Other pharmacological mechanisms suggested for CUR in IBS include regulating the brain–gut axis (by increasing serotonin (5-hydroxytryptamine or 5-HT), BDNF, and phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (pCREB) expression in the hippocampus and colon [83,84]) and restoring intestinal barrier integrity (increased expression of tight junction proteins zonula occludens-1 (ZO-1) and occluding), as well as altering the overall composition of the gut microbiota [85]. Here, BDNF is linked to irritable bowel syndrome.