Neurotransmitters, along with electrical impulses. Deficiency leads to depressed state. Diets high in carbohydrates lead to high levels of serotonin and high protein lowers the serotonin concentration. PEA is produced from phenylalanine, an amino acid found in protein-rich foods. Agonists are drugs that mimic the action of other substances, such as hormones and neurotransmitters.
Antagonists block the action of hormones and neurotransmitters.