Featured Research

from universities, journals, and other organizations

Depressed fish could help in the search for new drug treatments

Date:
August 5, 2013
Source:
Max-Planck-Gesellschaft
Summary:
Antidepressant normalizes the behavior of zebrafish with a defective stress hormone receptor.

The zebrafish (Danio rerio) is a popular model organism for many questions in the field of genetics and developmental biology.
Credit: MPI f. Neurobiology

Antidepressant normalises the behaviour of zebrafish with a defective stress hormone receptor.

Chronic stress can lead to depression and anxiety in humans. Scientists working with Herwig Baier, Director at the Max Planck Institute of Neurobiology in Martinsried, recently discovered a very similar link in fish. Normally, the stress hormone cortisol helps fish, as in humans, to regulate stress. Fish that lack the receptor for cortisol as a result of a genetic mutation exhibited a consistently high level of stress. They were unable to adapt to a new and unfamiliar situation. The fishes' behaviour returned to normal when an antidepressant was added to the water. These findings demonstrate a direct causal link between chronic stress and behavioural changes which resemble depression. The findings could also open the door to an effective search for new drugs to treat psychiatric disorders.

In stressful situations, the body releases hormones in order to ready itself for a fight or flight reaction. But it is equally important for the hormone level to return to normal after a certain time. If that does not happen, chronic stress can result, a condition that is linked to depression and anxiety, among other things. Whether stress is a trigger or merely a side effect of such affective disorders remains unclear.

The indication of a causal relationship between stress and depression comes from totally unexpected quarters. An international team led by Herwig Baierfrom the Max Planck Institute of Neurobiology in Martinsried and the University of California in San Francisco observed that zebrafish suffering from chronic stress as a result of a genetic mutation showed signs of depression in behavioural tests. The zebrafish is a popular model organism for biological and medical research. So far, however, it has not been an obvious research object for the study of psychiatric disorders. This may be about to change.

"These mutant fish behaved very strangely when we moved them to a new aquarium," reports Herwig Baier. All animals experience stress upon moving to an unfamiliar environment. Being separated from members of their own species places the fish under added pressure. Zebrafish initially act withdrawn in this situation and swim around very hesitantly in the first few minutes. But ultimately, curiosity prevails, and they begin to investigate their new tank. However, the fish with the mutation had a particularly strong reaction to the isolation: they sank to the bottom of the tank and stayed completely still. They took an exceptionally long time to get used to the new environment.

An analysis of these "lethargic" fish showed that they had an extremely elevated concentration of the stress hormones cortisol, CRH and ACTH. "We therefore postulated that these fish were suffering from chronic stress and were exhibiting certain aspects of depressive or perhaps hyper-anxious behaviour," says Baier. To put this assumption to the test, the scientists added the antidepressant fluoxetine (marketed under the trade name Prozac, among others) to the water. Shortly afterwards, the fish's behaviour returned to normal.

What was it that made these fish so different? The scientists uncovered a mutation in the glucocorticoid receptor, which is present in almost all of the body's cells and which binds the hormone cortisol. Normally, when cortisol is bound to this receptor it restricts the release of the stress hormones CRH and ACTH. It is this regulating mechanism that enables humans and many animal species to cope with stress. In the type of fish the scientists examined, however, the glucocorticoid receptor was unable to function, and so the level of stress hormones remained high.

"Although there are a whole range of drugs available for depression, no one yet knows what the relationship is between their effect and the stress hormones," explains Herwig Baier. "Our findings provide the first evidence of a possible connection." Understanding the molecular and neurobiological relationships between stress regulation and affective disorders is important in the search for new treatments and drugs. The scientists' discovery is therefore also of interest to the pharmaceutical industry, given that the zebrafish could turn out to be a good model organism for a large-scale screen for new drugs.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. L Ziv, A Muto, P J Schoonheim, S H Meijsing, D Strasser, H A Ingraham, M J M Schaaf, K R Yamamoto, H Baier. An affective disorder in zebrafish with mutation of the glucocorticoid receptor. Molecular Psychiatry, 2012; 18 (6): 681 DOI: 10.1038/mp.2012.64

Cite This Page:

Max-Planck-Gesellschaft. "Depressed fish could help in the search for new drug treatments." ScienceDaily. ScienceDaily, 5 August 2013. <www.sciencedaily.com/releases/2013/08/130805112959.htm>.
Max-Planck-Gesellschaft. (2013, August 5). Depressed fish could help in the search for new drug treatments. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2013/08/130805112959.htm
Max-Planck-Gesellschaft. "Depressed fish could help in the search for new drug treatments." ScienceDaily. www.sciencedaily.com/releases/2013/08/130805112959.htm (accessed September 1, 2014).

Share This




More Health & Medicine News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Liberia Continues Fight Against Ebola

Liberia Continues Fight Against Ebola

AFP (Aug. 30, 2014) Authorities in Liberia try to stem the spread of the Ebola epidemic by raising awareness and setting up sanitation units for people to wash their hands. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
California Passes 'yes-Means-Yes' Campus Sexual Assault Bill

California Passes 'yes-Means-Yes' Campus Sexual Assault Bill

Reuters - US Online Video (Aug. 30, 2014) California lawmakers pass a bill requiring universities to adopt "affirmative consent" language in their definitions of consensual sex, part of a nationwide drive to curb sexual assault on campuses. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
New Drug Could Reduce Cardiovascular Deaths

New Drug Could Reduce Cardiovascular Deaths

Newsy (Aug. 30, 2014) The new drug from Novartis could reduce cardiovascular deaths by 20 percent compared to other similar drugs. 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