TBI Rats Research Articles

Evaluating the therapeutic effect of LIPUS in the early stage of traumatic brain injury using FA and T2* in rats.

To evaluate the protective effect of LIPUS at the early stage of brain trauma in rats, 45 rats were randomly divided into 3 groups: sham (n = 15), TBI (n = 15) and LIPUS treatment groups (n = 15). Ipsilateral and contralateral cortical and thalamic parameters obtained by diffusion tensor imaging (DTI) and fast low-angle shot magnetic resonance imaging (FLASH-MRI) were measured at different times after trauma. For fractional anisotropy (FA) and T2* values, two-way repeated measures ANOVA with Tukey's post hoc was used for intergroup comparisons. With observation time prolonged, the FA values of the ipsilateral cortex in the TBI group gradually increased and were significantly higher than those in the LIPUS treatment group on Day 7 (adjusted P = 0.0067). FA values in the contralateral cortex decreased at this time and were significantly lower than those in the LIPUS treatment group (adjusted P = 0.0192). Meanwhile, compared with LIPUS group, FA values were significantly higher in the injured thalamus (adjusted P = 0.0025). Combined with correlation analysis, FA values were positively correlated with neuronal damage (P = 0.0148, r2 = 0.895). At 7 days after trauma, T2* values in the ipsilateral cortex of the TBI group were significantly lower. After analysis of ferritin content and correlation, we found that T2* values were negatively correlated with ferritin (P = 0.0259, r2 = -0.849). By measuring post-traumatic changes in FA and T2* values, it is possible to demonstrate a neuronal protective effect of LIPUS in the early phase of TBI rats and promote brain rehabilitation.

AnGong NiuHuang (AGNH) pill attenuated traumatic brain injury through regulating NF-κB/Nlrp3 axis and glycerophospholipid metabolism

BackgroundTraumatic brain injury (TBI), especially neuroinflammation after TBI persists for a long time and causes significant neurodegenerative pathologies and neuropsychiatric problems. PurposeIn this study, the neuroprotective effect of AnGong NiuHuang (AGNH) on TBI was investigated and the mechanism was revealed by integrating multiple omics. MethodsThe rats with TBI were administrated with AGNH for 5 consecutive days and the effect was evaluated by using modified neurologic severity score (mNSS), brain edema, H&E staining, Nissl staining and TUNEL staining. The mechanism was revealed by using RNA sequencing (RNA-seq) and metabolomic analysis. The inflammatory factors, apoptosis-related proteins and identified vital targets were validated by enzyme-linked immunosorbent assay, western blotting and immunofluorescence staining. ResultsAdministration of AGNH decreased mNSS, brain edema, brain structure damage, but increased Nissl body density in the rats with TBI. Additionally, AGNH reduced IL-1β, IL-17A, TNF-α, MMP9, MCP-1, IL-6, Bax and TUNEL staining,but elevated Bcl2 level. Integrating transcriptomic analysis and metabolomic analysis identified vital targets and critical metabolic pathways. Importantly, AGNH treatment reduced the expression of TLR4, MYD88, NLRP3, BTK, IL-18 and Caspase 1 as well as glycerophospholipid metabolism-related protein AGPAT2 and PLA2G2D, and decreased the nuclear translocation of NF-κB p65 in the brain of TBI rats. Additionally, AGNH increased phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylserine (PS), phosphatidylethanolamine (PE), but decreased 1-acyl-sn-glycero-3-phosphocholine (LysoPC) in the metabolic pathway of glycerophospholipid metabolism. ConclusionTaken together, AGNH inhibited NF-κB/NLRP3 axis to suppress neuroinflammation, cell apoptosis and pyroptosis, and improved metabolic pathways of glycerophospholipid metabolism after TBI.

Inhibition of SENP5 reduces brain injury in TBI rats by regulating NEDD4L/TCF3 axis

Background The underlying mechanism of SENP5 influences neuronal regeneration and apoptosis in the context of TBI remains largely unexplored. Methods In the present study, PC12 cells treated with scratch for 24 h were regarded as a TBI cell model. The expression of SENP5 in PC12 cells was measured via Quantitative Real-Time PCR (qRT-PCR) and western blot assays. Cell Counting Kit 8 (CCK–8) and Flow cytometry assays were used to evaluate the activity of TBI cells. In addition, we assessed the effect of inhibiting SENP5 in vivo on neurological function deficits and apoptosis in the hippocampal tissues of TBI rats. The relationship between SENP5 and NEDD4L/TCF3 axis was proved via immunoprecipitation (IP) and double luciferase assays. Results Following TBI cell modeling, an increase in SENP5 expression has been found. Moreover, TBI modeling resulted in reduced cell viability and increased apoptosis, which was rescue by inhibition of SENP5. In vivo experiments demonstrated that SENP5 inhibition could mitigate TBI-induced brain injury in rats. Specifically, this inhibition led to lower neurological impairment scores, improved neuronal morphology and structure, and decreased neuronal apoptosis. In addition, NEDD4L has been proved to be relevant to the enhanced stability of the transcription factor TCF3, which in turn promoted the expression of SENP5. Conclusions This study reveals that inhibiting SENP5 can alleviate brain injury following TBI. NEDD4L/TCF3 axis can regulate the expression of SENP5 to affect the development of TBI. However, SENP5 regulates downstream targets of TBI and important mechanisms need to be further explored.

TAK-3 Inhibits Lipopolysaccharide-Induced Neuroinflammation in Traumatic Brain Injury Rats Through the TLR-4/NF-κB Pathway.

The activation of the inflammatory response is regarded as a pivotal factor in the pathogenesis of TBI. Central nervous system infection often leads to the exacerbation of neuroinflammation following TBI, primarily caused by Gram-negative bacteria. This study aims to elucidate the effects of the novel anti-inflammatory drug TAK-3 on LPS-induced neuroinflammation in TBI rats. In conjunction with the rat controlled cortical impact model, we administered local injections of Lipopolysaccharide to the impact site. Subsequently, interventions were implemented through intraperitoneal injections of TAK-3 and NF-κB activitor2 to modulate the TLR4/NF-κB axis The impact of LPS on neurological function was assessed using mNSS, open field test, and brain water content measurement. Inflammatory markers, including TNF-α, IL-1β, IL-6 and IL-10 were assessed to evaluate the condition of neuritis by Elisa. The activation of the TLR-4/NF-κB signaling pathway was detected by immunofluorescence staining and Western blot to assess the anti-inflammatory effects of TAK-3. The administration of LPS exacerbated neurological damage in rats with TBI, as evidenced by a reduction in motor activity and an increase in anxiety-like behavior. Furthermore, LPS induced disruption of the blood-brain barrier integrity and facilitated the development of brain edema. The activation of microglia and astrocytes by LPS at the cellular and molecular levels has been demonstrated to induce a significant upregulation of neuroinflammatory factors. The injection of TAK-3 attenuated the neuroinflammatory response induced by LPS. The present study highlights the exacerbating effects of LPS on neuroinflammation in TBI through activation of the TLR-4/NF-κB signaling pathway. TAK-3 can modulate the activity of this signaling axis, thereby attenuating neuroinflammation and ultimately reducing brain tissue damage.

Evaluation of canine adipose-derived mesenchymal stem cells for neurological functional recovery in a rat model of traumatic brain injury

BackgroundTraumatic brain injury (TBI) is a common condition in veterinary medicine that is difficult to manage.Veterinary regenerative therapy based on adipose mesenchymal stem cells seem to be an effective strategy for the treatment of traumatic brain injury. In this study, we evaluated therapeutic efficacy of canine Adipose-derived mesenchymal stem cells (AD-MSCs)in a rat TBI model, in terms of improved nerve function and anti-neuroinflammation.ResultsCanine AD-MSCs promoted neural functional recovery, reduced neuronal apoptosis, and inhibited the activation of microglia and astrocytes in TBI rats. According to the results in vivo, we further investigated the regulatory mechanism of AD-MSCs on activated microglia by co-culture in vitro. Finally, we found that canine AD-MSCs promoted their polarization to the M2 phenotype, and inhibited their polarization to the M1 phenotype. What’s more, AD-MSCs could reduce the migration, proliferation and Inflammatory cytokines of activated microglia, which is able to inhibit inflammation in the central system.ConclusionsCollectively, the present study demonstrates that transplantation of canine AD-MSCs can promote functional recovery in TBI rats via inhibition of neuronal apoptosis, glial cell activation and central system inflammation, thus providing a theoretical basis for canine AD-MSCs therapy for TBI in veterinary clinic.

Effect of valproic acid combined with transplantation of olfactory ensheathing cells modified by neurotrophic 3 gene on nerve protection and repair after traumatic brain injury

BackgroundTraumatic brain injury (TBI) often leads to cognitive and neurological dysfunction. Valproic acid (VPA) has a neuroprotective effect in acute central nervous system diseases; the neurotrophin 3 gene (NT-3) can maintain the survival of neurons, and olfactory ensheathing cells (OECs) can promote the growth of nerve axons. This study aimed to evaluate the restorative effect of VPA combined with NT-3 modified OECs (NT-3-OECs) on neurological function after TBI. MethodsThe neurological severity score (NSS) of rats was evaluated on the 1st, 7th, 14th, and 28th day after TBI modeling and corresponding intervention. Hematoxylin-eosin (HE) staining, p75 nerve growth factor receptor (P75), glial fibrillary acidic protein (GFAP), and neurofilament protein (NF)staining, and argyrophilic staining were used to observe the morphology of brain tissue 28 days after modeling. Moreover, TdT-mediated dUTP Nick-End Labeling (TUNEL) was used to detect the apoptosis rate of neurons. The changes in synapses and mitochondria in the injured area were observed by electron microscope. ResultsNT-3-OECs transplantation can increase the content of NT-3 in brain tissue, and NT-3-OECs can survive for >28 days. The NSS score of the TBI-VPA-NT-3-OECs group 28 days after cell transplantation was significantly lower than that of the other model treatment groups (P < 0.05). The morphological structure of the brain tissue was more complete, and the neurofilament fibers were neatly arranged, achieving better results than those of the other groups. The apoptosis rate of nerve cells in the TBI-VPA-NT-3-OECs group was significantly lower than in the other treatment groups (P < 0.05). Furthermore, the number of synapses in the combined intervention group was significantly higher than in the other treatment groups, and the mitochondrial structure was more complete. ConclusionNT-3-OECs have good biological function, and VPA combined with NT-3-OECs transplantation can effectively improve the prognosis of TBI rats.

Diffusion MRI approaches for investigating microstructural complexity in a rat model of traumatic brain injury

Our study explores the potential of conventional and advanced diffusion MRI techniques including diffusion tensor imaging (DTI), and single-shell 3-tissue constrained spherical deconvolution (SS3T-CSD) to investigate complex microstructural changes following severe traumatic brain injury in rats at a chronic phase. Rat brains after sham-operation or lateral fluid percussion (LFP) injury were scanned ex vivo in a 9.4 T scanner. Our region-of-interest-based approach of tensor-, and SS3T-CSD derived fixel-, 3-tissue signal fraction maps were sensitive to changes in both white matter (WM) and grey matter (GM) areas. Tensor-based measures, such as fractional anisotropy (FA) and radial diffusivity (RD), detected more changes in WM and GM areas as compared to fixel-based measures including apparent fiber density (AFD), peak FOD amplitude and primary fiber bundle density, while 3-tissue signal fraction maps revealed distinct changes in WM, GM, and phosphate-buffered saline (PBS) fractions highlighting the complex tissue microstructural alterations post-trauma. Track-weighted imaging demonstrated changes in track morphology including reduced curvature and average pathlength distal from the primary lesion in severe TBI rats. In histological analysis, changes in the diffusion MRI measures could be associated to decreased myelin density, loss of myelinated axons, and increased cellularity, revealing progressive microstructural alterations in these brain areas five months after injury. Overall, this study highlights the use of combined conventional and advanced diffusion MRI measures to obtain more precise insights into the complex tissue microstructural alterations in chronic phase of severe brain injury.

Protective Mechanisms of 3-Acetyl-11-keto-β-Boswellic Acid and Piperine in Fluid Percussion Rat Model of Traumatic Brain Injury Targeting Nrf2 and NFkB Signaling.

The current study aimed to investigate the neuroprotective effect of 3-acetyl-11-keto-β-boswellic acid (AKBA) in combination with bioenhancer piperine in lateral fluid percussion injury-induced TBI in experimental rats. Fluid percussion injury was introduced in the rat brain by delivering 50mmHg of pressure for 3min to the exposed brain. AKBA 25mg/kg, 50mg/kg orally, and AKBA (25mg/kg, p.o.) in combination with piperine (2.5mg/kg, p.o.) were administered from day 1 to day 14 to the assigned groups. On the 1st, 7th, and 14th day, behavioral parameters were checked. On the 15th day, animals were euthanized. In TBI rat model, AKBA-piperine combination significantly restored the altered performance of grip strength, rotarod test, open field task, narrow beam task (beam crossing time and no. of foot slips), and Morris water maze (escape latency and time spent in target quadrant) (p < 0.001 vs TBI control). Furthermore, the AKBA-piperine combination significantly reduced pro-inflammatory cytokine level in TBI rat model (&p < 0.001 vs TBI control). The combined effect of AKBA and piperine significantly restored oxidative stress parameters level, catecholamines level, and neurotransmitters level (p < 0.001 vs TBI control). Further findings showed that the AKBA-piperine combination prevented histopathological changes (p < 0.001), and the immunohistological study confirmed increased Nrf2-positive cells (p < 0.001 vs TBI control) and reduced nuclear factor kappa B (NFkB) expression (p < 0.001 vs TBI control, p < 0.01 vs TBI + AKBA 50mg/kg) in the cortical region following AKBA-piperine administration. The present study concluded that AKBA along with piperine achieved anti-oxidant, and anti-inflammatory effects, and also prevented neuronal injury via targeting Nrf2 and NFkB expressions.

Exosomes derived from bone marrow mesenchymal stem cells attenuate neurological damage in traumatic brain injury by alleviating glutamate-mediated excitotoxicity

BackgroundTraumatic brain injury (TBI) is one of the major contributors to disability and death worldwide. Glutamate-mediated excitotoxicity, one of the secondary injuries occurring after TBI, leads to extreme neuronal apoptosis, and can be a potential target for intervention. Bone marrow mesenchymal stem cells-derived exosomes (BMSCs-Exos) have demonstrated neuroprotective effects on TBI. However, their precise role and the underlying mechanism by which they regulate glutamate-mediated excitotoxicity have not yet been determined. Therefore, this study aimed to determine whether BMSCs-Exos alleviate glutamate excitotoxicity post-TBI and their associated mechanism. MethodsBMSCs-Exos were extracted from the BMSCs incubation medium and identified by transmission electron microscopy, nanoparticle trafficking analysis, and western blotting. The neuroprotective effects of BMSCs-Exos on glutamate excitotoxicity were investigated in the glutamate-mediated excitotoxicity neuronal cell model and the TBI rat model (TBI induced by controlled cortical impact) using western blotting and TUNEL assay. Cortical lesion samples were collected post-TBI on day-1 and day-14 to study histology. In addition, cortical lesion volume on days 1, 3 and 7 following TBI was determined using T2-weighted magnetic resonance imaging (MRI), and cognitive function was assessed at 4 weeks following TBI using the Morris water maze (MWM) test. ResultsBMSCs-Exos were observed to be spherical with a mean diameter of 109.9 nm, and expressed exosomal markers CD9, CD81 and TSG101. BMSCs-Exos were efficiently endocytosed by astrocytes after co-incubation for 24 h. In vitro studies revealed that 125 μM of glutamate significantly induced neuronal apoptosis, which was attenuated by BMSCs-Exos in astrocyte–neuron co-cultures. This attenuation was mediated by the upregulation of glutamate transporter-1 (GLT-1) level and the downregulation of p-p38 MAPK level in astrocytes. Similar results were obtained in vivo, wherein we verified that PKH67-labeled BMSCs-Exos administered intravenously could reach the perilesional cortex crossing the blood-brain barrier and significantly reduce glutamate levels in the perilesional cortex of the TBI rat, accompanied by increased GLT-1 level and downregulation in p-p38 MAPK level. Additionally, western blotting and TUNEL staining also revealed that BMSCs-Exos significantly downregulated the expression of pro-apoptosis markers, including cleaved caspase-3 and cleaved caspase-9, and attenuated neuronal apoptosis following TBI. Immunohistochemical analysis and Nissl staining showed that BMSCs-Exos significantly increased GLT-1-positive cells, and the number of apoptotic neurons decreased in the perilesional cortex. Moreover, MRI and MWM results revealed that BMSCs-Exos significantly minimized cortical lesion volume and ameliorated cognitive function after TBI. The underlying neuroprotective mechanism of BMSCs-Exos may be due to an increase in GLT-1 level in astrocytes by blocking the p38 MAPK signaling pathway. ConclusionTaken together, our findings demonstrate that the implementation of BMSCs-Exos may be an effective prospective therapy for attenuating post-TBI neurological damage.

Large-N Rat Data Enables Phenotyping of Risky Decision-Making: A Retrospective Analysis of Brain Injury on the Rodent Gambling Task.

Decision-making is substantially altered after brain injuries. Patients and rats with brain injury are more likely to make suboptimal, and sometimes risky choices. Such changes in decision-making may arise from alterations in how sensitive individuals are to outcomes. To assess this, we compiled and harmonized a large dataset from four studies of TBI, each of which evaluated behavior on the Rodent Gambling Task (RGT). We then determined whether the following were altered: (1) sensitivity to overall contingencies, (2) sensitivity to immediate outcomes, or (3) general choice phenotypes. Overall sensitivity was evaluated using the matching law, immediate sensitivity by looking at the probability of switching choices given a win or loss, and choice phenotypes by k-means clustering. We found significant reductions in sensitivity to the overall outcomes and a bias toward riskier alternatives in TBI rats. However, the substantial individual variability led to poor overall fits in matching analyses. We also found that TBI caused a significant reduction in the tendency to repeatedly choose a given option, but no difference in win- or loss-specific sensitivity. Finally, clustering revealed 5 distinct decision-making phenotypes and TBI reduced membership in the “optimal” type. The current findings support a hypothesis that TBI reduces sensitivity to contingencies. However, in the case of tasks such as the RGT, this is not a simple shift to indiscriminate or less discriminate responding. Rather, TBI rats are more likely to develop suboptimal preferences and frequently switch choices. Treatments will have to consider how this behavior might be corrected.

The neuroprotective mechanism of sevoflurane in rats with traumatic brain injury via FGF2

BackgroundTraumatic brain injury (TBI) is a kind of acquired brain injury, which is caused by external mechanical forces. Moreover, the neuroprotective role of sevoflurane (Sevo) has been identified in TBI. Therefore, this research was conducted to figure out the mechanism of Sevo in TBI via FGF2.MethodsThe key factors of neuroprotective effects of Sevo in TBI rats were predicted by bioinformatics analysis. A TBI model was induced on rats that then inhaled Sevo for 1 h and grouped via lentivirus injection. Modified Neurological Severity Score was adopted to evaluate neuronal damage in rats, followed by motor function and brain water content measurement. FGF2, EZH2, and HES1 expression in brain tissues was evaluated by immunofluorescence staining, and expression of related genes and autophagy factors by RT-qPCR and Western blot analysis. Methylation-specific PCR was performed to assess HES1 promoter methylation level, and ChIP assay to detect the enrichment of EZH2 in the HES1 promoter. Neuronal damage was assessed by cell immunofluorescence staining, and neuronal apoptosis by Nissl staining, TUNEL staining, and flow cytometry.ResultsSevo diminished brain edema, improved neurological scores, and decreased neuronal apoptosis and autophagy in TBI rats. Sevo preconditioning could upregulate FGF2 that elevated EZH2 expression, and EZH2 bound to the HES1 promoter to downregulate HES1 in TBI rats. Also, FGF2 or EZH2 overexpression or HES silencing decreased brain edema, neurological deficits, and neuronal autophagy and apoptosis in Sevo-treated TBI rats.ConclusionsOur results provided a novel insight to the neuroprotective mechanism of Sevo in TBI rats by downregulating HES1 via FGF2/EZH2 axis activation.

Potentiating Hemorrhage in a Periadolescent Rat Model of Closed-Head Traumatic Brain Injury Worsens Hyperexcitability but Not Behavioral Deficits.

Post-traumatic epilepsy (PTE) and neurocognitive deficits are devastating sequelae of head injuries that are common in adolescents. Investigating desperately needed treatments is hindered by the difficulties in inducing PTE in rodents and the lack of established immature rat models of pediatric PTE. Hemorrhage is a significant risk factor for PTE, but compared to humans, rats are less prone to bleeding because of their rapid blood coagulation system. In this study, we promoted bleeding in the controlled cortical impact (CCI) closed-head injury model with a 20 min pre-impact 600 IU/kg intraperitoneal heparin injection in postnatal day 35 (P35) periadolescent rats, given the preponderance of such injuries in this age group. Temporo-parietal CCI was performed post-heparin (HTBI group) or post-saline (TBI group). Controls were subjected to sham procedures following heparin or saline administration. Continuous long-term EEG monitoring was performed for 3 months post-CCI. Sensorimotor testing, the Morris water maze, and a modified active avoidance test were conducted between P80 and P100. Glial fibrillary acidic protein (GFAP) levels and neuronal damage were also assessed. Compared to TBI rats, HTBI rats had persistently higher EEG spiking and increased hippocampal GFAP levels (p < 0.05). No sensorimotor deficits were detected in any group. Compared to controls, both HTBI and TBI groups had a long-term hippocampal neuronal loss (p < 0.05), as well as contextual and visuospatial learning deficits (p < 0.05). The hippocampal astrogliosis and EEG spiking detected in all rats subjected to our hemorrhage-promoting procedure suggest the emergence of hyperexcitable networks and pave the way to a periadolescent PTE rat model.

Arousing Effects of Electroacupuncture on the "Shuigou Point" in Rats with Disorder of Consciousness after Traumatic Brain Injury.

Orexin is an important neuropeptide that stimulates cortical activation and arousal and is involved in the regulation of wakefulness and arousal. Our previous meta-analysis showed that acupuncture fared well in the treatment of TBI-induced DOC in which “shuigou (DU 26)” was the most important and frequent point targeted. In the present study, we investigated whether electroacupuncture (EA) promotes TBI-induced unconsciousness wakefulness via orexin pathway. A TBI rat model was established using a control cortical impact (CCI) model. In the stimulated group, TBI rats received EA (15 Hz, 1.0 mA, 15 min). In the antagonist group, TBI rats were intraperitoneally injected with the orexin receptor 1 (OX1R) antagonist SB334867 and received EA. Unconsciousness time was observed in each group after TBI, and electrocorticography (ECoG) was applied to detect rats' EEG activity. Immunohistochemistry, enzyme-linked immunosorbent assay, and western blot were used to assess the levels of orexin-1(OX1) and OX1R expression in the mPFC. We show that duration of unconsciousness and the ratio of delta power in ECoG in the EA group were significantly reduced compared with those in the TBI group. EA could increase OX1 and OX1R expression in the mPFC and reduced the loss of orexin-producing neurons in LHA. However, all the efficacy of EA was blocked by the OX1R antagonist SB334867. Our findings suggest that EA promotes the recovery of consciousness of TBI-induced unconscious rats via upregulation of OX1and OX1R expression in mPFC.

Traumatic brain injury metabolome and mitochondrial impact after early stage Ru360 treatment

Ru360, a mitochondrial Ca2+ uptake inhibitor, was tested in a unilateral fluid percussion TBI model in developing rats (P31). Vehicle and Ru360 treated TBI rats underwent sensorimotor behavioral monitoring between 24 and 72 h, thereafter which 185 brain metabolites were analyzed postmortem using LC/MS. Ru360 treatment after TBI improved sensorimotor behavioral recovery, upregulated glycolytic and pentose phosphate pathways, mitigated oxidative stress and prevented NAD+ depletion across both hemispheres. While neural viability improved ipsilaterally, it reduced contralaterally. Ru360 treatment, overall, had a global impact with most benefit near the strongest injury impact areas, while perturbing mitochondrial oxidative energetics in the milder TBI impact areas.

Traumatic brain injury substantially reduces the conditioned reinforcing effects of environmental cues in rats

Traumatic brain injury affects millions of people each year and is an established risk factor for addiction. Recent animal studies have causally demonstrated that injuries can increase drug self-administration across a variety of substances. One potential behavioral mediator for this finding is an increased responsivity to drug-associated cues. This endophenotype can be identified by profiling non-drug-related behaviors. The current study evaluated several paradigms (conditioned approach, conditioned reinforcement, extinction from variable interval responding, conditioned facilitation) to determine how rats with a frontal TBI differed in their response to Pavlovian conditioning in response to food-paired cues. Surprisingly, rats with a TBI demonstrated increased goal-tracking in a conditioned approach paradigm and exerted less effort for a conditioned reinforcer. Moreover, they had slightly facilitated extinction (as demonstrated by significantly larger interresponse times) in the face of reinforcer-associated cues. Despite these effects, TBI rats still demonstrated conditioned facilitation to an auditory stimulus. Together, these effects suggest a phenotype in the opposite direction of what might be anticipated. Cues still served a strong discriminative function and altered behavior; however, they did not function as strong conditioned reinforcers for TBI animals. One potential reason for this is that substantial changes to the dopamine system after TBI may reduce the conditioned reinforcing effects of cues, but sensitize the brain to potent drugs of abuse. More research will be needed to determine whether this is the case.

Traumatic Brain Injury Impairs Flow‐Dependent Constrictions of Isolated Rat Middle Cerebral Arteries, Primarily by Interfering with the Flow Sensing Mechanisms

BackgroundTraumatic brain injury (TBI) is a major health problem worldwide due to its high mortality (35–40%), and morbidity (headache, brain edema, cognitive, behavioral, and communicative disabilities). Previously we have shown that mechanotransductions of two hemodynamic factors, pressure and flow are importantly involved in the autoregulation of cerebral blood flow, which may become inefficient after TBI. Indeed, previously we have shown that TBI diminishes pressure‐induced myogenic constriction of middle cerebral arteries (MCA). In the present study we hypothesized that TBI effects also flow‐induced constrictor response of MCA.MethodsTBI was induced in anaesthetized rat by Marmarou’s weight drop model, then MCA was isolated and transferred into pressure‐flow chamber. Inflow and outflow pressures were controlled and measured. The internal diameter was continuously measured by a videomicroscopy equipped with a microangiometer and recorded digitally by PowerLab system (AD Instruments). Data are mean±SEM.ResultsThe active (242,2±6,1 μm) and passive (277,9±8,8) diameters (p&lt;0.05) of isolated MCAs of control rats (n=39) indicate that a substantial myogenic tone developed in response to pressure (80 mmHg: Δ−35,7 ±2,7 μm, p&lt;0.05). Arachidonic acid (AA) ‐ after initial dilations (+6±3 and +9±2,5 μm) ‐ elicited dose dependent constrictions (−9±2,1 and −20±3,2 μm) of MCA of control rats. Step increases in flow elicited gradual constrictions of MCA of control rats (from max.: 229,3±6,6 to 191±6 μm, Δ−38,3 ±0,6 μm, p&lt;0.05), which was eliminated after TBI (from 227,3±14,1 to 227,4±13,3 μm). U46619, a thromboxane A2 (TXA2) / prostaglandin H2 (PGH2) receptor (TP receptor) agonist elicited similar constrictions of MCA of control and TBI rats (max.: Δ−66,1 ±0,7 μm vs. Δ−49 ±4 μm) rats, which were eliminated by SQ 29,548 a TP receptor antagonist. CYP‐450 metabolite 20‐HETE elicited similar constrictions of MCA in control (Δ−18 ±0,9 μm and TBI rats (Δ−15 ±0,1 μm) which were eliminated by HET0016, an inhibitor of CYP‐450. Paxilline (an inhibitor of potassium channel blocker) inhibited flow‐induced constrictions of MCA of control (max.: Δ−37,5 ±3 μm vs. max.: Δ−2,8 ±1 μm, p&lt;0.05), whereas did not affect the diameters of MCA after TBI (max.: Δ−0,1 ±1,6 μm vs. Δ−2,5 ±3 μm).ConclusionsThese findings suggest that 1) flow‐induced constrictor response of MCA depends on AA‐metabolites acting on TP receptors, 2) constrictor responses to TP agonists remain intact after TBI, 3) thus TBI interferes primarily with the flow sensing mechanisms of the vascular wall, which 4) likely leads to diminished autoregulation of cerebral blood flow.Support or Funding InformationScientific Excellence Program 2019., at the University of Physical Education, Innovation and Technology Ministry, Hungary TUDFO/51757/2019‐ITM and Higher Education Institutional Excellence Program at Semmelweis University and the National Bionika Program ED_17‐1‐2017‐0009, Hungary, and the University of Pecs within the framework of the 5th. thematic programme, National Research Development and Innovation Office NKFI‐FK123798.

Chitosan-based thermosensitive composite hydrogel enhances the therapeutic efficacy of human umbilical cord MSC in TBI rat model

Recently, stem cell–based therapy shows great promise in treating traumatic brain injury. However, the low rate of cell engraftment and survival are two major barriers for efficacy. To improve the therapeutic effect, a new thermosensitive hydrogel based on chitosan, hydroxyethyl cellulose, hyaluronic acid, and β-glycerophosphate (CS-HEC-HA/GP) was developed in this study. This CS-HEC-HA/GP hydrogel exhibits a faster gelation process and better biocompatibility to human umbilical cord mesenchymal stem cells (hUC-MSC) versus CS/GP or CS-HEC/GP hydrogels. The suitable rheological behavior similar to brain tissue supports that the CS-HEC-HA/GP hydrogel might be a preferable neural scaffold. In addition, CS-HEC-HA/GP hydrogel loaded with hUC-MSC could enhance the retention, survival, and migration of encapsulated hUC-MSC, improve survival and proliferation of endogenous neural cells probably by secreting neurotrophic factors and inhibiting apoptosis, and thereby accelerate remodeling of brain structure and neurological function recovery in TBI rats. Thus, this hydrogel shows enormous potentials in stem cell–based neural tissue repair and regeneration.

Role of edaravone in alleviating prognosis of rats following traumatic brain injury

Objective To investigate the effects of edaravone on improving the prognosis of TBI rats. Methods A total of 150 SD male rats were divided into normal control group (10 rats), TBI group (70 rats) and edaravone group (70 rats). In the edaravone treatment group, the rats were injected intraperitoneally once a day continously for 2 weeks with the injection dose of 5.4 mg·kg-1·d-1. At 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 1 week and 2 weeks after injury, the neurobehavioral and motor function scores of rats were monitored respectively, with 10 rats monitored at each time point. Serum and cerebrospinal fluid samples were collected and the levels of β-endorphin and gonadotropin-releasing hormone (GnRH) were determined by radioimmunoassay (RIA). Results In the edaravone group, the neurobehavioral and motor function scores were higher than those of the TBI group at 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 1 week and 2 weeks after injury. At 48 hours after injury, the neurobehavioral scores of the TBI group and the edaravone treatment group were (8.2±0.9)points and (10.3±0.7)points, respectively (P<0.05), and the motor function scores were (5.9±1.0)points and (6.9±1.2)points respectively (P<0.05). Meanwhile, the contents of β-endorphin in blood and cerebrospinal fluid of the normal control group were (50.2±9.5)pg/ml and (16.2±2.8)pg/ml, and the contents of GnRH were (75.2±11.2)pg/ml and (36.2±10.8)pg/ml, respectively.The levels of β-endorphin and GnRH in serum and cerebrospinal fluid were significantly increased at 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 1 week and 2 weeks after injury. The levels of β-endorphin and GnRH in the edaravone group were lower than those of TBI group. At 72 hour after injury, the levels of β-endorph in serum in TBI group and edaravone group were (165.2±8.5) pg/ml and (109.5±6.3)pg/ml respectively (P< 0.05), and the levels of β-endorph in cerebrospinal fluid were (63.3±3.1)pg/ml and (38.2±2.3)pg/ml respectively (P<0.05). At 72 hour after injury, the levels of GnRH in serum in TBI group and edaravone group were (203.7±17.1)pg/ml and (110.4±19.2)pg/ml respectively (P<0.05), and the levels of GnRH in cerebrospinal fluid is (153.0±13.4)pg/ml and (93.2±10.5)pg/ml respectively (P<0.05). Conclusion During acute and recovery periods after TBI, continuous treatment with edaravone can obviously reduce the levels of β-endorphin and GnRH, which is beneficial to alleviate the secondary brain injury after TBI in rats, promote the recovery of nerve and function, and improve the prognosis. Key words: Brain injuries; β-Endorphin; Gonadotropin-releasing hormone; Edaravone

Enhanced descending pain facilitation in acute traumatic brain injury

Acute and persistent pain are recognized consequences of TBI that can enhance suffering and significantly impair rehabilitative efforts. Both experimental models and clinical studies suggest that TBI may result in an imbalance between descending pain facilitatory and inhibitory pathways. The aim of this study was to assess the role of enhanced descending serotonin-mediated pain facilitation in a rat TBI model using selective spinal serotonergic fiber depletion with 5, 7-dihydroxytryptamine (DHT). We observed significant hindpaw allodynia in TBI rats that was reduced after DHT but not vehicle treatment. Immunohistochemical studies demonstrated profound spinal serotonin depletion in DHT-treated rats. Furthermore, lumbar intrathecal administration of the 5-HT3 receptor antagonist ondansetron at 7 days post-injury (DPI), when hindpaw allodynia was maximal, also attenuated nociceptive sensitization. Additional immunohistochemical analyses of the lumbar spinal cord at 7 DPI revealed a robust bilateral microglial response in the superficial dorsal horns that was significantly reduced with DHT treatment. Furthermore, serotonin depletion also prevented the TBI-induced bilateral increase in c-Fos positive cells within the Rexed laminae I and II of the dorsal horns. These results indicate that in the weeks following TBI, pain may be responsive to 5-HT3 receptor antagonists or other measures which rebalance descending pain modulation.

Effect of exogenous thyroxine on regeneration and repair of central nervous system in rats with severe traumatic brain injury

Objective To investigate the effect of exogenous thyroxine on the regeneration and repair of central nervous system in rats with severe traumatic brain injury. Methods A total of 108 male SD rats were randomly divided into Group A (normal group), Group B (thyroxine group), Group C (TBI group), Group D [TBI+ low dose of thyroxine (6.5 μg/kg) group], Group E [TBI+ medium dose of thyroxine (10 μg/kg) group)] and Group F [TBI+ high dose of thyroxine (15.4 μg/kg)] by random number table method, with 18 rats in each group. The animal model was established according to the Feeney method. Groups A and C were given saline and thyroxine 6 hours after TBI. At 1 day, 3 days and 7 days after injury, six rats were selected from each group according to random number table method for brain tissue harvest. The pathological changes of brain tissues were observed, and the expressions of Wnt3a and β-catenin, brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were detected by RT-PCR and immunohistochemistry respectively. Results (1) There were no pathological changes in brain tissue in Groups A and B. The pathological changes in brain tissue of TBI rats in Groups D, E and F were significantly mitigated than those in Group C, and the effect of Groups E and F were more obvious. (2) RT-PCR showed that the expressions of Wnt3a and β-catenin mRNA in hippocampus of Group D at 7 days after injury were significantly higher [(6.46±2.02) vs. (4.08±1.06); (13.53±1.64) vs. (2.11±0.63); P<0.05); Wnt3a mRNA expression of Groups E and F were increased significantly at 3 days and 7 days after injury [(5.45±1.54) vs. (2.78±1.04), (8.59±1.88) vs. (4.08±1.06), (5.40±1.38) vs. (2.78±1.04), (8.63±1.74) vs. (4.08±1.06); P<0.05)]. The expressions of β-catenin mRNA were increased significantly at 1 day, 3 days, and 7 days after injury [(3.10±0.59) vs. (1.45±0.28), (5.28±0.62) vs. (1.45±0.28), (4.12±0.43) vs. (1.64±0.31), (8.78±0.92) vs. (1.64±0.31), (23.80±2.38)vs. (2.11±0.63), (25.94±3.79) vs. (2.11±0.63); P<0.05)]. The expressions of Wnt3a and β-catenin in hippocampus of Group B did not change significantly. (3) Immunohistochemical staining showed that the expression of BDNF and NGF in hippocampus of B did not change significantly after thyroxine treatment, but that of BDNF and NGF in Group D did not change significantly after treatment. The expressions of BDNF and NGF of Groups E and F were significantly higher than that in Group C and reached the peak at 3 days after injury [BDNF: (77.3±5.4) vs. (55.0±5.6), (78.0±7.8) vs. (55.0±5.6); NGF: (83.7±5.8) vs. (62.2±10.3), (86.8±4.8) vs. (62.2±10.3); P<0.05]. Conclusions Exogenous thyroxine has no effect on the Wnt/β-catenin pathway in normal rats. But exogenous thyroxine can significantly promote the centralis regeneration and repair in TBI rats, which might be associated with its role in upregulating the expression of mRNA and increasing the secretion of BDNF and NGF. Key words: Thyroxine; Brain injuries; Nerve regeneration; Wnt/β-catenin signaling pathway