are SAD like us: Research shines a light on a mood disorder. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2010/11/101108140921.htm
American Friends of Tel Aviv University. "Fat sand rats are SAD like us: Research shines a light on a mood disorder." ScienceDaily. www.sciencedaily.com/releases/2010/11/101108140921.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com
What's To Blame For Worst Ebola Outbreak In History?

What's To Blame For Worst Ebola Outbreak In History?

Newsy (July 27, 2014) A U.S. doctor has tested positive for the deadly Ebola virus, as the worst-ever outbreak continues to grow. Video provided by Newsy
Powered by NewsLook.com
The New York Times Backs Pot Legalization

The New York Times Backs Pot Legalization

Newsy (July 27, 2014) The New York Times has officially endorsed the legalization of marijuana, but why now, and to what end? 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:
from the past week

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