Brain-derived neurotrophic factor augments peristalsis by augmenting 5-HT and calcitonin gene-related peptide release

Background & Aims: Brain-derived neurotrophic factor (BDNF) acts rapidly to modulate synaptic neurotransmission in the brain. Although present in neurons, glial cells, and mucosal cells of the colon, and in higher concentrations than in brain, the action of BDNF in gut have not been characterized. The aim of this study was to identify the role of BDNF in mediating the peristaltic reflex. Methods: BDNF and a specific antiserum were examined for their effects on the peristaltic reflex and release of the sensory mediators serotonin and calcitonin gene-related peptide in rat colon. The peristaltic reflex and release of serotonin and calcitonin gene-related peptide were also examined in genetically modified mice (BDNF+/-) with reduced levels of BDNF. Results: Endogenous brain-derived neurotrophic factor was released into the sensory compartment in a stimulus-dependent manner during the peristaltic reflex induced by mucosal stimulation but not muscle stretch. BDNF stimulated and immunoneutralization of endogenous BDNF reduced ascending contraction and descending relaxation of circular muscle and release of serotonin and calcitonin gene-related peptide during the peristaltic reflex induced by mucosal stimulation but not muscle stretch. The peristaltic reflex and release of serotonin and calcitonin gene-related peptide during the peristaltic reflex induced by mucosal stimulation but not muscle stretch were significantly reduced in BDNF+/- mice. Conclusions: Endogenous BDNF enhances the peristaltic reflex by augmenting the release of serotonin and calcitonin gene-related peptide that mediate the sensory limb of the reflex induced by mucosal stimulation.