“…Therefore, a reduction in SERT function impairs intracellular uptake and degradation, increasing availability of 5-HT within the mucosa. Coates et al [4] reported that mucosal 5-HT, tryptophan hydroxylase 1 messenger RNA (mRNA), SERT mRNA, and SERT immunoreactivity were all significantly reduced in rectal biopsy specimens of patients with UC, constipation-predominant IBS (IBS-C), and IBS-D compared with that of control groups. These data demonstrated that patients with UC and IBS shared similar molecular changes in serotonergic signaling mechanisms, and shared defects in 5-HT signaling which could plausibly alter motility, secretion, and sensation in the intestinal tract.…”