Douglas Institute: A new study published by the team of Naguib Mechawar, Ph.D., a researcher with the McGill Group for Suicide Studies (MGSS) of the Douglas Institute (CIUSSS de l’Ouest-de-l’Île de Montréal) and Associate Professor in the Department of Psychiatry at McGill University, sheds new light on the disruption of astrocytes in depression. Astrocytes, a class of non-neuronal cells, have previously been implicated in depression and suicide. However, it was not known whether these cells were affected throughout the brain or only in certain regions.
This research provides evidence that networks of astrocytes are
altered specifically in areas of the brain associated with mood
regulation. In addition, in describing the existence of new subtypes of
astrocyte, this study reveals features specific to the human brain.
The diversity and functional and morphological complexity of cortical
astrocytes in humans, as well as their involvement in normal and
pathological brain function, have only recently begun to be recognized.
In particular, accumulating data generated by the MGSS and other
independent research groups have indicated an abnormal regulation of
astrocytic genes in the prefrontal cortex of patients who died while
suffering from depression.
Breaking new ground
This work, carried out by MGSS doctoral candidates Susana Gabriela
Torres-Platas and Corina Nagy, breaks new ground. Based on the analysis
of postmortem brain samples from the Douglas-Bell Canada Brain Bank, it
demonstrates that the expression of the astrocyte-specific marker GFAP,
which is significantly decreased in the prefrontal cortex of depressed
suicides compared to that of healthy controls, is normal in other
cortical areas that are not traditionally associated with depression,
such as the visual cortex.
However, GFAP expression was also found to be decreased in
subcortical brain regions that are interconnected to the prefrontal
cortex or that were previously implicated in mood disorders. “Within
these subcortical regions, in samples from both patients and healthy
individuals, we also observed astrocytes that were larger and more
complex than those seen in cortical areas. We are currently analyzing
these cells to better understand their unique properties in the human
brain. I am convinced that it is important to describe how the human
brain is organized at the microscopic level, and how this organization
is altered in depression, in order to better understand the biological
causes of this illness. This should help develop new therapeutical
targets,” explains Dr. Mechawar. This study appears today in the journal
This work was funded by the Canadian Institutes of Health Research
(CIHR) and the Fonds de recherche du Québec-Santé (ERANET-NEURON).