Behavioral Characterization of Graded, Bilateral Cervical Spinal Cord Contusion Injury in Rats
Spinal cord injury (SCI) is estimated to affect roughly 1.28 million individuals in the United States today and continually increases with 12,400 new incidences each year. The effects of SCI result in varying complications that depend on impact magnitude and location along the spinal cord. More rostral injuries are more severe as they affect greater proportions of signaling pathways. Over half the SCI population has injuries at the cervical level, and a fifth of those are mechanistically due to compression or contusion of the cord. Cervical SCI jeopardize fundamental functions for survival like respiratory capability and locomotive abilities including motor and sensory transmission and autonomic nervous system functions. Thus, a reproducible cervical contusion SCI in experimental settings is of interest. The Infinite Horizons (IH) Impactor was used to create a cervical C5 SCI at graded severities, and an array of varying behavioral tests were utilized to assess overall rat performance: Irvine, Beatties, and Bresnahan (IBB), grip strength, weight-supported hanging, catwalk, and gridwalk analyses. Based on the combination of these behavioral assays that evaluated both fore- and hindlimb deficits, the 200 kilodynes (kdyn) severity group would be the optimal force setting used on the IH Impactor in rat models because the force was strong enough to create moderately severe functional deficits without compromising basic functions of life. Further work should fully assess histological characterization of the spinal cord at the injury site to confirm behavioral findings about the 200 kdyn group. Overall, establishment of a clinically-relevant and reproducible cervical SCI model is important for the improved clinical translation of putative pharmacological therapeutic modalities.