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Abstracts
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Our Research Presentation
Development of the Barnes Maze as an Alternative to the Morris Water Maze Following TBI in Mice.
Scott Ferguson1,2, Benoit Mouzon1,2, John Phillips1, Vani Ganapapthi1, Alex Bishop1, Gogce Kayihan1,2, Venkatarajan Mathura1,2, Michael Mullan1,2 , Fiona Crawford1,2
1The Roskamp Institute, Sarasota, FL, USA; 2 James A Haley Veterans Administration, Tampa, FL, USA
Traumatic brain injury (TBI) is suffered by approximately 1.4 million people in the United States each year. TBI is the leading cause of death and disability in the most active population (under 45 years of age) in industrialized countries. Within the military, TBI is associated with 59% of blast-associated injuries seen at Walter Reed Army Medical Center, and between January 2003 and May 2005, 31% of all admissions to WRAMC had a brain injury. Apolipoprotein E (APOE) polymorphisms are known to impact the outcome after TBI, with the APOE4 allele (and concomitant ApoE4 expressed protein) associated with worse outcome than ApoE3 following TBI. As part of our TBI research program we are exploring the molecular, neurobehavioral and neuropathological outcome after TBI in mouse models of injury, including APOE transgenic mice.
In order to evaluate differential outcomes of injury and its effects on motor skills and memory, we have optimized a series of neurobehavioral tests in mice. The Rotarod test measures motor skill and learning via a programmable rotating bar. Rotarod has shown the ability to distinguish between injured and uninjured mice, and has shown appropriate trends between differing levels of injury. Morris water maze is a test of spatial memory and learning originally designed for rats but later adapted for mice. APOE3 mice performed better than APOE4 mice in our Rotarod results, demonstrating an APOE genotype-dependent effect on motor function following TBI. However, in the cognitive paradigm not only did we fail to detect any APOE genotype-dependent effects, we observed no significant differences in performance between injured and uninjured mice. We therefore explored other cognitive paradigms for their ability to discriminate between injured and uninjured mice.
The Barnes maze is analogous to the Morris water maze in that it is also a test of spatial memory and learning, but because swimming is not involved it is associated with less stress than MWM typically induces in mice. Others have shown that there is a strain-dependent effect on the ability of mice to learn the water maze task as well as the Barnes maze task. Given that C57BL/6J mice are reported to perform better on the Barnes maze task, and this is the background strain utilized in our research, we optimized a paradigm of the Barnes maze for use in our TBI studies. Our results show a statistically significant effect of injury on the spatial memory and learning of C57BL/6J wild type mice. Future studies will re-examine the effect of APOE genotype on spatial memory following TBI using this test.
This research was funded by a Department of Defense award (W81XWH-07-1-0700) to Dr. Fiona Crawford and by the Roskamp Foundation
APP is Internalized After CD40 Ligation Which Increases Aß Production
Ghania Ait-Ghezala, Jeremy Frieling, Myles Mullan, Claude-Henry Volmar, and Michael J. Mullan.
CD40, a member of the tumor necrosis factor receptor superfamily, and its cognate ligand CD40L are both elevated in the brains of Alzheimer’s disease (AD) patients compared to controls. We have shown that pharmacological or genetic interruption of CD40/CD40L interaction results in mitigation of AD-like pathology in vivo in transgenic AD mouse models, and in vitro. Recently, we showed that CD40L stimulation could increase Aß levels, but the mechanism causing this phenomenon is not known. Here we show that CD40 ligation triggers internalization of APP and that internalization by endocytosis is associated with increased Aß production. Furthermore, anthocyanins, which are known to impact trafficking to and from lipid rafts, impair the production of Aß by CD40L stimulated CD40. However, anthocyanins have no effect on CD40L treatment of a neuroblastoma cell line over-expressing the C-99 APP fragment suggesting that CD40L internalization has no effect on ?-secretase. This finding is consistent with previous data suggesting that endocytosis increases BACE activity. In summary, these data suggest that a general mechanism of increased Aß generation may be lipid raft mediated internalization of APP allowing increased BACE activity on its substrate.
Neurobehavioral profiles of two mouse models of Gulf War Illness
Laila Abdullah1, Alex Bishop1, John Phillips1, Benoit Mouzon1,2, Scott Ferguson1,2, Vani Ganapathi1, Myles Mullan1,2, Ghania Ait-Ghezala PhD1,2, Michael Mullan MD, PhD1,2 and Fiona Crawford PhD1,2
Affiliations: 1Roskamp Institute, 2040 Whitfield Ave, Sarasota, FL, 34243, 2James A. Haley VA Hospital, 13000 Bruce B. Downs Blvd, Tampa, FL, 33612.
Background: Gulf War Illness (GWI) is a multisymptom condition associated with service in the 1990-1991 Persian Gulf War conflict and affects around 250,000 US veterans. It is largely attributed to combined exposure to pyridostigmine bromide (PB) and overuse of pesticides and insect repellants. After nearly two decades, there is still no treatment for GWI and the underlying pathologic factors associated with the observed central nervous system (CNS)-based symptoms in veterans remain unclear. Current GWI animal models do not demonstrate the full spectrum of neurobehavioral features reported to be associated with GWI, which makes it particularly difficult to explore the efficacy of possible therapeutic options. Therefore, we tested two different treatment paradigms in order to establish a mouse model of GWI, which exhibits motor, cognitive and anxiety-related symptoms that are observed in veterans with this illness. Methods: For model A, a previously established treatment paradigm was used which showed pathological changes suggestive of neurodegeneration, however extensive neurobehavioral profiling was not performed. Treated C57BL6 mice received oral administration of 1.3mg/kg of PB in water, dermal application of 0.13mg/kg of permethrin (PER) and 40 mg/kg of N-N-diethyl m-toluamide 2 (DEET) in 70% ethanol and 5 minutes of restrained stress daily for 28 days, whereas control mice received vehicle for the same duration. For model B, a new treatment paradigm was developed where CD1 mice in the treatment group were administered 2mg/kg of PB and 200 mg/kg of PER via i.p. in DMSO daily for 10 days and the control group received DMSO only. Following treatment, neurobehavioral profiles were examined using the Rotarod test to assess motor deficits, the Open Field test for anxiety-related changes and the Morris Water Maze test to assess spatial memory. Results: In model A, treatment was associated with significant impairment in sensorimotor function and presence of anxiety-related behavior, but there was no deficit in spatial memory. In model B, a delayed adverse effect of treatment was observed on the outcome measures of anxiety and spatial memory, but there was no evidence of sensorimotor impairment. Conclusion: These findings suggest that combined exposure to PB and pesticides/insect repellents may lead to CNS-based effects in mice that mimic some of the clinical symptoms observed in veterans with GWI. Additional studies are required to determine whether all three neurobehavioral features can be produced in one mouse model and whether these changes correlate with pathological features associated with neurodegeneration.
Acknowledgment: Funding for this research is provided by a Congressionally Directed Medical Research award (GW080094) to Dr. Fiona Crawford, Roskamp Institute.
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In the Institute of Medicine Report on Gulf War and Health released April 9, 2010, the IOM determines that "Gulf War service causes post-traumatic stress disorder (PTSD) and that service is associated with multisymptom illness;gastrointestinal disorders such as irritable bowel syndrome; alcohol and other substance abuse; and anxiety disorders and other psychiatric disorders. To ensure that our veterans receive the best possible care, now and in the future, the government should continue to monitor their health and conduct research to identify the best treatments to assist Gulf War veterans still suffering from persistent, unexplained illnesses."
