Functional and Histological Outcomes of Bilateral Cervical Spinal Cord Contusion Injury in Fischer Rats

Abstract

Cervical contusion trauma is the most common form of spinal cord injury (SCI) from which 10% of individuals regain motor function. Pathology of SCI often leads to full quadriplegia or paraplegia due to secondary injury following initial trauma resulting from compression or contusion of the cord. The exploration and use of experimental cervical SCI models are limited. Thus, the current study developed a reproducible rat model of contusive cervical (C5) SCI using the Infinite Horizons (IH) Impactor to induce graded severities. Adult female Fischer rats received C5 laminectomy only (sham group) or laminectomy plus graded contusion injury (150, 200, or 250 kiloDyn (kDyn)). Animals were assessed seven and 14 days post-cervical SCI with a variety of functional tests: IBB forelimb scale, weight-supported hanging and griping strength test, BBB open field locomotion score, gridwalk and catwalk test, and by histological analysis. The pathological change of the injured spinal cord was assessed by Luxol Fast Blue (LFB) - Hemotoxylin and Eosin –(H&E) Staining. Injured animals’ demonstrated loss in gray matter and cell necrosis at the lesion, consistent with severity of SCI. Significant decreases in digit movement, inability to use upper body strength to suspend from a metal rod and for gripping, were all indicative of forelimb dysfunction. Hindlimb dysfunctions were observed through significant decreases in ability of paw placement and coordination, Regularity Index (RI), and stride length. Thus, forelimb and hindlimb locomotor deficits observed in this bilateral cervical SCI model are similar to patients with cervical SCI, suggesting the utility of this model for future investigations of the pathophysiological mechanisms and potential therapeutic approaches for cervical SCI repair.