Physical Validation of a Residual Impedance Rejection Method during Ultra-Low Frequency Bio-Impedance Spectral Measurements.

Accurate and reliable measurement of the electrical impedance spectrum is an essential requirement in order to draw relevant conclusions in many fields and a variety of applications; in particular, for biological processes. Even in the state-of-the-art methods developed for this purpose, the accuracy and efficacy of impedance measurements are reduced in biological systems, due to the regular occurrence of parameters causing measurement errors such as residual impedance, parasitic capacitance, generator anomalies, and so on. Recent observations have reported the necessity of decreasing such inaccuracies whenever measurements are performed in the ultra-low frequency range, as the above-mentioned errors are almost entirely absent in such cases. The current research work proposes a method which can reject the anomalies listed above when measuring in the ultra-low frequency range, facilitating data collection at the same time. To demonstrate our hypothesis, originating from the consideration of the determinant role of the measuring frequency, a physical model is proposed to examine the effectiveness of our method by measuring across the commonly used vs. ultra-low frequency ranges. Validation measurements reflect that the range of frequencies and the accuracy is much greater than in state-of-the-art methods. Using the proposed new impedance examination technique, biological system characterization can be carried out more accurately.

Rapid non-classical effects of steroids on the membrane receptor dynamics and downstream signaling in neurons.

Contribution to Special Issue on Fast effects of steroids. Although rapid effects of steroid hormones on membrane receptors and intracellular signaling molecules have been extensively studied in neurons, we are only beginning to understand the molecular mechanisms behind these non-classical steroid actions. Single molecule tracking (SMT) studies on live cells demonstrated that surface trafficking of membrane receptors determines their ligand binding properties and downstream signaling events. Recent findings suggest that one of the underlying mechanisms of non-classical steroid actions is the alteration of receptor movements on the membrane surface. In order to highlight this novel aspect of steroid effects, we first address the types of receptor movements in the plasma membrane and the role of cortical actin dynamics in receptor movement. We then discuss how single molecules and the surface movements of receptors can be detected in live cells. Next, we review the fundamental processes, which determine the effect of steroids on the plasma membrane: steroid movement through the lipid bilayer and the role of steroid membrane receptors. Using glutamate and neurotrophin receptors (NTRs) as examples, we demonstrate the features of receptor dynamics in the membrane. In addition, we survey the available data of rapid steroid actions on membrane receptor trafficking: we discuss how glucocorticoids act on the surface diffusion of glutamate receptor molecules and how estradiol acts on NTRs and gamma-aminobutyric acid type A receptors (GABAARs) and their related signaling events as well as on cortical actin. Finally, we address the physiological relevance of rapid steroid action on membrane receptors dynamics.

Oxidative stress induces transient O-GlcNAc elevation and tau dephosphorylation in SH-SY5Y cells.

O-linked ß-N-acetlyglucosamine or O-GlcNAc modification is a dynamic post-translational modification occurring on the Ser/Thr residues of many intracellular proteins. The chronic imbalance between phosphorylation and O-GlcNAc on tau protein is considered as one of the main hallmarks of Alzheimer's disease. In recent years, many studies also showed that O-GlcNAc levels can elevate upon acute stress and suggested that this might facilitate cell survival. However, many consider chronic stress, including oxidative damage as a major risk factor in the development of the disease. In this study, using the neuronal cell line SH-SY5Y we investigated the dynamic nature of O-GlcNAc after treatment with 0.5 mM H2 O2 for 30 min. to induce oxidative stress. We found that overall O-GlcNAc quickly increased and reached peak level at around 2 hrs post-stress, then returned to baseline levels after about 24 hrs. Interestingly, we also found that tau protein phosphorylation at site S262 showed parallel, whereas at S199 and PHF1 sites showed inverse dynamic to O-Glycosylation. In conclusion, our results show that temporary elevation in O-GlcNAc modification after H2 O2 -induced oxidative stress is detectable in cells of neuronal origin. Furthermore, oxidative stress changes the dynamic balance between O-GlcNAc and phosphorylation on tau proteins.

In vivo detection of hyperacute neuronal compaction and recovery by MRI following electric trauma in rats.

PURPOSE: To verify the following phenomenon in vivo using quantitative magnetic resonance imaging (MRI). Neuronal compression may occur following brain injuries in the cortex and hippocampus. As well being characterized by previous histological studies in rats, the majority of these neurons undergo hyperacute recovery rather than apoptotic death. MATERIALS AND METHODS: Twenty male Wistar rats were assigned into injured or sham-injured groups (n = 10). The injured group underwent an electric trauma model to provoke compacted neuron formation. A T1 map was acquired prior to the injury and 10 T1 maps were acquired consecutively over a period of 2.5 hours after the injury, using a 3.0T scanner. Voxelwise statistical analyses were performed between timepoints. To enable comparison with the histological appearance of the compacted neurons, silver staining was performed on a sham-injured rat and five injured rats, 10, 40, 90, 150, and 300 minutes after the injury. RESULTS: A significant (corrected P < 0.05) increase in average T1 from the preinjury (895.24 msec) to the first postinjury timepoint (T1 = 951.37 msec) was followed by a significant (corrected P < 0.05) decrease (return) up to the last postinjury timepoint (T1 = 913.16 msec) in the voxels of the cortex and hippocampus. No significant (corrected P < 0.05) change in T1 was found in the sham-injured group. CONCLUSION: The spatial and temporal linkages between the MRI T1 changes and the histological findings suggest that neuronal compaction and recovery is associated with T1 alterations. MRI therefore offers the possibility of in vivo investigations of neuronal compaction and recovery. J. MAGN. RESON. IMAGING 2016;44:814-822.

Mechanism of the "dark" axonal degeneration in the central nervous system.

BACKGROUND AND PURPOSE: In the central nervous tissue, two types of transsection-resulted axonal degeneration are generally accepted: "watery" and "dark". The present paper deals with the assumption that the mechanism of this kind of "dark" axonal degeneration has a relationship with that of the "dark" neuronal degeneration. METHODS: A minute stab wound is inflicted in the parietal cortex of the rat brain. From 1 h to 3 months postinjury, the resulted ultrastructural events in two distant regions of the corticospinal tract (internal capsule and C3 region of the corticospinal tract) are studied. RESULTS: As a novel finding, the first morphological process of "dark" axonal degeneration was found to consists in a striking reduction of the distances between neighboring neurofilaments, which were readily distinguishable and apparently undamaged. This pattern (compacted ultrastructure) persisted for hours. By day 1 postinjury, the compacted axoplasmic elements aggregated into a homogenous and dense ("dark") mass in which hardly any ultrastructural elements could be distinguished. Surrounded by apparently normal or mildly abnormal myelin sheat, this mass underwent a non-isotropic shrinkage during the next three months. Morphological signs of phagocytosis were insignificant. CONCLUSION: The ultrastructural events during the first day post-injury suggest a non-enzymatic mechanism as an alternative to the prevailing molecular-biological mechanism.

Short-term hyperoxia-induced functional and morphological changes in rat hippocampus.

Excess oxygen (O2) levels may have a stimulating effect, but in the long term, and at high concentrations of O2, it is harmful to the nervous system. The hippocampus is very sensitive to pathophysiological changes and altered O2 concentrations can interfere with hippocampus-dependent learning and memory functions. In this study, we investigated the hyperoxia-induced changes in the rat hippocampus to evaluate the short-term effect of mild and severe hyperoxia. Wistar male rats were randomly divided into control (21% O2), mild hyperoxia (30% O2), and severe hyperoxia groups (100% O2). The O2 exposure lasted for 60 min. Multi-channel silicon probes were used to study network oscillations and firing properties of hippocampal putative inhibitory and excitatory neurons. Neural damage was assessed using the Gallyas silver impregnation method. Mild hyperoxia (30% O2) led to the formation of moderate numbers of silver-impregnated "dark" neurons in the hippocampus. On the other hand, exposure to 100% O2 was associated with a significant increase in the number of "dark" neurons located mostly in the hilus. The peak frequency of the delta oscillation decreased significantly in both mild and severe hyperoxia in urethane anesthetized rats. Compared to normoxia, the firing activity of pyramidal neurons under hyperoxia increased while it was more heterogeneous in putative interneurons in the cornu ammonis area 1 (CA1) and area 3 (CA3). These results indicate that short-term hyperoxia can change the firing properties of hippocampal neurons and network oscillations and damage neurons. Therefore, the use of elevated O2 concentration inhalation in hospitals (i.e., COVID treatment and surgery) and in various non-medical scenarios (i.e., airplane emergency O2 masks, fire-fighters, and high altitude trekkers) must be used with extreme caution.

Aquaporin-4 distribution in control and stressed astrocytes in culture and in the cerebrospinal fluid of patients with traumatic brain injuries.

Distribution of aquaporin-4 (AQP4) was studied by western analysis and immunofluorescence in rat astrocytes exposed to either hypothermic (30 °C) or hyperosmolar (0.45 M sucrose) stress, and in the cerebrospinal fluid (CSF) of patients who suffered traumatic brain injury (TBI). CSF was obtained from 5 healthy subjects and from 20 patients suffering from severe TBI. CSF samples were taken at admission and on days 3 and 5-7. Here we report that, in response to both hypothermia and hyperosmolar stress, AQP4 was markedly reduced in cultured astrocytes. We also found that AQP4 significantly increased in patients with severe brain injury in respect to healthy subjects (P < 0.002). AQP4 in CSF remained unchanged in patients with elevated intracranial pressure (ICP), whereas there was a clear tendency to further increase in those patients whose ICP could be controlled within the normal range. We conclude that AQP4 levels in CSF are elevated after TBI and it might serve as a useful biochemical marker to assess brain water metabolism in clinical settings.

Mild hypoxia-induced structural and functional changes of the hippocampal network.

Hypoxia causes structural and functional changes in several brain regions, including the oxygen-concentration-sensitive hippocampus. We investigated the consequences of mild short-term hypoxia on rat hippocampus in vivo. The hypoxic group was treated with 16% O2 for 1 h, and the control group with 21% O2. Using a combination of Gallyas silver impregnation histochemistry revealing damaged neurons and interneuron-specific immunohistochemistry, we found that somatostatin-expressing inhibitory neurons in the hilus were injured. We used 32-channel silicon probe arrays to record network oscillations and unit activity from the hippocampal layers under anaesthesia. There were no changes in the frequency power of slow, theta, beta, or gamma bands, but we found a significant increase in the frequency of slow oscillation (2.1-2.2 Hz) at 16% O2 compared to 21% O2. In the hilus region, the firing frequency of unidentified interneurons decreased. In the CA3 region, the firing frequency of some unidentified interneurons decreased while the activity of other interneurons increased. The activity of pyramidal cells increased both in the CA1 and CA3 regions. In addition, the regularity of CA1, CA3 pyramidal cells' and CA3 type II and hilar interneuron activity has significantly changed in hypoxic conditions. In summary, a low O2 environment caused profound changes in the state of hippocampal excitatory and inhibitory neurons and network activity, indicating potential changes in information processing caused by mild short-term hypoxia.

Effect of PACAP in central and peripheral nerve injuries.

Pituitary adenylate cyclase activating polypeptide (PACAP) is a bioactive peptide with diverse effects in the nervous system. In addition to its more classic role as a neuromodulator, PACAP functions as a neurotrophic factor. Several neurotrophic factors have been shown to play an important role in the endogenous response following both cerebral ischemia and traumatic brain injury and to be effective when given exogenously. A number of studies have shown the neuroprotective effect of PACAP in different models of ischemia, neurodegenerative diseases and retinal degeneration. The aim of this review is to summarize the findings on the neuroprotective potential of PACAP in models of different traumatic nerve injuries. Expression of endogenous PACAP and its specific PAC1 receptor is elevated in different parts of the central and peripheral nervous system after traumatic injuries. Some experiments demonstrate the protective effect of exogenous PACAP treatment in different traumatic brain injury models, in facial nerve and optic nerve trauma. The upregulation of endogenous PACAP and its receptors and the protective effect of exogenous PACAP after different central and peripheral nerve injuries show the important function of PACAP in neuronal regeneration indicating that PACAP may also be a promising therapeutic agent in injuries of the nervous system.

The influence of benzamil hydrochloride on the evolution of hyponatremic brain edema as assessed by in vivo MRI study in rats.

OBJECTIVE: The present study was undertaken to reveal the influence of intracerebroventricular (ICV) benzamil on the dynamics of brain water accumulation in hyponatremic rats. Parameters of brain water homeostasis were continuously monitored, using in vivo magnetic resonance imaging (MRI) methods. The results were compared with those obtained in a previous study by tissue desiccation. METHODS: A 3-T MRI instrument was applied to perform serial diffusion-weighted imaging to measure the apparent diffusion coefficient (ADC) and MR spectroscopy to determine water signal. A decrease of ADC is thought to represent an increase of intracellular water, whereas water signal is used to quantify brain water content. Five groups of male Wistar rats were studied as follows: normonatremic, native animals (group NN, n = 7), hyponatremic animals (group HN, n = 8), hyponatremic animals treated with ICV benzamil (group HNB, n = 8), hyponatremic animals treated with ICV saline (group HNS, n = 5) and normonatremic animals treated with ICV benzamil (group NNB, n = 5). Hyponatremia was induced by intraperitoneal administration of 140 mmol/l dextrose solution in a dose of 20% of body weight. Benzamil hydrochloride (4 µg) was injected ICV to the treated animals. RESULTS: During the course of hyponatemia, ADC declined steadily from the baseline (100%) to reach a minimum of 92.32 ± 3.20% at 90 min (p < 0.0005). This process was associated with an increase in water signal to a maximum of 5.95 ± 2.62% at 100 min (p < 0.0005). After pretreatment with benzamil, no consistent changes occurred either in ADC or in water signal. CONCLUSIONS: These findings suggest that sodium channel blockade with ICV benzamil has an immediate protective effect against the development of hyponatremic brain edema. Sodium channels, therefore, appear to be intimately involved in the initiation and progression of brain water accumulation in severe hyponatremia.

Muscle damage in response to a single bout of high intensity concentric exercise in patients with Pompe disease.

BACKGROUND: In Pompe disease, resistance exercise could be an effective treatment to delay motor function impairment, however, the acute effects of this exercise modality are unclear. METHODS: In a prospective cohort study, we compared responses to a single bout of resistance exercise by serum markers of muscle damage and quantitative muscle magnetic resonance imaging (MRI) in patients (n=12) and age- and gender-matched healthy controls (n=12). Participants performed 50 maximal effort concentric knee flexions on a dynamometer. RESULTS: Twenty-four hours after exercise, levels of serum creatine kinase, lactate dehydrogenase and myoglobin increased in controls. In contrast, only myoglobin level increased in patients. All elevated serum markers declined by 48 hours after exercise in both groups. Mild soreness developed at 24 hours, which disappeared at 48 hours in both groups. In controls, MRI R2* relaxation rate reduced immediately and 24 hours after exercise, indicating increased water content and muscle perfusion. In patients, exercise had no effect on R2* values. The resistance exercise did not induce acute strength deficit in patients, rather, patients increased their strength by 24 hours. When serum marker changes were normalized to the magnitude of knee flexor tension developed during exercise, lactate dehydrogenase response was greater in patients. CONCLUSIONS: Late-onset Pompe disease did not exacerbate exercise-induced muscle damage, however, lactate dehydrogenase may be monitored to screen high responders during high intensity resistance exercise interventions.

Update on protein biomarkers in traumatic brain injury with emphasis on clinical use in adults and pediatrics.

PURPOSE: This review summarizes protein biomarkers in mild and severe traumatic brain injury in adults and children and presents a strategy for conducting rationally designed clinical studies on biomarkers in head trauma. METHODS: We performed an electronic search of the National Library of Medicine's MEDLINE and Biomedical Library of University of Pennsylvania database in March 2008 using a search heading of traumatic head injury and protein biomarkers. The search was focused especially on protein degradation products (spectrin breakdown product, c-tau, amyloid-beta(1-42)) in the last 10 years, but recent data on "classical" markers (S-100B, neuron-specific enolase, etc.) were also examined. RESULTS: We identified 85 articles focusing on clinical use of biomarkers; 58 articles were prospective cohort studies with injury and/or outcome assessment. CONCLUSIONS: We conclude that only S-100B in severe traumatic brain injury has consistently demonstrated the ability to predict injury and outcome in adults. The number of studies with protein degradation products is insufficient especially in the pediatric care. Cohort studies with well-defined end points and further neuroproteomic search for biomarkers in mild injury should be triggered. After critically reviewing the study designs, we found that large homogenous patient populations, consistent injury, and outcome measures prospectively determined cutoff values, and a combined use of different predictors should be considered in future studies.

A novel PARP inhibitor L-2286 in a rat model of impact acceleration head injury: an immunohistochemical and behavioral study.

We examined the neuro/axono-protective potential of a novel poly (ADP-ribose) polymerase (PARP) inhibitor L-2286 in a rat impact acceleration brain injury model. Male Wistar rats (n = 70) weighing 300-350 grams were used to determine the most effective intracerebroventricular (i.c.v.) dose of L-2286 administered 30 min after injury, and to test the neuroprotective effect at two time points (immediately, and 30 min after injury). The neuroprotective effect of L-2286 was tested using immunohistochemical (amyloid precursor protein and mid-sized mouse anti-neurofilament clone RMO-14.9 antibody) and behavioral tests (beam-balance, open-field and elevated plus maze). At both time-points, a 100 microg/rat dose of i.c.v. L-2286 significantly (p < 0.05) reduced the density of damaged axons in the corticospinal tract and medial longitudinal fascicle compared to controls. In the behavioral tests, treatment 30 min post-injury improved motor function, while the level of anxiety was reduced in both treatment protocols.

Invariant Valpha7.2-Jalpha33 TCR is expressed in human kidney and brain tumors indicating infiltration by mucosal-associated invariant T (MAIT) cells.

The anti-tumor response of human invariant NKT (NKT) cells is well established. A novel T cell subset, mucosal-associated invariant T (MAIT) cells, possesses similar regulatory properties to NKT cells in autoimmune models and disease. Here, we examined the clonality of four T cell subsets expressing invariant alphaTCR, including Valpha7.2-Jalpha33 of MAIT cells, in 19 kidney and brain tumors. The MAIT clonotype was identified and co-expressed with NKT clonotype in half of the tumors. In contrast, two other invariant T cell clonotypes (Valpha4 and Valpha19) were not present in tumors. Such tumors also expressed Vbeta2 and Vbeta13, the restricted TCRbeta chain of MAIT cells and the antigen-presenting molecule MR1. A high percentage of infiltrating T cells was CD8+ and expressed HLA-DR suggesting activation. Although the MAIT alphaTCR was identified in both peripheral CD56+ and CD56- subsets, infiltrating lymphocytes were CD56 negative. The clonal presence of MAIT cells in tumors correlated with the expression of pro-inflammatory cytokines but no IL-4, IL-5 and IL-10, suggesting that a pro-inflammatory subset of human MAIT cells may exist. Our data imply that a CD56- subset of MAIT cells may participate in tumor immune responses similarly to NKT cells.

Impaired function of innate T lymphocytes and NK cells in the acute phase of ischemic stroke.

BACKGROUND: Functional alterations of innate lymphocytes, which can mount rapid immune responses and shape subsequent T cell reactions, were examined in the acute phase of ischemic stroke. METHODS: Frequencies, intracellular perforin and interferon-gamma (IFN-gamma) expression of Vdelta2 T cells, CD3+ CD56+ natural killer T (NKT)-like and NK cells were examined in the peripheral blood of 20 healthy controls and 28 patients within 6 h of the onset of acute ischemic stroke and after 72 h by flow cytometry. Cytokine production of isolated NKT-like and NK cells following in vitro activation was measured by cytometric bead array. NK cytotoxicity was examined in the peripheral blood mononuclear cells. RESULTS: Percentages of Vdelta2, NKT-like and NK cells were constant, and similar to percentages in healthy subjects. In contrast, proinflammatory intracellularIFN-gamma expression by Vdelta2 T cells, NKT-like cells and NK cells and IFN-gamma production by isolated NK cells in culture was low at 6 h and reached the level of healthy subjects by 72 h after stroke. Production of anti-inflammatory cytokines was unaltered. Intracellular perforin expression by Vdelta2 T cells, NKT-like cells and NK cells, and NK cytotoxicity was low at 6 h, and reached the level of healthy subjects by 72 h. Increases in IFN-gamma and perforin expression by Vdelta2 T cells correlated with clinical improvement indicated by decreases in NIHSS scores. CONCLUSIONS: Pro-inflammatory and cytotoxic responses of NK, NKT-like and Vdelta2 T cells become acutely deficient in ischemic stroke, which may contribute to an increased susceptibility to infections.

Clinical and model research of neurotrauma.

Modeling traumatic brain injury represents a major challenge for neuroscientists - to represent extremely complex pathobiological processes kept under close surveillance in the most complex organ of a laboratory animal. To ensure that such models also reflect those alterations evoked by and/or associated with traumatic brain injury (TBI) in man, well-defined, graded, simple injury paradigms should be used with clear endpoints that also enable us to assess the relevance of our findings to human observations. It is of particular importance that our endpoints should harbor clinical significance, and to this end, biological markers ultimately associated with the pathological processes operant in TBI are considered the best candidate. This chapter provides protocols for relevant experimental models of TBI and clinical materials for neuroproteomic analysis.

Benzamil prevents brain water accumulation in hyponatraemic rats.

BACKGROUND: It has been recently shown that A6 cells exposed to hyponatraemic stress respond with increased sodium uptake via activation of benzamil-sensitive sodium channels. This study was performed, therefore, to explore the possible involvement of benzamil-sensitive sodium channels and cellular sodium influx in brain oedema formation in hyponatraemic rats. METHODS: Four groups of male Wistar rats were studied (n = 13 in each group). Animals in group I with normonatraemia received intracerebroventricular (icv) 0.9% NaCl; animals in group II-IV were made hyponatraemic by intraperitoneal administration of isotonic glucose solution in a dose of 20% per body weight. Rats were pretreated with icv 0.9% NaCl (group II), 120 microg arginine vasopressin (AVP) (group III) or 4 microg benzamil-hydrochloride (group IV). Plasma sodium (ion-selective electrode) plasma osmolality (vapour pressure osmometer) and brain sodium and potassium content (flame photometer) as well as brain water content (desiccation method) were measured after a 2-h hydration period. RESULTS: Plasma sodium, osmolality and tissue sodium and potassium contents were markedly depressed in hyponatraemic rats (group II-IV, p < 0.0005 for each group) irrespective of drug pretreatment. Brain water content, however, responded to hyponatraemia with an increase from 77.55 +/- 1.00% to 78.45 +/- 0.94% (p < 0.01), and it was further augmented to 79.35 +/- 0.80% (p < 0.0005) by icv AVP pretreatment. By contrast, benzamil administration prevented the rise of brain water caused by hyponatraemia (77.61 +/- 1.04%). CONCLUSION: Early in the course of hyponatraemia, brain sodium channels may be activated, and the subsequent cellular sodium uptake may generate osmotic gradient to allow passive water flow into the cells. The simultaneous reduction of osmotic water conductivity of brain-specific aquaporin-4 by hyponatraemia, however, may limit water accumulation.

Calpain inhibition reduces axolemmal leakage in traumatic axonal injury.

Calcium-induced, calpain-mediated proteolysis (CMSP) has recently been implicated to the pathogenesis of diffuse (traumatic) axonal injury (TAI). Some studies suggested that subaxolemmal CMSP may contribute to axolemmal permeability (AP) alterations observed in TAI. Seeking direct evidence for this premise we investigated whether subaxolemmal CMSP may contribute to axolemmal permeability alterations (APA) and pre-injury calpain-inhibition could reduce AP in a rat model of TAI. Horseradish peroxidase (HRP, a tracer that accumulates in axons with APA) was administered one hour prior to injury into the lateral ventricle; 30 min preinjury a single tail vein bolus injection of 30 mg/kg MDL-28170 (a calpain inhibitor) or its vehicle was applied in Wistar rats exposed to impact acceleration brain injury. Histological detection of traumatically injured axonal segments accumulating HRP and statistical analysis revealed that pre-injury administration of the calpain inhibitor MDL-28170 significantly reduced the average length of HRP-labeled axonal segments. The axono-protective effect of pre-injury calpain inhibition recently demonstrated with classical immunohistochemical markers of TAI was further corroborated in this experiment; significant reduction of the length of labeled axons in the drug-treated rats implicate CMSP in the progression of altered AP in TAI.

Traumatic axonal injury in the spinal cord evoked by traumatic brain injury.

Although it is well known that traumatic brain injury (TBI) evokes traumatic axonal injury (TAI) within the brain, TBI-induced axonal damage in the spinal cord (SC) has been less extensively investigated. Detection of such axonal injury in the spinal cord would further the complexity of TBI while also challenging some functional neurobehavioral endpoints frequently used to assess recovery in various models of TBI. To assess TAI in the spinal cord associated with TBI, we analyzed the craniocervical junction (CCJ), cervico-thoracic (CT), and thoraco-lumber (ThL) spinal cord in a rodent model of impact acceleration of TBI of varying severities. Rats were transcardially fixed with aldehydes at 2, 6, and 24 h post-injury (n = 36); each group included on sham-injured rodent. Semi-serial vibratome sections were reacted with antibodies targeting TAI via alteration in cytoskeletal integrity or impaired axonal transport. Consistent with previous observations in this model, the CCJ contained numerous injured axons. Immunoreactive, damaged axonal profiles were also detected as caudal, as the ThL spinal cord displayed morphological characteristics entirely consistent with those described in the brainstem and the CCJ. Quantitative analyses demonstrated that the occurrence and extent of TAI is positively associated with the impact/energy of injury and negatively with the distance from the brainstem. These observations show that TBI can evoke TAI in regions remote from the injury site, including the spinal cord itself. This finding is relevant to shaken baby syndrome as well as during the analysis of data in functional recovery in various models of TBI.

Posttraumatic administration of pituitary adenylate cyclase activating polypeptide in central fluid percussion injury in rats.

Several in vitro and in vivo experiments have demonstrated the neuroprotective effects of pituitary adenylate cyclase activating polypeptide (PACAP) in focal cerebral ischemia, Parkinson's disease and traumatic brain injury (TBI). The aim of the present study was to analyze the effect of PACAP administration on diffuse axonal injury (DAI), an important contributor to morbidity and mortality associated with TBI, in a central fluid percussion (CFP) model of TBI. Rats were subjected to moderate (2 Atm) CFP injury. Thirty min after injury, 100 microg PACAP was administered intracerebroventricularly. DAI was assessed by immunohistochemical detection of beta-amyloid precursor protein, indicating impaired axoplasmic transport, and RMO-14 antibody, representing foci of cytoskeletal alterations (neurofilament compaction), both considered classical markers of axonal damage. Analysis of damaged, immunoreactive axonal profiles revealed significant axonal protection in the PACAP-treated versus vehicle-treated animals in the corticospinal tract, as far as traumatically induced disturbance of axoplasmic transport and cytoskeletal alteration were considered. Similarly to our former observations in an impact acceleration model of diffuse TBI, the present study demonstrated that PACAP also inhibits DAI in the CFP injury model. The finding indicates that PACAP and derivates can be considered potential candidates for further experimental studies, or purportedly for clinical trials in the therapy of TBI.