Table 2.
Evidence that Facilitation of Serotonin Neurotransmission in the Hippocampus is Involved in Adaptation to Stress
| Challenge | Response | Hippocampal 5-HT | References |
|---|---|---|---|
| Restraint stress | Decrease in food intake & open field activity | 5-HT increased in many brain regions except the hippocampus | [91] |
| Repeated restraint | Normal food intake & open field activity | 5-HT increased only in the hippocampus | [91] |
| Acute exposure to elevated platform | Increase in plasma corticosterone | Extra cellular 5-HT increased in the frontal cortex but not the hippocampus | [66] |
| Repeated daily (10 days) exposure to elevated platform | Normal plasma corticosterone response | Extra cellular 5-HT increased in the hippocampus but not the frontal cortex | [66] |
| Inescapable foot shock | Escape impairment in shuttle box | The behavioral deficit normalized with bilateral intra hippocampal serotonin reuptake inhibitor | [97] |
| Subordination stress | Neurogenesis | Stress-induced suppression of neurogenesis in the hippocampus prevented by 5-HT-1A agonists | [98-99] |
| Forced swimming | Immobility | Decreased 5-HT-1A receptor binding in the hippocampus | [125] |
| Restraint stress | Feedback control over 5-HT | Exaggerated feedback control over hippocampal 5-HT | [107] |
| Restraint stress | Density of 5-HT-1A receptor | 5-HT-1A receptor binding decreased in the hippocampus | [99, 110, 119] |
| Unpredictable, mild to moderate stressors | 5-HT-1A mRNA | 5-HT-1A expression decreased in the hippocampus | [23] |
| Long term administration of SSRIs | Feedback control over 5-HT | Smaller feedback effects over hippocampal 5-HT | [13, 14, 104] |