Expression and detrimental role of hematopoietic prostaglandin D synthase in spinal cord contusion injury

Prostaglandin D(2) (PGD(2) ) is a potent inflammatory mediator, which is implicated in both the initiation and resolution of inflammation in peripheral non-neural tissues. Its role in the central nervous system has not been fully elucidated. Spinal cord injury (SCI) is associated with an acute inflammatory response, which contributes to secondary tissue damage that worsens functional loss. We show here, with the use of hematopoietic prostaglandin D synthase (HPGDS) deficient mice and a HPGDS selective inhibitor (HQL-79), that PGD(2) plays a detrimental role after SCI. We also show that HPGDS is expressed in macrophages in the injured mouse spinal cord and contributes to the increase in PGD(2) in the contused spinal cord. HPGDS(-/-) mice also show reduced secondary tissue damage and reduced expression of the proinflammatory chemokine CXCL10 as well as an increase in IL-6 and TGFβ-1 expression in the injured spinal cord. This was accompanied by a reduction in the expression of the microglia/macrophage activation marker Mac-2 and an increase in the antioxidant metallothionein III. Importantly, HPGDS deficient mice exhibit significantly better locomotor recovery after spinal cord contusion injury than wild-type (Wt) mice. In addition, systemically administered HPGDS inhibitor (HQL-79) also enhanced locomotor recovery after SCI in Wt mice. These data suggest that PGD(2) generated via HPGDS has detrimental effects after SCI and that blocking the activity of this enzyme can be beneficial.     

Expression of inflammatory cytokines following acute spinal cord injury in a rodent model

Many therapies that have been developed for acute spinal cord injury (SCI) either influence or are influenced by posttraumatic inflammation. Many such therapies have reportedly produced promising neurologic benefits in animal models of SCI, but demonstrating convincing efficacy in human clinical trials has remained elusive. This discrepancy may be related in part to differences in the inflammatory response to SCI between human patients and the widely studied rodent models. Our objectives were, therefore, to establish the time course of inflammatory cytokine release in the spinal cord of rats after a thoracic contusion, to determine whether the cytokine release was injury dependent, and to correlate these findings with those that we have recently reported for the cerebrospinal fluid (CSF) of human SCI patients. After rodent SCI, GRO (the rat equivalent of IL-8), IL-6, IL-1α, IL-1β, IL-13, MCP-1, MIP1α, RANTES, and TNFα were elevated within the spinal cord, whereas IL-12p70 was decreased. In human SCI, IL-6, IL-8, and MCP-1 were also elevated within the cerebrospinal fluid but at later times than those observed in the rodent spinal cord. IL-6, IL-8, and MCP-1 were released in an injury-dependent manner in both the rodent model of SCI and the human condition. In this regard, similar patterns of expression were observed for a number of inflammatory cytokines after SCI in rodent spinal cords and in human CSF. Such proteins may therefore have potential utility as biomarkers and surrogate outcome measures for evaluating biological response to therapeutic interventions.     

表没食子儿茶素没食子酸酯对半切型脊髓损伤大鼠的神经保护

Epigallocatechin-3-gallate (EGCG),a naturally occurring compound in green tea,has been widely used as an antioxidant agent.In the present study,model rats with acute spinal cord injury were intraperitoneally injected with 25,50,and 100 mg/kg EGCG,and spinal cord ultrastructure,oxidative stress reaction,inflammatory factors,and apoptosis-associated gene expression were observed.Results showed that EGCG attenuated neuronal and axonal injury 24 hours post injury.It also decreased serum interleukin-1β,tumor necrosis factor-α,and intercellular adhesion molecule-1 release,and decreased apoptosis-associated gene expression.Furthermore,it increased the level of the superoxide anion (O2-),superoxide dismutase,and B-cell lymphoma/leukemia-2,and reduced malondialdehyde levels.Furthermore,it reduced the expression of the pro-apoptotic protein Bax.Noticeably,EGCG at the 100 mg/kg dosage exhibited similar effects as methylprednisolone sodium succinate,which has been frequently used for clinical acute spinal cord injury.The results demonstrated that EGCG can significantly inhibit inflammation,suppress oxidation,and reduce apoptosis in acute spinal cord injury.     

Dynamics of the inflammatory response after murine spinal cord injury revealed by flow cytometry

Spinal cord injury (SCI) triggers a robust inflammatory response that contributes in part to the secondary degeneration of spared tissue. Here, we use flow cytometry to quantify the inflammatory response after SCI. Besides its objective evaluation, flow cytometry allows for levels of particular markers to be documented that further aid in the identification of cellular subsets. Analyses of blood from SCI mice for CD45 (common leukocyte antigen), CD11b (complement receptor-3), Gr-1 (neutrophil/monocyte marker), and CD3 (T-cell marker) revealed a marked increase in circulating neutrophils (CD45(high):Gr-1(high)) at 12 hr compared with controls. Monocyte density in blood increased at 24 hr, and in contrast, lymphocyte numbers were significantly decreased. Mirroring the early increase in neutrophils within the blood, flow analysis of the spinal cord lesion site revealed a significant (P < 0.01) and maintained increase in blood-derived leukocytes (CD45(high):CD11b(high)) from 12 to 96 hr compared with sham-injured and naive controls. Importantly, this technique clearly distinguishes blood-derived neutrophils (CD45:Gr-1(high):F4/80(negative)) and monocyte/macrophages (CD45(high)) from resident microglia (CD45(low)) and revealed that the majority of the blood-derived infiltrate were neutrophils. Our results highlight an assumed, but previously uncharacterized, marked and transient increase in leukocyte populations in blood early after SCI followed by the orchestrated invasion of neutrophils and monocytes into the injured cord. In contrast to mobilization of neutrophils, SCI induces lymphopenia that may contribute negatively to the overall outcome after spinal cord trauma.     

人参皂甙对损伤脊髓诱发电位的影响

目的　研究猫急性脊髓损伤 (SCI)后脊髓诱发电位 (SCEP)的变化规律及人参皂甙 (GS)对其的影响 ,探讨 GS对 SCI的作用 ,旨在寻求治疗 SCI的新方法。方法　采用改良 Allen氏重量打击法制作猫急性脊髓损伤模型 ,动物随机分组 ,通过电生理及病理学方法 ,研究 SCEP的变化规律及 GS对其的影响 ,脊髓形态学的改变作为进一步的佐证。结果　 (1)损伤组伤后 SCEP辐值随时间延长逐渐变小 ,潜伏期逐渐延长 ;治疗组波形则逐渐恢复 ,6 h全部恢复 ,差异显著。(2 )光镜下两组均有水肿、中心性出血 ,神经元空泡变性 ,核溶解或固缩 ,尼氏小体消失 ,部分神经纤维脱髓鞘或断裂 ,损伤组最重 ,治疗组均有不同程度的恢复。结论　 GS对 SCI有治疗作用。     

RhoA/Rho kinase in spinal cord injury

A spinal cord injury refers to an injury to the spinal cord that is caused by a trauma instead of diseases. Spinal cord injury includes a primary mechanical injury and a much more complex secondary injury pro-cess involving inlfammation, oxidation, excitotoxicity, and cell death. During the secondary injury, many signal pathways are activated and play important roles in mediating the pathogenesis of spinal cord injury. Among them, the RhoA/Rho kinase pathway plays a particular role in mediating spinal degeneration and regeneration. In this review, we will discuss the role and mechanism of RhoA/Rho kinase-mediated spinal cord pathogenesis, as well as the potential of targeting RhoA/Rho kinase as a strategy for promoting both neuroprotection and axonal regeneration.     

Alpinetin inhibits neuroinflammation and neuronal apoptosis via targeting the JAK2/STAT3 signaling pathway in spinal cord injury

Background

A growing body of research shows that drug monomers from traditional Chinese herbal medicines have antineuroinflammatory and neuroprotective effects that can significantly improve the recovery of motor function after spinal cord injury (SCI). Here, we explore the role and molecular mechanisms of Alpinetin on activating microglia-mediated neuroinflammation and neuronal apoptosis after SCI.

Methods

Stimulation of microglia with lipopolysaccharide (LPS) to simulate neuroinflammation models in vitro, the effect of Alpinetin on the release of pro-inflammatory mediators in LPS-induced microglia and its mechanism were detected. In addition, a co-culture system of microglia and neuronal cells was constructed to assess the effect of Alpinetin on activating microglia-mediated neuronal apoptosis. Finally, rat spinal cord injury models were used to study the effects on inflammation, neuronal apoptosis, axonal regeneration, and motor function recovery in Alpinetin.

Results

Alpinetin inhibits microglia-mediated neuroinflammation and activity of the JAK2/STAT3 pathway. Alpinetin can also reverse activated microglia-mediated reactive oxygen species (ROS) production and decrease of mitochondrial membrane potential (MMP) in PC12 neuronal cells. In addition, in vivo Alpinetin significantly inhibits the inflammatory response and neuronal apoptosis, improves axonal regeneration, and recovery of motor function.

Conclusion

Alpinetin can be used to treat neurodegenerative diseases and is a novel drug candidate for the treatment of microglia-mediated neuroinflammation.     

Effect of methylprednisolone on motor function and spinal cord blood flow after spinal cord compression in rats

The effect of methylprednisolone (MP) on neurologic recovery and spinal cord blood flow (SCBF) was investigated up to 4 days after a spinal cord compression injury in rats. The injury was produced at midthoracic level by applying a load of 35 g on a 2.2 x 5.0 mm compression plate for 5 min, which resulted in transient paraparesis. MP was given as a bolus dose of 30 mg/kg i.v. 60 min after injury (n = 20) and controls were given saline (n = 10). The motor performance was assessed daily as the capacity angle on the inclined plane and SCBF was measured by 14C-iodoantipyrine autoradiography on Days 1 or 4. On Day 1 the capacity angle was reduced from about 63 degrees preoperatively to 33 +/- 2 degrees (mean +/- SEM) in the control group and to 50 +/- 1 degrees in the group treated with MP (p less than 0.05). Thereafter there was a slight improvement in both groups, but the difference persisted throughout the observation period. On Day 4 both gray and white matter SCBF was better preserved in MP-treated animals than in the control group (59 +/- 4 versus 49 +/- 3 ml/min/100 g tissue for gray matter and 13.6 +/- 0.6 versus 10.7 +/- 0.8 ml/min/100 g tissue for white matter). Posttraumatic treatment with MP, thus, improved both the neurologic recovery during the first 4 days and SCBF as measured on Day 4. It is speculated that the effect of MP is at least partly exerted on the vascular bed.     

Necrostatin-1在小鼠脊髓损伤后继发性损伤中的作用

目的 探讨Necrostatin-1(Nec-1)在小鼠脊髓损伤后继发性损伤中的作用及机制。方法 将168只健康成年雌性LCR小鼠随机分为4组:对照组（48只）、脊髓损伤组（48只）、溶剂组（36只,鞘内注射4 μl二甲基亚砜）和治疗组[36只,鞘内注射4 μl Nec-1（4 mmol/L）]。采用血管夹钳夹小鼠脊髓建立脊髓损伤模型。伤后6、12、24、48 h采用免疫印迹法检测脊髓组织受体相互作用蛋白（RIP）1、3的表达;伤后24 h采用免疫共沉淀法评估RIP1和RIP3的相互作用;伤后24 h检测脊髓组织丙二醛（MDA）和活性氧簇（ROS）水平,电镜观察小鼠脊髓组织神经元线粒体损伤情况。结果 伤后48 h内,小鼠脊髓RIP1表达水平无明显变化;伤后6 h,小鼠脊髓RIP3表达水平明显增高,持续到伤后48 h。伤后24 h,治疗组和溶剂组RIP1和RIP3的表达水平均无明显差异;正常脊髓组织RIP1和RIP3相互作用较弱,脊髓损伤后RIP1和RIP3相互作用加强,而Nec-1显著抑制RIP1和RIP3相互作用。伤后24 h,脊髓神经元线粒体不同程度受损,而治疗组小鼠脊髓神经元线粒体结构保存相对较好。伤后24 h,脊髓组织MDA和ROS含量明显升高,而Nec-1能明显减少小鼠脊髓MDA和ROS含量。结论 小鼠脊髓损伤后,Nec-1通过抑制RIP1和RIP3的相互作用,进而抑制程序性坏死,减轻脊髓继发性损伤。Nec-1能降低ROS产物,减轻氧化应激损伤,保护线粒体功能。     

Upregulation of annexins I, II, and V after traumatic spinal cord injury in adult rats

The posttraumatic inflammatory reaction contributes to progressive tissue damage after spinal cord injury (SCI). Annexins, a family of structurally related calcium- and phospholipid-binding proteins, have potent anti-inflammatory effects by inhibiting the activity of phospholipase A(2) (PLA(2)), a key enzyme responsible for inflammation and cytotoxicity. We investigated spatiotemporal expression of annexins I, II, and V after a contusive SCI using the New York University impact device (a 10-g rod, height 12.5 mm) in adult rats. Western blot analysis revealed that annexin I expression increased at 3 days after injury, peaked at 7 days (1.75-fold above the baseline level; P < 0.01), started to decline at 14 days, and returned to the baseline level at and beyond 28 days post-injury. The expression of annexin II started to increase at 3 days, reached its maximal level at 14 days (2.73-fold; P < 0.01), remained at a high level up to 28 days, and then declined to the basal level by 56 days after injury. Annexin V expression started at 3 days, reached its maximal level at 7 days (1.61-fold; P < 0.05) and remained at this level until 56 days after injury. RT-PCR results confirmed expression of all three annexins at the mRNA level after SCI. Immunohistochemistry and immunofluorescence double-labeling analyses revealed that increased annexins I, II, and V were localized in neurons and glial cells. The present study thus revealed increased expression of the three annexin isoforms after moderate contusive SCI. The precise role of annexins in posttraumatic inflammation and neuroprotection after SCI remains to be determined.     

Chemokine antagonist infusion promotes axonal sparing after spinal cord contusion injury in rat

Spinal cord injury produced by mechanical contusion causes the onset of acute and chronic degradative events. These include blood brain barrier disruption, edema, demyelination, axonal damage and neuronal cell death. Posttraumatic inflammation after spinal cord injury has been implicated in the secondary injury that ultimately leads to neurologic dysfunction. Studies after spinal cord contusion have shown expression of several chemokines early after injury and suggested a role for them in the ordered recruitment of inflammatory cells at the lesion site (McTigue et al. [1998] J. Neurosci. Res. 53:368-376; Lee et al., [2000] Neurochem Int). We have demonstrated previously that infusion of the broad-spectrum chemokine receptor antagonist (vMIPII) in the contused spinal cord initially attenuates leukocyte infiltration, suppresses' gliotic reaction and reduces neuronal damage after injury. These changes are accompanied by increased expression of bcl-2, the endogenous apoptosis inhibitor, and reduced neuronal apoptosis (Ghirnikar et al. [2000] J. Neurosci. Res. 59:63-73). We demonstrate that 2 and 4 weeks of vMIPII infusion in the contusion-injured spinal cord also results in decreased hematogenous infiltration and is accompanied by reduced axonal degeneration in the gray matter. Luxol fast blue and MBP immunoreactivity indicated reduced myelin breakdown in the dorsal and ventral funiculi. Increased neuronal survival in the ventral horns of vMIPII infused cords was seen along with increased bcl-2 staining in them. Immunohistochemical identification of fiber phenotypes showed increased presence of calcitonin gene related peptide, choline acetyl transferase and tyrosine hydroxylase positive fibers as well as increased GAP43 staining in treated cords. These results suggest that sustained reduction in posttraumatic cellular infiltration is beneficial for tissue survival. A preliminary report of this study has been published (Eng et al. [2000] J. Neurochem. 74(Suppl):S67B). In contrast to vMIPII, infusion of MCP-1 (9-76), a N-terminal analog of the MCP-1 chemokine showed only a modest reduction in cellular infiltration at 14 and 21 dpi without significant tissue survival after spinal cord contusion injury. Comparing data on tissue survival obtained with vMIPII and MCP-1 (9-76) further validate the importance of the use of broad-spectrum antagonists in the treatment of spinal cord injury. Controlling the inflammatory reaction and providing a growth permissive environment would enhance regeneration and ultimately lead to neurological recovery after spinal cord injury. J. Neurosci. Res. 64:582-589, 2001. Published 2001 Wiley-Liss, Inc.     

不同类型脊髓损伤患者和正常成人外周血白细胞糖皮质激素受体的比较及意义

目的 比较正常成人和急性脊髓损伤患者、慢性脊髓压迫症患者外周血白细胞塘皮质激素受体的结合位点数并探讨其意义。方法 采用放射配体结合法测定15例正常成人、20例急性脊髓损伤患者和21例慢性脊髓压迫症患者外周血白细胞上糖皮质激素受体结合位点数。结果 正常成人外周血白细胞精皮质激素受体结合位点数为4462±891.6个/细胞,慢性脊髓压迫症患者为4225±1271个/细胞,急性脊髓损伤患者为2517±857.8个/细胞,经统计学比较正常成人组和慢性脊髓压迫症患者组没有显著性差异,急性脊髓损伤组与其他两者相差均有显著性意义。急性脊髓损伤组中,全瘫患者为2279±921个/细胞,不全瘫患者为2806±718个/细胞,两者无统计学差异。结论 外周血白细胞上的糖皮质激素受体有高亲和力和低亲和力两种结合位点,急性脊髓损伤后外周血白细胞的精皮质激素受体结合位点数的减少主要是高亲和力位点的减少,低亲和力位点维持不变。大剂量的糖皮质激素和白细胞的低亲和力位点结合,抑制白细胞的趋向移动,减少白细胞进入损伤脊髓区,减轻损伤后的急性炎症反直,起到神经保护作用。慢性脊髓压迫症患者予以糖皮质激素治疗无疗效。     

Function of microglia and macrophages in secondary damage after spinal cord injury

Spinal cord injury （SCI） is a devastating type of neurological trauma with limited therapeutic op- portunities. The pathophysiology of SCI involves primary and secondary mechanisms of injury. Among all the secondary injury mechanisms, the inflammatory response is the major contrib- utor and results in expansion of the lesion and further loss of neurologic function. Meanwhile, the inflammation directly and indirectly dominates the outcomes of SCI, including not only pain and motor dysfunction, but also preventingneuronal regeneration. Microglia and macrophages play very important roles in secondary injury. Microglia reside in spinal parenchyma and survey the microenvironment through the signals of injury or infection. Macrophages are derived from monocytes recruited to injured sites from the peripheral circulation. Activated resident microglia and monocyte-derived macrophages induce and magnify immune and inflammatory responses not only by means of their secretory moleculesand phagocytosis, but also through their influence on astrocytes, oligodendrocytes and demyelination. In this review, we focus on the roles of mi- croglia and macrophages in secondary injury and how they contribute to the sequelae of SCI.     

Rapid upregulation of caspase-3 in rat spinal cord after injury: mRNA, protein, and cellular localization correlates with apoptotic cell death

Although the precise mechanisms explaining loss of, and failure to regain, function after spinal cord injury are unknown, there is increasing interest in the role of "secondary cell death." One prevalent theme in cell loss in other regions of the CNS involves apoptosis executed by the intracellular caspase proteases. A recent study demonstrated that spinal cord injury rapidly increased the activation of caspase-3. Our previous studies demonstrated peak apoptosis in three of four cellular compartments 3 days after controlled contusion in the rat. We have extended these analyses to include enzyme and substrate studies of caspase subfamilies both in rostral and in caudal adjacent segments compared to the lesion site. Although presumed activation of programmed proenzyme is considered the mechanism for enhanced caspases, our novel analyses were designed to detect upregulation of gene expression. We surveyed traumatically injured spinal cord for caspase family messages with a modified differential mRNA display approach and found that the caspase-3 (CASP3) message was present and upregulated severalfold after injury. Our results clearly demonstrate that cell death in the spinal cord occurs after posttranslational activation of caspases that follow, at least for caspase-3, initial upregulation of CASP3 mRNA levels.     

FK 506 reduces tissue damage and prevents functional deficit after spinal cord injury in the rat

We examined the efficacy of FK 506 in reducing tissue damage after spinal cord injury in comparison to methylprednisolone (MP) treatment. Rats were subjected to a photochemical injury (T8) and were given a bolus of MP (30 mg/kg), FK 506 (2 mg/kg), or saline. An additional group received an initial bolus of FK 506 (2 mg/kg) followed by daily injections (0.2 mg/kg intraperitoneally). Functional recovery was evaluated using open-field walking, inclined plane tests, motor evoked potentials (MEPs), and the H-reflex response during 14 days postoperation (dpo). Tissue sparing and glial fibrillary acidic protein (GFAP), biotinylated tomato lectin LEC, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and interleukin 1 beta (IL-1 beta) immunoreactivity were quantified in the injured spinal cord. FK 506-treated animals demonstrated significantly better neurologic outcome, higher MEP amplitudes, and lower H-wave amplitude compared to that of saline-treated rats. In contrast, administration of MP did not result in significant differences with respect to the saline-treated group. Histologic examination revealed that tissue sparing was largest in FK 506-treated compared to saline and MP-treated animals. GFAP and COX-2 reactivity was decreased in animals treated with FK 506 compared to that in animals given MP or saline, whereas IL-1 beta expression was similarly reduced in both FK 506- and MP-treated groups. Microglia/macrophage response was reduced in FK 506 and MP-injected animals at 3 dpo, but only in MP-treated animals at 7 dpo with respect to saline-injected rats. Repeated administrations of FK 506 improved functional and histologic results to a greater degree than did a single bolus of FK 506. The results indicate that FK 506 administration protects the damaged spinal cord and should be considered as potential therapy for treating spinal cord injuries.     

LncRNA Airsci increases the inflammatory response after spinal cord injury in rats through the nuclear factor kappa B signaling pathway

Spinal cord injury(SCI) is a serious traumatic event to the central nervous system. Studies show that long non-coding RNAs(lncRNAs) play an important role in regulating the inflammatory response in the acute stage of SCI. Here, we investigated a new lncRNA related to spinal cord injury and acute inflammation. We analyzed the expression profile of lncRNAs after SCI, and explored the role of lncRNA Airsci(acute inflammatory response in SCI) on recovery following acute SCI. The rats were divided into the control group, SCI group, and SCI + lncRNA Airsci-siRNA group. The expression of inflammatory factors, including nuclear factor kappa B [NF-κB(p65)], NF-κB inhibitor IκBα and phosphorylated IκBα(p-IκBα), and the p-IκBα/IκBα ratio were examined 1–28 days after SCI in rats by western blot assay. The differential lncRNA expression profile after SCI was assessed by RNA sequencing. The differentially expressed lncRNAs were analyzed by bioinformatics technology. The differentially expressed lncRNA Airsci, which is involved in NF-κB signaling and associated with the acute inflammatory response, was verified by quantitative real-time PCR. Interleukin(IL-1β), IL-6 and tumor necrosis factor(TNF-α) at 3 days after SCI were measured by western blot assay and quantitative real-time PCR. The histopathology of the spinal cord was evaluated by hematoxylin-eosin and Nissl staining. Motor function was assessed with the Basso, Beattie and Bresnahan Locomotor Rating Scale. Numerous differentially expressed lncRNAs were detected after SCI, including 151 that were upregulated and 186 that were downregulated in the SCI 3 d group compared with the control group. LncRNA Airsci was the most significantly expressed among the five lncRNAs involved in the NF-κB signaling pathway. LncRNA Airsci-siRNA reduced the inflammatory response by inhibiting the NF-κB signaling pathway, alleviated spinal cord tissue injury, and promoted the recovery of motor function in SCI rats. These findings show that numerous lncRNAs are differentially expressed following SCI, and that inhibiting lncRNA Airsci reduces the inflammatory response through the NF-κB signaling pathway, thereby promoting functional recovery. All experimental procedures and protocols were approved by the approved by the Animal Ethics Committee of Jining Medical University(approval No. JNMC-2020-DW-RM-003) on January 18, 2020.     

Neurotrophic factors expressed in both cortex and spinal cord induce axonal plasticity after spinal cord injury

We reported recently that overexpression of neurotrophin-3 (NT-3) by motoneurons in the spinal cord of rats will induce sprouting of corticospinal tract (CST) axons (Zhou et al. [2003] J. Neurosci. 23:1424-1431). We now report that overexpression of brain-derived neurotrophic factor (BDNF) or glial cell-derived neurotrophic factor (GDNF) in the rat sensorimotor cortex near the CST neuronal cell bodies together with overexpression of NT-3 in the lumbar spinal cord significantly increases axonal sprouting compared to that induced by NT-3 alone. Two weeks after unilaterally lesioning the CST at the level of the pyramids, we injected rats with saline or adenoviral vectors (Adv) carrying genes coding for BDNF (Adv.BDNF), GDNF (Adv.GDNF) or enhanced green fluorescent protein (Adv.EGFP) at six sites in the sensorimotor cortex, while delivering Adv.NT3 to motoneurons in each of these four groups on the lesioned side of the spinal cord by retrograde transport from the sciatic nerve. Four days later, biotinylated dextran amine (BDA) was injected into the sensorimotor cortex on the unlesioned side to mark CST axons in the spinal cord. Morphometric analysis of axonal sprouting 3 weeks after BDA injection showed that the number of CST axons crossing the midline in rats treated with Adv.BDNF or Adv.GDNF were 46% and 52% greater, respectively, than in rats treated with Adv.EGFP or PBS (P < 0.05). These data demonstrate that sustained local expression of neurotrophic factors in the sensorimotor cortex and spinal cord will promote increased axonal sprouting after spinal cord injury, providing a basis for continued development of neurotrophic factor therapy for central nervous system damage.