Research establishes the effects of brain stimulation against depression

Studies developed in collaboration between researchers from Brazil and Canada, with support from FAPESP, seek to understand how patients who suffer from depression respond to stimulation of the region responsible for releasing hormones in the brain

How will patients with symptoms of depression respond to deep brain stimulation (DBS) in specific regions of the brain? Will this stimulation modify the response in laboratory animals subjected to stress? What changes will be related to the hormones produced in the region of the hypothalamus and hypophisis? These are questions that researchers Luciene Covolan from the Federal University of São Paulo (Unifesp) in São Paulo, and Clement Hamani, professor of neurosurgery at the University of Toronto (UofT) intend to answer in research developed in collaboration through the agreement signed in 2011 between FAPESP and the UofT.

The project was presented during the first symposium of FAPESP Week 2012, held in Toronto, Canada, October 17. The event includes three other meetings through October 24: at the Massachusetts Institute of Technology (MIT) in Boston (October 22), at the Woodrow Wilson International Center for Scholars, in Washington, DC (October 23) and at West Virginia University in Morgantown, WV (October 24).

Nearly one year ago, Covolan and Hamani adopted a model to study depression that involves the use of DBS in a region known as the pre-frontal cortex in rats subjected to constant chronic stress, with symptoms of depression. The conclusion of the initial experiments showed significant results in reducing anhedonia (inability to experience pleasure) – a sign of depression – was published in the journal Biological Psychiatry in 2012 and presented a new challenge: establishing the mechanisms involved in reducing the symptoms of depression by applying DBS.

Encouraged by the article’s reviewers and by the editor of the journal, the researchers decided to conduct additional tests that led to the identification of cortisol (or cortisone) as the principal substance involved in the cellular mechanism by which electric current, when applied to certain regions of the brain of experimental animals results in a reduction of symptoms of depression. The idea is to establish how this mechanism works.

In the new project, the scientists will analyze the response to the treatment that uses DBS in the brain region known as the hypothalamus-hypophisis axis, responsible for the release of hormones. “We’re going to study the system that is involved in stress, the state whereby the brain produces higher amounts of cortisol,” explains professor Hamani. “That will enable us to understand how the hormones behave and how changes occur in depression.”

The project will be developed by teams of three researchers in São Paulo and two in Toronto. Unifesp researchers will conduct experiments on stress developed in São Paulo at the University of Toronto and the Canadian team will conduct the experiments using DBS in the laboratory of the São Paulo School of Medicine.