CRH and irritable bowel syndrome: Mast cells and neurons in the GI tract express CRF and its receptors (31, 40, 42, 45, 49–52) and an electron micrograph from IBS patient colonic mucosa has shown membrane–membrane contacts between degranulating mast cell and a nerve fiber, proving the complex integrated interactions between neurons and immune cells via the CRF signaling in the pathophysiology of IBS.