Milena Saqui, Ph.D., Research Fellow (Merchant laboratory), Department of Internal Medicine, University of Michigan Medical School

This  is  an  image  of  mouse  colon,  stained  with markers of cell membranes  (b-catenin, red)  and  cell  nuclei  (blue).  The green   cell   is   an   enteroendocrine cell (EC) that   produces serotonin.   EC are scattered throughout the intestine and  colon.  During acute  injury,  or  bacterial  or  viral infection (for example in the case of food poisoning),  the serotonin secreted by  EC  induces  muscle contraction and fluid secretion. This results in increased gut motility (producing crampy abdominal pain) and generates diarrhea, both of which help to expel the infectious agents or toxins from the GI tract.