Felix-Martin Werner and Rafael Coveñas
Major depression, a frequent psychiatric disease, is associated with neurotransmitter alterations in the midbrain, hypothalamus and hippocampus. Deficiency of postsynaptic excitatory neurotransmitters such as dopamine, noradrenaline and serotonin and a surplus of presynaptic inhibitory neurotransmitters such as GABA and glutamate (mainly a postsynaptic excitatory and partly a presynaptic inhibitory neurotransmitter), can be found in the involved brain regions. However, neuropeptide alterations (galanin, neuropeptide Y, substance P) also play an important role in its pathogenesis. A neural network is described, including the alterations of neuroactive substances at specific subreceptors. Currently, major depression is treated with monoamine reuptake inhibitors. An additional therapeutic option could be the administration of antagonists of presynaptic inhibitory neurotransmitters or the administration of agonists/antagonists of neuropeptides.