Direct comparison of the rapid axonal transport of norepinephrine and dopamine-beta-hydroxylase activity

Case Report: Painful Peripheral Neuropathy Following Treatment With Docetaxel for Breast Cancer

Peripheral neuropathy is a common side effect of many chemotherapy agents. As many as 60% of patients receiving taxane therapy report symptoms such as numbness, tingling, burning, pain, and, in severe cases, weakness in a stocking and glove pattern. These symptoms are associated with problems in physical mobility and decreased quality of life, yet few articles in the literature discuss collaborative interdisciplinary assessment and treatment of this population. This article describes the care of a patient with diabetes and docetaxel-induced, painful peripheral neuropathy by a multidisciplinary team of nurses, physicians, and physical therapists. Because nurses are often the first clinicians to recognize symptoms of chemotherapy-induced peripheral neuropathy, they provide the essential coordination of care by appropriate medical and rehabilitative services. This case also raises important questions about the relationship between diabetes mellitus and persistent, painful peripheral neuropathy.

Relationships between the rapid axonal transport of newly synthesized proteins and membranous organelles

Rapid axonal transport is generally viewed as being exactly analogous to the secretory process in nonneuronal cells. The cell biology of rapid axonal transport is reviewed, the central concern being to explore those aspects that do not fit into the general secretory model and which may thus represent specific neuronal adaptations. Particular attention is paid to the relationship between the transport of newly synthesized proteins and of the membranous organelles that act as carriers. Sites in the transport sequence at which the behavior of axonal transport may differ from the secretory model are at the initiation of axonal transport at the trans-side of the Golgi apparatus, within the axon where molecules are deposited from the moving phase to a stationary phase, and at nerve terminals or axonal lesions where transport reversal takes place.

Synapsin I expression in the rat retina during postnatal development

The expression of the synapsin I gene was studied during postnatal development of the rat retina at the mRNA and protein levels. In situ hybridization histochemistry showed that synapsin I mRNA was expressed already in nerve cells in the ganglion cell layer of the neonatal retina, while it appeared in neurons of the inner nuclear layer from postnatal day 4 onward. Maximal expression of synapsin I mRNA was observed at P12 in ganglion cells and in neurons of the inner nuclear layer followed by moderate expression in the adult. At the protein level a shift of synapsin I appearance was observed from cytoplasmic to terminal localization during retinal development by immunohistochemistry. In early stages (P4 and P8), synapsin I was seen in neurons of the ganglion cell layer and in neurons of the developing inner nuclear layer as well as in the developing inner plexiform layer. In the developing outer plexiform layer synapsin I was localized only in horizontal cells and in their processes. Its early appearance at P4 indicated the early maturation of this cell type. A shift and strong increase of labelling to the plexiform layers at P12 indicated the localization of synapsin I in synaptic terminals. The inner plexiform layer exhibited a characteristic stratified pattern. Photoreceptor cells never exhibited synapsin I mRNA or synapsin I protein throughout development.

Storage and fast transport of noradrenaline, dopamine beta-hydroxylase and neuropeptide Y in dog sciatic nerve axons

The axonal transport and subcellular distribution of noradrenaline (NA), dopamine beta-hydroxylase (DBH) and neuropeptide Y (NPY) were determined in dog sciatic nerve using an accumulation technique. The results were compared with those obtained by application of the same procedures and methods on the splenic nerve in the same animal species. Evidence was found for the coexistence of NA and NPY in large dense-cored vesicles in dog sciatic nerve axons. After differential centrifugation and isopyenic sucrose density gradient centrifugation of 24 h ligated sciatic nerve pieces NA and NPY equilibrated around 1M sucrose. The DBH activity was dispersed broadly on the gradient. Subsequently, the accumulation of NA, DBH and NPY was studied in proximal and sital segments of 8, 12 and 24 h dog ligated sciatic nerve and inferences were made concerning the axonal transport of these compounds. NA, DBH and NPY displayed a divergent accumulation proximal to the ligation. After 12 h of ligation a transport rate was calculated of 4.8 +/- 1.8 mm/h for NA, of 5.9 +/- 1.5 mm/h for DBH and of 4.9 +/- 2.0 mm/h for NPY. With a correction for the stationary fractions, a similar fast transport rate of approximately 10 to 12 mm/h was proposed for NA, DBH and NPY. The occurrence was shown of a limited retrograde transport of DBH and possibly NPY, but not of NA.

Partial isolation of two classes of dopamine beta-hydroxylase-containing particles undergoing rapid axonal transport in rat sciatic nerve

The rapid bidirectional transport of dopamine beta-hydroxylase (DBH) in adrenergic axons provides a means of analyzing the life cycle of adrenergic storage vesicles. We compared the physical characteristics of DBH-containing particles traveling to or returning from the terminal varicosities of ligated rat sciatic nerves. Density gradient centrifugation and Sephacryl S1000 gel-permeation chromatography were used to fractionate extracts from nerve segments proximal or distal to the ligatures. A series of experiments indicated the existence of at least two populations of rapidly transported DBH-containing particles, a "light" 85-nm particle and a larger "dense" 120-nm particle. The 85-nm particles were prevalent in unligated nerve, but accounted for only one-third of the total anterogradely transported DBH activity accumulated after 18 h. The 120-nm particles were barely detectable in the unligated nerve, but they accumulated at twice the rate of the 85-nm particles and accounted for the rest of the anterogradely transported particulate DBH activity. These two populations of particles were readily isolated from proximal nerve extracts by sucrose density gradient centrifugation. Similar-appearing dense and light peaks of particulate DBH activity were obtained from distal nerve extracts. Much of the retrogradely transported DBH of the extracts, however, was associated with large particles (greater than 300 nm) not resolved by Sephacryl S1000. Retrogradely transported exogenous NGF was found only in the dense sucrose gradient peak. We propose that the 85-nm DBH-containing particles correspond to "large dense-cored vesicles," and that the 120-nm particles are derived from the dense tubules visualized in adrenergic nerves by the chromaffin reaction.

Translocations of fodrin and its binding proteins

Fodrin, a protein related to erythrocyte spectrin, redistributes within the cell in certain situations. We compare such movements of fodrin and several fodrin binding proteins during the processes of axonal transport in neurons, and capping of surface proteins in lymphocytes. In neurons, three different populations of newly synthesized fodrin appear to be transported down the axons at different velocities corresponding to those of groups of transported proteins designated II, IV, and V. Actin, which can interact with fodrin, is transported at the velocity of group IV. Synapsin, a component of synaptic vesicles, is also reported to bind to fodrin. One population of synapsin is transported more rapidly than fodrin, at the velocity of group I: two additional populations of transported synapsin may overlap fodrin in groups II and IV. We consider possible functional associations of these different populations of fodrin and fodrin binding proteins. We note that the transport of group IV proteins resembles in certain respects the process of capping in lymphocytes, suggesting the possibility of a common mechanism. We outline one of several possible mechanisms.

Axonal transport of synapsin I- and cholinergic synaptic vesicle-like material; further immunohistochemical evidence for transport of axonal cholinergic transmitter vesicles in motor neurons

The axonal transport of organelles in motor axons in the sympathectomized rat sciatic has been studied using two antisera which recognize specific components of synaptic vesicles. Anti-synapsin I recognizes synapsin I (SYN I) which is affiliated with the external membrane of synaptic vesicles, while rabbit-anti-synaptic vesicle antiserum (RASVA) recognizes integral membrane glycoproteins in cholinergic synaptic vesicles. Immunofluorescence studies, including cytofluorimetric scanning, show that immunoreactive (IR) material recognized by both antisera: rapidly accumulate proximal to a crush; the material has a granular appearance in the microscope; is redistributed in an isolated segment, and that the transport of the material is sensitive to vinblastine. Thus the proximodistal transport has the characteristics of fast axonal transport. Furthermore, recycling organelles, accumulating on the distal side of a crush are recognized by RASVA, but carry only very little SYN I-IR. The results give further support to the hypothesis that motor cholinergic axons transport axonal cholinergic vesicles towards the motor endplates.

Characteristics of the axonal transport of vasoactive intestinal polypeptide (VIP) in nerves of the cat

The axonal transport of vasoactive intestinal polypeptide (VIP) was examined in anesthetized cats. The distally directed (anterograde) flux of peptide was found to be about 35 fmol/h in the sciatic nerve. A smaller retrograde flux (8.5 fmol/h) weas also detected. In ulnar, radial and sciatic nerves, the average velocity of transport was calculated to be 2.5 mm/h in the anterograde and 0.6 mm/h in the retrograde direction. Clearance experiments indicated that the amounts of peptide available for transport in these two phases were 28% and 15% of the total, respectively. Estimates of true velocity based on these figures are 9 mm/h for anterograde transport and 4 mm/h for retrograde transport. Local injections of vinblastine were found to induce marked local increases in VIP-immunoreactivity, indicating that microtubules play a role in peptide transport. Subcellular distribution experiments showed that most of the transported VIP was associated with a particulate fraction, possibly corresponding to large vesicles. Only one molecular form of VIP-immuno-reactivity was detected by gel permeation chromatography and no evidence was obtained for cleavage of VIP precursors in the axon. Comparison of axonal flux of peptide with the apparent content of VIP in terminal regions indicated that the turnover time for this peptide is 5 days or longer in the periphery. The results are consistent with the view that peripheral neurons are dependent upon rapid axonal transport for the supply of vip to their terminals.

Axonal transport and subcellular distribution of dopamine-beta-hydroxylase in the cod, Gadus morhua

The axonal transport of dopamine-beta-hydroxylase (DBH; E.C. 1.14.17.1) was studied in the splanchnic nerve of the cod in vivo, and the subcellular localization of the same enzyme was studied in the chromaffin tissue from the cod head kidney. The mean rate of axonal transport for cod DBH was 18.6 mm/24 h at 10 degrees C. The mobile fraction was estimated to 22%, giving an absolute rate of transport of 85 mm/24 h at 10 degrees C. Evidence for a retrograde transport of DBH was also obtained, with an accumulation distal to a ligature of 12% of the accumulation proximal to the ligature at 3 days. DBH from the chromaffin tissue appeared to be strongly bound to the adrenergic granules, with only a small amount (ca 4%) recovered in the soluble phase.

Retrograde axonal transport following injection of [3H]serotonin in the olfactory bulb. I. Biochemical study

A retrograde axonal transport from the serotonergic nerve terminals in the olfactory bulb (OB) to their parent cell bodies in the midbrain raphe nuclei has been demonstrated after stereotaxic injection of [2H]5-HT into the OB of rats pretreated with a monoamine oxidase (MAO) inhibitor: at various time intervals thereafter (4-92 h) there was a preferential accumulation of radioactivity mainly in the raphe dorsalis nucleus (RDN). Maximal accumulation occurred at 24 h. Of this radioactivity, 30-50% was recovered as 5-HT. The accumulation was estimated to take place at two rates: a fast one (48 mm/day) and a slower one (16 mm/day). Under the same experimental conditions there was no clear evidence for a retrograde accumulation of [3H]norepinephrine in the RDN. A passive diffusion mechanism could be excluded since the diffuson of tracer towards the cerebrospinal fluid was prevented by prior mechanical obstruction of the olfactory diverticle of the lateral ventricle. Furthermore, colchicine strongly reduced (by 80%) the radioactive accumulatin in the RDN. Destruction of serotonergic nerve terminals by 5,6-dihydroxytryptamine or inhibiton of 5-HT uptake by fluoxetine decreased this retrograde accumulation whereas destruction of catecholaminergic nerve terminals by 6-hydroxydopamine was without effect. Pretreatment with reserpine decreased the amount of radioactivity transported to the RDN by 40%. In the absence of MAO inhibition pretreatment, animals still presentd 35% of the tracer transported to the RDN. Intrabulbar injection of MAO inhibitor did not affect the accumulation rates when compared with animals which received the inhibitor by the intraperitoneal route. In conclusion, the retrograde axonal transport following [3H]5-HT injection in the serotonergic RDN-OB system occurs via an active process which depends on a colchicine-sensitive mechanism and is partially linked to a reserp ine-sensitive structure. During its transport, the amine seems to be relatively protected from metabolic inactivation.

Axonal transport of proteins. A new view using in vivo covalent labeling

The injection of [2,3-3H]N-succinimidyl propionate ([3H]N-SP) into the rat sciatic nerve was used to covalently label both intra- and extra-axonal proteins. While extra-axonal proteins (e.g., myelin proteins) remained in the injection site, the intra-axonal proteins were transported in both the anterograde and retrograde directions. The mobile labeled proteins appeared to move by normal axonal transport processes because: (a) autoradiographic studies showed that they were localized exclusively within the axon at considerable distances from the injection site, (b) specific and identifiable proteins (by SDS gel electrophoresis) moved at expected rates in the anterograde direction, and (c) an entirely different profile of proteins moved in the anterograde vs. retrograde direction. This novel experimental approach to axonal transport, which is independent of de novo protein synthesis, provided a unique view of slow anterograde transport, and particularly of retrograde transport of endogenous proteins. A large quantity of a 68,000 mol wt proteins, moving at approximately 3-6 mm/day, dominated the retograde transport profile. [3H]N-SP, therefore, represents a new and unique "vital stain" which may find many applications in cell biology.

The use of neurotoxins to characterize the rates and subcellular distributions of axonally transported dopamine-beta-hydroxylase, tyrosine hydroxylase and norepinephrine in the rat brain

The effect of 6-hydroxydopamine (6-OHDA), colchicine and cytochalasin B on the transport and subcellular distribution of proteins, tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and norepinephrine (NE) were studied in the noradrenergic neurons of the rat locus coeruleus (LC). Four waves of transported 3H-labeled proteins and glycoproteins, defined by previous studies, as well as hypothalamic levels of TH, DBH and NE, were examined after injection of each neurotoxin into the ascending dorsal noradrenergic bundle. Blockade of subcellular components of TH, DBH and NE was compared to their endogenous hypothalamic distributions. 6-Hydroxydopamine variably blocked transport of all 4 waves of 3H protein and bilateral injections decreased hypothalamic levels of TH, DBH and NE by 58.2, 56.9 and 52.2% of controls, respectively. Cytochalasin B blocked transport of protein waves I (72--192 mn/day) and III (13--20 mm/day) and decreased hypothalamic levels of TH to 60.1% of control after bilateral injections. Colchicine blocked transport of waves I, II (24--48 mm/day) and V (1.4--2.9 mm/day) and blocked [3H]NE transport, while decreasing hypothalamic levels of DBH and NE to 56.6 and 69.3% of control after bilateral injections. Colchicine and 6-OHDA, but not cytochalasin B, caused a backup of DBH immunofluorescence proximal to the injection site. DBH and NE appeared to be transported primarily in particulate form, while TH transport was predominantly soluble in distribution. None of the toxins differentially affected the transport of one particular subcellular component of TH, DBH or NE. Based on the differential blocking effects of these toxins, DBH and NE appeared to be associated with wave II, and TH with wave III, travelling at 24--48 mm/day and 13--20 mm/day respectively.

Qualitative analysis of proteins rapidly transported in ventral horn motoneurons and bidirectionally from dorsal root ganglia

Two-dimensional electrophoresis has allowed a higher-resolution comparison of rapid transport in ventral horn motoneurons and bidirectionally in dorsal root sensory neurons. Dorsal root ganglia 8 and 9, or hemisected spinal cords, from frog were selectively exposed in vitro to 35S-methionine. Transported, labelled proteins that accumulated in 3 mm segments proximal to ligatures on dorsal roots and spinal nerves or sciatic nerves were subjected to two-dimensional gel electrophoresis. Comparisons were made of fluorographic patterns from dried gels. Sixty-five species of proteins were found to be rapidly transported in both bifurcations of dorsal root sensory neurons. No abundant species of protein was rapidly transported in dorsal roots that was not also found in spinal nerves. A comparison of proteins rapidly transported in the sciatic nerve from ventral horn motoneurons with those from dorsal root sensory neurons yielded 50 common species of polypeptides. At most four minor species were possibly transported only in ventral horn motoneurons. An overall comparison indicates that at least 45 species of proteins, including all of the more abundantly transported ones, were consistently common to both dorsal root bifuractions and to ventral horn motoneurons. This appears to be the case despite the very different functions carried out by motoneurons and sensory neurons.

A histofluorescence study of events accompanying accumulation and migration of norepinephrine within locally cooled nerves

Glyoxylic acid was used to induce fluorescence in sections of rabbit sciatic nerve. In fresh nerves treated with this agent there were scattered finely beaded axons with a weak blue-green fluorescence. During local cooling, blue-green fluorescence accumulated steadily at the proximal boundary of the cooled region but never at its distal boundary. This accumulation gave rise to dilated axons that often swelled into brilliantly fluorescent balloon-like structures up to 10 microgram in diameter. Axonal fluorescence was probably specific for norepinephrine, being enhanced by inhibition of the metabolism and diminished by inhibition of the synthesis or storage of this neurotransmitter. After local cooling of nerves for 1.5 hr, specific fluorescence was confined within 0.8 mm of the cooled region. Rewarming led to rapid removal of fluorescence from the cooled region and to disappearance of most of the balloon-like swellings. Simultaneously, rewarming caused brightly fluorescent fibers that were neither dilated nor swollen to appear in distal regions of nerve. As this wave of fluorescence migrated distally with increasing duration of rewarming, it was spread over increasingly broad regions of nerve, which suggests that axonal transport of norepinephrine may invole some kind of dispersive process.