Relationship between circulating IGF-1 levels and traumatic brain injury-induced hippocampal damage and cognitive dysfunction in immature rats

It is well known that traumatic brain injury (TBI) induces the cognitive dysfunction resulting from hippocampal damage. In the present study, we aimed to assess whether the circulating IGF-I levels are associated with cognition and hippocampal damage in 7-day-old rat pups subjected to contusion injury. Hippocampal damage was examined by cresyl violet staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Spatial memory performance was assessed in the Morris water maze. Serum IGF-1 levels decreased in both early and late period of TBI. Decreased levels of serum IGF-1 were correlated with hippocampal neuron loss and spatial memory deficits. Circulating IGF-1 levels may be predictive of cognitive dysfunction resulted from hippocampal damage following traumatic injury in developing brain. Therapy strategies that increase circulating IGF-1 may be highly promising for preventing the unfavorable outcomes of traumatic damage in young children.     

MK-801对新生大鼠脑外伤后神经元凋亡的影响

目的：探讨N-甲基-D-天冬氨酸(NMDA)受体拮抗剂MK-801对新生大鼠创伤性脑外伤(traumatic brain injury,TBI)后神经元凋亡的影响。方法：建立新生7 d大鼠顶叶皮质挫伤模型,在TBI前30 min、TBI后即刻、TBI后30 min分别给予腹腔注射MK-8011 mg/kg,在TBI后24 h取脑,连续切片,行H-E染色和Caspase-3免疫组化染色,检测脑神经元细胞的损伤和凋亡。结果：MK-801三组不同时间用药组与TBI组相比,在创伤同侧的扣带皮质、顶叶皮质和丘脑神经元凋亡细胞数减少,有显著性差异。其中TBI后即刻用MK-801治疗效果最好。结论：MK-80l能明显减少TBI后神经元的凋亡。     

Protective effect of melatonin against head trauma-induced hippocampal damage and spatial memory deficits in immature rats

It is well known that head trauma induces the cognitive dysfunction resulted from hippocampal damage. In the present study, we aimed to demonstrate the effect of melatonin on hippocampal damage and spatial memory deficits in 7-day-old rat pups subjected to contusion injury. Melatonin was injected intraperitoneally at the doses of 5 or 20 mg/kg of body weight immediately after induction of traumatic injury. Hippocampal damage was examined by cresyl violet staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Spatial memory performance was assessed in the Morris water maze. Melatonin significantly attenuated trauma-induced neuronal death in hippocampal CA1, CA3 regions and dentate gyrus, and improved spatial memory deficits, which was equally effective at doses of 5-20 mg/kg. The present results suggest that melatonin is a highly promising agent for preventing the unfavorable outcomes of traumatic brain injury in young children.     

Neuroprotective effect of ginseng total saponins in experimental traumatic brain injury

In the present study, we investigated whether ginseng total saponins (GTSs) protect hippocampal neurons after experimental traumatic brain injury (TBI) in rats. A moderate-grade TBI was made with the aid of a controlled cortical impact (CCI) device set at a velocity of 3.0 m/sec, a deformation of 3.0 mm, and a compression time of 0.2 sec at the right parietal area for adult male Sprague-Dawley rats. Shamoperated rats that underwent craniectomy without impact served as controls. GTSs (100 and 200 mg/kg) or saline was injected intraperitoneally into the rats immediately post-injury. Twenty-four hours after the injury, the rats underwent neurological evaluation. Contusion volume and the number of hippocampal neurons were calculated with apoptosis evaluated by TUNEL staining. 24 hr post-injury, saline-injected rats showed a significant loss of neuronal cells in the CA2 region of the right hippocampus (53.4%, p<0.05) and CA3 (34.6%, p<0.05) compared with contralateral hippocampal region, a significant increase in contusion volume (34+/-8 microL), and significant increase in neurologic deficits compared with the GTSs groups. Treating rats with GTSs seemed to protect the CCI-induced neuronal loss in the hippocampus, decrease cortical contusion volume, and improve neurological deficits.     

MK-801对新生鼠脑外伤性神经变性的超微结构的影响

目的:研究非竞争性N-甲基-D-天门冬氨酸受体拮抗剂MK-801对新生鼠创伤性颅脑损伤(TBI)后同侧顶叶皮质和海马神经元超微结构的影响.方法:新生7 d SD大鼠,被随机分成正常对照组和实验组(实验组给予MK-801 1 mg/kg,并且细分为创伤前30 min给药、创伤即刻给药和创伤后30 min给药3个亚组).造模24 h取材,透射电镜下观察神经细胞超微结构的变化.结果:创伤后30 min给药的神经细胞出现胞质和核染色质的浓缩深染,胞质内充满大小不等的空泡;创伤即刻组的神经细胞胞质内线粒体有肿胀,但胞核的变化不明显.结论:适时和适量运用MK-180能延迟神经细胞核染色质和粒线体的变性损伤,使之停留在损伤早期,为临床联合其他药物治疗赢得时间.     

Anatibant,a selective non-peptide bradykinin B2 receptor antagonist,reduces intracranial hypertension and histopathological damage after experimental traumatic brain injury

Bradykinin, the main metabolite of the kallikrein-kinin system and one of the first mediators released during inflammation, is well known to increase the permeability of the blood brain barrier (BBB) by activation of kinin B₂ receptors and hence promote brain edema formation following traumatic brain injury (TBI). Anatibant^® (LF 16-0687), a selective non-peptide bradykinin B₂ receptor antagonist, reduces brain edema after experimental TBI, however, so far no data are available if Anatibant^® reduces also the sequels of brain edema formation, i.e. morphological brain damage. Therefore, we investigated the effect of Anatibant (3.0 mg/kg b.w.) on intracranial pressure (ICP) and contusion volume after experimental TBI. Male C57/Bl6 mice (25–28 g) were subjected to Controlled Cortical Impact trauma (CCI). Anatibant^® was administrated as a subcutaneous bolus 15 min and 8 h after TBI. ICP was measured 3, 6, and 10 h after injury and contusion volume was quantified 24 h after trauma. Our data demonstrate a significant reduction of ICP (16.6 ± 1.67 mmHg vs. 24.40 ± 3.58 mmHg; n = 6; p = 0.002) and of contusion volume 24 h after trauma (28.28 ± 5.18 mm³ vs. 35.0 ± 3.32 mm³n = 7; p = 0.003) in treated mice. Therefore we conclude, that inhibition of bradykinin B₂ receptors seems to be a promising treatment option, and might therefore be investigated in clinical trails for the treatment of TBI.     

Sleep deprivation has a neuroprotective role in a traumatic brain injury of the rat

During the process of a brain injury, responses to produce damage and cell death are activated, but self-protective responses that attempt to maintain the integrity and functionality of the brain are also activated. We have previously reported that the recovery from a traumatic brain injury (TBI) is better in rats if it occurs during the dark phase of the diurnal cycle when rats are in the waking period. This suggests that wakefulness causes a neuroprotective role in this type of injury. Here we report that 24 h of total sleep deprivation after a TBI reduces the morphological damage and enhances the recovery of the rats, as seen on a neurobiological scale.     

Delayed glucose treatment improves cognitive function following fluid-percussion injury

Experimental traumatic brain injury (TBI) results in marked neurochemical and metabolic changes. Research has demonstrated that after the initial insult the brain undergoes an immediate state of hypermetabolism followed by a sustained period of hypometabolism. The altered extra- and intracellular environment can compromise neuronal performance and limit functional recovery. If brain metabolism is depressed chronically after TBI, then interventions that are designed to increase metabolism may be beneficial to outcome. Glucose treatment has been shown to improve cognition in many populations, particularly those with cognitive deficits. The following experiments examined the effects of delayed postinjury glucose supplementation on cognitive function following TBI. Male Sprague-Dawley rats received either sham or lateral fluid-percussion (LFP) injury. Cognitive functioning was assessed with the Morris water maze (MWM) on postinjury days 11-15. In the first experiment, saline or 100mg/kg glucose was administered 10 min before cognition assessment. Injured animals treated with glucose displayed significantly shorter latencies to reach the goal platform compared to injured saline-treated animals. Glucose had no effect on sham-injured rats. In the second experiment, injured rats were given daily injections of saline or 100mg/kg glucose for 10 days beginning 24h after injury. Rats were then tested in the MWM on days 11-15 without glucose or saline treatment. In this experiment, glucose treatment did not affect MWM performance. These data provide evidence that the chronic energy supplementation after TBI improves outcome when administered shortly before cognitive assessment.     

The effects of selenium against cerebral ischemia-reperfusion injury in rats

It is known that the brain tissue is extremely sensitive to ischemia-reperfusion (IR) injury and therefore, brain ischemia and consecutive reperfusion result in neural damage and apoptosis. The proinflammatory cytokines such as tumor necrosis factor alfa (TNF-α) and interleukin-1 beta (IL-1β) are produced during neurological disorders including cerebral ischemia. On the other hand, nerve growth factor (NGF), which is essential for the differentiation, survival and functions of neuronal cells in the central nervous system, regulate neuronal development through cell survival and cell death signaling. In the present study, we aimed to investigate the effect of selenium (Se) on prefrontal cortex and hippocampal damage in rats subjected to cerebral IR injury. Selenium was injected intraperitoneally at the doses of 0.625 mg/(kg day) after induction of IR injury. Prefrontal cortex and hippocampal damage was examined by cresyl-violet staining. Apostain and caspase-3 immune staining were used to detect apoptosis. TNF-α, IL-1β and NGF levels were also evaluated. Histopathological evaluation showed that treatment with selenium after ischemia significantly attenuated IR-induced neuronal death in prefrontal cortex and hippocampal CA1 regions of rats. Apoptotic cells stained with apostain and caspase-3 were significantly decreased in treatment group when compared with the IR group. Additionally, treatment with selenium decreased the TNF-α and IL-1β levels and increased the NGF levels in prefrontal cortex and hippocampal tissue of animals subjected to IR. The present results suggest that selenium is potentially a beneficial agent in treating IR-induced brain injury in rats.     

Resveratrol attenuates spinal cord injury-induced inflammatory damage in rat lungs

Spinal cord injury (SCI)-induced systemic inflammatory response affects multiple organs outside the spinal cord. Treatment options for such complications are lacking. We studied the potential protective effects of resveratrol on SCI-induced inflammatory damage in rat lungs. Sprague-Dawley rats were subjected to weight-drop impact at the T10 vertebral level with administration of resveratrol (100 mg/kg) or vehicle (via the intraperitoneal route) immediately after trauma. Lung injury was studied by measuring: vascular permeability-related pulmonary edema; histopathologic scores, neutrophil infiltration and concentrations of inflammatory cytokines in bronchoalveolar fluid; expression of inflammatory enzymes and sirtuin (SIRT) 1 as well as nuclear factor-kappa B (NF-κB) activity in pulmonary tissues. Resveratrol treatment significantly alleviated SCI-induced pulmonary edema as indicated by the ratio of the wet weight to dry weight of lung tissue and pulmonary permeability index. Resveratrol significantly reduced neutrophil infiltration and production of inflammatory mediators. Resveratrol treatment was accompanied by up-regulation of expression of SIRT1 and suppression of NF-κB activity in pulmonary tissues. These data suggest that resveratrol may protect the lungs from SCI-induced inflammatory damage, and could be used as a therapeutic option against pulmonary problems after SCI.     

Vascular damage: A persisting pathology common to Alzheimer’s disease and traumatic brain injury

Alzheimer’s disease (AD) and traumatic brain injury (TBI) are both significant clinical problems characterized by debilitating symptoms with limited available treatments. Interestingly, both neurological diseases are characterized by neurovascular damage. This impaired brain vasculature correlates with the onset of dementia, a symptom associated with hippocampal degeneration seen in both diseases. We posit that vascular damage is a major pathological link between TBI and AD, in that TBI victims are predisposed to AD symptoms due to altered brain vasculature; vice versa, the progression of AD pathology may be accelerated by TBI especially when the brain insult worsens hippocampal degeneration. Our hypothesis is supported by recent data reporting expedited AD pathology in presymptomatic transgenic AD mice subjected to TBI. If our hypothesis is correct, treatments targeted at repairing the vasculature may prove effective at treating both diseases and preventing the evolution of AD symptoms in TBI victims.     

4-苯基丁酸钠盐通过抑制内质网应激反应改善大鼠创伤性脑损伤

目的 观察内质网应激相关蛋白葡萄糖调控蛋白78(GRP78)、磷酸化胰腺内质网激酶(p-PERK)和C/EBP同源蛋白(CHOP)在大鼠弥漫性脑创伤后的表达变化,探讨4-苯基丁酸钠盐(4-PBA)通过抑制内质网应激,减轻创伤后脑损伤(TBI)程度的机制.方法 将90只雄性SD大鼠随机分为假手术(sham)组、TBI组和4-PBA组.Marmarou法建立SD大鼠中度弥漫性脑创伤模型;于伤后即刻腹腔注射4-PBA(120 mg/kg)每天1次,共3d.分别于伤后3、6、12、24、48和72 h处死大鼠,观察伤后24、48和72 h大鼠的神经行为表现;HE染色观察病理学改变;免疫组织化学法及Western blotting检测伤后不同时间点皮质区GRP78、p-PERK和CHOP蛋白的表达.结果 4-PBA组大鼠脑创伤后的神经功能缺损明显改善,与TBI组相比差异具有统计学意义(P<0.05).与Sham组相比,TBI组GRP78、p-PERK和CHOP蛋白表达明显升高(P<0.05),GRP78于伤后3 h增加,12 h达高峰,之后逐渐减少,72 h回落至基线水平;p-PERK于12 h达高峰(P<0.05);CHOP于24 h达高峰,48～72h回落,仍高于基线水平(P<0.05);4-PBA组GRP78、p-PERK与CHOP的表达均低于TBI组(P<0.05).结论 脑创伤后启动内质网应激反应,4-PBA对脑创伤大鼠具有脑保护作用,其机制之一是通过阻断内质网应激启动的PERK/CHOP途径而实现的.     

依达拉奉通过抑制细胞外信号调节激酶1/2信号通路减轻大鼠弥漫性脑创伤后神经细胞凋亡

目的:探讨依达拉奉对脑创伤后神经细胞凋亡的影响及其机制.方法:雄性SD大鼠随机分为对照组、创伤组、依达拉奉组,Marmarou's法建立弥漫性脑创伤模型.H-E染色观察皮质区神经细胞组织形态变化;免疫组织化学法和免疫印迹法检测磷酸化ERK1/2及Bax的表达;原位缺口末端标记法(TUNEL)检测神经细胞的凋亡,并对大鼠综合运动功能进行评定.结果:与对照组比较,创伤组中皮质区部分神经细胞出现变性坏死和凋亡的改变,磷酸化 ERK1/2(1、 6、 24、 48h)和Bax(6、 24、 48、 72h)表达水平增高;神经细胞凋亡数目(6、 24、 48、 72h)增多;大鼠综合运动能力评分下降.与创伤组比较,依达拉奉组中脑组织形态结构损伤程度、磷酸化ERK1/2和Bax表达、神经细胞凋亡数目显著下降;大鼠的运动功能评分升高.结论:依达拉奉通过抑制ERK1/2信号途径活化,进而抑制促凋亡蛋白Bax表达,减少神经细胞凋亡,发挥对弥漫性脑创伤的保护作用.     

Delayed sodium pyruvate treatment improves working memory following experimental traumatic brain injury

Prior work indicates that cerebral glycolysis is impaired following traumatic brain injury (TBI) and that pyruvate treatment acutely after TBI can improve cerebral metabolism and is neuroprotective. Since extracellular levels of glucose decrease during periods of increased cognitive demand and exogenous glucose improves cognitive performance, we hypothesized that pyruvate treatment prior to testing could ameliorate cognitive deficits in rats with TBI. Based on pre-surgical spatial alternation performance in a 4-arm plus-maze, adult male rats were randomized to receive either sham injury or unilateral (left) cortical contusion injury (CCI). On days 4, 9 and 14 after surgery animals received an intraperitoneal injection of either vehicle (Sham-Veh, n = 6; CCI-Veh, n = 7) or 1000 mg/kg of sodium pyruvate (CCI-SP, n = 7). One hour after each injection rats were retested for spatial alternation performance. Animals in the CCI-SP group showed no significant working memory deficits in the spatial alternation task compared to Sham-Veh controls. The percent four/five alternation scores for CCI-Veh rats were significantly decreased from Sham-Veh scores on days 4 and 9 (p < 0.01) and from CCI-SP scores on days 4, 9 and 14 (p < 0.05). Measures of cortical contusion volume, regional cerebral metabolic rates of glucose and regional cytochrome oxidase activity at day 15 post-injury did not differ between CCI-SP and CCI-Veh groups. These results show that spatial alternation testing can reliably detect temporal deficits and recovery of working memory after TBI and that delayed pyruvate treatment can ameliorate TBI-induced cognitive impairments.     

Chronic administration of antipsychotics impede behavioral recovery after experimental traumatic brain injury

Antipsychotics are often administered to traumatic brain injured (TBI) patients as a means of controlling agitation, albeit the rehabilitative consequences of this intervention are not well known. Hence, the goal of this study was to evaluate the effects of risperidone (RISP) and haloperidol (HAL) on behavioral outcome after experimental TBI. Anesthetized rats received either a cortical impact or sham injury and then were randomly assigned to five TBI (RISP 0.045mg/kg, RISP 0.45mg/kg, RISP 4.5mg/kg, HAL 0.5mg/kg and VEHicle 1mL/kg) and three Sham (RISP 4.5mg/kg, HAL 0.5mg/kg and VEH 1mL/kg) groups. Treatments began 24h after surgery and were provided once daily for 19 days. Behavior was assessed with established motor (beam-balance/walk) and cognitive (spatial learning/memory in a water maze) tasks on post-operative days 1-5 and 14-19, respectively. RISP and HAL delayed motor recovery, impaired the acquisition of spatial learning, and slowed swim speed relative to VEH in both TBI and sham groups. These data indicate that chronic administration of RISP and HAL impede behavioral recovery after TBI and impair performance in uninjured controls.     

神经节苷脂联合神经干细胞移植对颅脑损伤大鼠海马的作用***

背景：应用神经干细胞移植治疗脑损伤后神经功能障碍的实验研究是目前的热点。 目的：观察神经节苷脂联合神经干细胞移植对创伤性脑损伤大鼠海马神经元的影响。 方法：健康Wistar大鼠66只,采用改进Feeney法制作创伤性脑损伤致海马神经元损伤模型,存活的60只大鼠伤后24 h给予相应治疗随机分为3组：创伤性脑损伤组注射1 mL DMEM/F12培养液;神经干细胞组注射1×1010 L-1神经干细胞悬液;神经干细胞+神经节苷脂组注射1×1010 L-1神经干细胞悬液后经腹腔注射30 mg/kg神经节苷脂水溶液,1次/d,连续3 d。 结果与结论：荧光显微镜观察PKH26标记的神经干细胞呈球形,呈现均匀分布的红色荧光;PKH26标记神经干细胞的阳性率为95%。各组平均潜伏时间均逐渐缩短,神经干细胞+神经节苷脂组3~5 d时平均潜伏时间较神经干细胞组缩短(P < 0.05),较创伤性脑损伤组明显缩短(P < 0.01);神经干细胞+神经节苷脂组穿越平台次数及在目标象限游泳距离与总距离百分比均高于其他两组(P < 0.05)。PKH26阳性细胞和苏木精-伊红染色切片中的神经元数量及脑源性神经营养因子mRNA的表达神经干细胞+神经节苷脂组多于神经干细胞组,神经干细胞组多于创伤性脑损伤组(P < 0.05)。提示神经干细胞移植对创伤性脑损伤大鼠海马神经元有保护作用,联合应用神经节苷脂有协同效果。     

Elucidating the role of 5-HT(1A) and 5-HT(7) receptors on 8-OH-DPAT-induced behavioral recovery after experimental traumatic brain injury

8-OH-DPAT is a 5-HT(1A/7) receptor agonist that enhances behavioral recovery after traumatic brain injury (TBI). This study is a first attempt to decipher whether the benefits induced by 8-OH-DPAT after TBI are mediated by 5-HT(1A) or 5-HT(7) receptors. A single i.p. injection of 8-OH-DPAT (0.5 mg/kg) alone or co-administered with either the 5-HT(1A) or 5-HT(7) receptor antagonists WAY 100635 (0.5 mg/kg) or SB 269970 HCl (2.0 mg/kg), respectively, or vehicle control (1.0 mL/kg) was given 15 min after cortical impact or sham injury. Function was assessed by established motor and cognitive tests. No difference in motor performance was observed among the TBI groups. Spatial acquisition was enhanced, relative to vehicle controls, by 8-OH-DPAT alone and when co-administered with WAY 100635, but not when combined with SB 269970 HCl. These data imply that 5-HT(1A) receptor antagonism does not abate the 8-OH-DPAT-induced cognitive benefits, but 5-HT(7) receptor antagonism does, which suggests that the 8-OH-DPAT-induced benefits in this single administration paradigm may be mediated more by 5-HT(7) versus 5-HT(1A) receptors. Evaluation of a specific 5-HT(7) receptor agonist will further elucidate the contribution of 5-HT(1A) and 5-HT(7) receptors on behavioral recovery conferred by acute 8-OH-DPAT treatment after TBI.     

Zinc supplementation provides behavioral resiliency in a rat model of traumatic brain injury

Depression, anxiety, and impairments in learning and memory are all associated with traumatic brain injury (TBI). Because of the strong link between zinc deficiency, depression, and anxiety, in both humans and rodent models, we hypothesized that dietary zinc supplementation prior to injury could provide behavioral resiliency to lessen the severity of these outcomes after TBI. Rats were fed a marginal zinc deficient (5 ppm), zinc adequate (30 ppm), or zinc supplemented (180 ppm) diet for 4 weeks followed by a moderately-severe TBI using the well-established model of controlled cortical impact (CCI). Following CCI, rats displayed depression-like behaviors as measured by the 2-bottle saccharin preference test for anhedonia. Injury also resulted in evidence of stress and impairments in Morris water maze (MWM) performance compared to sham-injured controls. While moderate zinc deficiency did not worsen outcomes following TBI, rats that were fed the zinc supplemented diet for 4 weeks showed significantly attenuated increases in adrenal weight (p < 0.05) as well as reduced depression-like behaviors (p < 0.001). Supplementation prior to injury improved resilience such that there was not only significant improvements in cognitive behavior compared to injured rats fed an adequate diet (p < 0.01), there were no significant differences between supplemented and sham-operated rats in MWM performance at any point in the 10-day trial. These data suggest a role for supplemental zinc in preventing cognitive and behavioral deficits associated with TBI.     

Increased apoptotic neuronal cell death and cognitive impairment at early phase after traumatic brain injury in aged rats

Progressive age-associated increases in cerebral dysfunction have been shown to occur following traumatic brain injury (TBI). Moreover, levels of neuronal mitochondrial antioxidant enzymes in the aged brain are reduced, resulting in free radical-induced cell death. It was hypothesized that cognitive impairment after TBI in the aged progresses to a greater degree than in younger individuals, and that damage involves neuronal degeneration and death by free radicals. In this study, we investigated the effects of free radicals on neuronal degeneration, cell death, and cognitive impairment in 10-week-old (young group) and 24-month-old rats (aged group) subjected to TBI. Young and aged rats received TBI with a pneumatic controlled injury device. At 1, 3 and 7 days after TBI, immunohistochemistry, lipid peroxidation and behavioral studies were performed. At 1, 3 and 7 days post-TBI, the number of 8-hydroxy-2′-deoxyguanosine-, 4-hydroxy-2-nonenal- and single-stranded DNA (ssDNA)-positive cells, and the levels of malondialdehyde around the damaged area after TBI significantly increased in the aged group when compared with the young group (P < 0.05). In addition, the majority of ssDNA-positive cells in both groups co-localized with neuronal cells around the damaged area. There was a significant decrease in the number of surviving neurons and an increase in cognitive impairment after TBI in the aged group when compared with the young group (P < 0.05). These results indicate that following TBI, high levels of free radicals are produced in the aged rat brain, which induces neuronal degeneration and apoptotic cell death around the damaged area, resulting in cognitive impairment.