神经干细胞移植后在视神经损伤大鼠视网膜内表达BDNF的研究

目的探讨神经干细胞(NSC)移植入视神经损伤(ONI)的SD大鼠玻璃体下腔后在视网膜内表达脑源性神经营养因子(BDNF)的情况,为进一步探索NSC移植治疗视神经损伤提供实验依据。方法体外培养NSC,其上清液采用酶联免疫吸附实验(ELISA)定量分析BDNF含量。取34只SD大鼠,其中4只作为正常对照,另外30只制作成右眼ONI模型并随机等分为N组和P组。ONI术后随即向N组大鼠右眼玻璃体下腔注入定量NSC,P组注入等量PBS,并采用半定量RT-PCR方法检测正常大鼠视网膜及N组、P组大鼠术后第3天、1周、2周、3周、4周时视网膜BDNFmRNA的表达水平,行统计学分析。结果正常视网膜内可见BDNF表达;N组与P组大鼠视网膜内表达BDNF的量除第1周差异无统计学意义外,余时间段N组均高于P组。结论NSC能促使视神经损伤大鼠视网膜高表达BDNF,NSC移植治疗视神经损伤值得进一步深入研究。     

An enriched environment improves cognitive performance in mice from the senescence-accelerated prone mouse 8 strain Role of upregulated neurotrophic factor expression in the hippocampus

In this study,we examined 3-month-old female mice from the senescence-accelerated prone mouse 8 strain and age-matched homologous normal aging female mice from the senescence accelerated-resistant mouse 1 strain.Mice from each strain were housed in an enriched environment(including a platform,running wheels,tunnel,and some toys)or a standard environment for 3 months.The mice housed in the enriched environment exhibited shorter escape latencies and a greater percentage of time in the target quadrant in the Morris water maze test,and they exhibited reduced errors and longer latencies in step-down avoidance experiments compared with mice housed in the standard environment.Correspondently,brain-derived neurotrophic factor mRNA and protein ex- pression in the hippocampus was significantly higher in mice housed in the enriched environment compared with those housed in the standard environment,and the level of hippocampal brain-derived neurotrophic factor protein was positively correlated with the learning and memory abilities of mice from the senescence-accelerated prone mouse 8 strain.These results suggest that an enriched environment improved cognitive performance in mice form the senescence-accelerated prone mouse 8 strain by increasing brain-derived neurotrophic factor expression in the hippocampus.     

神经再生素对实验性急性高眼压兔眼视网膜神经节细胞的保护：与脑源性神经营养因子的作用相似？

【摘要】 目的 探讨中药提取物神经再生素（Nerve Regeneration Factor,NRF）对实验性急性高眼压（Hyper-intraocular pressure , HIOP）兔眼视网膜神经节细胞（RGCs）的保护作用。方法 16只健康中华大耳白兔随机等分为实验组（NRF）组和空白对照（PBS）组,前房灌注法建立右眼实验性急性HIOP模型,左眼作为正常对照。于灌注前、灌注后4、7d ,NRF组和PBS组右眼玻璃体腔内分别注射NRF 4.5μg或等量0.1M 磷酸缓冲液（PBS）。实验兔第14d安乐致死。实验兔致死前48h以辣根过氧化物酶（HRP）逆向标记双眼RGCs,视网膜铺片后以3,3',5,5'-四甲基联苯胺（TMB）法呈色,计数下半视网膜距视盘边缘2、4、6mm处的RGCs密度。结果 距视盘边缘2、4、6mm处,正常对照组的RGCs密度为(1 621±407)、(762±235)、(366±125)个/mm2;NRF组的RGCs密度为(1 268±378)、(699±253)、(284±104)个/mm2,距视盘边缘2、6mm处,NRF组与正常对照组RGCs密度的差异有非常显著意义（P均<0.01）;PBS组的RGCs密度为(1 002±410)、(627±211)、(264±107)个/mm2,与正常对照组RGCs密度的差异均有非常显著意义（P均<0.01）;距视盘边缘2mm处,NRF组与PBS组的RGCs密度的差异有显著意义（P<0.05）。结论 神经再生素可提高实验性急性高眼压兔眼RGCs的存活率,对RGCs具有保护作用。     

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.     

Retinal ganglion cell response to axotomy and nerve growth factor antiserum treatment in the regenerating visual system of the goldfish (Carassius auratus): An in vivo and in vitro analysis

In vitro nerve growth factor (NGF) antiserum (anti-NGF) treatment was found to significantly depress retinal ganglion cell neurite outgrowth in goldfish explant culture. Goldfish retinas, conditioned by a 14-day prior optic nerve crush, demonstrated a significant dose response inhibition of neurite outgrowth if incubated with various concentrations of the antiserum (i.e. concentrations from full strength to 1:100) before explanation for tissue culture. NGF added to the incubation medium containing antiserum partially eliminated the inhibition of neurite outgrowth during the first 4 days of explant culture. Antiserum treatment at the higher concentrations (i.e. full strength and 1:1.5 dilution) caused a cessation of nerve growth from explants between culture days 3 and 4. However, controls at this time still exhibited vigorous neurite outgrowth.In vivo treatment with anti-NGF administered intraocularly at 7 days after optic nerve crush (i.e. 7 DPA) was found to significantly reduce the size and complexity of retinal ganglion cell nucleoli when analyzed morphometrically at 14 DPA. No other cell parameters measured (i.e. cell size, nuclear size, cell/nuclear ratios and mitochondrial, Golgi and RER densities) were found to be affected by the single antiserum treatment.     

BDNF blood levels after non-invasive brain stimulation interventions in major depressive disorder: A systematic review and meta-analysis

Objectives. To evaluate whether the antidepressant effects of novel non-invasive brain stimulation (NIBS) therapies are associated with neurotrophic effects, indexed by peripheral brain-derived neurotrophic factor (BDNF) levels. Methods. Systematic review and meta-analysis. We included trials published in PubMed/Medline from the first date available to June 2014 measuring BDNF blood levels before and after repetitive transcranial magnetic stimulation or transcranial direct current stimulation in depression. Results. Eight datasets (n = 259) were included. These studies enrolled mostly treatment-resistant depression patients, who received daily stimulation sessions on the left dorsolateral prefrontal cortex. BDNF did not increase after NIBS (Hedges’ g = 0.03, 95% CI = –0.21 to 0.27), even when examining each intervention separately. Meta-regressions did not identify the influence of any clinical and demographic predictors on the outcome. Finally, Begg's funnel plot did not suggest publication bias and results were robust according to sensitivity analysis. Conclusions. Peripheral BDNF levels do not increase after NIBS in depression. Such biomarker might, therefore, not be suitable to index NIBS antidepressant response. Further trials are needed, particularly exploring non-medicated populations, performing subsequent BDNF assessments in a larger timeframe and employing more intensive NIBS treatment protocols.     

Artemin augments survival and axon regeneration in axotomized retinal ganglion cells

Artemin, a recently discovered member of the glial cell line‐derived neurotrophic factor (GDNF) family, has neurotrophic effects on damaged neurons, including sympathetic neurons, dopamine neurons, and spiral ganglion neurons both in vivo and in vitro. However, its effects on retinal cells and its intracellular signaling remain relatively unexplored. During development, expression of GFRα3, a specific receptor for artemin, is strong in the immature retina and gradually decreases during maturation, suggesting a possible role in the formation of retinal connections. Optic nerve damage in mature rats causes levels of GFRα3 mRNA to increase tenfold in the retina within 3 days. GFRα3 mRNA levels continue to rise within the first week and then decline. Artemin, a specific ligand for GFRα3, has a neuroprotective effect on axotomized retinal ganglion cells (RGCs) in vivo and in vitro via activation of the extracellular signal‐related kinase? and phosphoinositide 3‐kinase?Akt signaling pathways. Artemin also has a substantial effect on axon regeneration in RGCs both in vivo and in vitro, whereas other GDNF family members do not. Therefore, artemin/GFRα3, but not other GDNF family members, may be of value for optic nerve regeneration in mature mammals. © 2014 Wiley Periodicals, Inc.     

Synergetic effects of ciliary neurotrophic factor and olfactory ensheathing cells on optic nerve reparation (complete translation)

At present, there is no effective treatment for the repair of the optic nerve after injury, or improvement of its microenvironment for regener-ation. Intravitreally injected ciliary neurotrophic factor (CNTF) and olfactory ensheathing cells (OECs) promote the long-distance regrowth of severed optic nerve ifbers after intracranial injury. Here, we examined the efifcacy of these techniques alone and in combination, in a rat model of optic nerve injury. We injected condensed OEC suspension at the site of injury, or CNTF into the vitreous body, or both simulta-neously. Retrograde tracing techniques showed that 4 weeks postoperatively, the number of surviving retinal ganglion cells and their axonal density in the optic nerve were greater in rats subjected to OEC injection only than in those receiving CNTF injection only. Furthermore, combined OEC + CNTF injection achieved better results than either monotherapy. These ifndings conifrm that OECs are better than CNTF at protecting injured neurons in the eye, but that combined OEC and CNTF therapy is notably more effective than either treatment alone.     

Ginsenoside Rg1 changes brain-derived neurotrophic factor expression in the facial nucleus of rats after ovariectomy:A semiquantitative analysis

BACKGROUND: Estrogen is neuroprotective, but long-term estrogen treatment can induce side effects such as breast carcinoma, endometrial cancer, and stroke. However, phytoestrogen is neuroprotective without these side effects.OBJECTIVE: To study the effects of Ginsenoside Rg1 on facial neurons and brain-derived neurotrophic factor (BDNF) expression in the facial nucleus in ovariectomized rats.DESIGN, TIME AND SETTING: The randomized, controlled animal experiments were performed at the Ultrasonic Institute, Second Affiliated Hospital, Chongqing Medical University, China, from September 2007 to September 2008.MATERIALS: Ginsenoside Rg1 (Sigma, USA), rabbit anti-rat BDNF, Bcl-2, Bax antibodies, biotin-labeled goat anti-rabbit IgG (Boster, China), and a TUNEL kit (Roche, Germany) were used in this study.METHODS: A total of 48 adult Sprague Dawley rats undergoing ovariectomy were randomly assigned into sham operation (n=8), model (n=20), and Ginsenoside Rg1 (n=20) groups. Facial nerve damage was induced by bilateral clamping of the facial nerve trunk. The bilateral facial nerve trunk was exposed in the sham operation group, with no clamping. Rats in the Ginsenoside Rg1 group were intraperitoneally injected with 10 mg/kg per day Ginsenoside Rg1; other groups received 2 mL saline, once a day, for 14 days.MAIN OUTCOME MEASURES: Morphologic changes in neurons of the facial nucleus were observed following hematoxylin-eosin staining. Neuronal apoptosis was detected by TUNEL. Changes in ultrastructure of the facial nerve fibers were observed with a transmission electron microscope. Expression of BDNF, Bcl-2, and Bax protein was quantified by semiquantitative immunohistochemistry.RESULTS: At 3-14 days following facial nerve damage, Ginsenoside Rg1 increased BDNF expression and the number of regenerated nerve fibers, and produced thicker myelin sheaths (P< 0.05). Ginsenoside Rg1 also gradually increased Bcl-2 protein expression and decreased Bax protein expression (P < 0.05). By day 7, apoptosis was observed in facial neurons, but Ginsenoside Rg1 reduced the number of apoptotic neurons. Sham animals did not show any changes in BDNF, Bcl-2, or Bax expression or facial neuron morphology.CONCLUSION: Ginsenoside Rg1 can substantially inhibit facial neuronal apoptosis by increasing endogenous BDNF and Bcl-2 expression and by decreasing Bax expression in ovariectomized rats after facial nerve damage.     

The visual system of a Palaeognathous bird: Visual field,retinal topography and retino‐central connections in the Chilean Tinamou (Nothoprocta perdicaria)

Most systematic studies of the avian visual system have focused on Neognathous species, leaving virtually unexplored the Palaeognathae, comprised of the flightless ratites and the South American tinamous. We investigated the visual field, the retinal topography, and the pattern of retinal and centrifugal projections in the Chilean tinamou, a small Palaeognath of the family Tinamidae. The tinamou has a panoramic visual field with a small frontal binocular overlap of 20°. The retina possesses three distinct topographic specializations: a horizontal visual streak, a dorsotemporal area, and an area centralis with a shallow fovea. The maximum ganglion cell density is 61,900/ mm², comparable to Falconiformes. This would provide a maximal visual acuity of 14.0 cycles/degree, in spite of relatively small eyes. The central retinal projections generally conform to the characteristic arrangement observed in Neognathae, with well‐differentiated contralateral targets and very few ipsilateral fibers. The centrifugal visual system is composed of a considerable number of multipolar centrifugal neurons, resembling the “ectopic” neurons described in Neognathae. They form a diffuse nuclear structure, which may correspond to the ancestral condition shared with other sauropsids. A notable feature is the presence of terminals in deep tectal layers 11–13. These fibers may represent either a novel retinotectal pathway or collateral branches from centrifugal neurons projecting to the retina. Both types of connections have been described in chicken embryos. Our results widen the basis for comparative studies of the vertebrate visual system, stressing the conserved character of the visual projections' pattern within the avian clade. J. Comp. Neurol. 523:226–250, 2015. © 2014 Wiley Periodicals, Inc.     

Stroke gets in your eyes: stroke-induced retinal ischemia and the potential of stem cell therapy

Stroke persists as a global health and economic crisis,yet only two interventions to reduce stroke-induced brain injury exist.In the clinic,many patients who experience an ischemic stroke often further suffer from retinal ischemia,which can inhibit their ability to make a functional recovery and may diminish their overall quality of life.Despite this,no treatments for retinal ischemia have been developed.In both cases,ischemia-induced mitochondrial dysfunction initiates a cell loss cascade and inhibits endogenous brain repair.Stem cells have the ability to transfer healthy and functional mitochondria not only ischemic neurons,but also to similarly endangered retinal cells,replacing their defective mitochondria and thereby reducing cell death.In this review,we encapsulate and assess the relationship between cerebral and retinal ischemia,recent preclinical advancements made using in vitro and in vivo retinal ischemia models,the role of mitochondrial dysfunction in retinal ischemia pathology,and the therapeutic potential of stem cell-mediated mitochondrial transfer.Furthermore,we discuss the pitfalls in classic rodent functional assessments and the potential advantages of laser Doppler as a metric of stroke progression.The studies evaluated in this review highlight stem cell-derived mitochondrial transfer as a novel therapeutic approach to both retinal ischemia and stroke.Furthermore,we posit the immense correlation between cerebral and retinal ischemia as an underserved area of study,warranting exploration with the aim of these treating injuries together.     

Effects of electromagnetic field (PEMF) exposure at different frequency and duration on the peripheral nerve regeneration: in vitro and in vivo study

Purpose: The purpose was to clarify the influence of frequency and exposure time of pulsed electromagnetic fields (PEMF) on the peripheral nerve regeneration. Materials and methods: Immortalized rat Schwann cells (iSCs) (1 × 10²/well) were exposed at four different conditions in 1 mT (50 Hz 1 h/d, 50 Hz 12 h/d, 150 Hz 1 h/d and 150 Hz 12h/d). Cell proliferation, mRNA expression of S100 and brain-derived neurotrophic factor (BDNF) were analyzed. Sprague-Dawley rats (200–250 g) were divided into six groups (n = 10 each): control, sham, 50 Hz 1 h/d, 50 Hz 12 h/d, 150 Hz 1 h/d and 150 Hz 12 Hr/d. Mental nerve was crush-injured and exposed at four different conditions in 1 mT (50 Hz 1 Hr/d, 50 Hz 12 Hr/d, 150 Hz 1 h/d and 150 Hz 12 h/d). Nerve regeneration was evaluated with functional test, histomorphometry and retrograde labeling of trigeminal ganglion. Results: iSCs proliferation with 50 Hz, 1 h/d was increased from fourth to seventh day; mRNA expression of S100 and BDNF was significantly increased at the same condition from first week to third week (p < .05 vs. control); difference score was increased at the second and third week, and gap score was increased at the third under 50 Hz 1 h PEMF compared with control while other conditions showed no statistical meaning. Axon counts and retrograde labeled neurons were significantly increased under PEMF of four different conditions compared with control. Although there was no statistical difference, 50 Hz, 1 h PEMF showed highest regeneration ability than other conditions. Conclusion: PEMF enhanced peripheral nerve regeneration, and that it may be due to cell proliferation and increase in BDNF and S100 gene expression.     

Application of peripheral nerve conduits in clinical practice: A literature review

Understanding the pathomechanisms behind peripheral nerve damage and learning the course of regeneration seem to be crucial for selecting the appropriate methods of treatment. Autografts are currently the gold standard procedure in nerve reconstruction. However, due to the frequency of complications resulting from autografting and a desire to create a better environment for the regeneration of the damaged nerve, artificial conduits have become an approved alternative treatment method. The aim of this mini-review is to present the nerve scaffolds that have been applied in clinical practice to date, and the potential directions of developments in nerve conduit bioengineering.Articles regarding construction and characterization of nerve conduits were used as the theoretical background. All papers, available in PubMed database since 2000, presenting results of application of artificial nerve conduits in clinical trials were included into this mini-review.Fourteen studies including ≤10 patients and 10 trials conducted on >10 patients were analyzed as well as 24 papers focused on artificial nerve conduits per se. Taking into consideration the experiences of the authors investigating nerve conduits in clinical trials, it is essential to point out the emergence of bioresorbable scaffolds, which in the future may significantly change the treatment of peripheral nerve injuries. Also worth mentioning among the advanced conduits are hybrid conduits, which combine several modifications of a synthetic material to provide the optimal regeneration of a damaged nerve.     

State-dependent increase in the levels of neurotrophin-3 and neurotrophin-4/5 in patients with bipolar disorder: A meta-analysis

Bipolar disorder (BD) is one of the most serious psychiatric disorders in the world, but its pathophysiology is still unclear. Regulation of neurotrophic factors have been thought to play a role in this process. There have been inconsistent findings regarding the differences in blood neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4/5) between patients with BD and healthy controls (HCs). The aim of the current meta-analysis is to examine the changes in the levels of NT-3 and NT-4/5 in BD patients at different affective states. Eight articles (including 465 BD patients and 353 HCs) were included in the analysis, and their results were pooled by using a random effects model. We found the levels of both NT-3 (p = 0.0046) and NT-4/5 (p = 0.0003) were significantly increased in BD patients, compared to HCs. Through subgroup analysis, this increase persisted only in patients in depressed state (p = 0.0038 for NT-3 and p = 0.0001 for NT-4/5), but not in manic or euthymic state. In addition, we found the differences in NT-3 and NT-4/5 were significantly associated with the duration of illness, but not by the mean age or female proportion. Our results suggest a state-dependent increase in NT-3 and NT-4/5 levels in patients with BD. Further studies are needed to examine dynamic changes of these neurotrophins in BD patients along the disease course.