According to experts at the 21st Congress of the European College of Neuropsychopharmacology, the brain is key in our response to stress.
Brain changes occur in a complex, orchestrated manner related to the activation and inhibition of neural structures involved in sensory, motor, autonomic, cognitive and emotional processes.
Indeed, it is the brain which finally determines what in the world is threatening and might be stressful for us, and which regulates the stress responses that can be either adaptive or maladaptive.
Chronic stress can affect the brain and lead into depression: Environmental stressors (e.g. job and family situation, neighborhood) and especially stressful life events such as trauma or abuse are amongst the most potent factors to induce depression.
Since the development of novel approaches to antidepressant treatment is based upon an improved neurobiological understanding of this condition, new information about the cellular changes that take place in the brain is required.
New research has discovered the adult nervous system is capable of replacing its cells, a finding that reverses prior opinion that neural networks in adults were fixed and immutable, without the potential to regenerate.
Neurogenesis or nerve regeneration can be modified by positive modulators such as learning, physical exercise, and hormonal influence, as well as negative modulators such as acute and chronic stress.
There is increasing evidence that in addition to neurogenesis, stress and antidepressant treatment also induce changes in the formation of specific glial support cells (=gliogenesis) that are critical for the survival of the neurons in the brain.
There are about 100 times more glial cells than nerve cells, providing energy and nutrition to the neurons.
Besides their ´housekeeping´ functions, glial cells are instrumental to neural communication and regarded as dynamic regulators of synaptic strength and synapse formation.
They also possess receptors for neurotransmitters and steroid hormones that, similarly to receptors of neurons, can trigger electrical and biochemical events in the cell.
Therefore, structural changes of glial cells are likely to have an important functional significance for the communication between neurons and between neurons and glial cells.
Experiments show that stress and depression inhibit the growth of new nerve cells as well as glial support cells, and that this inhibitory effect can be counteracted by antidepressive therapy.
On the basis of this research it might be possible to develop new strategies for more effective therapies of depressive diseases.