What many people do not understand is that serotonin also plays a role in gastrointestinal disorders. In fact, the majority of our serotonin is produced in the gut, roughly 95%. Serotonin is produced in the enterochromaffin cells (EC) in the intestinal mucosa.Serotonin is produced, and then it bonds with its receptors.hat many people do not understand is that serotonin also plays a role in gastrointestinal disorders. In fact, the majority of our serotonin is produced in the gut, roughly 95%. Serotonin is produced in the enterochromaffin cells (EC) in the intestinal mucosa.
Early signs of mono in teens: 1  Early symptoms of viral infectious mono disease in teens are similar to flu symptoms. 2  Fever with shivering. 3  Teens may get headaches, severe fatigue, and pain in the muscles.  Sore throat with swollen tonsils, a common flu symptom, is also seen in mono.
The more classic symptoms of mono then follow and include: 1  a severe sore throat, with tonsils that are red, enlarged and covered in pus. 2  swollen glands (lymphadenopathy) in the neck. 3  fever, which can be as high as 104 F to 105 F and may last one to two weeks.  continued malaise and fatigue, which can be extreme.