In urine samples from an aging female cohort with overactive bladder syndrome (OAB), the proteolytic activity of matrix metalloproteinase-9 (MMP-9), an enzyme which degrades mature NGF, was elevated and associated with low levels of nerve growth factor (NGF). Given that a substantial portion of urine constituents originate from bladder cellular processes, we examined the synthesis of NGF and MMP-9 in rat urothelial (UROs) and smooth muscle (SMCs) cells in culture. NGF and proNGF were found expressed and released by both cell types while UROs were the major source of secreted MMP-9. THX-B, a highly specific p75