Serotonin and Dopamine in Biological Models of Depression

• DOI: 10.1007/s11055-019-00828-7
• Publication Date: 2019-11-19T15:40:43Z
• Authors: A. V. Latanov; V. A. Korshunov; V. I. Maiorov; A. N. Serkov
• Keywords: Depression

Depression in the biological models considered here can be split into two opposite patterns of changes in serotonin and dopamine levels, corresponding to passive and active stress response tactics [Selye, 1979] – ↑5HT, ↓DA and ↓5HT, ↑DA. Unavoidable pain stimulation, chronic moderate aversive stimulation, unavoidable social suppression, and learned helplessness in response to social defeats are characterized by the ↑5HT, ↓DA pattern. Aggressive behavior to an intruder, avoidance of an aggressive inhabitant, avoidance of pain stimulation, and injection of ketamine all activate the ↓5HT, ↑DA pattern. The physiological nucleus of learned helplessness and social avoidance may be the Pavlovian conditioned freezing reflex in response to a threat and the conditioned avoidance reaction, respectively. Further studies should address the following questions: how does neuron activity in the raphe nuclei change during forced swimming? Why does the increase in the serotonin level in response to antidepressants increase swimming while serotonin neurons are inhibited during swimming? Why is the increase in the serotonin level in the state of learned helplessness combined with suppression of active swimming?