Axonal transport of mitochondria is critical for neuronal survival and function. Automatically quantifying and analyzing mitochondrial movement in a large quantity remain challenging. Here, we report an efficient method for imaging and quantifying axonal mitochondrial transport using microfluidic-chamber-cultured neurons together with a newly developed analysis package named "MitoQuant". This tool-kit consists of an automated program for tracking mitochondrial movement inside live neuronal axons and a transient-velocity analysis program for analyzing dynamic movement patterns of mitochondria. Using this method, we examined axonal mitochondrial movement both in cultured mammalian neurons and in motor neuron axons of Drosophila in vivo. In 3 different paradigms (temperature changes, drug treatment and genetic manipulation) that affect mitochondria, we have shown that this new method is highly efficient and sensitive for detecting changes in mitochondrial movement. The method significantly enhanced our ability to quantitatively analyze axonal mitochondrial movement and allowed us to detect dynamic changes in axonal mitochondrial transport that were not detected by traditional kymographic analyses.
Animals ; Axonal Transport ; physiology ; Cerebral Cortex ; cytology ; metabolism ; Drosophila melanogaster ; cytology ; metabolism ; Embryo, Mammalian ; Gene Expression ; Lab-On-A-Chip Devices ; Microscopy, Confocal ; Mitochondria ; metabolism ; ultrastructure ; Motor Neurons ; metabolism ; ultrastructure ; Movement ; Mutation ; Primary Cell Culture ; RNA-Binding Protein FUS ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Software

OBJECTIVETo study the changes in microtubule motor protein expression in the spinal cord and sciatic nerve of rats exposed to carbon disulfide, and to investigate the possible molecular mechanism of changes in axonal transport in carbon disulfide-induced peripheral neuropathy.

METHODSHealthy adult male Wistar rats were randomly divided into one control group and three experimental groups (10 rats per group). The rats in experimental groups were intoxicated by gavage of carbon disulfide at a dose of 200, 400, or 600 mg/kg 6 times a week for 6 consecutive weeks, while the rats in control group were given the same volume of corn oil by gavage. Animals were sacrificed after exposure, with nerve tissue separated. The levels of dynein, dynactin, and kinesin in the spinal cord and sciatic nerve were determined by Western blot.

RESULTSThe content of dynein, dynactin, and kinesin in the sciatic nerve decreased significantly under exposure to carbon disulfide. The levels of dynein in the sciatic nerve were reduced by 23.47% and 33.34% at exposure doses of 400 and 600 mg/kg, respectively. The levels of dynactin in the sciatic nerve of the three experimental groups were reduced by 19.91%, 24.23%, and 41.30%, respectively. The level of kinesin was reduced by 25.98%under exposure to 600 mg/kg carbon disulfide. All the differences were statistically significant (P < 0.01). As compared with the control group, the 600 mg/kg group experienced a 28.24% decrease in level of dynactin in the spinal cord (P < 0.01), but no significant change was observed in the level of dynein or kinesin.

CONCLUSIONCarbon disulfide has an impact on microtubule motor protein expression in nerve tissues, which might be involved in the development of carbon disulfide-induced peripheral neuropathy.

Animals ; Axonal Transport ; drug effects ; physiology ; Carbon Disulfide ; toxicity ; Dynactin Complex ; Male ; Microtubule-Associated Proteins ; metabolism ; Nerve Tissue ; metabolism ; Peripheral Nervous System Diseases ; chemically induced ; metabolism ; Rats, Wistar ; Sciatic Nerve ; metabolism ; Spinal Cord ; metabolism

OBJECTIVETo review the updated research on neuroprotection in glaucoma, and summarize the potential agents investigated so far.

DATA SOURCESThe data in this review were collected from PubMed and Google Scholar databases published in English up to September 2012, with keywords including glaucoma, neuroprotection, and retinal ganglion cells, both alone and in combination. Publications from the past ten years were selected, but important older articles were not excluded.

STUDY SELECTIONArticles about neuroprotection in glaucoma were selected and reviewed, and those that are cited in articles identified by this search strategy and judged relevant to this review were also included.

RESULTSAlthough lowering the intraocular pressure is the only therapy approved as being effective in the treatment of glaucoma, increasing numbers of studies have discovered various mechanisms of retinal ganglion cells death in the glaucoma and relevant neuroprotective strategies. These strategies target neurotrophic factor deprivation, excitotoxic damage, oxidative stress, mitochondrial dysfunction, inflammation, activation of intrinsic and extrinsic apoptotic signals, ischemia, and protein misfolding. Exploring the mechanism of axonal transport failure, synaptic dysfunction, the glial system in glaucoma, and stem cell used in glaucoma constitute promising research areas of the future.

CONCLUSIONSNeuroprotective strategies continue to be refined, and future deep investment in researching the pathogenesis of glaucoma may provide novel and practical neuroprotection tactics. Establishing a system to assess the effects of neuroprotection treatments may further facilitate this research.

Apoptosis ; Axonal Transport ; Brain-Derived Neurotrophic Factor ; physiology ; Ciliary Neurotrophic Factor ; physiology ; Glaucoma ; etiology ; therapy ; Humans ; Mitochondria ; physiology ; Neuroprotective Agents ; therapeutic use ; Oxidative Stress ; Protein Folding ; Receptors, N-Methyl-D-Aspartate ; physiology ; Retinal Ganglion Cells ; physiology

The present study was performed to evaluate the relationship between the neurotoxicity of acrylamide and the differential gene expression pattern in mice. Both locomotor test and rota-rod test showed that the group treated with higher than 30 mg/kg/day of acrylamide caused impaired motor activity in mice. Based on cDNA microarray analysis of mouse brain, myelin basic protein gene, kinesin family member 5B gene, and fibroblast growth factor (FGF) 1 and its receptor genes were down-regulated by acrylamide. The genes are known to be essential for neurofilament synthesis, axonal transport, and neuro-protection, respectively. Interestingly, both FGF 1 and its receptor genes were down-regulated. Genes involved in nucleic acid binding such as AU RNA binding protein/enoyl-coA hydratase, translation initiation factor (TIF) 2 alpha kinase 4, activating transcription factor 2, and U2AF 1 related sequence 1 genes were down-regulated. More interesting finding was that genes of both catalytic and regulatory subunit of protein phosphatases which are important for signal transduction pathways were down-regulated. Here, we propose that acrylamide induces neurotoxicity by regulation of genes associated with neurofilament synthesis, axonal transport, neuro-protection, and signal transduction pathways.
Acrylamide ; Activating Transcription Factor 2 ; Animals ; Axonal Transport ; Brain ; Fibroblast Growth Factors ; Gene Expression ; Humans ; Kinesin ; Mice ; Motor Activity ; Myelin Basic Protein ; Oligonucleotide Array Sequence Analysis ; Peptide Initiation Factors ; Phosphoprotein Phosphatases ; Phosphotransferases ; RNA ; Signal Transduction

The reaction of neuroactive substances to ischemic conditions in the rat retina evoked by different methods was immunochemically evaluated in adult Sprague-Dawley rats. Ocular ischemic conditions were unilaterally produced by elevating intraocular pressure (EIOP) or by middle cerebral artery occlusion (MCAO). Two EF-hand calcium binding proteins, calbindin D28K (CB) and calretinin (CR), in the normal retina showed similar immunolocalization, such as the amacrine and displaced amacrine cells, the ganglion cells, and their processes, particularly CB in horizontal cells. CB immunoreactive neurons in the ganglion cell layer in both types of ischemic retinas were more reduced in number than CR neurons compared to those in a normal retina. The CB protein level in both ischemic retinas was reduced to 60-80% of normal. The CR protein level in MCAO retinas was reduced to about 80% of normal but increased gradually to the normal value, whereas that in the EIOP showed a gradual reduction and a slight recovery. SMI32 immunoreactivity, which detects a dephosphorylated epitope of neurofilaments-M and -H, appeared in the axon bundles of ganglion cells in the innermost nerve fiber layer of normal retinas. The reactivity in the nerve fiber bundles appeared to only increase slightly in EIOP retinas, whereas a moderate increase occurred in MCAO retinas. The SMI32 protein level in MCAO retinas showed a gradual increasing tendency, whereas that in the EIOP showed a slight fluctuation. Interestingly, the MCAO retinas showed additional SMI32 immunoreactivity in the cell soma of presumed ganglion cells, whereas that of EIOP appeared in the Muller proximal radial fibers. Glial fibrillary acidic protein (GFAP) immunoreactivity appeared in the astrocytes located in the nerve fiber layer of normal retinas. Additional GFAP immunoreactivity appeared in the Muller glial fibers deep in EIOP retinas and at the proximal end in MCAO retinas. These findings suggest that the neurons in the ganglion cell layer undergo degenerative changes in response to ischemia, although EIOP retinas represented a remarkable Muller glial reaction, whereas MCAO retinas had only a small-scaled axonal transport disturbance.
Adult ; Amacrine Cells ; Animals ; Astrocytes ; Axonal Transport ; Axons ; Calcium-Binding Protein, Vitamin D-Dependent ; Calcium-Binding Proteins ; Carisoprodol ; Ganglion Cysts ; Glial Fibrillary Acidic Protein ; Humans ; Infarction, Middle Cerebral Artery ; Intraocular Pressure ; Ischemia ; Middle Cerebral Artery ; Nerve Fibers ; Neurons ; Rats ; Rats, Sprague-Dawley ; Reference Values ; Retina

OBJECTIVETo study the expression of tau-related protein in spinal cord of Chinese patients with Alzheimer's disease.

METHODSGallays-Braak stain and immunohistochemical study for tau protein (AT8) were carried out in the spinal cord tissue (T2, T8, T10, L2 and S2 segments) of 3 Chinese patients with Alzheimer's disease. Seven age-matched cases without evidence of dementia or neurologic disease were used as controls.

RESULTSNeurofibrillary tangles were identified in the neurons of anterior horn in 2 Alzheimer's disease cases but none was observed in the controls. Tau-positive axons and astroglia were detected in all Alzheimer's disease cases. Tau immunoreactivity in spinal cord of the patients correlated with that in brain tissue.

CONCLUSIONThe expression of tau-related protein is demonstrated in the spinal cord of Alzheimer's disease patients suggesting that axonal transport defect may play a role in the pathogenesis of Alzheimer's disease.

Aged ; Alzheimer Disease ; metabolism ; pathology ; Axonal Transport ; Axons ; metabolism ; pathology ; Humans ; Male ; Neurofibrillary Tangles ; metabolism ; pathology ; Phosphorylation ; Spinal Cord ; metabolism ; pathology ; tau Proteins ; metabolism

Hereditary peripheral neuropathies can be categorized as hereditary motor and sensory neuropathies (HMSN), hereditary motor neuropathies (HMN), and hereditary sensory neuropathies (HSN). HMSN, HMN, and HSN are further subdivided into several subtypes. Here, we review the most recent findings in the molecular diagnosis and therapeutic strategy for hereditary peripheral neuropathies. The products of genes associated with hereditary peripheral neuropathy phenotypes are important for neuronal structure maintenance, axonal transport, nerve signal transduction, and functions related to the cellular integrity. Identifying the molecular basis of hereditary peripheral neuropathy and studying the relevant genes and their functions is important to understand the pathophysiological mechanisms of these neurodegenerative disorders, as well as the processes involved in the normal development and function of the peripheral nervous system. These advances and the better understanding of the pathogenesis of peripheral neuropathies represent a challenge for the diagnoses and managements of hereditary peripheral neuropathy patients in developing future supportive and curative therapies.
Axonal Transport ; Hereditary Sensory and Autonomic Neuropathies ; Hereditary Sensory and Motor Neuropathy ; Humans ; Neurodegenerative Diseases ; Neurons ; Peripheral Nervous System ; Peripheral Nervous System Diseases ; Phenotype ; Signal Transduction ; Wills

Alzhelmer's disease (AD) is the most common cause of dementia that arises on a neuropathological background of amyloid plaques containing betaamylold (Abeta) derived from amyloid precursor protein (APP) and tau-rich neurofibrillary tangles. To date, the cause and progression of familial or sporadic AD have not been fully elucidated. About 10% of all cases of AD occur as autosomal dominant inherited forms of early-onset AD, which are caused by mutations in the genes encoding APP, presenilin-1 and presenilin-2. Proteolytic processing of APP by beta-gamma-secretase and caspase generates Abetaand carboxyl-terminal fragments of APP (APP-CTFs), which have been implicated in the pathogenesis of AD. The presenilins function as one of the gamma-secretases. Abetawhich is the main component of the amyloid plaques found, is known to exert neurotoxicity by accumulating free radicals, disturbing calcium homeostasis, evoking inflammatory response and activating signaling pathways. The CTFs have been found in AD patients' brain and reported to exhibit much greater neurotoxicity than Abeta. Furthermore CTFs are known to impair calcium homeostasis and learning and memory, triggering a strong inflammatory reaction through MAPKs- and NF-kappaB-dependent astrocytosis and iNOS induction. Recently, it was reported that CTF translocated into the nucleus and in turn, affected transcription of genes including glycogen synthase kinase-3beta which results in the induction of tau-rich neurofibrillary tangles and subsequently cell death. One of the hallmarks of AD, neurofibrillary tangles (NFT), is formed by insoluble intracellular polymers of hyperphosphorylated tau that is believed to cause apoptosis by disrupting cytoskeletal and axonal transport. This review covers the processing of APP, toxic mechanisms of Abetaand CTFs of APP, presenilin and also tau in relation to the pathogenesis of AD.
Amyloid ; Apoptosis ; Axonal Transport ; Brain ; Calcium ; Cell Death ; Dementia* ; Free Radicals ; Gliosis ; Glycogen Synthase ; Homeostasis ; Learning ; Memory ; Neurofibrillary Tangles ; Plaque, Amyloid ; Polymers ; Presenilin-1 ; Presenilin-2 ; Presenilins

PURPOSE: To investigate the replication of HSV within cultured cell and axonal transport of HSV within the axon of the ciliary nerve following the injection of HSV into a cultured ciliary nerve. METHODS: The explant of the ciliary nerve was cultured with a medium containing nerve growth factor for 30 days when the suspension of HSV-1 (Kos strain) was introduced into the culture dish to co-culture with the ciliary nerve. The ciliary nerve was examined with transmission electron microscopy 30 days after culture and 6 days after co-culture with HSV. RESULTS: The ultrastructure of the explant of the ciliary nerve co-cultured with HSV showed that the viral capsid acquired a viral envelope and viral core, and a capsid and inclusion body within the nucleus. The enveloped virus was scattered within the vesicles of the cytoplasm. The virus-like particles were identified at the axonal fibers. CONCLUSIONS: The co-culture of the explant of the ciliary nerve and HSV showed the replicative process of the HSV within the cultured cell. The virus-like particles within the axon showed the evidence axonal transport of the virus under culture conditions.
Axonal Transport* ; Axons ; Capsid ; Cells, Cultured ; Coculture Techniques ; Cytoplasm ; Herpes Simplex* ; Herpesvirus 1, Human ; Inclusion Bodies ; Microscopy, Electron, Transmission ; Nerve Growth Factor ; Simplexvirus*

Glaucoma is characterized by loss of retinal ganglion cells (RGCs) and their axons. Retrograde axoplasmic transport blockade and excitotoxicity were proposed to be a major cause of RGC apoptosis. We conducted this study to characterize the episcleral vessel cauterization glaucoma model in the rat with respect to decreased retrograde axoplasmic flow and subsequent apoptotic RGC death. After episcleral vessels were cauterized in Sprague-Dawley rats, Fluorogold was injected into their superior colliculi by stereotactic method. Retrograde axoplasmic flow and TUNEL-stained apoptotic dead cells were observed microscopically. Elevated intraocular pressure was maintained for up to 6 weeks during follow-up. Retrograde axoplasmic flow to the rat retina was significantly decreased. Apoptotic RGC was selectively TUNELstained in the retina, especially at the ganglion cell layers. We concluded that elevated intraocular pressure caused apoptotic RGC death through retrograde axoplasmic flow blockage. Further studies will elucidate the neuroprotection strategies in glaucoma patients.
Animals ; *Apoptosis ; Axonal Transport ; Disease Models, Animal ; In Situ Nick-End Labeling ; *Intraocular Pressure ; Male ; Ocular Hypertension/*complications ; Rats ; Rats, Sprague-Dawley ; Retinal Ganglion Cells/*pathology ; Retrograde Degeneration/etiology ; Sclera/blood supply