Depression locus ceruleus

The vagus nerve terminates in the nucleus of the solitary tract with widespread projections, including the locus ceruleus. There are several lines of evidence that support the potential efficacy of vagus nerve stimulation (VNS) for depression, including the following ... 

Norepinephrine Mostly excitatory, but inhibitory in some areas. Secreted by neurons in the locus ceruleus (subcortical area) to widespread areas of the brain, controlling wakefulness, overall activity, and mood. Also diffusely secreted in the sympathetic nervous system. Diffuse and widespread symptoms, including depression, changes in blood pressure, heart rate, and diffuse physiological responses, among many others. An important transmitter in the sympathetic branch of the autonomic nervous system. Diffusely affected by many medications. Several antidepressants work specifically on this neurotransmitter and its receptor sites. Many medications for general medical conditions affect this neurotransmitter as well. 

The enzyme MAOA is located in synapses of NE, 5-HT, and DA neurons, which are located in the locus ceruleus, placenta, intestine, and autonomic nervous system. MAOA breaks down 5-HT, NE and DA, rendering them inactive. Inhibition of MAOA activity helps alleviate depression because it slows the breakdown of epinephrine and NE. 

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