When you think about serotonin always think about happiness or mood. The best way to remember this is with 5HT2, the H is for happiness and without happiness there are symptoms…
Serotonin Functions: as you can see in the above graphic, 5HT innervates ALL over the brain but it’s dull or inhibitive, which is good because it serves MANY functions such as mood control, sleep regulation, pain perception, body temperature, blood pressure, sexual, and hormonal activity. Thus, we don’t want serotonin firing off, getting too low or excited, and all over the place.
Serotonin Pathways & Receptors
- The neurons of the raphe nuclei are the principal source of 5-HT release in the brain.
- There are nine raphe nuclei, designated B1-B9, which contain the majority of serotonin-containing neurons all of which are located along the midline of the brainstem and centered on the reticular formation.
- Axons from the neurons of the raphe nuclei form a neurotransmitter system reaching almost every part of the central nervous system.
-Most atypical antipsychotics target 5HT2 receptors
Serotonin Pathology (decreased levels)
- Think about the opposite of happiness -> lack of satisfaction, depression, emotional disorders, migraines, decreased immune function
- Serotonin also plays a role in the circadian rhythm, decreased levels lead to -> sleep disturbances, poor memory, irritability, anger
- Serotonin receptors are the greatest in the GI -> low levels also leads to an increased appetite for carbohydrates (starchy foods)
Drugs that Affect Serotonin
- Several classes of drugs target the 5-HT system, including antidepressants, antipsychotics, anxiolytics, antiemetics, and antimigraine drugs, as well as psychedelic drugs and empathogens.
- Increased serotonin (i.e. SSRIs) and sexual adverse effects have unknown mechanisms. Therefore, more serotonin is NOT more happiness and has serious consequences including serotonin syndrome. About Serotonin Syndrome and Discontinuation
