The serotonin receptor is a neurotransmitter receptor largely associated with a general sense of well-being. It is found primarily in the central nervous system, but also in the peripheral nervous system. Aside from making one feel well, the serotonin receptor also is associated with many other aspects of human and animal life — including nausea, sleep, aggression, hunger, learning and more — because this receptor releases a wide range of neurotransmitters responsible for these feelings or cognitive actions. Most of a human’s serotonin store is created in the gut, where it regulates intestinal movement; it is created from many food sources, including sugar, protein and fat.
Serotonin, which causes the serotonin receptor to activate, is a neurotransmitter that is most often associated with feeling well, but it also has many other important functions in animal and human life. Erroneously called a hormone by some, this substance is created naturally and stimulated by food intake. This is one reason why, when humans and animals do not eat correctly, all the functions associated with serotonin begin to falter.
Biochemically, serotonin is created from the amino acid called tryptophan. Found commonly in most meats and animal byproducts, this protein is directly responsible for serotonin production, but the body needs more than just this amino acid. The human body needs to have at least a small amount of complex carbohydrates, such as fruit or brown rice, and healthy unsaturated fats, for the serotonin to be properly produced. For vegans and vegetarians, both the healthy fats and tryptophan amino acid are found in nuts and beans.
Once serotonin is produced, it directly interacts with the serotonin receptor in the nervous system. Depending on the level of serotonin in the body, the receptor will release neurotransmitters or hormones that affect mood and neural activity. For example, if serotonin is high, then dopamine will be released to create a good and healthy feeling. If serotonin is low, then cortisol — a steroid hormone that gives humans and animals an adrenal response — will be produced.
Most drugs, both pharmaceutical and illegal, affect the serotonin receptor. For example, an antidepressant will cause serotonin receptors to produce higher levels of dopamine so the subject does not feel depressed and can live a normal life. Epinephrine and norepinephrine, two forms of adrenaline, also are often affected by drugs that interact with serotonin receptors. Depending on the goal of the drug, it can help either to regulate or produce in excess the adrenaline neurotransmitters.