TRANSPORT OF NORADRENALINE IN SYMPATHETIC NERVES AND THE EFFECT OF NERVE IMPULSES ON ITS CONTRIBUTION TO TRANSMITTER STORES

Abstract— —A study has been made of the contribution of noradrenaline transport along sympathetic nerves to their terminal stores of transmitter by ligating the splenic nerves of the cat, and measuring both the noradrenaline that accumulates above the constriction, and the noradrenaline content of the spleen. The biochemical estimations were supplemented by fluorescence histochemistry. The effect of abolishing efferent impulses in the splenic nerves was examined by cutting their preganglionic nerve supply.
The proximo-distal flow rate for noradrenaline was calculated as 1.4-3.3 mm/hr assuming that all the noradrenaline that accumulates is derived from the cell bodies in the ganglion without net addition or loss in the axons. The process was not dependent on impulse traffic in the nerves, since decentralization did not significantly effect the accumulation. The amount of noradrenaline arrested by the constriction in 24 hr was only 1 per cent of the stores in the terminals of those nerves, and consequently no change was detected in the spleen's noradrenaline content as a result of constricting its nerve supply.
In the presence of an intact reflex pathway to the spleen, the stress of the operative procedure produced a marked constriction of the spleen, and depletion of its noradrenaline content. These changes could be prevented either by section of the preganglionic splanchnic nerves, or by ligation of the splenic nerves, thereby blocking the conduction of efferent nerve impulses.
The evidence favours a proximo-distal flow of noradrenaline in sympathetic nerves, independent of nerve impulses, which makes, however, a negligible quantitative contribution to the terminal stores of transmitter.     

DO MELANOPHORE NERVES SHOW ANTIDROMIC RESPONSES?

1. In Fundulus heteroclitus the dispersing melanophore nerve fibers have a relatively high threshold for faradic stimulation and a low one for stimulation by cutting. When they are protected from the competing action of the concentrating fibers, they show through the responses of their melanophores well marked antidromic activities which can also be seen to a slight degree even where the concentrating fibers are active. 2. The concentrating melanophore nerve fibers in this fish have a relatively low threshold for faradic stimulation and a high one for stimulation by cutting. They also exhibit clear antidromic responses as shown by their associated melanophores.     

The central consequences of the application of capsaicin to one peripheral nerve in adult rat

This paper reviews the central consequences of local application of capsaicin to one nerve in adult animals. 1) Marked chemical changes occur in the central terminals of C fibres. These include depletion of the enzyme FRAP and the peptides SP, CCK, somatostatin, CGRP and an increase of VIP. Maximal depletions occur if the nerve is soaked with capsaicin solutions with a concentration higher than 3 mM. The depletion begins by 7 days and is complete by 11. Recovery begins at about 110 days and is largely complete by 200. Our studies have concentrated on the effects of 40 mM capsaicin examined 14 days after the application. 2) Capsaicin treatment of a peripheral nerve decreased the ability of C fibres in that nerve to excite or to inhibit spinal cord cells. It produces a marked expansion of receptive fields of some cells in the dorsal horn which respond to A fibre stimulation. It is proposed that this change is not due to anatomical changes but to disinhibition. A further example of receptive field expansion is seen after treatment of the mouse infraorbital nerve which defocuses the normally precise projection of individual whiskers onto single cells in the barrel field of the somatosensory cortex. 3) Behavioural consequences follow the treatment of one adult nerve with capsaicin. In the area subserved by the treated nerve, there is a raised threshold to response to chemical and thermal stimuli, no change in the response to mechanical stimuli and an increase of autotomy following nerve section. 4) The aim of the experiments was to determine the role of C fibres in producing the changes seen in spinal cord following peripheral nerve section. Capsaicin treatment of nerve imitates the central effect of complete nerve section in certain important ways. Both result in a marked expansion of the receptive field of some cells. The effect is produced by a change of chemical transport. The results show that C fibres influence the connection of A fibres onto spinal cord cells.     

Fine structure of nerve-melanophore contacts in the angelfish Pterophyllum scalare

Contacts between small unmyelinated nerve fibres and dermal melanophores of the angelfish, Pterophyllum scalare, exhibit several features characteristic of synapses, including small synaptic vesicles and dense core vesicles, a narrow synaptic cleft, electron-dense material at the postsynaptic membrane (cell membrane of the melanophore) and, occasionally, presynaptic densities. An analysis of serial thin sections shows that the synapses described here represent varicosities of an otherwise more or less straight nerve fibre. A single axon thereby may form several en passant synapses with a single melanophore. It is suggested that the synaptic contacts described here not only represent sites of transmitter release but also play a role as sites of firm attachment between nerves and melanophores which guarantee a stable arrangement of nerve fibres and melanophores.Supported by the Deutsche Forschungsgemeinschaft     

Tris buffer effects on melanophore aggregating responses

The adverse effects of tris (hydroxymethyl)-aminomethane (Tris) are for the first time reported on melanophore responses to agonists and potassium chloride. Melanophore responses in Tris- or bicarbonate-buffered solutions were compared. In the presence of Tris, the cumulative dose-response curve to norepinephrine was significantly shifted to the left, whereas methoxamine dose-response curves were similar in both buffers. The percentage aggregation in response to synthetic MCH (melanin concentrating hormone) was not affected by Tris in the bathing medium. The cumulative dose-response curve to potassium chloride was leftward shifted (one log case) in Tris-buffered solution. These results suggest that in fish melanophore preparations Tris might exert its actions on the presynaptic membrane and/or on the synaptic cleft enzyme COMT, drawing on a greater availability of neurotransmitters at the melanophore membrane receptors.     

Absence of 'superfast' axonal transport in rat sciatic nerve.

Axonal transport of labelled protein was studied in rat sciatic nerve by analyzing nerve segments at intervals after injection of L-[3H]leucine into the lumbar spinal cord. Some nerves were sectioned before injection so that material in transit accumulated proximal to the section. The segments distal to the section served as controls for incorporation into the nerve of blood-borne label. An analysis of TCA-soluble and TCA-insoluble activity in cut and intact nerve segments was also made. No evidence was found for the existence of a 'superfast' component of axonal transport (velocity 2000 mm/day). Results showed that the most rapidly transported protein derived from the neuron soma had a conventional 'fast' velocity of 350-420 mm/day. There was no transport of TCA-soluble material. It is suggested that 'superfast' transport, detected in mice by other investigators, is an artefact resulting from failure to control for incorporation of circulating label into the sciatic nerve.     

Adaptive mechanisms of spinal locomotion in cats

This paper reviews some aspects of locomotor plasticity afterspinalisation and after peripheral nerve lesions. Adult catscan recover spontaneous hindlimb locomotion on a treadmill severaldays or weeks after a complete section of the spinal cord atT13. The kinematics as well as the electromyographic activityare compared in the same animal before and after the spinalsection to highlight the resemblance of locomotor characteristicsin the two conditions. To study further the mechanisms of spinalplasticity potentially underlying such locomotor recovery, wealso summarize the locomotor adaptation of cats submitted tovarious types of peripheral nerve section of either ankle flexoror extensor muscles or after denervation of the hindpaws' cutaneousinputs. It is argued that, even in the spinal state, cats havethe ability to compensate for such lesions of the peripheralnervous system suggesting that the spinal cord has a significantpotential for adaptive plasticity that could be used in rehabilitationstrategies to restore locomotion after spinal cord injury.     

Changes in lectin binding of lumbar dorsal root ganglia neurons and peripheral axons after sciatic and spinal nerve injury in the rat

Summary The effects of chronic lesions of rat lumbar spinal or sciatic nerves on the binding of Glycine max (soybean) agglutinin to galacto-conjugates, in small-and medium-size primary sensory neurons of the L₄ and L₅ dorsal root ganglia, were examined over a 580-day period. Spinal nerve section resulted in a marked decrease in the population of stained neurons within 7 days. However, despite some retrograde morphological changes triggered by axonal injury, the proportion of stained nerve cells was normalized 180 days postoperatively. This temporary decrease in perikaryal lectin reactivity was initially associated with a marked accumulation of stained material in the nerve, proximal and distal to the site of section, with similar accumulations also being noticeable at each level of injury in sciatic nerves subjected to double ligature. This may reflect the presence of glycocompounds linked to the autolysis of nerve fibers during the phase of retrograde dying-back and Wallerian degeneration. At later stages, stained deposits could be seen scattered along central and peripheral axonal processes of the dorsal root ganglion neurons in the vicinity of the cell body. They may indicate a disturbance in the peripheral turnover of glycoproteins in chronically-transected nerves, with piling up of neuronal products. Sciatic nerve injury caused similar but less severe effects which, except for the L₄ ganglion cells, were rapidly reversible.     

The role of calcium in MSH stimulated melanosome dispersion

We have examined the role of the calcium ion in the response of the melanophores of the lizard, Anolis carolinensis to alpha-melanocyte stimulating hormone (alpha-MSH) by a rate method which allows kinetic analysis of melanosome dispersion. Dose-response curves to alpha-MSH were compared in the presence of different calcium concentrations, and Schild regression plots were constructed. An avidly binding analogue of alpha-MSH, Nle4-D-Phe7-alpha-MSH, was used to demonstrate kinetically the involvement of calcium in the melanophore response both for MSH receptor binding and the subsequent transduction of the MSH signal across the melanophore membrane.     

Patterning of the cranial nerves in the chick embryo is dependent on cranial mesoderm and rhombomeric metamerism

The vertebrate peripheral nervous system (PNS) consists of two groups of nerves that have a metamerical series of proximal roots along the body axis: the branchial and spinal nerves. Spinal nerve metamerism is brought about by the presence of somites, while that of the branchial nerves is, in part, intrinsic to rhombomeres, the segmental compartments of the hind-brain. As the distribution pattern of neural crest cells prefigures the morphology of the PNS, we constructed tissue-recombinant chick embryos in order to determine factors that might regulate the crest cell distribution pattern. When the segmental plate was transplanted between the hind-brain and the head mesoderm before crest cell emigration, it developed into ectopic somites that inhibited the dorsolateral migration of crest cells such that formation of the cranial nerve trunks was disturbed. Even so, proximal portions of the nerve roots were intact. An ectopic graft of lateral mesoderm did not inhibit the directional migration of the crest cells, but allowed their ectopic distribution, resulting in the fusion of cranial nerve trunks. When spinal neurectoderm was transplanted into the hind-brain, the graft behaved like an even-numbered rhombomere and caused the fusion of cranial nerve roots. The identity of the spinal neurectoderm was preserved in the ectopic site analyzed by the immunolocalization of Hoxb-5 protein, a spinal cord marker. We conclude that the spatial distribution of cephalic crest cells is regulated by successive processes that act on their proximal and distal distribution. The migratory behavior of crest cells is achieved partly by an embryonic environment that is dependent upon the presence of somitomeres, which do not epithelialize as somites, in the trunk.     

Mechanism of hypothalamic control of cardiac component of sinus nerve reflex.

The modulatory influence of hypothalamic structures on sinus nerve induced bradycardia was investigated in anaesthetized cats. Stimulation of the hypothalamic defence area inhibits the bradycardia produced by sinus nerve stimulation both in intact animals and also in animals with the spinal cord sectioned at C1 or C6. This inhibition was accompanied in the normal animal by an increased sympathetic discharge and by a sustained inspiration or tachypnoea. The same respiratory effects were noted in a spontaneously breathing C6 spinal animal, while an artificially ventilated C1 spinal animal still displayed a powerful central inspiratory drive in its recurrent laryngeal electroneurogram. The presence of central inspiratory activity was found to be an absolute impediment to the development of bradycardia. If this activity was eliminated by simultaneous stimulation of the superior laryngeal nerve, it was possible to obtain bradycardia during combined sinus nerve and hypothalamic defence area stimulation, though this bradycardia was modified by the presence of sympathetic discharge. The level of sympathetic neural discharge affects the magnitude of the bradycardia produced by sinus nerve stimulation. The bradycardia was less with normal or augmented level of sympathetic activity and was greater if this activity was reduced or absent. A lesion just caudal to the mammillary bodies disclosed a tonic hypothalamic influence both on respiration and on sympathetic discharge; stimulation of the sinus nerve produced a much more powerful bradycardia after the lesion. The existence of a respiratory "gate" through which afferent stimuli pass on their way to the nucleus ambiguus, and which can be operated by the hypothalamic defence and depressor areas, is postulated and discussed.     

Survey of Intermediate Filament Proteins in Optic Nerve and Spinal Cord: Evidence for Differential Expression

The distribution of intermediate filament proteins in optic nerve and spinal cord from rat, hamster, goldfish, frog, and newt were analyzed by two-dimensional gel electrophoresis. General as well as specific monoclonal and polyclonal antibodies were reacted against putative intermediate filament proteins. In vitro incubations of excised optic nerve in the presence of [35S]methionine distinguished between neuronal and nonneuronal intermediate filament proteins. The proteins of the intermediate filament complex in the two tissues for rat and hamster were similar. The typical neurofilament triplet and glial fibrillary acidic protein (GFAP) were observed. Vimentin was more concentrated in the optic nerve than in the spinal cord. The goldfish, newt, and frog contained neurofilament proteins in the 145-150K range and in the 70-85K range. In addition, predominant neurofilament proteins in the 58-62K molecular-weight range were found in all three species. In contrast to mammalian species, the goldfish, newt, and frog displayed extensive heterogeneity between optic nerve and spinal cord in the expression of both neuronal and nonneuronal intermediate filament proteins. The distinctive presence of low-molecular-weight intermediate filament proteins and their high concentration in the optic nerve and spinal cord of these nonmammalian vertebrates is discussed in terms of neuronal development and regeneration.     

Effects of peripheral inputs from hindlimb on the monosynaptic reflex of motoneurons innervating tail muscles.

The effects of group II muscle (PBSt, GS) and cutaneous afferent (Sur, SPc, Tib) inputs from the hindlimb on the monosynaptic reflexes of motoneurons innervating tail muscles were studied in lower spinalized cats. Stimulation of the cutaneous nerves at the conditioning-test stimulus interval of about 10-20 ms facilitated and inhibited the monosynaptic reflexes of ipsilateral and contralateral tail muscles, respectively. The effects of the muscle nerve stimulation were not so prominent as those elicited by cutaneous nerve stimulation. The monosynaptic reflex was also inhibited by muscle nerve stimulation at 10-50 ms intervals. The effects of conditioning stimulation of the hindlimb peripheral nerves at short intervals were depressed or blocked by section of the ipsilateral lateral funiculus at S1 spinal segment. These findings show that the neuronal pathway from hindlimb afferents to tail muscle motoneurons passed the lateral funiculus of the spinal cord and modulates the motoneuronal activity of tail muscles.     

电刺激兔肾脏传入神经对血压,心率及加压素释放的影响

本工作以兔为实验对象,观察电刺激肾脏传入神经（ＡＲＮ）对血压、心率、颈交感神经放电、以及加压素（ＡＶＰ）合成和释放的影响,并对ＡＲＮ进入中枢的通路作了观察。结果显示,电刺激ＡＲＮ可以引起血压下降、心率减慢、颈交感神经放电抑制等反应,ＡＲＮ的兴奋还可使下丘脑的视上核、室旁核中的ＡＶＰ含量增加,垂体中ＡＶＰ含量下降,血浆ＡＶＰ水平升高。硝普钠的降压实验和静脉注射ＡＶＰ受体阻断剂ＡＶＰａ的实验均证实了Ａ     

Pigment cell mechanism of postembryonic stripe pattern formation in the Japanese four‐lined snake

Postembryonic changes in the dermal and epidermal pigment cell architecture of the striped and nonstriped morph of the Japanese four‐lined snake Elaphe quadrivirgata were examined to reveal stripe pattern formation after hatching. The striped and nonstriped morphs were distinguishable at the hatching, suggesting that the basis of stripe pattern was formed during embryonic development. In the striped morph, the color of stripes changed from red‐brown in juveniles to vivid dark‐brown in adults, and density of dermal melanophore increased much more in the stripe than background dorsal scales with growth. This increase in density of dermal melanophore was accompanied not only by the increased epidermal melanophore density but also by the change in vertical structures of dermal melanophore. By contrast, the density of epidermal and dermal melanophore evenly increased over the dorsal scales in the nonstriped morph. Thus, the increased vividness of the stripe pattern after hatching is achieved through localized increase of melanophore density particularly in the stripe region but not over the whole dorsal scales. J. Morphol. 277:196–203, 2016. © 2015 Wiley Periodicals, Inc.     

Immunofluorescence and Histochemical Methods for Neural M1 Pyruvate Kinase Localization

Abstract: The distribution of pyruvate kinase (ATP pyruvate phosphotransferase, EC 2.7.1.40) in the nervous system has been studied by both immunofluorescence and a histochemical procedure using nitro blue tetrazolium. The localization in various parts of rat central nervous system in situ , cerebellar and cerebral cortex, was compared to that found in vitro in cultures of cerebellum, spinal ganglia, cerebral astrocytes, and skin fibroblasts. (1) Pyruvate kinase was found predominantly in the cytoplasm of neuronal cell bodies. (2) Large neurons were better visualized than small ones. (3) No glial localization was clearly demonstrated in situ , although this does not rule out the presence of some M₁ pyruvate kinase. (4) Regions expected to be rich in nerve terminals, such as the cerebellar glomeruli or the cerebellar molecular layer, showed intense staining even when the cell bodies themselves were negative. This was expected, owing to the previous demonstration of the presence of M₁ pyruvate kinase in nerve ending by subcellular fractionation methods. (5) The localization was similar in situ and in tissue culture, except that nerve processes were better seen in the latter and astrocytes were sometimes stained in vitro. (6) Variation in intensity of staining was observed in similar cell types in the same section or in the same culture. This could represent different metabolic or functional or maturational states.     

Dosage effects of the white (d) and melanoid (m) genes on pigment pattern in the Mexican axolotl,Ambystoma mexicanum,Shaw

Two unlinked autosomal recessive genes, white (d) and melanoid (m), are known to affect wild-type coloration in the axolotl. The d allele in the homozygous recessive condition reduces the total number of melanophores and restricts their migration to the top of the head and along the spinal column. The m allele in the homozygous recessive condition increases the number of melanophores and effects a more uniform distribution. The action of these genes was further investigated by studying the phenotypes of triploid larvae of known genotype at the d and m loci. Triploidy was induced by heat treating the eggs immediately after oviposition to inhibit the second maturation division. Triploidy was verified by chromosomal counts in epidermal cells of tail-tip preparations. Melanophore distribution and number were recorded at 16 and 30 days after oviposition. Two d alleles in Ddd triploids effect a reduction in melanophore number and their rate of proliferation, but have no effect on melanophore distribution. Two m alleles in Mmm triploids effect an increase in the number of melanophores and their rate of proliferation, but have no effect on their distribution. Therefore, it appears that there are at least two separate physiological actions of gene D and M, one that determines melanophore distribution and another that determines their number and rate of proliferation.     

BDNF 和 IL-1α 免疫组织化学阳性细胞在商城肥鲵脊神经节中的表达

采用了组织学和免疫组织化学的方法对商城肥鲵的脊髓和脊神经节的石蜡切片进行了研究。结果显示,商城肥鲵的脊髓可分为灰质和白质;白质外有3层膜包围,由外向内依次是硬脊膜、蛛网膜和软脊膜。常规染色显示脊神经节位于脊神经后根,外包被膜,呈不规则的卵圆形,神经节内的细胞有两种,一种为节细胞,胞体圆形或者卵圆形,大小不等,根据胞体的大小又可分为大脊神经节细胞和小脊神经节细胞;另一种细胞叫做卫星细胞,包裹在脊神经节细胞的周围。BDNF和IL-1α一抗均显示脊神经节细胞呈阳性,卫星细胞呈阴性,前者大神经节细胞阳性明显强于小神经节细胞,后者两种神经节细胞的阳性强度无显著差异。     

Adaptive changes of locomotion after central and peripheral lesions

This paper reviews findings on the adaptive changes of locomotion in cats after spinal cord or peripheral nerve lesions. From the results obtained after lesions of the ventral/ventrolateral pathways or the dorsal/dorsolateral pathways, we conclude that with extensive but partial spinal lesions, cats can regain voluntary quadrupedal locomotion on a treadmill. Although tract-specific deficits remain after such lesions, intact descending tracts can compensate for the lesioned tracts and access the spinal network to generate voluntary locomotion. Such neuroplasticity of locomotor control mechanisms is also demonstrated after peripheral nerve lesions in cats with intact or lesioned spinal cords. Some models have shown that recovery from such peripheral nerve lesions probably involves changes at the supra spinal and spinal levels. In the case of somesthesic denervation of the hindpaws, we demonstrated that cats with a complete spinal section need some cutaneous inputs to walk with a plantigrade locomotion, and that even in this spinal state, cats can adapt their locomotion to partial cutaneous denervation. Altogether, these results suggest that there is significant plasticity in spinal and supraspinal locomotor controls to justify the beneficial effects of early proactive and sustained locomotor training after central (Rossignol and Barbeau 1995; Barbeau et al. 1998) or peripheral lesions.     

Effects of partial bulbar section on inhibition of jaw-opening reflexes induced by central gray matter stimulation in the cat

The effects of severing the spinal trigeminal tract and its caudal nucleus on high-threshold jaw-opening reflex elicited by tooth pulp stimulation were investigated during experiments on cats under chloralose-Nembutal anesthesia. Low-threshold jaw-opening reflex produced by stimulating the A--infraorbital nerve at an intensity 2–3 thresholds in relation to the most excitable fibers on this nerve was also observed, as well as suppression of these reflexes induced by central gray matter stimulation. It was found that spinal trigeminal tract section produces a 8–52% increase in high-threshold reflex. The amplitude of low-threshold reflex either remained unchanged or showed a slight tendency to rise or fall. Brief stimulation of the central gray matter produced a 100% decrease in high-threshold reflex in intact animals compared with a 40–60% decrease after section of the trigeminal tract. Protracted stimulation of the central gray brought about an 80% decline in high-threshold reflex in intact animals as against 25–30% after section. The degree to which brief stimulation of the central gray produced depression of low-threshold stimulation remained unchanged by trigeminal tract section. Protracted stimulation of the central gray matter brought about a 25–50% reduction in low-threshold reflex in intact animals and a reduction of 75% in three animals and 15–20% in four animals. This implied that the caudal nucleus of the spinal trigeminal tract exerts a more substantial influence on the process of high- than low-threshold reflex inhibition when the central gray matter is stimulated.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 362–368, May–June, 1987.