Journal of neurotrauma
-
Journal of neurotrauma · Feb 2013
Evaluation of metric, topological, and temporal ordering memory tasks after lateral fluid percussion injury.
Impairments in learning and memory occur in as many as 50% of patients following traumatic brain injury (TBI). Similar impairments occur in rodent models of TBI, and the development of new memory testing procedures provides an opportunity to examine how TBI affects memory processing in specific neural memory systems. Specifically, metric, topological, and temporal ordering tasks are object-based tests for memory of spatial orientation and temporal sequencing working memory developed for use in rodents. ⋯ Two weeks following a moderate lateral fluid percussion TBI, adult rats demonstrated significant deficits in both the metric and temporal ordering tasks (p<0.05) but not in the topological task. Stereological analysis identified a significant reduction in neurons in the CA2/3 (p<0.05) but not the CA1 of the hippocampus. These data demonstrate the utility of three object-based tasks to expand our understanding of how different neural memory systems are affected by TBI.
-
Journal of neurotrauma · Feb 2013
Inhibition of Nogo-66 receptor 1 enhances recovery of cognitive function after traumatic brain injury in mice.
Central nervous system (CNS) axons recover poorly following injury because of the expression of myelin-derived inhibitors of axonal outgrowth such as Nogo, myelin-associated glycoprotein (MAG), and oligodendrocyte-myelin glycoprotein (OMgp), all of which bind to the Nogo-66 receptor 1 (NgR1). Herein we examine the role of NgR1 in the recovery of motor and cognitive function after traumatic brain injury (TBI) using a controlled cortical impact (CCI) model in NgR1 knockout (KO) and wild-type (WT) mice. Four weeks post-injury, scores on the Novel Object Recognition test were significantly increased in NgR1 KO mice compared with WT mice (p<0.05), but motor behavior test scores did not differ significantly between the two groups. ⋯ The number of bromodeoxyuridine (BrdU)+ cells did not differ between the two groups at 4 weeks post-trauma, but KO mice had higher numbers of cells that co-stained with NeuN, a marker of mature neurons. Increased transcription of growth-associated protein (GAP)-43 in both the injured and contralateral sides of the hippocampus (both p<0.05) was detected in NgR1 KO mice relative to WT. These data suggest that NgR1 negatively influences plasticity and cognitive recovery after TBI.
-
Journal of neurotrauma · Feb 2013
Hindlimb muscle morphology and function in a new atrophy model combining spinal cord injury and cast immobilization.
Contusion spinal cord injury (SCI) animal models are used to study loss of muscle function and mass. However, parallels to the human condition typically have been confounded by spontaneous recovery observed within the first few post-injury weeks, partly because of free cage activity. We implemented a new rat model combining SCI with cast immobilization (IMM) to more closely reproduce the unloading conditions experienced by SCI patients. ⋯ We observed a significant degree of asymmetry in muscle CSA in SCI but not IMM. This effect increased between day 7 and 21 in SCI, but also in SCI+IMM, suggesting a minor dependence on muscle activity. SCI+IMM offers a clinically relevant model of SCI to investigate the mechanistic basis for skeletal muscle adaptations after SCI and develop therapeutic approaches.
-
Journal of neurotrauma · Feb 2013
The validity of administrative data to classify patients with spinal column and cord injuries.
International Classification of Diseases (ICD) codes are used to document patient morbidity in administrative databases. Although administrative data are used for research purposes, the validity of the data to accurately describe clinical diagnostic information is uncertain. We compared the clinical diagnoses for spinal cord and column injuries from a longitudinal patient registry, the Rick Hansen Spinal Cord Injury Registry (RHSCIR), to the ICD-10 spinal injury codes from the Discharge Abstract Database (DAD) at one institution. ⋯ The most problematic spinal cord injury ICD-10 code was the incomplete lesion of the lumbar spinal cord (S34.1X); 66.7% of incomplete lesions of the lumbar spinal cord in RHSCIR were correctly coded in the DAD. The validity of DAD data to code spinal injuries is variable, and cannot be reliably used to classify all types of spinal injuries. Patient registries, such as RHSCIR, should be used if accurate detailed diagnostic data are required.
-
Spinal cord injury (SCI) researchers have predominately utilized rodents and mice for in vivo SCI modeling and experimentation. From these small animal models have come many insights into the biology of SCI, and a growing number of novel treatments that promote behavioral recovery. It has, however, been difficult to demonstrate the efficacy of such treatments in human clinical trials. ⋯ Histological analysis of the spinal cords 12 weeks post-injury revealed that animals with the more biomechanically severe injuries had less spared white matter and gray matter and less neurofilament immunoreactivity. Additionally, the PTIBS scores correlated strongly with the extent of tissue sparing through the epicenter of injury. This large animal model of SCI may represent a useful intermediary in the testing of novel pharmacological treatments and cell transplantation strategies.