This proposal examines the neurotrophic influence of partial outlet obstruction on afferent and efferent innervation to the urinary bladder of the rat. The major goals of this study are to identify the mechanism responsible for the enhanced growth of bladder neurons following partial urethral ligation and to explore the relationship between cellular components in the bladder and neurons. Preliminary experiments show that the concentration of nerve growth factor (NGF) increases in obstructed bladders. Since all neurons do not respond to NGF and a heterogenous group of neurons supply the bladder organ it is also possible that other trophic factors play a role in the neuroplasticity associated with obstruction. This trophic interaction has profound clinical and functional significance. NGF will be quantitated in the bladder and cultured bladder tissues using a 2-site ELISA (Westcamp & Otten,'87) while immunocytochemistry will be used to examine NGF distribution. The roles of neural input versus mechanical stimulation due to increased voiding frequency on NGF production will be studied in denervated, decentralized and diuresing rats. The specificity of NGF-induced neuronal hypertrophy will be assessed by in vivo application of NGF using osmotic minipumps in normal rats or in ligated rats immunized to NGF. The size of retrogradely labelled bladder neurons in these experiments will be imeasured using image analysis. A search for non-NGF factors will be made by adding obstructed bladder extracts to cultured adult and neonatal neurons and noting cell survival and process outgrowth. Biochemical characterizatin of a bladder-derived trophic factor would then be performed. Factors effecting growth, tranmitter expression and electrophysiological properties of cultured adult bladder neurons will be examined. Assessment of neuronal responsiveness to NGF or non-NGF factors will be based on survival and process outgrowth data. Immunocytochemistry will be used to examine cultured neurons (2da.-2wk.). Obstruction causes smooth muscle hypertrophy and neuronal enlargement with functional changes in micturition reflexes. In vitro studies show that the rat pelvic ganglion can be used to assess trophic factor availability. In addition to gaining insight into adult neuronal plasticity, this study may help optimize the timing of therapy in obstructed patients or lead to the development of growth factor based therapies for sensory symptoms and bladder hyperactivity associated with obstruction.
