Journal of NeurotraumaVol. 31, No. 12 AbstractsFree AccessAbstracts fromThe 32nd AnnualNational Neurotrauma SymposiumJune 29–July 2, 2014San Francisco, CaliforniaPublished Online:17 Jun 2014https://doi.org/10.1089/neu.2014.9935.abstractsAboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail Top Student Competition FinalistsT1-01 REPEAT MILD TRAUMATIC BRAIN INJURY IN ADOLESCENT RATS ACCELERATES ALZHEIMER'S DISEASE PATHOGENESISGrant D.A., Teng E., Serpa R.O., Prins M.L.University of California, Los Angeles, Los Angeles, USATraumatic brain injury (TBI) is a risk factor for Alzheimer's disease (AD), but the cumulative effects of mild repeat TBI (RTBI) in the adolescent brain on AD pathogenesis are unknown. We hypothesized that RTBI would increase secretase concentration acutely in the wild-type Sprague-Dawley rats and accelerate the accumulation of amyloid beta (Aβ) chronically in amyloid precursor protein/presenilin 1 transgenic rats (APP/PS1). Postnatal day 35 (P35) male wild-type rats received sham or 4 RTBI at 24 hour intervals (4RTBI24) using a closed-head injury model. Bilateral cortices were analyzed 24 or 48 hours post-injury using western blots to measure the concentration of beta-site-APP-cleaving-enzyme-1 (BACE1) and PS1, two secretases required for Aβ production. The P35 APP/PS1 rats received sham, 4RTBI24 or 4 RTBI at 72 hour intervals (4RTBI72) and were perfused at 12 months of age. One-way ANOVA with Tukey-Kramer post-hoc was used to compare optical densities of BACE1, PS1, and total Aβ deposits (including puncta, clusters, and plaques) between injury groups. In wild-types, 4RTBI24 increased 24 hour BACE1 levels in ipsilateral cortex 35% greater than sham (p=0.02), but returned to sham levels by 48 hours. 4RTBI24 did not affect PS1 levels in wild-type rats at either time point. In APP/PS1 rats, 4RTBI24 had significantly more Aβ deposits in the ipsilateral hippocampus relative to the sham (p=0.040) and 4RTBI472 (p=0.046) groups, which did not differ from each other. There was no difference between ipsilateral and contralateral hippocampi. These findings demonstrate that repeat injuries in adolescence may accelerate subsequent Aβ deposition. Since BACE1 increased transiently, its relationship with chronic Aβ remains uncertain. Interestingly, when injury levels were increased to allow metabolic recovery between impacts, chronic Aβ deposition is similar to that seen after sham. This study emphasizes the need for compliance in return-to-play guidelines to minimize the risk for accelerated Aβ accumulation among those pre-disposed to AD.Supported by UCLA BIRC, KO8AG34628, NS058489-01Key wordsAlzheimer's disease, developmental, mild TBIT1-02 THE DEVELOPMENT OF EPILEPTOGENIC ACTIVITY AFTER DIFFUSE BRAIN INJURY IN SWINEUlyanova A.V., Koch P.F., Grovola M.R., Harris J.P., Cullen D.K., Wolf J.A.University of Pennsylvania, Department of Neurosurgery, Philadelphia, USAThe potential mechanisms of epileptogenesis after diffuse brain injury were studied using a model of closed-head rotational acceleration in swine. We performed in vivo extracellular recordings in order to investigate changes in hippocampal function post injury. We compared baseline oscillatory activity and responses to stimulation in sham, single, and repetitively injured animals.Male Yucatan swine (6m) underwent coronal rotational acceleration (180–260 rad/sec) with little or no loss of consciousness and minimal subdural bleeding. We recorded changes in the synaptic inputs post stimulation with 32-channel probes and correlated the results to our previous in vitro hippocampal slice recordings 7 days post injury. Paired-pulse paradigms were utilized in order to examine changes in excitability and neurotransmitter release, while theta burst stimulation was induced to provoke epileptiform activity.Hippocampal recordings were analyzed for epileptiform activity, synaptic facilitation, and changes in excitability after theta burst stimulation. Stimulation was performed in the Schaffer collaterals and the entorhinal cortex while recording from all layers of the dorsal hippocampus. Traces recorded in CA1 in response to single and paired stimulations had significantly altered waveforms. Paired pulse facilitation in CA1 was altered at 7 d post injury, potentially due to changes in neurotransmitter release probability. There were also significant changes in responses to single pulse stimulation after theta burst stimulation, as well as altered baseline activity (sharp waves and paroxysmal depolarizing shifts) compared to sham. Responses to stimulation in animal injured twice (2X180 rad/sec, 7 days apart) produced long-lasting depolarization compared to a single injury. These alterations suggest an increased post-synaptic excitability or a shift in the excitation-inhibition balance of the local circuitry.These data suggest that diffuse brain injury may induce hippocampal axonal and synaptic dysfunction, and changes in hippocampal cellular excitability. Over time post injury these changes may lead to circuit-level changes in the hippocampus that will elicit sub-clinical epileptiform activity and potentially lower seizure thresholds.Support: CURE Taking Flight, VA RRD MeritKey wordscircuitry, electrophysiology, excitability, hippocampus, in vivo, mild traumatic brain injury (mTBI)T1-03 AUDITORY SELECTIVE ATTENTION IMPAIRMENTS IN BLAST-EXPOSED VETERANS WITH TRAUMATIC BRAIN INJURYBressler S.C.1, Bharadwaj H.1, Choi I.1, Bogdanova Y.2, Shinn-Cunningham B.G.11Boston University, CompNet, Boston, MA, USA2VA Healthcare Boston, Jamaica Plain, MA, USAA common complaint among returning combat veterans who have experienced some form of blast-related traumatic brain injury (bTBI) is difficulty understanding speech in noisy environments. Given that many veterans have noise-induced hearing deficits, hearing loss is one factor that may contribute to such complaints. Specifically, sensorineural hearing loss likely interacts with damage to cortical structures important for controlling selective attention, leading to severe difficulties when trying to communicate in everyday social settings. We evaluated 10 bTBI veterans' hearing status as well as their performance on a selective auditory attention task. In the veterans tested, audiograms revealed near normal auditory thresholds (within 20 dB of normal limits). In addition, a more sensitive test of supra-threshold temporal coding fidelity in the brainstem recently developed in our laboratory revealed responses within the normal range for healthy young adults. Thus, in this pilot study, there was no evidence for sensorineural hearing deficits, even using new methods for revealing differences in supra-threshold hearing. The bTBI veterans performed a selective auditory attention task in which they were instructed to categorize the pitch contour of one of three simultaneously occurring melodies presented from three differently perceived locations (either rising, falling, or alternating). Such a task not only requires fine attentional control, but also temporally precise neural representations of the incoming sensory information. Performance was significantly worse compared to 17 normal-hearing, non-TBI controls. EEG-recorded evoked response potentials to correctly identified trials showed that in those veterans who could perform the task at above-chance levels, attention modulated the neural representation of the auditory input weakly or not at all, whereas healthy controls consistently show such modulation. Although these results do not rule out auditory sensory deficits as a contributing factor to selective auditory attention deficits in the general population of bTBI veterans, they suggest that blast exposure damage affects cortical regions responsible for controlling selective auditory attention. These findings are a step toward developing early pre-clinical diagnostic markers for long-term neurobehavioral disorders commonly associated with bTBI.Key wordsaudiotory selective attention, behavioral, blast injury, EEG, veteransT1-04 CCR2 ANTAGONISM ALTERS BRAIN MACROPHAGE POLARIZATION AND AMELIORATES COGNITIVE DYSFUNCTION INDUCED BY TRAUMATIC BRAIN INJURYMorganti J.M., Jopson T.D., Liu S., Riparip L.K., Guandique C.K., Gupta N., Rosi S.University of California, San Francisco, USATraumatic brain injury (TBI) initiates a robust innate immune response, which has been shown to persist for years following the initial event, and ultimately affects cognitive function. In patients who survive TBI, there are increased levels of the chemokine CCL2 in the cerebrospinal fluid (CSF), suggesting involvement of CCL2-CCR2 signaling axis following trauma. However, it is unclear what role CCR2+ macrophages play in TBI-induced sequelae. Herein we used the unique CX3CR1GFP/+CCR2RFP/+ reporter mice, to define the temporal kinetics of TBI-induced CCR2 macrophage accumulation in the brain spanning acute (3–6 hrs), subacute (12–48 hrs) and chronic (7–28 d) time points. We found that accumulation of CCR2+ macrophages is temporally restricted following to 12–24 hrs post injury. Interestingly, a significant number of CCR2+ cells began to express CX3CR1 simultaneously, which persisted through 7 days post injury. Gene expression analyses of multiple macrophage polarization markers revealed distinct temporal expression spanning the M1/M2 activation continuum across all time points. Moreover, multivariate analysis revealed distinct relationships between three macrophage subsets and their inflammatory gene expression profile. Combined, these findings identified a therapeutic window for targeting CCR2+ macrophage accumulation following TBI. In wildtype mice, treatment with a novel phase-1 CCR2 antagonist, reduced accumulation of peripheral macrophages, disrupted neurotoxic macrophage polarization and prevented increased NADPH oxidase gene expression one day post-injury. Cumulatively, this treatment strategy prevented TBI-induced hippocampal learning and memory deficits 28 days post-injury. These data suggest that the accumulation of CCR2+ macrophages contributes to TBI-induced cognitive decline and that pharmacologic agents can reverse this cognitive decline, which supports early intervention in patients with TBI.FundingThis work was supported by the NIH R01 CA133216 (S.R.), R21 AG042016 (S.R.), Alzheimer Association IIRG-11-202064 (S.R.).Key wordsantagonist, CCR2, hippocampus, macrophage, multivariate analysisT1-05 INFLAMMATION IN THE PAIN PATHWAY IN A MODEL OF MILD CLOSED HEAD INJURY: IMPLICATIONS FOR POST-CONCUSSION HEADACHEMacolino C.M.1, Daiutolo B.V.1, Tyburski A.L.1, Elliott M.B.1,21Thomas Jefferson University Department of Neurological Surgery, Philadelphia, USA2Thomas Jefferson University Department of Neuroscience, Philadelphia, USAHeadache is a hallmark symptom of concussion. Post-concussion headache (PCH) can be a new headache resulting from concussion or worsening of a pre-existing headache disorder. In many patients, it resolves in three months; in others, it persists for much longer. Understanding the post-concussion symptomology including headache is important for concussion management. The goal of this study was to compare changes in the trigeminal pain pathway and related behavior between a mild CCI injury (with focal-diffuse features) and a mild closed head injury (CHI) injury (with diffuse injury only). Male Sprague Dawley rats were randomized into CCI, single CHI, or repetitive (2-hit) CHI and compared to control groups. Baseline and weekly post-injury testing included von Frey (mechanical) sensory testing for the presence of allodynia, rotarod for balance, and Barnes maze for detecting deficits in spatial learning and memory. Changes in markers of injury/inflammation including beta amyloid precursor protein (β-APP), glial fibrillary acidic protein (GFAP), Iba-1 microglial, and inducible nitric oxide synthase (iNOS) were determined in the trigeminal pain pathway using immunohistochemistry, western blot, or qRT-PCR. Changes in the nociceptive neuropeptide, calcitonin gene-related peptide (CGRP) were also compared between injuries. Periorbital allodynia along with motor and learning deficits were dependent on the type of injury and number of injuries (p<0.01). Group differences were found in the location and grading of β-APP accumulation, astrogliosis and microglial activation. Graded increases in CGRP and iNOS levels were found in the trigeminal pathway in CCI and CHI groups, p<0.001. In conclusion, the type of injury (primarily focal or diffuse) and number of injuries influence the degree and distribution of inflammation, and nociceptive responses. Peripheral and central sensitization are evidenced by the presence of mechanical allodynia, inflammation, and alterations in trigeminal pain pathway. Findings indicate the importance of post-concussion inflammation in headache chronification with implications for the management of post-concussion syndrome.Key wordsclosed head injury, concussion, headache, post-concussion syndrome, post-traumatic headacheT1-06 ADVANCED BIOMATERIAL STRATEGIES FOR MICRO-TISSUE ENGINEERED NEURAL NETWORKS TO RESTORE BRAIN CIRCUITSHarris J.P.1,2, Struzyna L.A.1, Murphy P.L.1, Cullen D.K.1,21Center for Brain Injury and Repair, Dept of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA2Philadelphia Veterans Administration Hospital, Philadelphia, PA, USADisruption of the connectome is a prominent feature of many neurological diseases and trauma. There is currently no strategy to repair long-distance axonal connections in the brain; therefore, we have developed micro-tissue engineering techniques to generate neurons with long axonal tracts encased in miniature hydrogel tubes as a strategy to restore long-distance axonal connections and neural populations. We previously found that these preformed micro-tissue engineered neural networks (TENNs) may be drawn into a needle and stereotaxically delivered into the rodent brain to reconstruct lost cortico-thalamic pathways, with evidence of transplant neuronal survival, maintenance of axonal architected, and synaptic integration into the cortex. Here, we have advanced the biomaterial encasement strategy to allow for needle-less delivery of preformed micro-TENNs to minimize insertion trauma. The micro-TENNs were composed of a small hollow hydrogel shell (≤700 μm OD) with an extracellular matrix interior (350 μm ID). These micro-TENNs consisted of agarose coated with low viscosity carboxymethylcellulose (CMC). Upon mild dehydration, coated micro-TENNs were able to withstand a force of 0.89+/− 0.45 N before buckling, whereas a solid agarose cylinder of the same size only withstood a force of less than 10 μN, thus the CMC coating increased the stiffness by five orders of magnitude. The needle to insert control (uncoated) micro-TENNs was almost 1/6 bigger than the needle-less (coated) micro-TENN; therefore, we anticipate that the needle-less method will minimize insertion damage due to a reduced form factor. We are currently evaluating host responses and micro-TENN neuronal survival and integration using needle versus needle-less delivery. Our novel micro-TENNs are the first strategy capable of facilitating nervous system repair by simultaneously providing neuronal replacement and re-creating long-distance axon pathways in the brain. The micro-TENN approach offers a new ability to treat several disorders that disrupt the connectome, including Parkinson's disease, TBI, stroke, Gulf War Illness, and brain tumor excision.Key wordsaxonal tracts, biomaterials, cell replacement, tissue engineeringT1-07 INCREASED CSF NLRP3 BUT NOT NLRP1 AFTER SEVERE TRAUMATIC BRAIN INJURY IN CHILDRENSimon D.W.1,2, Wallisch J.1, Bell M.J.1,2, Bayir H.1,2,3, Aneja R.K.1,2, Janesko-Feldman K.2, Kochanek P.M.1,2, Clark R.S.1,21Departments of Critical Care and Pediatrics Children's Hospital of Pittsburgh of UPMC, Pittsburgh, USA2Safar Center for Resuscitation Research, Pittsburgh, USA3Center for Free Radical and Antioxidant Health, Pittsburgh, USAThe NOD-like receptor, pyrin domain containing (NLRP) 1 and 3 inflammasomes are implicated in inflammation and secondary injury following traumatic brain injury (TBI). NLRPs recruit pro-caspase-1 and pro-interleukin-1β into the inflammasome, resulting in activation of caspase-1 and formation of interleukin-1β, both shown to be increased in cerebrospinal fluid (CSF) of children following severe TBI. NLRP1 is classically recognized for activation by Bacillus anthracis toxin, whereas in addition to microbial pathogens, NLRP3 is activated by oxidative stress and β-amyloid. We sought to determine whether one or both of the inflammasome proteins NLRP1 and NLRP3 were detectable in CSF of pediatric patients following severe TBI. CSF was obtained from children (n=18) treated with CSF diversion via an external ventricular drain after severe TBI in this IRB approved study. Lumbar CSF from children without TBI or meningitis served as controls (n=8). CSF levels of NLRP1 and NLRP3 were determined at four time intervals (0–24 h, 45–48 h, 49–72 h, and >72 h after injury) using enzyme-linked immunosorbent assay. CSF NLRP1 levels were below level of detection (<18.75pg/mL) in control subjects and were detected in only 2/18 TBI patients and only at a single time point (<24 h). In contrast, CSF NLRP3 levels were increased vs. controls across points (control=0.36±0.04, 0–24 h=14.13±2.90, 25–48 h=4.08±1.01, 49–72 h=5.80±1.67,>72 h=8.48±1.92 ng/mL; mean±SEM; p<0.001). However, CSF NLRP3 levels did not correlate with age, sex, mechanism of injury, or outcome by univariate analysis. In conclusion, NLRP3, but not NLRP1, was increased in CSF of pediatric patients following severe TBI. To our knowledge, this represents the first study evaluating specific NLRPs after pediatric TBI and suggests prominent NLRP3 inflammasome formation, perhaps triggered by oxidative stress and/or β-amyloid, after TBI. Support: T32HD40686Key wordsinflammasome, NLRP3, traumatic brain injuryT1-08 THE POST TRAUMATIC BRAIN INJURY INFLAMMASOME AND RESPONSE TO AUTOLOGOUS CELL THERAPYLiao G.P., Hetz R.A., Jimenez F., Chang J.T., Moore A.N., Kosmach S.C., Day M., Lee D.A., Worth L.L., Savitz S.I., Dash P., Cox C.S.University of Texas Medical School at Houston, Department of Pediatric Surgery, Houston, USATraumatic brain injury (TBI) elicits a complex neurologic and systemic inflammatory response. Cell therapy may have potential advantages over single agents as cellular bioreactors sense and respond to numerous environmental signals. However, interpreting the inflammasome response using biomarker data in clinical trials is challenging. This study evaluates the ability of bioinformatic techniques to evaluate cell therapy effects to relevant biomarkers during neurointensive care.Interval plasma samples from 24–96 hours post TBI were obtained from three groups (TBI alone (n=3), TBI+6 million cells/kg (n=4), TBI+9 million cells/kg (n=5)) in the prospective Phase II Adult Bone Marrow Derived Mononuclear Cell Therapy for TBI clinical trial. The cell therapy groups were treated intravenously within 48 hours of injury. A multiplex magnetic bead-based assay was used to quantify select pro- (IL-1ß, IL-6, IFN-γ, TNF-α) and anti- (IL-4, IL-10) inflammatory cytokines. After normalizing each cytokine to baseline levels per patient, hierarchical clustering was used to generate dendrogram heat maps using Pearson correlated row distance measures and pairwise average-linkage clustering. Each cytokine dendrogram heat map was examined to determine if rows (patients) stratified according to treatment group.Hierarchal clustering and dendrogram heat map generation identified IL-1β, IL-4 and TNF-α as cytokines where the dendrogram pattern correlated with the assigned treatment groups. The dendrogram clustering also demonstrated a treatment dose dependent reduction for the pro-inflammatory cytokines (IL-1β and TNF-α) and increase for the anti-inflammatory cytokine (IL-4) levels from 24–96 hours.Our study suggests that hierarchical clustering and dendrogram heat mapping may be used to identify plasma cytokines associated with the treatment effect of cell therapy. The treatment effect of intravenous autologous bone marrow mononuclear cells for TBI in the acute setting appears to be most associated with the reduction of pro-inflammatory IL-1β and TNF-α levels and increase of anti-inflammatory IL-4 levels.Key wordsbiomarker, cell therapy, clincal trial, inflammasome, inflammationT1-09 INVERSE NEUROVASCULAR COUPLING TO CORTICAL SPREADING DEPOLARIZATIONS IN SEVERE BRAIN TRAUMAHinzman J.M.1, Andaluz N.1, Shutter L.A.2, Okonkwo D.O.2, Pahl C.3, Strong A.J.3, Dreier J.P.4, Hartings J.A.11University of Cincinnati, Cincinnati, United States2University of Pittsburgh, Pittsburgh, United States3Kings College, London, UK4Charite University, Berlin, GermanyCortical spreading depolarization (CSD) causes breakdown of electrochemical gradients following TBI, but also elicits dynamic changes in regional cerebral blood flow (rCBF) that range from physiologic neurovascular coupling (hyperemia) to pathological inverse coupling (hypoperfusion). The purpose of this study was to determine whether pathological inverse neurovascular coupling occurs as a mechanism of secondary injury. In 24 TBI patients requiring craniotomy, CSDs were monitored with subdural electrode strips and rCBF was measured with a parenchymal thermal diffusion probe. The status of cerebrovascular autoregulation was monitored as a correlation between blood pressure and rCBF. The rCBF response to CSD was obtained for 196 events in 5 patients. In one patient with intact cerebrovascular autoregulation, CSD induced only hyperemic responses (794% increase), while another patient with impaired autoregulation exhibited only the inverse (hypoperfusion) response (−24% decrease). By contrast, three patients exhibited dynamic changes in neurovascular coupling to CSDs through the course of monitoring. One exhibited increasing severity of the pathological inverse response (−14%, −29%, −79% decrease, p<0.05) that coincided with progressive worsening of cerebrovascular autoregulation (Pearson coefficient 0.04, 0.14, 0.28, p<0.05). Another exhibited a transformation from physiological hyperemic coupling (44% increase) to pathological inverse coupling (−30% decrease) (p<0.05) that coincided with a loss of autoregulation (Pearson coefficient 0.19→0.32, p<0.05). Pathologic inverse coupling was only observed with electrodes placed in or adjacent to evolving lesions. Patients with good 6-month outcomes had higher perfusion (46.8±6.5 ml/100 g/min) than patients with poor outcomes (32.3±3.7 ml/100 g/min) (p<0.05). These results establish inverse neurovascular coupling to CSD as a novel mechanism of secondary injury in TBI and suggest that CSD, the neurovascular response, cerebrovascular autoregulation, and ischemia are critical processes to monitor and target therapeutically in the management of brain injury.Key wordscortical spreading depolarization, ischemia, neurovascular coupling, regional cerebral blood flowT1-10 GENETICALLY-MODIFIED NEURAL PROGENITOR CELL TRANSPLANTATION FOR THE TREATMENT OF TRAUMATIC BRAIN INJURYBlaya M.O., Tsoulfas P., Furones-Alonso O., Bramlett H.M., Dietrich W.D.University of Miami Miller School of Medicine, Miami, USATraumatic brain injury (TBI) represents a serious public health problem as there are no clinically-available treatments to mitigate the functional consequences experienced by patients. Neural progenitor cells (NPCs) hold significant promise as a potential treatment strategy for TBI due to the numerous intrinsic advantages of the cells, including the secretion of neurotrophic factors. Neurotrophins are critical for neuronal repair and survival, but their clinical use after injury is limited by differential binding specificities, short half-lives, and complicated delivery issues. We hypothesized that pericontusional transplantation of NPCs that were genetically modified to secrete a synthetic, human multineurotrophin (MNTS1) would overcome some of the limitations of traditional neurotrophin therapy. MNTS1 is a multifunctional, multitargeting neurotrophin that recapitulates the combined biological activity of three neurotrophins and induces the prosurvival signaling activity of all three tropomyosin-related kinase (Trk) receptors. NPCs were obtained from Sprague-Dawley fetuses at embryonic stage E15 and transduced with either GFP and MNTS1 constructs (MNTS1-NPCs) or with a GFP construct alone (control GFP-NPCs). Adult rats received moderate fluid percussion-induced TBI or sham surgery. Animals were transplanted 1 week later with either control GFP-NPCs, MNTS1-NPCs, or injected with saline (vehicle). Five weeks after surgery, animals were evaluated for hippocampal-dependent spatial memory and then sacrificed for immunohistochemical analyses. Six weeks after TBI, we observed significant survival and neuronal differentiation of MNTS1-NPCs, as well as injury-activated migration towards contused brain regions. NPCs displayed long processes with spine-like formations that extended into cortical and subcortical structures, including the hippocampus and contralateral hemisphere. Transplanted NPCs, irrespective of transduction profile, conferred significant preservation of pericontusional host tissues and enhanced endogenous hippocampal neurogenesis in the posttraumatic brain. Furthermore, NPC transplantation significantly improved spatial memory capacity on the hippocampal-dependent Morris water maze task. Transplant recipients exhibited escape latencies approximately half that of injured vehicle controls. Our findings support the potential of NPC transplantation and multineurotrophin therapy to enhance endogenous neuroreparative responses, and therefore may be an effective treatment for TBI.Key wordsadult hippocampal neurogenesis, learning and memory, neural progenitor cell transplantation, neuroprotection, traumatic brain injuryT1-11 EARLY HINDLIMB UNLOADING PRODUCES MALADAPTIVE PLASTICITY THAT LIMITS FUNCTIONAL RECOVERY AFTER SPINAL CORD INJURY (SCI)Morioka K.1,2, Tazoe T.2,3, Ma X.1, Guandique C.F.1, VanCitters L.1, Huie J.R.1, Bresnahan J.C.1, Beattie M.S.1, Tanaka S.4, Ferguson A.R.1, Ogata T.21Brain and Spinal Injury Center (BASIC), Dept Neurological Surgery, UCSF, San Francisco, USA2Research Institute, National Rehabilitation Center for Persons with the Disabilities, Saitama, Japan3Dept Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, USA4Dept Orthopaedic Surgery, The University of Tokyo, Tokyo, JapanPartial weight bearing gait training for SCI induces adaptive plasticity and/or inhibits maladaptive spinal cord plasticity to promote functional recovery and re-organization of spinal reflex circuits. Weightless conditions such as prolonged bed rest in chronic SCI are thought to facilitate maladaptive spinal cord plasticity, leading to exaggerated withdrawal reflexes that can interfere with locomotor recovery. Hence, it has been suggested that appropriate shaping of loading-related spinal plasticity contributes to recovery in chronic SCI. However, the specific mechanisms by which loading and unloading shape spinal plasticity early after SCI remain poorly understood. We investigated hind-limb unloading (HU) early after SCI using adult female SD rats subjected to mild bilateral SCI (50 kdyn IH device) at T9. Groups were 1) chronic HU by tail suspension, and 2) normal loading controls. The HU group was returned to normal loading conditions at 2 wks and all animals were observed for 8 wks post-SCI. Assessments included: 1) Locomotor recovery using the BBB and kinematics, 2) reflex modulation using H-reflex testing of the plantaris muscle at 8 wks, 3), tissue biochemistry, and 4) unbiased high-resolution robotic confocal microscopy for plasticity-related changes. HU early after SCI impaired locomotor recovery and produced over-excitation of spinal reflex circuits. Biochemical and confocal microscopic studies into the substrates of this plasticity are ongoing. Our findings suggest that complete limb unloading early after SCI produces maladaptive spinal cord plasticity that impairs functional recovery. Our data suggest that loading-related spinal plasticity early after SCI plays an essential role in functional recovery.Key wordsloading, maladaptive spinal plasticity, recovery of function, synaptic plasticityT1-12 INCREASED NODOSE GANGLION EXPRESSION OF CCK, CCK-1R, AND TRPV1 AND THE PATHOPHYSIOLOGY OF VAGAL AFFERENT DYSFUNCTIONSwartz E.M.1, Deiter G.M.2, Stocker S.D.2, Holmes G.M.11Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, USA2Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, USASpinal cord injury (SCI) causes immediate changes to gastrointestinal (GI) tract physiology. Parasympathetic control from the esophagus to the proximal colon is modulated by vago-vagal circuits which remain anatomically intact following SCI. Our previous reports indicate that SCI reduces gastric reflexes and vagal afferent sensitivity to GI peptides such as cholecystokinin (CCK). Furthermore, mesenteric hypoperfusion initiates a GI inflammatory response. Evidence in other models of GI dysfunction suggests that inflammatory mechanisms co-activate the transient receptor potential vanilloid type 1 receptor (TRPV1) that, in turn, contributes to the symptomatology of GI dysregulation. We tested the hypothesis that acute SCI induces molecular and neurophysiological alterations in gastric vagal afferents, cell bodies of which reside in the nodose ganglion, through the increased expression of TRPV1 and CCK and reduction in expression of CCK-1 receptor (CCK-1r). We used qRT-PCR to quantify the levels of CCK, CCK-1r, and TRPV1