Posted November 13, 2013
Charles Hubscher, Ph.D., University of Louisville
Maintaining control of bladder function after a spinal cord injury (SCI) is important to both the quality of life and health of the injured individuals. Research in this area to date has found an association between bladder function and a family of molecules called neurotrophic factors - which are involved in the growth and maintenance of neurons. Dr. Charles Hubscher and his team noticed that individuals with severe incomplete injuries who underwent treadmill step training often had concurrent improvement in bladder function with a reduction in external bladder maintenance, in accordance with a documented account (Schalow G. 2010. Electromyography and Clinical Neurophysiology 50(3-4):155-179). Dr. Hubscher received a fiscal year 2010 Investigator-Initiated Research Award from the Spinal Cord Injury Research Program to pursue these anecdotal clinical findings in a clinically relevant animal model. By testing in a controlled setting using rats with SCI, Dr. Hubscher hopes to determine a potential relationship between step training and bladder control that can inform patient treatment.
To measure the effectiveness of the training on bladder function, Dr. Hubscher and his team are evaluating three groups of rats with severe incomplete SCI; all three groups will be supported by a harness, with the experimental group receiving daily step training with manual assistance, a second group undergoing upper body training with only forepaws on the treadmill, and the control group in the harness without exercise for the duration of the training period. In their initial experiments, significant improvements in bladder function (more efficient emptying of the bladder) with normalized expression of bladder nerve growth factor (NGF) mRNA levels were found in the step trained group of animals. Their latest data also suggest that 60 minutes, but not 30 minutes, of step training may attenuate SCI-induced polyuria, an increase in urine production with no change in fluid intake, which the group recently documented in their rat contusion model (Ward P.J. and Hubscher C.H. 2012. Journal of Neurotrauma 29: 2490-2498). Taken together, the urologic benefits of activity based training could lead to the development of a home-based therapeutic intervention involving a combination of daily step training and drug therapy (targeting bladder neurotrophins such as NGF for example) to improve bladder control in individuals with SCI.