Bose P, Wang DC, Parmer R, Wiley RG, Thompson FJ (2001) Monoamine modulation of spinal reflex excitability of the lower limb in the rat: Intrathecal infusion (i.t.) of anti-DBH saporin toxin – time course for behavior. Neuroscience 2001 Abstracts 771.3. Society for Neuroscience, San Diego, CA.
Summary: Progressive neurophysiological changes in the excitability of ankle extensor stretch reflexes were observed following T8 spinal cord contusion injury. Our previous study indicated that nonspecific monoamine depletion (reserpine, i.p.)contributed to pathologic hyperreflexia. To test a more specific hypothesis, a longitudinal study was performed to evaluate the time course of changes in reflex excitability after i.t. injection of 250ng of anti-DBH saporin toxin (that specifically lesions descending spinal noradrenergic neurons) into the lumbar spinal cord of normal rats. Measures of ankle torque and time-locked EMGs were used to scale stretch reflex excitability across a broad range of stretch velocities (49-612°/sec) before and at weekly intervals following i.t. injection of toxin (n=12) or vehicle (n=6) using instrumentation and protocol previously reported. An elevated pattern of ankle toque was noted in all velocities tested on day 1 and week 1 of toxin treated animals compared with vehicle controls. By week-2, and for the remaining 5 weeks of testing, significant elevation of the ankle torque was only observed in the faster velocities. Significant increases in hindlimb axis and base of support were also observed from footprint analysis. These findings indicate that selective lesion of spinal noradrenergic fibers produced some of the specific changes in the reflex excitability that were observed following midthoracic spinal contusion injury.
Related Products: Anti-DBH-SAP (Cat. #IT-03)