Thiamine preserves mitochondrial function in a rat model of traumatic brain injury,preventing inactivation of the 2-oxoglutarate dehydrogenase complex

Background and purpose

Based on the fact that traumatic brain injury is associated with mitochondrial dysfunction we aimed at localization of mitochondrial defect and attempted to correct it by thiamine.

Alterations of cerebral cortex and hippocampal proteasome subunit expression and function in a traumatic brain injury rat model

Following cellular stress or tissue injury, the proteasome plays a critical role in protein degradation and signal transduction. The present study examined the β-subunit expression of constitutive proteasomes (β1, β2, and β5), immunoproteasomes (β1i, β2i, and β5i) and the 11S proteasome activator, PA28α, in the rat CNS after traumatic brain injury (TBI). Concomitant measures assessed changes in proteasome activities. Quantitative real time PCR results indicated that β1 and β2 mRNA levels were not changed, while β5 mRNA levels were significantly decreased in injured CNS following TBI. However, β1i, β2i, β5i, and PA28α mRNA levels were significantly increased in the injured CNS. Western blotting studies found that β1, β2, β5, β2i, and β5i subunit protein levels remained unchanged in the injured CNS, but β1i and PA28α protein levels were significantly elevated in ipsilateral cerebral cortex and hippocampus. Proteasome activity assays found that peptidyl glutamyl peptide hydrolase-like and chymotrypsin-like activity were significantly reduced in the CNS after TBI, and that trypsin-like proteasome activity was increased in the injured cerebral cortex. Our results demonstrated that both proteasome composition and function in the CNS were affected by trauma. Treatments that preserve proteasome function following CNS injury may be beneficial as an approach to cerebral neuroprotection.     

Progesterone and vitamin D: Improvement after traumatic brain injury in middle-aged rats

Progesterone (PROG) and vitamin D hormone (VDH) have both shown promise in treating traumatic brain injury (TBI). Both modulate apoptosis, inflammation, oxidative stress, and excitotoxicity. We investigated whether 21 days of VDH deficiency would alter cognitive behavior after TBI and whether combined PROG and VDH would improve behavioral and morphological outcomes more than either hormone alone in VDH-deficient middle-aged rats given bilateral contusions of the medial frontal cortex. PROG (16 mg/kg) and VDH (5 μg/kg) were injected intraperitoneally 1 h post-injury. Eight additional doses of PROG were injected subcutaneously over 7 days post-injury. VDH deficiency itself did not significantly reduce baseline behavioral functions or aggravate impaired cognitive outcomes. Combination therapy showed moderate improvement in preserving spatial and reference memory but was not significantly better than PROG monotherapy. However, combination therapy significantly reduced neuronal loss and the proliferation of reactive astrocytes, and showed better efficacy compared to VDH or PROG alone in preventing MAP-2 degradation. VDH + PROG combination therapy may attenuate some of the potential long-term, subtle, pathophysiological consequences of brain injury in older subjects.     

An analytical model of traumatic diffuse brain injury

Diffuse axonal injury (DAI) with prolonged coma has been produced in the primate using an impulsive, rotational acceleration of the head without impact. This pathophysiological entity has been studied subsequently from a biomechanics perspective using physical models of the skull-brain structure. Subjected to identical loading conditions as the primate, these physical models permit one to measure the deformation within the surrogate brain tissue as a function of the forces applied to the head. An analytical model designed to approximate these experiments has been developed in order to facilitate an analysis of the parameters influencing brain deformation. These three models together are directed toward the development of injury tolerance criteria based upon the shear strain magnitude experienced by the deep white matter of the brain. The analytical model geometry consists of a rigid, right-circular cylindrical shell filled with a Kelvin-Voigt viscoelastic material. Allowing no slip on the boundary, the shell is subjected to a sudden, distributed, axisymmetric, rotational load. A Fourier series representation of the load allows unrestricted load-time histories. The exact solution for the relative angular displacement (V) and the infinitesimal shear strain (epsilon) at any radial location in the viscoelastic material with respect to the shell was determined.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence to support mitochondrial neuroprotection,in severe traumatic brain injury

Journal of Bioenergetics and Biomembranes - Traumatic brain injury (TBI) is still the leading cause of disability in young adults worldwide. The major mechanisms – diffuse axonal injury,...     

Plasma copeptin concentration and outcome after pediatric traumatic brain injury

Higher plasma copeptin level has been associated with poor outcomes of critical illness. The present study was undertaken to investigate the plasma copeptin concentrations in children with traumatic brain injury (TBI) and to analyze the correlation of copeptin with disease outcome. Plasma copeptin concentrations of 126 healthy children and 126 children with acute severe TBI were measured by enzyme-linked immunosorbent assay. Twenty-one patients (16.7%) died and 38 patients (30.2%) had an unfavorable outcome (Glasgow Outcome Scale score of 1–3) at 6 months. Plasma copeptin level was obviously higher in patients than in healthy children (46.2 ± 20.8 pmol/L vs. 9.6 ± 3.0 pmol/L, P < 0.001). Plasma copeptin level was identified as an independent predictor for 6-month mortality [odds ratio (OR) 1.261, 95% confidence interval (CI) 1.112–1.538, P = 0.005] and unfavorable outcome (OR 1.313, 95% CI 1.146–1.659, P = 0.003). The predictive value of copeptin was similar to that of Glasgow Coma Scale (GCS) score for 6-month mortality [area under curve (AUC) 0.832, 95% CI 0.755–0.892 vs. AUC 0.873, 95% CI 0.802–0.926, P = 0.412] and unfavorable outcome (AUC 0.863, 95% CI 0.790–0.918 vs. AUC 0.885, 95% CI 0.816–0.935, P = 0.596). Copeptin improved the AUC of GCS score for 6-month unfavorable outcome (AUC 0.929, 95% CI 0.869–0.967, P = 0.013), but not for 6-month mortality (AUC 0.887, 95% CI 0.818–0.936, P = 0.600). Thus, plasma copeptin level represents a novel biomarker for predicting 6-month clinical outcome in children with TBI.     

在大鼠创伤性脑损伤模型中神经干细胞移植对突触素表达的影响

目的探讨神经干细胞（NSCs）移植对创伤性脑损伤（TBI）模型大鼠感觉运动功能的恢复作用及其对损伤脑组织中突触素（SYP）表达的影响。方法体外培养大鼠胚胎皮质NSCs;采用Feeney法制备TBI模型,于造模后72h,移植组采用PKH26荧光示踪剂标记的NSCs直接移植于脑损伤区,对照组以等量生理盐水代替NSCs;分别于移植后不同时间点,采用Gridwalk和Latency试验检测TBI大鼠的感觉运动功能;荧光显微镜下计数移植细胞的存活数量;采用免疫印迹和RT-PCR技术检测脑损伤区及周围组织中SYP的表达。结果 NSCs移植大鼠前、后肢功能分别在移植后第2w和4w恢复至手术前水平,而直到第8w,对照组大鼠后肢功能和通过平板移动时间与NSCs移植组和基线比较仍有显著性差异（P〈0.05）。移植的NSCs随移植时间延长存活数量减少,移植后第4w和8w的存活数分别为6.3%±1.0%和4.1%±0.9%。在移植后的8w期间,移植组脑损伤区及周围组织中SYP的表达均明显高于对照组（P〈0.05）。结论移植的NSCs在TBI脑内能够存活,并明显改善了TBI大鼠对侧肢体的感觉运动功能;NSCs移植促进了脑损伤区及周围组织中SYP的表达,这可能是NSCs移植促进功能恢复的机理之一。     

Serum metabolomic markers for traumatic brain injury: a mouse model

Introduction

Traumatic brain injury (TBI) is physical injury to brain tissue that temporarily or permanently impairs brain function.

Objectives

Evaluate the use of metabolomics for the development of biomarkers of TBI for the diagnosis and timing of injury onset.

Methods

A validated model of closed injury TBI was employed using 10 TBI mice and 8 sham operated controls. Quantitative LC–MS/MS metabolomic analysis was performed on the serum.

Results

Thirty-six (24.0 %) of 150 metabolites were altered with TBI. Principal component analysis (PCA) and Partial least squares discriminant analysis (PLS-DA) analyses revealed clear segregation between TBI versus control sera. The combination of methionine sulfoxide and the lipid PC aa C34:4 accurately diagnosed TBI, AUC (95 % CI) 0.85 (0.644–1.0). A combination of metabolite markers were highly accurate in distinguishing early (4 h post TBI) from late (24 h) TBI: AUC (95 % CI) 1.0 (1.0–1.0). Spermidine, which is known to have an antioxidant effect and which is known to be metabolically disrupted in TBI, was the most discriminating biomarker based on the variable importance ranking in projection (VIP) plot. Several important metabolic pathways were found to be disrupted including: pathways for arginine, proline, glutathione, cysteine, and sphingolipid metabolism.

Conclusion

Using serum metabolomic analysis we were able to identify novel putative serum biomarkers of TBI. They were accurate for detecting and determining the timing of TBI. In addition, pathway analysis provided important insights into the biochemical mechanisms of brain injury. Potential clinical implications for diagnosis, timing, and monitoring brain injury are discussed.

     

Increased expression of BAG-1 in rat brain cortex after traumatic brain injury

BAG-1 protein was initially identified as a Bcl-2-binding protein. It was reported to enhance Bcl-2 protection from cell death, suggesting that BAG-1 represents a new type of anti-cell death gene. Moreover, recent study has shown that BAG-1 can enhance the proliferation of neuronal precursor cells, attenuate the growth inhibition induced by siah1. However, its function and expression in the central nervous system lesion are not been understood very well. In this study, we performed a traumatic brain injury (TBI) model in adult rats and investigated the dynamic changes of BAG-1 expression in the brain cortex. Double immunofluorescence staining revealed that BAG-1 was co-expressed with NEURON and glial fibrillary acidic protein (GFAP). In addition, we detected that proliferating cell nuclear antigen had the co-localization with GFAP, and BAG-1. All our findings suggested that BAG-1 might involve in the pathophysiology of brain after TBI.     

The expression changes of Numblike in rat brain cortex after traumatic brain injury

Numblike (Numbl) plays an important role in ependymal wall integrity and subventricular zone neuroblast survival. And Numbl is specifically expressed in the brain. However, its expression and function in the central nervous system lesion are still unclear. In this study, we performed a traumatic brain injury (TBI) model in adult rats and investigated the dynamic changes of Numbl expression in the brain cortex. Western blot and immunohistochemistry analysis revealed that Numbl was present in normal brain. It gradually decreased, reached the lowest point at day 3 after TBI, and then increased during the following days. Double immunofluorescence staining showed that Numbl immunoreactivity was found in neurons, but not astrocytes and microglia. Moreover, the 3rd day post injury was the apoptotic peak implied by the alteration of caspase-3. All these results suggested that Numbl may be involved in the pathophysiology of TBI and further research is needed to have a good understanding of its function and mechanism.     

肌苷促进脑损伤后神经功能恢复的实验研究

目的：中枢损伤是目前致残率最高的疾病之一,肌苷对于神经损伤后功能恢复的促进作用已经成为研究热点,本研究拟建立一侧前肢瘫痪的大鼠脑外伤模型,证实肌苷治疗促进中枢损伤后上肢功能恢复的有效性,同时初步探索其机制。方法：建立一侧运动皮层冲击损毁的大鼠模型,通过肢体不对称实验、抓取实验等行为学观察证实其惠侧上肢功能受损,后在实验组进行肌苷药物14天,观察28天内上肢功能的恢复情况,与对照组作对比。证实其行为学上的有效性,同时对损伤侧大脑进行顺行BDA染色,探索其内在机制。结果：通过28天的观察发现经过肌苷治疗的的实验组大鼠肢体不对称实验、抓取实验等行为学评分明显好于隐性对照组,顺行BDA染色证实其有促进损伤周围健存皮层突触再生和代偿的作用。结论：肌苷可以促进中枢损伤后大鼠残存神经元得突触再生,使其大脑能在最大程度上代偿其丧失的功能,该药物可能会成为一种新的中枢损伤治疗的前体药物。     

肌苷促进脑损伤后神经功能恢复的实验研究

目的:中枢损伤是目前致残率最高的疾病之一,肌苷对于神经损伤后功能恢复的促进作用已经成为研究热点,本研究拟建立一侧前肢瘫痪的大鼠脑外伤模型,证实肌苷治疗促进中枢损伤后上肢功能恢复的有效性,同时初步探索其机制。方法:建立一侧运动皮层冲击损毁的大鼠模型,通过肢体不对称实验、抓取实验等行为学观察证实其患侧上肢功能受损,后在实验组进行肌苷药物14天,观察28天内上肢功能的恢复情况,与对照组作对比,证实其行为学上的有效性,同时对损伤侧大脑进行顺行BDA染色,探索其内在机制。结果:通过28天的观察发现经过肌苷治疗的的实验组大鼠肢体不对称实验、抓取实验等行为学评分明显好于隐性对照组,顺行BDA染色证实其有促进损伤周围健存皮层突触再生和代偿的作用。结论:肌苷可以促进中枢损伤后大鼠残存神经元得突触再生,使其大脑能在最大程度上代偿其丧失的功能,该药物可能会成为一种新的中枢损伤治疗的前体药物。     

Progesterone and low-dose vitamin D hormone treatment enhances sparing of memory following traumatic brain injury

Progesterone (PROG) has been shown to protect the brain from traumatic injury and is now in Phase III clinical trials. Our work shows that PROG's beneficial effects can be reduced in vitamin D hormone (VDH)-deficient subjects. VDH can modulate neuronal apoptosis, trophic factors, inflammation, oxidative stress, excitotoxicity, and myelin and axon repair. We investigated whether VDH combined with PROG could improve behavioral outcomes more than PROG alone in VDH-sufficient rats given bilateral contusions of the medial frontal cortex. PROG and different doses of VDH (1 μg/kg, VDH1; 2.5 μg/kg, VDH2; 5 μg/kg, VDH3) were injected intraperitoneally 1 h post-injury. Eight additional doses of PROG were given subcutaneously over 8 days with tapering over the last 2 days. Neurobehavioral tests, necrotic cavity, neuronal death and activation of astrocytes were evaluated 21 days post-injury. We found that PROG and PROG + VDH preserve spatial memory processing. VDH1 + PROG improved performance in acquisition more effectively than PROG alone, indicating that the low VDH dose is optimal for combination therapy. There were no significant differences in necrotic cavity size among the groups. The density of positive staining for reactive astrocytes (glial fibrillary acidic protein (GFAP)) increased and the cell bodies and processes of GFAP-positive cells were enlarged in the PROG + VDH1 group. Our data indicate that the combination of PROG and VDH is more effective than PROG alone in preserving spatial and reference memory, and that PROG plus low-dose VDH can activateGFAP reactions up to 21 days after injury. This effect may be one of the mechanisms underlying PROG's neuroprotective effects in combination with VDH.     

The expression pattern of ADP-ribosyltransferase 3 in rat traumatic brain injury

Mammalian ecto ADP-ribosyltransferases (ARTs) can regulate the biological functions of various types of cells by catalyzing the transfer of single ADP-ribose moiety from NAD⁺ to a specific amino acid in a target protein. ART3 is a member of the known ART family which is involved in cell division, DNA-repair and the regulation of the inflammatory response. To elucidate the expression, cellular localization and possible functions of ART3 in central nervous system (CNS) lesion and repair, we performed an acute traumatic brain injury model in adult rats. Western blot analysis showed that the expression of ART3 in ipsilateral brain cortex increased, then reached a peak at day 3 after traumatic brain injury (TBI), and gradually declined during the following days. But in the contralateral brain cortex, no obvious alterations were observed. Immunohistochemistry revealed the highly significant accumulation of ART3 at the ipsilateral brain in comparison to contralateral cerebral cortex. Double immunofluorescence labeling suggested that ART3 was localized mainly in the plasmalemma of neurons, but not in astrocytes or microglias within 3 mm from the lesion site at day 3 post-injury. In addition, we detected the expression profiles of caspase-3 and growth associated protein 43 (GAP-43) whose changes were correlated with the expression profiles of ART3 in this TBI model. Besides, co-localization of ART3/active caspase-3 and ART3/GAP43 were detected in NeuN-positive cells, respectively. Moreover, Pheochromocytoma (PC12) cells were treated with H₂O₂ to establish an apoptosis model. The results showed that the expression of ART3 was increased in the concentration and time dependence way. To further examine the involvement of ART3 in apoptosis of PC12, 3-Methoxybenzamide was used in flow cytometry analysis of apoptotic cells stained with Annexin V and PI. The experimental group in which 3-Methoxybenzamide used had a relative low level of apoptotic index compared with the untreated group. Together with previous reports, we hypothesize that ART3 may play important roles in CNS pathophysiology after TBI and further research is needed to have a good understanding of its function and mechanism.     

Relationship between plasma leptin levels and clinical outcomes of pediatric traumatic brain injury

High plasma leptin level has been associated with mortality after adult intracerebral hemorrhage. The present study was undertaken to investigate the plasma leptin concentrations in children with traumatic brain injury and to analyze the correlation of leptin with pediatric traumatic brain injury outcome. Plasma leptin concentration of eighty-nine healthy children and 142 children with acute severe traumatic brain injury was measured by enzyme-linked immunosorbent assay. Twenty-six patients (18.3%) died and 42 patients (29.6%) had an unfavorable outcome (Glasgow outcome scale score of 1-3) at 6 months after traumatic brain injury. Upon admission, plasma leptin level in patients was substantially higher than that in healthy controls. A forward stepwise logistic regression selected plasma leptin level as an independent predictor for 6-month mortality and unfavorable outcome of patients. A receiver operating characteristic curve analysis showed plasma leptin level better predicted 6-month mortality and unfavorable outcome. The prognostic value of leptin was similar to that of Glasgow Coma scale score for 6-month clinical outcomes. Thus, plasma leptin level represents a novel biomarker for predicting 6-month clinical outcome in children with traumatic brain injury.     

Resveratrol protects astrocytes against traumatic brain injury through inhibiting apoptotic and autophagic cell death

Traumatic brain injury (TBI) is often caused by accidents that damage the brain. TBI can induce glutamate excitotoxicity and lead to neuronal and glial cell death. In this study, we investigated the mechanism of cell death during the secondary damage caused by TBI in vivo and in vitro, as well as the protective effect of resveratrol (RV). Here we report that glycogen synthase kinase-3β (GSK-3β) activation and microtubule-associated protein light chain 3 processing were induced in rat brains exposed to TBI. In the in vitro TBI model, apoptotic and autophagic cell death were induced through glutamate-mediated GSK-3β activation in normal CTX TNA2 astrocytes. The GSK-3β inhibitor SB216763 or transfection of GSK-3β small-interfering RNA increases cell survival. By contrast, overexpression of GSK-3β enhanced glutamate excitotoxicity. Administration of RV reduced cell death in CTX TNA2 astrocytes by suppressing reactive oxygen species (ROS)-mediated GSK-3β activation, the mechanism by which RV also exerted protective effects in vivo. Mitochondrial damages, including the opening of mitochondrial permeability transition pore (MPTP) and mitochondrial depolarization, were induced by glutamate through the ROS/GSK-3β pathway. Moreover, cyclosporine A, an MPTP inhibitor, suppressed mitochondrial damage and the percentages of cells undergoing autophagy and apoptosis and thereby increased cell survival. Taken together, our results demonstrated that cell death occurring after TBI is induced through the ROS/GSK-3β/mitochondria signaling pathway and that administration of RV can increase cell survival by suppressing GSK-3β-mediated autophagy and apoptosis. Therefore, the results indicated that resveratrol may serve as a potential therapeutic agent in the treatment of TBI.     

Regulated expression of pancreatic triglyceride lipase after rat traumatic brain injury

Pancreatic triglyceride lipase (PTL), an enzyme of digestive system, plays very important roles in the digestion and absorption of lipids. However, its distribution and function in the central nervous system (CNS) remains unclear. In the present study, we mainly investigated the expression and cellular localization of PTL during traumatic brain injury (TBI). Western blot and RT–PCR analysis revealed that PTL was present in normal rat brain cortex. It gradually increased, reached a peak at the 3rd day after TBI, and then decreased. Double immunofluorescence staining showed that PTL was co-expressed with neuron, but had a few colocalizations in astrocytes. When TBI occurred in the rat cortex, the expression of PTL gradually increased, reached the peak at the 3rd day after TBI, and then decreased. Importantly, more PTL was colocalized with astrocytes, which is positive for proliferating cell nuclear antigen (PCNA). In addition, Western blot detection showed that the 3rd day post injury was not only the proliferation peak indicated by the elevated expression of PCNA, glial fibrillary acidic protein (GFAP) and cyclin D1, but also the apoptotic peak implied by the alteration of caspase-3 and bcl-2. These data suggested that PTL may be involved in the pathophysiology of TBI and PTL may be complicated after injury, more PTL was colocalized with astrocytes. Importantly, injury-induced expression of PTL was colabelled by proliferating cell nuclear antigen (proliferating cells marker), and the western blot for GFAP, PCNA and cyclin D1, showed that 3 days post injury was the proliferation peak, in coincidence to it, the protein level change of caspase-3 and bcl-2 revealed that the stage was peak of apoptotic too. These data suggested that PTL may be involved in the pathophysiology of TBI and that PTL may be implicated in the proliferation of astrocytes and the recovery of neurological outcomes. But the inherent mechanisms remained unknown. Further studies are needed to confirm the exact role of PTL after brain injury.     

Upregulation of p21-activated Kinase 6 in rat brain cortex after traumatic brain injury

p21-activated Kinase 6 (PAK6) is a serine/threonine kinase belonging to the p21-activated kinase (PAK) family. PAK kinases are well-known regulators of a wide variety of cellular functions, including regulation of cytoskeleton rearrangement, cell survival, apoptosis and the mitogen-activated protein kinase signaling pathway. To elucidate the expressions and possible functions of PAK6 in central nervous system (CNS) lesion and repair, we performed a traumatic brain injury (TBI) model in adult rats. Western blot analysis revealed that PAK6 level significantly increased at day 3 after damage, and then declined during the following days. Besides, double immunofluorescence staining showed PAK6 was primarily expressed in the neurons and a few of glial cells in the normal group. While after injury, the expression of PAK6 was increased significantly in the astrocytes and neurons, and the astrocytes had largely proliferated. We also examined the expression of proliferating cell nuclear antigen (PCNA) whose change was correlated with the expression of PAK6. Importantly, double immunofluorescence staining revealed that cell proliferation evaluated by PCNA appeared in many PAK6-expressing cells at day 3 after injury. In addition, injury-induced expression of PAK6 was co-labeled by active caspase-3 during neuronal apoptosis after injury. Collectively, we hypothesized PAK6 may play important roles in CNS pathophysiology after TBI and further research is needed to have a good understanding of its function and mechanism.