Quantitation of the in vitro neuroblastoma response to exogenous, purified gangliosides

Individual ganglioside species (possessing the gangliotetrose oligosaccharide) were purified from bovine brain gray matter and applied in varying concentrations to the culture medium of mouse neuroblastoma cells (N2A) in vitro. After 48 hr of incubation, the cells were stained, and the neuritogenic response quantitated with a video analysis system, employing a program to measure three parameters of neuroblastoma differentiation: neurites per cell (sprouting), neurite length (extension), and degree of neurite branching (arborization). All the individual gangliosides tested promoted neurite extension in a dose-dependent fashion. Asialogangliosides ("neutral" glycosphingolipids) were without effect, which suggests that sialic acid (N-acetylneuraminic acid) is necessary to elicit this cellular response. With increasing concentrations of GM1 (5 to 500 micrograms/ml), the average cellular neurite length increased significantly, whereas the number of neurites per cell decreased. With the trisialoganglioside GT1b, neurite length did not increase to the extent seen with GM1, but an increase in the number of neurites per cell (sprouting) and branch points per neurite (arborization) was observed. These results suggest that the in vitro neuronal response to exogenous gangliosides may combine specific responses to individual species making up the total.     

Effects of antipsychotic drugs on neurites relevant to schizophrenia treatment

Although antipsychotic drugs are mainly used for treating schizophrenia, they are widely used for treating various psychiatric diseases in adults, the elderly, adolescents and even children. Today, about 1.2% of the worldwide population suffers from psychosis and related disorders, which translates to about 7.5 million subjects potentially targeted by antipsychotic drugs. Neurites project from the cell body of neurons and connect neurons to each other to form neural networks. Deficits in neurite outgrowth and integrity are implicated in psychiatric diseases including schizophrenia. Neurite deficits contribute to altered brain development, neural networking and connectivity as well as symptoms including psychosis and altered cognitive function. This review revealed that (1) antipsychotic drugs could have profound effects on neurites, synaptic spines and synapse, by which they may influence and regulate neural networking and plasticity; (2) antipsychotic drugs target not only neurotransmitter receptors but also intracellular signaling molecules regulating the signaling pathways responsible for neurite outgrowth and maintenance; (3) high doses and chronic administration of antipsychotic drugs may cause some loss of neurites, synaptic spines, or synapsis in the cortical structures. In addition, confounding effects causing neurite deficits may include elevated inflammatory cytokines and antipsychotic drug-induced metabolic side effects in patients on chronic antipsychotic therapy. Unraveling how antipsychotic drugs affect neurites and neural connectivity is essential for improving therapeutic outcomes and preventing aversive effects for patients on antipsychotic drug treatment.     

The Nogo66 receptor pathway and CNS axon regeneration: new hopes for treating CNS injuries and neurodegeneration

The neuronal leucine-rich repeat Nogo66 receptor (NgR) interacts with the myelin proteins Nogo66, myelin associated glycoprotein and oligodendrocyte myelin glycoprotein to inhibit axon growth. Modulation of these cell surface NgR-dependent interactions or the inhibitory intracellular signalling pathways may promote axon growth in the CNS after injury and present an attractive axon regeneration platform for treating CNS injuries or even neurodegenerative disorders. Multiple NgR antagonism approaches, including soluble NgR proteins, anti-NgR antibodies, a Nogo-derived antagonist peptide and NgR signal transduction modulators, have demonstrated striking efficacies in promoting functional recoveries in animal models of spinal cord injury, stroke and multiple sclerosis. This review summarises the neurobiology of the NgR pathway and the various drug discovery strategies that are specifically based on modulation of the myelin–NgR interaction.     

Tenascin-C分子中FN6-8片段蛋白对培养的脊髓缺气损伤神经元的影响

目的 研究ＦＮＫ６－８片段能否促进损伤神经元的突起生长。方法 从包含有ＴＮ－Ｃ分子中ＦＮ６－８ＤＮＡ序列的质粒中表达度纯化ＧＳＴ－ＦＮ６－８融合蛋白，以０．０５ｍｇ／Ｌ的浓度加入培养的胚胎小鼠脊髓神经元的培养液中，对照组加入等量ＧＳＴ，然后液体石蜡封闭液面造成神经元缺气损伤，３d后做ＭＴＴ实验，测神经元活性并图像分析神 元突起的长度。结果 ＦＮ６－８组的神经元活性和神经元突起长度明显高于对照组。结论     

远志皂苷元对新生大鼠皮质神经元的营养作用

目的 研究远志皂苷元(senegenin)对新生大鼠皮质神经元的神经营养作用.方法 原代培养新生24 h内SD大鼠皮质神经元,采用0.4% B27+DMEM/F12培养基制备营养缺乏模型.远志皂苷元0.5,1 和2 μmol·L-1及阳性对照组碱性成纤维细胞生长因子(bFGF)10 μg·L-1.倒置显微镜下观察各组皮...     

Guided Neurite Elongation and Schwann Cell Invasion into Magnetically Aligned Collagen in Simulated Peripheral Nerve Regeneration

High-strength magnetic fields were used to align collagen gel formed into 4-mm-diameter rods during the self-assembly of type I collagen monomers into fibrils. We developed an in vitro assay to study neurite elongation into the magnetically aligned collagen gel rods from dorsal root ganglia (DRG) explants placed onto one end of the rods. The depth of neurite elongation from chick embryo DRG neurons into these rods was found to be substantially greater than that observed in controls and increased with an increase in magnetic field strength, as did the collagen gel rod birefringence, indicative of collagen fibril alignment along the rod axis. Moreover, the axial bias of neurite elongation became more pronounced with an increase in magnetic field strength, presumably due to a contact guidance response of growth cones at the neurite tips. Coinvasion of Schwann cells from neonatal rat DRG was also studied in these assays using double immunolabeling. In the absence of serum, Schwann cells were highly associated with, and often trailed, elongating neurites. In the presence of serum, Schwann cells showed significantly higher rates of invasion and formed axially aligned chords reminiscent of bands of Büngner. These results may translate into an improved method of entubulation repair of transected peripheral nerves by directing and stimulating axonal growth through a tube filled with magnetically aligned collagen gel.     

Aquilaria crassna Leaf Extract Ameliorates Glucose-Induced Neurotoxicity In Vitro and Improves Lifespan in Caenorhabditis elegans

Hyperglycemia is one of the important causes of neurodegenerative disorders and aging. Aquilaria crassna Pierre ex Lec (AC) has been widely used to relieve various health ailments. However, the neuroprotective and anti-aging effects against high glucose induction have not been investigated. This study aimed to investigate the effects of hexane extract of AC leaves (ACH) in vitro using human neuroblastoma SH-SY5Y cells and in vivo using nematode Caenorhabditis elegans. SH-SY5Y cells and C. elegans were pre-exposed with high glucose, followed by ACH treatment. To investigate neuroprotective activities, neurite outgrowth and cell cycle progression were determined in SH-SY5Y cells. In addition, C. elegans was used to determine ACH effects on antioxidant activity, longevity, and healthspan. In addition, ACH phytochemicals were analyzed and the possible active compounds were identified using a molecular docking study. ACH exerted neuroprotective effects by inducing neurite outgrowth via upregulating growth-associated protein 43 and teneurin-4 expression and normalizing cell cycle progression through the regulation of cyclin D1 and SIRT1 expression. Furthermore, ACH prolonged lifespan, improved body size, body length, and brood size, and reduced intracellular ROS accumulation in high glucose-induced C. elegans via the activation of gene expression in the DAF-16/FoxO pathway. Finally, phytochemicals of ACH were analyzed and revealed that β-sitosterol and stigmasterol were the possible active constituents in inhibiting insulin-like growth factor 1 receptor (IGFR). The results of this study establish ACH as an alternative medicine to defend against high glucose effects on neurotoxicity and aging.     

Along‐tract statistics of neurite orientation dispersion and density imaging diffusion metrics to enhance MR tractography quantitative analysis in healthy controls and in patients with brain tumors

Along‐tract statistics analysis enables the extraction of quantitative diffusion metrics along specific white matter fiber tracts. Besides quantitative metrics derived from classical diffusion tensor imaging (DTI), such as fractional anisotropy and diffusivities, new parameters reflecting the relative contribution of different diffusion compartments in the tissue can be estimated through advanced diffusion MRI methods as neurite orientation dispersion and density imaging (NODDI), leading to a more specific microstructural characterization. In this study, we extracted both DTI‐ and NODDI‐derived quantitative microstructural diffusion metrics along the most eloquent fiber tracts in 15 healthy subjects and in 22 patients with brain tumors. We obtained a robust intraprotocol reference database of normative along‐tract microstructural metrics, and their corresponding plots, from healthy fiber tracts. Each diffusion metric of individual patient''s fiber tract was then plotted and statistically compared to the normative profile of the corresponding metric from the healthy fiber tracts. NODDI‐derived metrics appeared to account for the pathological microstructural changes of the peritumoral tissue more accurately than DTI‐derived ones. This approach may be useful for future studies that may compare healthy subjects to patients diagnosed with other pathological conditions.     

Role of neurotrophic factors in enhancing linear axonal growth of ganglionic sensory neurons in vitro

Neurotrophins play a major role in the regulation of neuronal growth such as neurite sprouting or regeneration in response to nerve injuries. The role of nerve growth factor, neurotrophin-3, and brain-derived neurotrophic factor in maintaining the survival of peripheral neurons remains poorly understood. In regenerative medicine, different modalities have been investigated for the delivery of growth factors to the injured neurons, in search of a suitable system for clinical applications. This study was to investigate the influence of nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor on the growth of neurites using two in vitro models of dorsal root ganglia explants and dorsal root ganglia-derived primary cell dissociated cultures. Quantitative data showed that the total neurite length and tortuosity were differently influenced by trophic factors. Nerve growth factor and, indirectly, brain-derived neurotrophic factor stimulate the tortuous growth of sensory fibers and the formation of cell clusters. Neurotrophin-3, however, enhances neurite growth in terms of length and linearity allowing for a more organized and directed axonal elongation towards a peripheral target compared to the other growth factors. These findings could be of considerable importance for any clinical application of neurotrophic factors in peripheral nerve regeneration. Ethical approval was obtained from the Regione Piemonte Animal Ethics Committee ASLTO1(file # 864/2016-PR) on September 14, 2016.     

Heparan sulphate and HB-GAM (heparin-binding growth-associated molecule) in the development of the thalamocortical pathway of rat brain

Extracellular matrix (ECM) molecules, such as laminin, tenascin, chondroitin sulphate proteoglycans and heparan sulphate proteoglycans have been suggested to have 'signpost' and directing roles in the formation of axonal projections in cortical development. We show here that the expression of the neurite outgrowth-promoting protein heparin-binding growth-associated molecule (HB-GAM) and N-syndecan, a transmembrane heparan sulphate proteoglycan previously isolated as a receptor for HB-GAM, is spatiotemporally associated with the developing thalamocortical pathway in the rat brain. Using in situ hybridization, thalamic neurons were shown to express mRNA for N-syndecan, and in vitro, thalamic neurons grew more neurites on HB-GAM than on laminin. The HB-GAM-induced neurite outgrowth in thalamic neurons was inhibited by heparitinase, heparin, soluble N-syndecan and by an excess of soluble HB-GAM in the culture medium. In a pathway assay, thalamic neurons selectively preferred attaching and growing neurites on matrices containing HB-GAM than on those containing fibronectin or laminin alone, suggesting that HB-GAM may modulate the effect of other ECM proteins. On an unfixed brain slice preparation, thalamic neurons repeatedly showed a typical neurite outgrowth and attachment pattern resembling the expression pattern of HB-GAM. On the brain slices, the neurite outgrowth was significantly inhibited by heparitinase, heparin and soluble HB-GAM, thus displaying features of neurite outgrowth on matrix-bound HB-GAM. Our results suggest that HB-GAM is important for the neurite outgrowth of thalamic neurons and it may function as an ECM-bound guidance cue for thalamic neurons that possess HB-GAM-binding heparan sulphates on their cell membrane.