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.
George Hunka | EurekAlert!
Chips, light and coding moves the front line in beating bacteria
16.08.2018 | Okinawa Institute of Science and Technology (OIST) Graduate University
Protein droplets keep neurons at the ready and immune system in balance
16.08.2018 | Howard Hughes Medical Institute
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
16.08.2018 | Earth Sciences
16.08.2018 | Life Sciences
16.08.2018 | Materials Sciences