Establishing a cat model of acute optic nerve injury

BACKGROUND: In order to investigate the progress in optic nerve injury and the following regeneration and repair, many kinds of animal models of optic nerve injury have been established, such as models of acute and chronic ocular hypertension, compression, amputating wound, ischemia reperfusion or hypoxia, intravitreal injection of excitatory amino acids, etc. However, most of these models are established by squeezing intraorbital optic nerve, and suitable for ophthalmology, and there are fewer models suitable for the acute cranial contusion in neurosurgery. OBJECTIVE: To observe the changes of optic nerve after acute injury, and the characteristics of methods for establishing model of acute optic nerve injury in cats. DESIGN: A complete randomized grouping and controlled animal trial. SETTING: Department of Neurosurgery, General Hospital of Ji’nan Military Area Command of Chinese PLA. MATERIALS: Twenty-eight healthy adult cats, common degree, either sex, weighing 2.0–3.5 kg, were provided by the animal experimental center of Fudan University. The cats were randomly divided into control group (n =3) and model group (n =25), and 5 cats in the model group were observed at 6 hours and 1, 3, 7 and 14 days after injury respectively. JX-2000 biological signal processing system (Department of Physiology, Second Military Medical University of Chinese PLA, Shanghai); Inverted phase contrast microscope (Olympus); Axioplan 2 imaging microgram analytical system (Labsystems). METHODS: The experiments were carried out in the Department of Neurosurgery, General Hospital of Jinan Military Area Command of Chinese PLA from June 2004 to June 2005. The cats in the model groups were made into models of acute optic nerve injury: The cats were anesthetized, then the limbs were fixed in a lateral recumbent position. Pterion approach in human was imitated, the operative incision was made along the line between lateral canthus and tragus, and it could be seen deep along the skull base that white optic nerve (about 3 mm) went through optic foramen and entered into brain tissue. It was squeezed with noninvasive vascular clip for 20 seconds, then the clip was removed, and then the skull was closed after it was examined to be no bleeding. The size of bilateral pupils, direct and indirect light reflexes were observed postoperatively. Successfully established models were judged by larger operated pupil than controlateral one, disappearance of direct light reflex and the existence of indirect light reflex. No model establishment was performed in the control group. Each cat was tested with flash visual evoked potential (F-VEP) to observe the electrophysiological changes before and after experiment. All the cats in the control group and model groups were killed under anesthesia before model establishment and at 6 hours, 1, 3, 7 and 14 days after model establishment respectively, and the pathological changes of the optic nerve after injury were observed under electron microscope and light microscope. MAIN OUTCOME MEASURES: VEP and the ultrastructural changes of optic nerve after acute optic nerve injury in both groups. RESULTS: All the 28 cats were involved in the analysis of results. ① VEP results: The VEP latencies were obviously different between the control group and model group at each time point (P < 0.05), whereas there were no obvious differences among different time points in the model group (P > 0.05). The VEP amplitudes were obviously different between the control group and model group at each time point (P < 0.05), whereas there were no obvious differences among different time points in the model group (P > 0.05). ② Ultrastructural changes of the optic nerve: Under electron microscope, normal optic nerve myelin sheath had complete structure, tramal plates were clear and arranged tightly, axolemma was complete, whereas the structures of endoneurium, myelin sheath, tramal plates, axolemma and axon were in disorders after optic nerve injury. CONCLUSION: Models of acute optic nerve injury established by squeezing intracranial optic nerve with noninvasive vascular clip can be applied in studying intracranial acute optic nerve injury.     

Mechanisms of secondary degeneration after partial optic nerve transection

Secondary degeneration occurs commonly in the central nervous system after traumatic injuries and following acute and chronic diseases, including glaucoma. A constellation of mechanisms have been shown to be associated with secondary degeneration including apoptosis, necrosis, autophagy, oxidative stress, excitotoxicity, derangements in ionic homeostasis and calcium influx. Glial cells, such as microglia, astrocytes and oligodendrocytes, have also been demon- strated to take part in the process of secondary injury. Partial optic nerve transection is a useful model which was established about 13 years ago. The merit of this model compared with other optic nerve injury models used for glaucoma study, including complete optic nerve transection model and optic nerve crush model, is the possibility to separate primary degeneration from secondary degeneration in location. Therefore, it provides a good tool for the study of secondary degeneration. This review will focus on the research progress of the mechanisms of secondary degeneration using partial optic nerve transection model.     

Human umbilical cord blood-derived stem cells and brain-derived neurotrophic factor protect injured optic nerve：viscoelasticity characterization

The optic nerve is a viscoelastic solid-like biomaterial.Its normal stress relaxation and creep properties enable the nerve to resist constant strain and protect it from injury.We hypothesized that stress relaxation and creep properties of the optic nerve change after injury.Moreover,human brain-derived neurotrophic factor or umbilical cord blood-derived stem cells may restore these changes to normal.To validate this hypothesis,a rabbit model of optic nerve injury was established using a clamp approach.At 7 days after injury,the vitreous body received a one-time injection of 50 μg human brain-derived neurotrophic factor or 1 × 106 human umbilical cord blood-derived stem cells.At 30 days after injury,stress relaxation and creep properties of the optic nerve that received treatment had recovered greatly,with pathological changes in the injured optic nerve also noticeably improved.These results suggest that human brain-derived neurotrophic factor or umbilical cord blood-derived stem cell intervention promotes viscoelasticity recovery of injured optic nerves,and thereby contributes to nerve recovery.     

Early cyclosporin A treatment retards axonal degeneration in an experimental peripheral nerve injection injury model

Injury to peripheral nerves during injections of therapeutic agents such as penicillin G potassium is common in developing countries. It has been shown that cyclosporin A, a powerful immunosuppressive agent, can retard Wallerian degeneration after peripheral nerve crush injury. However, few studies are reported on the effects of cyclosporin A on peripheral nerve drug injection injury. This study aimed to assess the time-dependent efficacy of cyclosporine-A as an immunosuppressant therapy in an experimental rat nerve injection injury model established by penicillin G potassium injection. The rats were randomly divided into three groups based on the length of time after nerve injury induced by cyclosporine-A administration(30 minutes, 8 or 24 hours). The compound muscle action potentials were recorded pre-injury, early post-injury(within 1 hour) and 4 weeks after injury and compared statistically. Tissue samples were taken from each animal for histological analysis. Compared to the control group, a significant improvement of the compound muscle action potential amplitude value was observed only when cyclosporine-A was administered within 30 minutes of the injection injury(P < 0.05); at 8 or 24 hours after cyclosporine-A administration, compound muscle action potential amplitude was not changed compared with the control group. Thus, early immunosuppressant drug therapy may be a good alternative neuroprotective therapy option in experimental nerve injection injury induced by penicillin G potassium injection.     

Preemptive analgesic effects of low-dose ketamine on growth-associated protein expression in dorsal root ganglion of chronic constriction injury model rats★

BACKGROUND： Ketamine is a noncompetitive N-methyl-D-aspartate （NMDA） receptor antagonists and plays an important role in the treatment of pain. OBJECTIVE： To analyze the preemptive analgesic effects of different doses of ketamine on growth-associated protein-43 （GAP43） expression in dorsal root ganglion in a rat model of chronic sciatic nerve constricted injury, and to study the differences between high-dose and low-dose ketamine DESIGN： Randomized controlled animal study. SETTING： Medical College of Shantou University. MATERIALS： Thirty-five adult male Sprague Dawley rats were provided by the Experimental Animal Center of Guangzhou University of Traditional Chinese Medicine. Ketamine hydrochloride injection was provided by Hengrui Pharmaceutical Co., Ltd., Jiangsu. METHODS： This study was performed at the Immunological Laboratory, Medical College of Shantou University from September to December 2006. Model of chronic sciatic nerve constricted injury： after anesthesia, the right sciatic nerve was exposed and ligated l-cm distal to the ischiadic tuberosity with a No. 3-0 cat gut suture. Grouping and intervention： 35 rats were randomly divided into 4 groups： normal control group （n = 5）, chronic constriction injury （CCI） group （n = 10）, low-dose ketamine group （n = 10）, and high-dose ketamine group （n = 10）. Rats in the normal control group did not undergo any surgery or drug intervention. Rats in the CCI group received intraperitoneal injection of saline （1 mL）, and their sciatic nerves were ligated after 10 minutes. Rats in the low-dose ketamine group underwent intraperitoneal injection of ketamine （25 mg/kg） 10 minutes prior to ligation of sciatic nerve; while, rats in the high-dose ketamine group were given intraperitoneal injection of ketamine （50 mg/kg） 10 minutes prior to ligation of sciatic nerve. On the third and the seventh days after surgery, dorsal root ganglion were resected from the sciatic nerve and cut into sections. MAIN OUTCOME MEASURES：     

Cell proliferation and apoptosis in optic nerve and brain integration centers of adult troutOncorhynchus mykiss after optic nerve injury

Fishes have remarkable ability to effectively rebuild the structure of nerve cells and nerve fibers after central nervous system injury.However,the underlying mechanism is poorly understood.In order to address this issue,we investigated the proliferation and apoptosis of cells in contralateral and ipsilateral optic nerves,after stab wound injury to the eye of an adult trout Oncorhynchus mykiss.Heterogenous population of proliferating cells was investigated at 1 week after injury.TUNEL labeling gave a qualitative and quantitative assessment of apoptosis in the cells of optic nerve of trout 2 days after injury.After optic nerve injury,apoptotic response was investigated,and mass patterns of cell migration were found.The maximal concentration of apoptotic bodies was detected in the areas of mass clumps of cells.It is probably indicative of massive cell death in the area of high phagocytic activity of macrophages/microglia.At 1 week after optic nerve injury,we observed nerve cell proliferation in the trout brain integration centers:the cerebellum and the optic tectum.In the optic tectum,proliferating cell nuclear antigen(PCNA)-immunopositive radial glia-like cells were identified.Proliferative activity of nerve cells was detected in the dorsal proliferative(matrix) area of the cerebellum and in parenchymal cells of the molecular and granular layers whereas local clusters of undifferentiated cells which formed neurogenic niches were observed in both the optic tectum and cerebellum after optic nerve injury.In vitro analysis of brain cells of trout showed that suspension cells compared with monolayer cells retain higher proliferative activity,as evidenced by PCNA immunolabeling.Phase contrast observation showed mitosis in individual cells and the formation of neurospheres which gradually increased during 1–4 days of culture.The present findings suggest that trout can be used as a novel model for studying neuronal regeneration.     

Biomechanical analysis of optic nerve injury treated by compound light granules and ciliary neurotrophic factor

In this study, rabbit models of optic nerve injury were reproduced by the clamp method. After modeling, rabbit models were given one injection of 50 ng recombinant human ciliary neurotrophic factor into the vitreous body and/or intragastric injection of 4 g/kg compound light granules containing Radix Angelicae Sinensis and Raidix Paeoniae Alba at 4 days after modeling, once per day for 30 consecutive days. After administration, the animals were sacrificed and the intraorbital optic nerve was harvested. Hematoxylin-eosin staining revealed that the injured optic nerve was thinner and optic nerve fibers were irregular. After treatment with recombinant human ciliary neurotrophic factor, the arrangement of optic nerve fibers was disordered but they were not markedly thinner. After treatment with compound light granules, the arrangement of optic nerve fibers was slightly disordered and their structure was intact. After combined treatment with recombinant human ciliary neurotrophic factor and compound light granules, the arrangement of optic nerve fibers was slightly disordered and the degree of injury was less than after either treatment alone. Results of tensile mechanical testing of the optic nerve showed that the tensile elastic limit strain, elastic limit stress, maximum stress and maximum strain of the injured optic nerve were significantly lower than the normal optic nerve. After treatment with recombinant human ciliary neurotrophic factor and/or compound light granules, the tensile elastic limit strain, elastic limit stress, maximum stress and maximum strain of the injured optic nerve were significantly increased, especially after the combined treatment. These experimental findings indicate that compound light granules and ciliary neurotrophic factor can alleviate optic nerve injury at the histological and biochemical levels, and the combined treatment is more effective than either treatment alone.     

Neuronal apoptosis and neurofilament protein expression in the lateral geniculate body of cats following acute optic nerve injuries

BACKGROUND: The visual pathway have 6 parts, involving optic nerve, optic chiasm, optic tract, lateral geniculate body, optic radiation and cortical striatum area. Corresponding changes may be found in these 6 parts following optic nerve injury. At present, studies mainly focus on optic nerve and retina, but studies on lateral geniculate body are few. OBJECTIVE: To prepare models of acute optic nerve injury for observing the changes of neurons in lateral geniculate body, expression of neurofilament protein at different time after injury and cell apoptosis under the optical microscope, and for investigating the changes of neurons in lateral geniculate body following acute optic nerve injury. DESIGN: Completely randomized grouping design, controlled animal experiment. SETTING: Department of Neurosurgery, General Hospital of Ji’nan Military Area Command of Chinese PLA. MATERIALS: Twenty-eight adult healthy cats of either gender and common grade, weighing from 2.0 to 3.5 kg, were provided by the Animal Experimental Center of Fudan University. The involved cats were divided into 2 groups according to table of random digit: normal control group (n =3) and model group (n = 25). Injury 6 hours, 1, 3, 7 and 14 days five time points were set in model group for later observation, 5 cats at each time point. TUNEL kit （Bohringer-Mannheim company）and NF200& Mr 68 000 mouse monoclonal antibody （NeoMarkers Company）were used in this experiment. METHODS: This experiment was carried out in the Department of Neurosurgery, General Hospital of Ji’nan Military Area Command of Chinese PLA between June 2004 and June 2005. ① The cats of model group were developed into cat models of acute intracranial optic nerve injury as follows: The anesthetized cats were placed in lateral position. By imitating operation to human, pterion approach was used. An incision was made at the joint line between outer canthus and tragus, and deepened along cranial base until white optic nerve via optic nerve pore and further to brain tissue. Optic nerve about 3 mm was liberated and occluded by noninvasive vascular clamp for 20 s. After removal of noninvasive vascular clamp, the area compressed by optic nerve was hollowed and narrowed, but non-fractured. Skull was closed when haemorrhage was not found. Bilateral pupillary size, direct and indirect light reflect were observed. Operative side pupil was enlarged as compared with opposite side, direct light reflect disappeared and indirect light reflect existed, which indicated that the models were successful. Animals of control group were not modeled .② The animals in the control group and model group were sacrificed before and 6 hours, 1, 3, 7 and 14 days after modeling respectively. Lateral geniculate body sample was taken and performed haematoxylin & eosin staining. Immunohistochemical staining showed lateral geniculate body neurofilament protein expression, and a comparison of immunohistochemial staining results was made between experimental group and control group. Terminal deoxynucleo-tidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) was used to label apoptotic cells in lateral geniculate body. MAIN OUTCOME MEASURES: Neuronal morphological change, neurofilament protein expression and cell apoptosis in lateral geniculate body following acute optic nerve injury. RESULTS: Twenty-eight involved cats entered the final analysis. ① Histological observation results: In the control group, cell processes were obviously found, which were few or shortening in the model group. ② Neuronal neurofilament protein expression: Cells in lateral geniculate body in the control group and at 6 hours after injury presented clear strip-shaped staining, and those at 7 and 14 days presented irregular distribution without layers and obviously decreasing staining intensity. The positive rate of neurofilament protein in lateral geniculate body in control group and 6 hours, 1, 3, 7 and 14 days after injury was （10.22±0.42）%，（10.03±0.24）%，（9.94±0.14）%，（9.98±0.22）%，（8.18±0.34）% and (6.37±0.18)%, respectively. Positive rate of neurofilament protein in control group, at 6 hours, 1 or 3 days after injury was significantly different from that at 7 days after injury (P < 0.05); Positive rate of neurofilament protein in control group, at 6 hours, 1, 3 or 7 days after injury was significantly different from that at 14 days after injury (P < 0.05). It indicated that neuronal injury in lateral geniculate body was not obvious within short term after optic nerve injury, but obvious at 7 days after injury and progressively aggravated until at 14 days after injury. ③ Neuronal apoptosis: TUNEL staining showed that neuronal apoptosis in lateral geniculate body appeared at 7 days after injury, and a lot of neuronal apoptosis in lateral geniculate body was found at 14 days after injury. It indicated that neuronal injury in lateral geniculate body was related to apoptosis. CONCLUSION: In short term after optic nerve injury (within 7 days), nerve injury of lateral geniculate body is not obvious, then, it will aggravate with the elongation of injury time. The occurrence of neuronal injury of lateral geniculate body is related to the apoptosis of nerve cells.     

Effect of salviae miltiorrhizae and ligustrazine hydrochloride injection on axonal regeneration and nerve growth factor expression in a rat model of sciatic nerve injury

BACKGROUND： Studies have shown that both salviae miltiorrhizae and ligustrazine can promote protein expression of nerve growth factor （NGF） and regeneration of peripheral nerve. OBJECTIVE： To verify the effect of salviae miltiorrhizae and ligustrazine hydrochloride injection on axonal regeneration and NGF protein expression in a rat model of sciatic nerve injury. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Laboratory of Traditional Chinese Medicine and the Institute of Bioengineering of Jinan University from July to December 2008. MATERIALS： Salviae miltiorrhizae and ligustrazine hydrochloride injection （containing 20 mg salviae miJtiorrhizae and 100 mg ligustrazine per 100 mL injection） was provided by Guizhou Baite Pharmaceutical, China; salviae miltiorrhizae and ligustrazine decoctions （containing 1 g raw drug per 1 mL decoction） were provided by Guangzhou Baiyunshan Factory for Traditional Chinese Medicine, China; rabbit-anti-rat NGF monoclonal antibody was provided by Beijing Biosynthesis Biotechnology, China. METHODS： A total of 80 healthy, male, Sprague Dawley rats were used to establish a sciatic nerve injury model via neurotomy, and were then randomly assigned to 4 groups： salviae miltiorrhizae and ligustrazine hydrochloride injection group （intraperitoneal injection of 35 mL/kg per day salviae miltiorrhizae and ligustrazine hydrochloride injection）, saIviae miltiorrhizae group （intragastric peffusion of 2 mL salviae miltiorrhizae）, ligustrazine group （intragastric peffusion of 2 mL ligustrazine）, and model group （intraperitoneal injection of 35 mL/kg per day saline）, with 20 rats in each group. Thereafter, rats in each group were then divided into 4 subgroups according to varying time points of 1, 2, 4, and 8 weeks post-surgery, with 5 rats in each subgroup. MAIN OUTCOME MEASURES： Axons were quantified using chromotrope 2R-brilliant green and silver staining combined with image analysis to calculate the axonal regeneration rate; NGF expression was detected using immunohistochemistry and Western blot analysis; toe interspace was measured by behavior at 4 and 8 weeks. RESULTS： With increasing time after sciatic nerve expression, and toe interspace gradually increased njury, the axonal regeneration rate, NGF protein At 4 and 8 weeks post-surgery, axonal regeneration rate and NGF protein expression were significantly increased in the injured tissue of the salviae miltiorrhizae and ligustrazine hydrochloride injection, salviae miltiorrhizae, and ligustrazine groups, compared with the model group （P 〈 0.05 or P 〈 0.01）, and toe interspace was remarkably enlarged （P 〈 0.05 or P 〈 0.01）, especially in the salviae miltiorrhizae and ligustrazine hydrochloride injection group. CONCLUSION： Salviae miltiorrhizae and ligustrazine hydrochloride injection promoted axonal regeneration and NGF protein expression in the injured sciatic nerve, and also enhanced neurofunctional recovery. Its effect was superior to salviae miltiorrhizae or ligustrazine alone.     

Human umbilical cord blood stem cells and brain-derived neurotrophic factor for optic nerve injury:a biomechanical evaluation

Treatment for optic nerve injury by brain-derived neurotrophic factor or the transplantation of human umbilical cord blood stem cells has gained progress, but analysis by biomechanical indicators is rare. Rabbit models of optic nerve injury were established by a clamp. At 7 days after injury, the vitreous body received a one-time injection of 50 μg brain-derived neurotrophic factor or 1 × 106 human umbilical cord blood stem cells. After 30 days, the maximum load, maximum stress, maximum strain, elastic limit load, elastic limit stress, and elastic limit strain had clearly improved in rabbit models of optical nerve injury after treatment with brain-derived neurotrophic factor or human umbilical cord blood stem cells. The damage to the ultrastructure of the optic nerve had also been reduced. These findings suggest that human umbilical cord blood stem cells and brain-derived neurotrophic factor effectively repair the injured optical nerve, improve biomechanical properties, and contribute to the recovery after injury.     

Establishing a cat model of chronic optic nerve compression injury

BACKGROUND:An animal model of chronic optic nerve injury is necessary to further understand the pathological mechanisms involved.OBJECTIVE:To establish a stabilized,chronic,optic nerve crush model,which is similar to the clinical situation to explore histopathological and optic electrophysiological changes involved in this injury.DESIGN,TIME AND SETTING:A randomized and controlled animal trial was performed at Shanghai Institute of Neurosurgery from May to October 2004.MATERIALS:A BAL3XRAY undetachable balloon and Magic-BD catheter were provided by BLAT,France;JX-2000 biological signal processing system by Second Military Medical University of Chinese PLA,China;inverted phase contrast microscopy by Olympus,Japan.METHODS:A total of twenty normal adult cats were randomly assigned to control (n = 5) and model (n = 15) groups,according to different doses of contrast agent injected through balloons as follows:0.2 mL injection,0.25 mL injection,and 0.35 mL injection,with each group containing 5 animals.Imitating the clinical pterion approach,the optic nerves were exposed using micro-surgical methods.An engorged undetachable balloon was implanted beneath the nerve and connected to a catheter.Balloon size was controlled with a contrast agent injection (0.1 mL/10 min) to form an occupying lesion model similar to sellar tumors.MAIN OUTCOME MEASURES:The visually evoked potential examination was used to study optical electrophysiology changes in pre-post chronic optical nerve injury.Ultrastructural pathological changes to the optic nerve were analyzed by electron microscopy.RESULTS:During the early period (day 11 after modeling),visually evoked potential demonstrated no significant changes.In the late period (day 51 after modeling),recorded VEP demonstrated that P1 wave latency was prolonged and P1 wave amplitude was obviously reduced.Following injury,the endoneurium,myelin sheath,lamella,axolemma,and axon appeared disordered.CONCLUSION:Results demonstrated that the chronic,intracranial,optical nerve crush model was stable and could simulate optic nerve lesions induced by sellar tumors.Under the condition of chronic optical nerve crush,visually evoked potentials were aggravated.     

猫慢性视神经压迫损伤模型的建立

目的建立猫慢性视神经压迫损伤动物模型。方法成年健康猫20只,按置入球囊内注入不同剂量造影剂分为健康对照组、0.2ml、0.25ml、0.35ml 4个组,每组5只。模仿临床上翼点入路,显微手术暴露视神经后,置入充盈的不可脱球囊于其下,后接导管,以注入造影剂的方式控制球囊大小,形成类似鞍区肿瘤占位,并辅以CT和视觉诱发电位检查,研究慢性视神经损伤前后视觉电生理方面的变化。以上动物按分组处死后,取视神经标本,进行电镜分析,研究视神经损伤后的病理改变。结果早期(术后2周),因占位病变(0.2cm3)在颅内代偿范围内,视觉诱发电位改变不明显。术后4周颅内占位达0.3cm3时超出颅内代偿空间,视觉诱发电位改变,颅内占位达0.35cm3时视觉诱发电位改变更为明显,表现为P1波潜伏期明显延长,振幅明显减小。结论首次建立的慢性颅内段视神经压迫损伤模型稳定,可模仿鞍区肿瘤引起的视神经病变,慢性视神经压迫的视觉诱发电位改变呈渐进性,早期在代偿范围内改变并不明显,晚期表现为P1波潜伏期延长,振幅减小,如不去除压迫难以恢复。     

Morphological and functional analysis of an incomplete CNS fiber tract lesion: graded crush of the rat optic nerve

Fiber tract lesions in the central nervous system (CNS) often induce delayed retrograde neuronal degeneration, a phenomenon that represents an important therapeutic challenge in clinical neurotraumatology. In the present study, we report an in vivo trauma model of graded axonal lesion of CNS neurons. Controlled by a newtonmeter device, we induced retrograde degeneration of adult rat retinal ganglion cells (RGCs) by graded crush of the optic nerve. The extent of secondary RGC death increased linearly with the applied crush force. Moreover, visually evoked potentials were used to characterize the consequences of controlled optic nerve lesion on the functional integrity of the visual projection. The presented model of fiber tract lesion closely resembles the clinical conditions of traumatic brain injury and could prove useful to screen for neuroprotective drugs based on both a morphological and functional read-out.     

Methylprednisolone treatment does not influence axonal regeneration or degeneration following optic nerve injury in the adult rat.

BACKGROUND: Methylprednisolone (MP) is often used to treat optic nerve injury. However, its effects in experimental crush injury have not been extensively evaluated. METHODS: Adult Sprague-Dawley rats were subjected to a standardized optic nerve crush injury. Animals were treated either with 30 mg/kg MP intravenous bolus followed by subcutaneous injections every 6 hours for 48 hours, or with a drug vehicle alone. RESULTS: The injury resulted in a partial loss of neuronal nuclei-labeled retinal neurons and a corresponding degeneration of axons distal to the injury. EDI-labeled macrophages accumulated at the site of lesion, phagocyting FJ-labeled axonal debris. Regenerative fibers expressing growth associated protein-43 were seen proximal to the lesion, but did not traverse the glial scar. Analysis of optic nerve function using visual evoked potentials showed typical signals in intact animals, which were abolished after injury in MP-treated and untreated animals. CONCLUSIONS: We did not detect any effects of MP on retinal cell survival, macrophage activity at the site of injury, axonal degeneration/regeneration, or visual function. These experimental results provide a physiologic underpinning for the lack of efficacy demonstrated in a large trial of MP treatment of clinical optic nerve injury.     

神经干细胞移植对大鼠视神经损伤后视觉电生理的影响

目的　观察神经干细胞 (NSCs)对视神经损伤后视觉电生理变化的影响。方法　采用夹持视神经法制作大鼠视神经损伤模型 ,分别于夹伤当天和损伤后 4周一次性向视神经鞘膜内注射NSCs。植入后 4周检测夹伤视神经眼的闪光视觉诱发电位(flare visualevokedpotential,F VEP)。结果　视神经损伤后F VEP潜伏期 (wavelatency ,Wl)延长且振幅 (waveamplitude ,WA)降低 ,与正常眼比较有显著性差异 (P <0 0 1) ;NSCs移植组损伤眼F VEP与空白对照组相比有显著性差异 (P <0 0 5 ) ,延期移植组更为明显。结论　NSCs移植有效促进了视神经损伤后神经传导功能的恢复。     

Expression of glial fibrillary acidic protein and glutamine synthetase by Müller cells after optic nerve damage and intravitreal application of brain-derived neurotrophic factor

Müller glia play an important role in maintaining retinal homeostasis, and brain-derived neurotrophic factor (BDNF) has proven to be an effective retinal ganglion cell (RGC) neuroprotectant following optic nerve injury. The goal of these studies was to investigate the relation between optic nerve injury and Müller cell activation, and to determine the extent to which BDNF affects the injury response of Müller cells. Using immunocytochemistry and Western blot analysis, temporal changes in the expression of glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) were examined in rats after optic nerve crush alone, or in conjunction with an intravitreal injection of BDNF (5 microg). GFAP protein levels were normal at 1 day post-crush, but increased approximately 9-fold by day 3 and remained elevated over the 2-week period studied. Müller cell GS expression remained stable after optic nerve crush, but the protein showed a transient shift in its cellular distribution; during the initial 24-h period post-crush the GS protein appeared to translocate from the cell body to the inner and outer glial processes, and particularly to the basal endfeet located in the ganglion cell layer. BDNF alone, or in combination with optic nerve crush, did not have a significant effect on the expression of either GFAP or GS compared with the normal retina, or after optic nerve crush alone, respectively. The data indicate that although BDNF is a potent neuroprotectant in the vertebrate retina, it does not appear to have a significant influence on Müller cell expression of either GS or GFAP in response to optic nerve injury.     

Thrombospondin expression in nerve regeneration II. comparison of optic nerve crush in the mouse and goldfish

Expression of the extracellular matrix molecule thrombospondin (TSP) was examined following retrobulbar crush injury of the goldfish and mouse optic nerve. TSP was present within the glia limitans and surrounding axon fascicles of the control normal goldfish optic nerve, but was absent from the normal mouse optic nerve. Following crush injury of the goldfish optic nerve, TSP expression increased dramatically along the path of regenerating axons and returned to near normal levels following axonal outgrowth. In contrast, during the unsuccessful attempt at regeneration following crush injury of the mouse optic nerve, TSP expression was present only in glial fibrillary acidic protein (GFAP)-negative, macrophage-rich regions distal to ganglion cell axons. These results indicate that TSP expression is increased in a temporal pattern along the path of regenerating goldfish optic nerve axons and therefore may be involved in successful central nervous system regeneration. The absence of TSP in the environment encountered by damaged mouse optic nerve axons may correlate with the lack of regeneration observed in the mouse optic nerve.     

神经干细胞移植对大鼠视神经部分损伤后视觉诱发电位的影响

目的观察研究神经干细胞(NSCs)移植入视神经部分损伤SD大鼠后闪光视觉诱发电位(F-VEP)的变化。方法24只健康成年SD大鼠随机分为NSCs移植组(N组)和对照组(C组),每组12只大鼠,两组均使用精确校准方法在大鼠右眼造成部分视神经损伤,左眼为正常对照。从胚胎SD大鼠海马分离NSCs,利用细胞培养和体内移植技术,将培养后的NSCs注入视神经损伤后N组大鼠玻璃体内,C组大鼠视神经损伤眼玻璃体内注入同等体积的PBS。以上两组分6个时间段,即损伤前、损伤时、损伤后1周、2周、3周、4周分别检测损伤视神经眼的F-VEP,记录P1波幅及峰潜时,并进行统计分析。结果N组及C组P1波幅随时间延长均不同程度降低,但前者趋势较后者缓和。自第2周开始N组波幅均高于C组,且差异有显著性；N组及C组P1峰潜时均随时间变化,在第3周时达到最长,第4周时P1峰潜时有缩短；自第1周开始N组峰潜时均较C组缩短,且差异均有显著性意义。结论NSCs移植入视神经部分损伤大鼠可部分改善视神经传导功能。