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PubMed1985

Rapid axonal transport in Xenopus nerve in divalent cation free media.

An investigation was made of the effects of bathing media low in divalent cations on rapid axonal transport in the sciatic nerve of the amphibian Xenopus laevis. The anterograde transport of a pulse of [35S]methionine proteins was observed using a multiple proportional counter as the detector. Organelles undergoing anterograde and retrograde transport were detected by light microscopy. The structure of nerve fibers was examined by light and electron microscopy. There was no significant difference in the anterograde transport of proteins in nerves bathed in normal medium (NM) containing millimolar Ca2+ and Mg2+ and in those bathed in calcium-free medium (CaFM) containing Mg2+. The anterograde transport of labelled proteins continued at a normal velocity in nerves bathed in divalent cation free medium (DCFM) for at least 14 h. DCFM did cause some alterations in protein transport: the ratio of the plateau (following pulse passage) to the peak radioactivity was increased, the pulse amplitude decreased more rapidly, and the label continued to arrive at the distal end of the nerve for greater than 16 h. Anterograde and retrograde organelle transport continued normally for periods of greater than or equal to 4 h in fibres bathed in DCFM. All myelinated fibres became distorted within 4 h in DCFM. Similar distortion was rare in fibres bathed in CaFM. The results indicate that axonal transport in Xenopus is largely independent of lowered concentrations of divalent cations in the bathing medium. Those alterations in axonal transport that were produced by DCFM may have been secondary to morphological changes in the nerve fibres.

Animals↗
PubMed1981

Rapid axonal transport in primate optic nerve. Distribution of pressure-induced interruption.

Six primate eyes were studied after four hours of elevated intraocular pressure. Tissue specimens from the region of the lamina cribrosa were examined in cross section by transmission electron microscopy. Interruption in fast orthograde and retrograde axonal transport was identified in individual axons by noting accumulation of membraneous microorganelles, such as mitochondria and microvesicles within axon cylinders. Although organelle accumulation varied from bundle to bundle, involvement of individual axons was diffuse across the extent of a specific axon bundle. This observation contradicts the apparent association of axonal transport block with crosswise-oriented trabecular beams at the level of the lamina cribrosa as seen in tissue specimens examined in longitudinal section. It also fails to support the notion that blocked axonal transport with elevated pressure is produced by kinking of axons at the lamina.

Animals↗
PubMed1998

Unidirectional axonal transport in in vitro adult rat brain explants.

The present study examined the properties of anterograde and retrograde transport in central axonal pathways maintained in vitro. The commonly-used tracers biocytin, dextran rhodamine B, FluoroGold, True Blue or rhodamine latex microspheres were injected into the medial geniculate body or the inferior colliculus of the adult rat brain explant. Injection of biocytin into the inferior colliculus consistently resulted in extensive anterograde labelling of axonal trunks and terminals in the ipsilateral medial geniculate body and in the contralateral inferior colliculus. Labelled axons were obtained 2-3 h after the injection at a site 3-4 mm away from the injection site and could be found up to 1.5 mm below the explant surface. Despite massive anterograde labelling with biocytin, all the tracers applied in the gray or white matter failed to show retrograde transport. These results suggest that axonal transport can occur in an anterograde-selective fashion in adult brain explants in vitro.

Animals↗
PubMed1993

The fast axonal transport in hippocampal neurones is acutely enhanced by db-cAMP.

It has been observed that neurones have a certain capacity for the upregulation of fast axonal transport, for instance during nerve regeneration or reactive sprouting. However, the molecular regulation of this transport system is largely unknown. We show here by quantitative video-microscopy of endogenous organelles that application of 1 mM db-cAMP increases the velocity of fast axonal transport maximally by 32% within 60 minutes in neonatal hippocampal cells. At the same time, the jump length of the saltatory motions remains largely unchanged. The data suggest that activation of protein kinase A plays a role in the immediate upregulation of axonal transport.

Animals↗
PubMed1985

The effect of intraocular injection of tetrodotoxin on fast axonal transport of [3H]proline- and [3H]fucose-labeled materials in the developing rat optic nerve.

The fast axonal transport of [3H]proline-labeled proteins and [3H]fucose-labeled glycoproteins delivered to the dorsal lateral geniculate nucleus in the developing rat optic nerve was investigated during tetrodotoxin-induced monocular impulse blockade. Repeated intraocular injections of various dosages of tetrodotoxin or citrate buffer vehicle were made every two days in rats aged 5-21 days postnatal, and the accumulation of rapidly transported radioactivity in the lateral geniculate nucleus measured between three and twelve hours post-injection at each age. The effectiveness of prolonged tetrodotoxin treatment was monitored by loss of the pupillary light reflex and the level of cytochrome oxidase activity in the contralateral superior colliculus and dorsal lateral geniculate nucleus. Numbers of optic axons proximal to the chiasm and the frequency of retinal ganglion cells per unit distance from the optic disc were examined for signs of tetrodotoxin-induced degeneration of the retinofugal pathway. Tetrodotoxin-treatment reduced the amount of fucosyl glycoproteins, but not proline-labeled proteins, axonally transported to the lateral geniculate nucleus during the first three weeks of postnatal development. Other studies indicated that tetrodotoxin significantly reduced the incorporation of [3H]fucose into retinal proteins indicating that the reduction in transport was probably due to a decrease in precursor incorporation into retinal ganglion cells. Electron microscopy of ganglion cells at 21 days revealed dilated and vacuolated Golgi cisternae associated with tetrodotoxin treatment, suggesting that tetrodotoxin may alter fucose metabolism by secondarily disrupting Golgi organization. Other protein synthetic machinery in these cells, including ribosomes and rough endoplasmic reticulum, appeared normal throughout tetrodotoxin treatment. These data indicate that Na+-dependent optic impulse activity may be indirectly related to the axonal transport of glycoproteins during early postnatal development by mediating the incorporation of precursor into glycoproteins at the Golgi apparatus and their subsequent entrance into the fast transport system.

Animals↗
PubMed1981

Differential effects of cobalt on the initiation of fast axonal transport.

Effects of Co2+ on the fast axonal transport of individual proteins were examined in vitro in bullfrog spinal/sciatic nerves. 35S-methionine-labeled proteins, fast-transported in control and Co2+-treated preparations were separated via two-dimensional gel electrophoresis. While the overall amount of protein transported was reduced, no qualitative differences could be seen when gel fluorographic patterns were compared. Quantitative analyses of the 48 most abundantly transported species revealed two significantly different populations (p less than 0.01) differentially sensitive to Co2+ and distinguishable to a large extent by molecular weight. Those proteins less sensitive to Co2+ ranged from approximately 20,000 to 35,000 daltons while those more sensitive to Co2+ were greater than approximately 35,000 daltons. The finding that all proteins are affected by Co2+ supports the proposal that fast-transported proteins are subject to a common Co2+-sensitive, Ca2+-requiring step. The observed differential effects are consistent with more than one Ca2+-dependent step occurring during the initiation phase of fast transport.

Animals↗
PubMed1998

Axonal transport of herpes simplex virus-1 in an in vitro model based on the isolated sciatic nerve of the frog Rana ridibunda.

An in vitro model for the study of the axonal transport of herpes simplex virus-1 (HSV-1) in the nerve fibres of the sciatic nerve of the frog Rana ridibunda, has been developed. The nerve was placed along a three-chambered bath consisting of three isolated chambers arranged in series: the stimulating, perfusion and recording chambers. The HSV-1 inoculum was placed in the stimulating chamber, where the proximal part of the isolated sciatic nerve was immersed. HSV-1 was detected after 24-36 h in the recording chamber, where the distal part of the nerve was immersed in Dulbecco's Modified Eagle Medium (DMEM), indicating an axonal transport speed of 46-60 mm/day. The evoked maximum compound action potentials generated in the stimulating chamber was monitored continuously in the recording chamber as an indication of the viability of the nerve during axonal transport. The in vitro method presented here is a useful tool for the pharmacological study of various parameters, e.g. drugs diluted in the perfusion chamber, ionising radiation and temperature, which may affect the axonal transport or other properties of HSV-1.

Animals↗
PubMed1981

Reversal of axonal transport: similarity of proteins transported in anterograde and retrograde directions.

Reversal of axonal transport of endogenous labeled protein was studied in intact and injured nerve axons. Nerve crushes were used to collect labeled protein transported in anterograde and retrograde directions in rat sciatic nerve motoneuron axons after administration of L-[35S]methionine to the vicinity of the cell bodies. The collected proteins were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis and subsequent fluorography. In injured nerves, where the nerves were ligated distally at the time of precursor injection, the polypeptide composition of proteins moving in anterograde and retrograde directions, 9-11 h after precursor injection, was identical, indicating that reversal at a ligature is a nonselective process. In intact nerves, protein moving in the anterograde direction 22-24 h after injection was different from that found 9-11 h after injection, and was also different from protein moving in the retrograde direction 22-24 h after injection. However, protein moving in the retrograde direction 22-24 h after injection was similar to protein moving in the anterograde direction 9-11 h after injection. Thus it appears that the same group of proteins originally transported into the axon are later returned toward the cell body. In intact axons, also, reversal was nonselective, except that one major labeled polypeptide was reduced in amount in the protein moving in the retrograde direction.

Animals↗
PubMed1986

Inhibition of axonal transport 'in vivo' by a tubulin-specific antibody.

We have used antibodies against the major proteins of the cytoskeleton-tubulin, the neurofilament triplet proteins and actin-as in vivo probes to determine the contribution of separate components of the cytoskeleton in axonal transport. The injection of either Fast Blue or wheat germ agglutinin conjugated horseradish peroxidase into the caudate nucleus of adult rats resulted in the retrograde transport of these tracers to the neuronal cell bodies in the substantia nigra pars compacta. In experimental animals these tracer injections were immediately preceded by injections of antiserum against tubulin, neurofilament triplet protein or actin, into multiple sites in the caudate. Preimmune serum injection preceded tracer injection as a control in the contralateral caudate of the same animal. One antiserum against electrophoretically purified pig brain tubulin (NS-20) produced a dramatic decrease in the normal retrograde and anterograde transport of both tracers to the SN. Other antisera against tubulin, as well as neurofilament and actin antisera, had no effect on the axonal transport of the tracers. Affinity purified antibodies prepared from the NS-20 antitubulin serum also blocked axonal transport of the tracers. These results provide further support for a critical role of microtubules in axonal transport in vivo. Moreover, an antigenic determinant on tubulin that is uniquely recognized by the NS-20 antibodies may provide us with a way to define the site of association of transfer vesicles with microtubules.

Actins↗
PubMed1980

Influence of ischemia on retrograde axonal transport in the posterior column fibers of the dog.

The retrograde axonal transport rate in the posterior spinal root was studied by means of the horseradish peroxidase injection in the control dogs and the dogs with the ischemia induced by the lumbal aorta ligature. As the results show, the increase in the retrograde axonal transport rate after 4 h ischemia occured from 141 +/- 6 mm/24 h to 270 +/- 31 mm/24 h. The retrograde transport rate after 7 d ischemia being 137 +/- 7 mm/24h reaches approximately the control values.

Animals↗
PubMed1991

Immunocytochemical evidence for retrograde axonal transport of exogenous albumin in adult rat brain stem motor neurons.

Serum albumin is present in cranial nerve motor neurons in the brain. This is suggested to be due to uptake into peripheral axon terminals with subsequent retrograde axonal transport to the perikarya of the motor nuclei. Indirect evidence for uptake and retrograde axonal transport of albumin in a cranial nerve has been presented previously e.g. by demonstration of fluorescence of the albumin-bound dye Evans blue in the neurons of the hypoglossal nucleus subsequent to injection in the tongue. In this study we present direct evidence for retrograde axonal transport of albumin. Human albumin was injected into the tongue of adult rats, and immunocytochemically detected with an antibody, which selectively reacted with human albumin. In brains processed 24 hours or later after injection, a positive reaction was seen in the neurons of the hypoglossal nucleus. The immunoreaction product was localized as perinuclear granules in an otherwise unstained perikaryon probably associated with the endosomal-lysosomal system. Thus, albumin present in hypoglossal motor neurons appears to originate from uptake in peripheral axon terminals. Judging from the early appearance after injection, this transport probably occurs by a fast component of retrograde axonal transport.

Animals↗
PubMed1984

Orthograde and retrograde axonal transport of calmodulin in a cat noradrenergic neurone.

Subcellular distribution studies of calmodulin in cat sympathetic ganglia demonstrated that about 90% of the protein remained in the 27,000 g supernatant, suggesting that it is a cytosolic protein. Only 4.5% was recovered in the microsomal fraction pellet. The inferior mesenteric ganglia contained 93.3 +/- 3 ng calmodulin per ganglion, and segments of unligated cat hypogastric nerves had 6.53 +/- 0.32 ng per 5 mm segment. When the nerve was ligated in the middle and left in the cat for 1-6 days, substantial amounts of calmodulin accumulated in segments of nerve immediately proximal (P1) and distal (D1) to the ligature. The amounts found in P1 amounted to 15.3, 20, 30.4 and 39.4 ng calmodulin per 5 mm segment 1, 2, 3 and 6 days after ligation, respectively. The average rate of transport was 5.5 mm per day, which corresponds to a slow component b of axonal transport (SCb). The accumulation of calmodulin in D1 was also increased with the time of ligation. After 1, 2, 3 and 6 days, the amounts of the protein found in D1 were 14.4, 17.7, 19 and 21 ng per 5 mm segment, respectively. The calculated mean rate for the retrograde transport was 3.9 mm per day. Decentralization of the inferior mesenteric ganglia did not affect the rate of accumulation of calmodulin or the basal amounts found in ganglia and nerves. Local injection inhibited the orthograde, but not the retrograde axonal transport of the protein. It is concluded that calmodulin undergoes a process of slow orthograde axonal transport probably incorporated into the axoplasmic matrix of a network of actin microfilaments. The protein is also transported in a retrograde manner.

Animals↗
PubMed2000

Anterograde axonal transport of Boc-Arg-Val-Arg-Arg-MCA hydrolyzing enzyme in rat sciatic nerves: cleavage occurs between basic residues.

Axonal transport of Boc-Arg-Val-Arg-Arg-MCA hydrolyzing enzyme activity was studied in rat sciatic nerves from 12 to 120 h after double ligations. The anterograde axonal transport increased and peaked 72 h after ligation. The optimum pH for Boc-Arg-Val-Arg-Arg-MCA hydrolyzing enzyme activity was 6.5 to 6.9 and did not require Ca(2+) for the activity. Two molecular forms with enzyme activity were identified by size-exclusion chromatography and the molecular masses of the two enzymes were estimated to be 98 and 52 kDa. Two enzyme activities were strongly inhibited by Hg(2+), Cu(2+) and trypsin inhibitors such as TLCK, antipain and leupeptin. It cleaved the substrate, Boc-Arg-Val-Arg-Arg-MCA, between the dibasic sequence Arg-Arg, and needed a support of aminopeptidase B-like enzyme activity for the liberation of 7-amino-4-methylcoumarin. These results suggest that the enzyme is transported in rat sciatic nerves and involved in the post-translational processing of precursor proteins under the anterograde axonal transport. But there is absolutely no evidence for a role in precursor processing and such a putative role is purely speculative.

Animals↗
PubMed1985

Body temperature-dependent and independent actions of chlordimeform on visual evoked potentials and axonal transport in optic system of rat.

Pattern-reversal-evoked potentials (PREPs), flash-evoked potentials (FEPs), rapid axonal transport in the optic system and body temperature were measured in hooded rats, treated with either saline or the formamidine insecticide/acaricide, chlordimeform (CDM). Rats receiving chlordimeform had low body temperatures when housed at standard laboratory room temperature, 22 degrees C, but not at 30 degrees C. Peak latencies of flash-evoked potentials were prolonged by chlordimeform at 22 degrees C, but not at 30 degrees C. The rate of axonal transport was slowed in chlordimeform-treated hypothermic rats, but not in chlordimeform-treated warmed rats. These findings suggest that the flash-evoked potential and axonal transport changes produced by chlordimeform were an indirect consequence of hypothermia. In contrast, chlordimeform increased pattern-reversal evoked potential peak latencies and peak-to-peak amplitudes independent of body temperature. These findings confirm and extend previous reports of chlordimeform-induced hypothermia, emphasize the importance of changes in body temperature as a possible confounding factor in studies of neuroactive agents and demonstrate that chlordimeform has both body-temperature-dependent and independent actions in the visual system in the rat.

Amidines↗
PubMed1978

Effect of ischemia on axonal transport of choline acetyltransferase and acetylcholinesterase and on ultrastructural changes of isolated segments of rabbit nerves in situ.

Axonal transport of acetylcholinesterase (AChE) and choline acetyltransferase (ChAc) and ultrastructural degenerative changes were compared in isolated nerve segments of rabbit peroneal nerves kept in vivo for 22 h, either with preserved blood supply (control segments) or under conditions of ischemia (ischemic segments). Ischemia abolished the proximo-distal and disto-proximal axonal transport of AChE and the proximo-distal transport of ChAc which, in control segments, were revealed by accumulations of the enzymes at corresponding ends of the segments. Total activities of AChE and ChAc recovered in isolated segments with intact blood supply corresponded to the activities in normal nerves; in ischemic segments, 50% of ChAc activity was lost in 22 h, whereas all AChE activity was preserved. Ultrastructural changes were found in few fibres in control segments and in many fibres in ischemic segments 22 h after nerve interruption. The early changes in control segments correspond to those described in the literature for peripheral stump of severed nerves. The microtubules, neurofilaments and mitochondria were not affected. In ischemic segments, various stages of axoplasmic disintegration occurred in the myelinated and unmyelinated axons:flocculation and clumping of axoplasmic material, decomposition of neurofilaments and microtubules, swelling, formation of amorphous densities and breakdown of mitochondrial cristae. Swelling, amorphous densities, clumping of nuclear chromatin and necrotic mitochondrial changes appeared also in Schwann cells. It is concluded that ischemia blocks axonal transport and brings about, within 22 h, ultrastructural changes both in nerve fibres and in Schwann cells. Cytoplasmic ChAc is affected earlier by necrotic degeneration of the axons than membrane-bound AChE.

Acetylcholinesterase↗
PubMed1986

Effects of systemic methyl mercury-adulterated water consumption on fast axonal transport in the rat visual system.

The present study was designed in an effort to determine whether changes in fast axonal transport in the mature rat visual system can be directly correlated with the onset of neurological dysfunction. Methyl mercury was administered in the drinking water at a concentration of 54 micrograms Hg/ml. Fast axonal transport of proteins in the optic nerve and tract was quantified by scintillation spectrometry of protein-bound radioactivity along the visual pathway after an intraocular injection of 3H-proline. At 8 hours after injection the labeled protein had reached the lateral geniculate body both in controls and treated animals. However, two-way analysis of variance revealed a significant decrease in the volume of transported protein-bound radioactivity along the visual pathway. Thus, while the rate of fast axonal transport does not seem to be correlated with the onset of motor dysfunction, the onset of neurological symptoms may be associated with abnormal transport capacity. Treatment lowered body weight to the same extent in males and females. Hind limb cross-over occurred after 25.6 +/- 0.8 days and was followed quickly by hind limb paralysis (32 +/- 0.6 days). The cerebellum revealed pyknotic nuclei throughout the internal granular layer. Purkinje cells appeared normal. No pathological changes were noted in the kidneys.

Animals↗
PubMed2002

Neuropeptide Y inhibits axonal transport of particles in neurites of cultured adult mouse dorsal root ganglion cells.

Neuropeptide Y (NPY) plays a modulatory role in processing nociceptive information. The present study investigated the effects of NPY on axonal transport of particles in neurites of cultured adult dorsal root ganglion (DRG) cells using video-enhanced microscopy. Application of NPY decreased the number of particles transported in both the anterograde and retrograde directions. This effect was persistently observed during NPY application and was reversed after washout. The inhibitory effect of NPY was concentration dependent between 10(-9) M and 10(-6) M. The instantaneous velocity of individual particles moving in anterograde and retrograde directions was also reduced by NPY. Both the NPY Y1 receptor agonist [Leu31,Pro34]-NPY and NPY Y2 receptor agonist NPY(13-36) mimicked the effect of NPY on the number of transported particles. An immunocytochemical study using an antiserum against the NPY Y1 receptor protein revealed that the Y1 receptor was expressed in the majority (85.9 %) of cultured adult mouse DRG cells. Pre-treatment of cells with pertussis toxin, a GTP-binding protein (G protein) inhibitor, completely blocked the inhibitory effect of NPY. Each application of SQ-22536, an adenylate cyclase inhibitor, and H-89, a protein kinase A inhibitor, mimicked and occluded the effect of NPY. In contrast, dibutyryl cAMP (dbcAMP), a membrane permeable cAMP analogue, and forskolin, an activator of adenylate cyclase, produced a transient increase in axonal transport. The application of dbcAMP and forskolin in combination with NPY negated the effect of NPY alone. These results suggest that NPY, acting at Y1 and Y2 receptors, inhibits axonal transport of particles in sensory neurones. The effect seems to be mediated by a pertussis toxin-sensitive G protein, adenylate cyclase, and protein kinase A pathway. Therefore, NPY may be a modulatory factor for axonal transport in sensory neurones.

Age Factors↗
PubMed1989

Axonal transport of a clathrin uncoating ATPase (HSC70): a role for HSC70 in the modulation of coated vesicle assembly in vivo.

Clathrin plays an important role in many cellular processes, including endocytosis, secretion, and sorting of membranous organelles. Both the neuronal cell body and presynaptic terminals contain numerous coated vesicles, but few are detectable in the axonal regions that connect these two regions of the neuron. Clathrin heavy chains, light chains, and assembly proteins have all been shown to be axonally transported as part of slow component b (SCb). However, the paucity of coated vesicles present in the axon indicates the existence of a mechanism regulating clathrin coated assembly in vivo. A clathrin uncoating ATPase has been described that binds in stoichiometric amounts to clathrin and dissociates clathrin coats from vesicles in the presence of ATP in vitro. This clathrin uncoating ATPase is a major cytosolic protein of Mr 70 kD in bovine brain, forming 1% of soluble brain protein, and appears to be homologous with a constitutively expressed 70 kd heat shock protein (HSC70). We report here that a major 70 kD protein present in the SCb rate component of axonal transport is identical with HSC70 by both biochemical and immunochemical criteria. The cotransport of HSC70 with clathrin in SCb of axonal transport is consistent with a role for HSC70 in vivo in the regulation of clathrin function during axonal transport.

Adenosine Triphosphatases↗