Widespread Decrease of Cerebral Vimentin-Immunoreactive Astrocytes in Depressed Suicides.

Area of Science:

• Neuroscience
• Neurobiology
• Psychiatry

Background:

• Post-mortem studies suggest glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes are involved in depression and suicide.
• It is unknown if other astrocyte subpopulations, like vimentin (VIM)-immunoreactive astrocytes, are similarly affected in these conditions.
• VIM-IR astrocytes have different regional densities than GFAP-IR astrocytes in healthy brains, suggesting potential distinct alterations in depression.

Purpose of the Study:

• To compare densities of GFAP-IR and VIM-IR astrocytes in post-mortem brain samples from depressed suicides and controls.
• To quantitatively assess the fine morphology of VIM-IR astrocytes in these groups.
• To evaluate CD31-IR blood vessel densities in relation to astrocytic changes.

Main Methods:

• Post-mortem brain tissue analysis from depressed suicides and matched non-psychiatric controls.
• Immunohistochemical comparison of GFAP-IR and VIM-IR astrocyte densities in the dorsomedial prefrontal cortex, dorsal caudate nucleus, and mediodorsal thalamus.
• Quantitative morphological analysis of VIM-IR astrocytes and assessment of CD31-IR blood vessel densities.

Main Results:

• VIM-IR astrocyte densities were globally reduced in depressed suicides compared to controls, similar to GFAP-IR astrocytes.
• CD31-IR blood vessel density and VIM-IR astrocyte morphology were largely similar between groups.
• An exception was observed in prefrontal white matter, showing increased vascularization and astrocytes with fewer primary processes in suicides.

Conclusions:

• A widespread reduction in cerebral VIM-IR astrocytes is observed in depressed suicides.
• These findings reinforce the implication of astrocytic dysfunction in the pathophysiology of depression and suicide.
• Specific alterations in prefrontal white matter vascularization and astrocyte morphology warrant further investigation.