Nerve growth factor (NGF) is a mediator of hyperalgesia and has been previously associated with sensory and reflex changes after inflammation of the urinary bladder. A sensitive assay was developed to examine neurotrophin gene expression after bladder inflammation by turpentine, which causes a short-lived inflammatory response. Two hours, but not 6 or 24 h after induction of inflammation, there were significant increases in levels of NGF, brain-derived neurotrophic factor and neurotrophin-3 mRNAs. NGF immunoreactivity was elevated with a similar time course to its mRNA. Our results suggest that during bladder inflammation, endogenous NGF is rapidly up-regulated and released to mediating sensory and reflex changes. Brain-derived neurotrophic factor and neurotrophin-3 may also have a role in the inflammatory response.