BDNF and colitis: Prior functional and molecular studies from our laboratory identified an up-regulation of expression of calcitonin gene related peptide (CGRP), substance P (SP), and brain-derived neurotrophic factor (BDNF) genes in sensory and spinal neurons followed by subsequent release of these neuropeptides in the urinary bladder after transient colonic inflammation (Pan et al., 2010; Lei and Malykhina, 2012).