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A new breed of permanently "cheerful" mouse is providing hope of a new treatment for clinical depression. TREK-1 is a gene that can affect transmission of serotonin in the brain. Serotonin is known to play an important role in mood, sleep and sexuality. By breeding mice with an absence of TREK-1, researchers were able to create a depression-resistant strain. The details of this research, which involved an international collaboration with scientists from the University of Nice, France, are published in Nature Neuroscience this week.

"Depression is a devastating illness, which affects around 10% of people at some point in their life," says Dr. Guy Debonnel, an MUHC psychiatrist, professor in the Department of Psychiatry at ³ÉÈËVRÊÓƵ and principal author of the new research. "Current medications for clinical depression are ineffective for a third of patients, which is why the development of alternate treatments is so important."

Mice without the TREK-1 gene ("knock-out" mice) were created and bred in collaboration with Dr. Michel Lazdunski, co-author of the research, in his laboratory at the University of Nice, France. "These knock-out mice were then tested using separate behavioural, electrophysiological and biochemical measures known to gauge 'depression' in animals," says Dr. Debonnel. "The results really surprised us; our knock-out mice acted as if they had been treated with antidepressants for at least three weeks."

This research represents the first time depression has been eliminated through genetic alteration of an organism. "The discovery of a link between TREK-1 and depression could ultimately lead to the development of a new generation of antidepressant drugs," noted Dr. Debonnel.

According to Health Canada and Statistics Canada, approximately 8% of Canadians will suffer from depression at some point in their lifetime. Around 5% of Canadians seek medical advice for depression each year, a figure that has almost doubled in the past decade. Figures in the U.S. are comparable, with approximately 18.8 million American adults (about 9.5% of the population) suffering depression during their life.

Funding for this research was provided by the CNRS (Centre National de la Recherche Scientifique) and the Canadian Institutes for Health Research (CIHR).

The Research Institute of the ³ÉÈËVRÊÓƵ Health Centre (RI MUHC) is a world-renowned biomedical and health care hospital research centre. Located in Montreal, Quebec, the institute is the research arm of the MUHC, a university health centre affiliated with the Faculty of Medicine at ³ÉÈËVRÊÓƵ. The institute supports over 500 researchers, nearly 1,000 graduate and postdoctoral students, and operates more than 300 laboratories devoted to a broad spectrum of fundamental and clinical research. The Research Institute operates at the forefront of knowledge, innovation and technology and is inextricably linked to the clinical programs of the MUHC, ensuring that patients benefit directly from the latest research-based knowledge. For further details visit .

The ³ÉÈËVRÊÓƵ Health Centre (MUHC) is a comprehensive academic health institution with an international reputation for excellence in clinical programs, research and teaching. The MUHC is a merger of five teaching hospitals affiliated with the Faculty of Medicine at ³ÉÈËVRÊÓƵ — the Montreal Children's, Montreal General, Royal Victoria, and Montreal Neurological Hospitals, as well as the Montreal Chest Institute. Building on the tradition of medical leadership of the founding hospitals, the goal of the MUHC is to provide patient care based on the most advanced knowledge in the health care field, and to contribute to the development of new knowledge.

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