Glial, Not Neuronal, Deficits May Cause Depression
The brain consists of 12 billion neurons and four times as many glial cells. Neurons conduct electrical activity, and it is thought that changes in neural activity and synaptic activity (where neurons meet) underlie most behaviors. It was once thought that glia were just fluff, but new research shows that they may play a role in depression.
There are three types of glia: astrocytes, oligodendrocytes, and mico-glia. Researcher Mounira Banasr had previously shown that neuronal lesions in the prefrontal cortex of mice did not produce depressive-like behaviors, but glial lesions did.
In a new study presented at a recent scientific meeting, Banasr reported that destroying astrocytes in the prefrontal cortex of mice induced depressive- and anxiety-like deficits. Using a virus that specifically targeted astrocytes, the researchers documented that the depressive behavior was specifically related to loss of astrocytes and not loss of other glial cell types, such as oligodendrocytes or micro-glia.
Editor’s Note: There is evidence of glial abnormalities in patients with mood disorders. Banasr’s research raises the possibility that glial deficits (rather than neuronal alterations) could be crucially involved in depression. In this study, the depressive- and anxiety-like behaviors persisted for 8 days following the astrocyte ablation, but by day 14 the animals had recovered, possibly with the production of a new supply of astrocytes. These data also raise the possibility that targeting the mechanisms of glial dysfunction could be a new avenue to pursue in the therapeutic approaches to depression.
