BDNF and chronic cystitis: This hypothesis is generated based on several measures: a) NGF is elevated in the urinary bladder in cystitis [24,37,38]; b) NGF possesses the property of retrograde transport by activating neuronal cell bodies through activation of MAPK and Akt pathways [39,40,41,42]; and c) in cultured DRG explants retrograde NGF is able to increase BDNF expression in the DRG neuronal soma [43].