摘要:

AbstractA standard optokinetic response of the ipsilateral and contralateral (driven) eyes of the crabLeptograpsus variegatusto a sinusoidally oscillating striped drum was established. Optokinetic responses were then measured of animals that had been treated by introducing serotonin and octopamine into the blood stream via the heart and also into the neural tissue of the optic lobes via a micropipette. Both serotonin and octopamine enhance the optokinetic effect when applied in low doses. Experiments show that serotonin is most likely acting closer to the sensory input in the optokinetic system.

ISSN:0022-3034    

DOI:10.1002/neu.480200802

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe steroid hormone 20‐hydroxyecdysone regulates many aspects of nervous system development in the mothManduca sexta, including stage‐specific neuronal morphology and stage‐specific neuronal death. We have used steroid hormone autoradiography to study the distribution of cells that cocentrate ecdysteroids in the ventral nervous system of this insect. The ligand was [3H]‐ponasterone A, a bioactive phytoecdysone. Tissue was examined from three stages of development: the end of larval life (first day of wandering), the end of metamorphosis (pharate adult), and 4‐day‐old adults. In the abdominal ganglia of wandering larvae and pharate adults, a subset of neurons including both motoneurons and interneurons exhibited a nuclear concentration of radiolabeled hormone. The pattern of binding was reproducible but stage‐specific, with a greater proportion of neurons showing binding in the larvae than in pharate adults. No labeled neurons were found in abdominal ganglia from mature (4‐day‐old) adults. In the case of the pharate adult ganglia, the ecdysteroid receptor content of specific, identified motoneurons was determined. These results are discussed in light of the responses of these neurons to physiological changes in levels of circula

ISSN:0022-3034    

DOI:10.1002/neu.480200803

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe superficial flexor muscles of the crayfish are innervated in a position‐dependent connectivity pattern, which can be reestablished when the nerve to the muscle is cut. This article deals with the regeneration of the largest excitor motoneuron under three different target scenarios: (1) a normal target with all the muscle fibers present, (2) a reduced target lacking the medial or the lateral muscle fiber population, and (3) when the nerve enters the target in the middle of the muscle field. In scenario 1 the neuron is able to regenerate the normal connectivity pattern within 10 weeks after surgery: all the lateral fibers become innervated, with a linear decline in the probability of connections over the medial fibers. The medial fibers become transiently hyperinnervated before the normal pattern of connections is established. In scenario 2 the normal pattern of connections is established only when the lateral fibers were present; with only medial cells as a target, the transient hyperinnervation stage is stable and no decline in connections was observed. Analysis of regenerated junction potential sizes during the stable hyperinnervation stage show abnormal patterns, suggesting that some aspects of the regeneration program of this neuron can be affected when signals from its prime target cells are missing. In scenario 3 growth begins in both directions until the entire muscle becomes innervated. The normal pattern of connectivity finally emerges after continued lateral growth and diminished medial growth, suggesting that the position of the muscle fibers influences connectivity patterns during the final stages of regeneratio

ISSN:0022-3034    

DOI:10.1002/neu.480200804

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe regeneration of neuromuscular connections to the superficial flexor muscle system in the crayfish has been studied under a variety of experimental manipulations. These have provided insight into the factors that can influence the regeneration program of neurons. In this work the regeneration of the largest excitor motoneuron was studied under two different conditions: (1) when the original neuron and a transplanted neuron were growing simultaneously into a denervated target, and (2) when a transplanted neuron was growing into a target that had its original nerve supply intact. In condition 1 both the transplanted and the original neuron formed normal patterns of connectivity and synaptic strength in comparable periods of time. In condition 2 the rate of growth of the transplanted neuron is significantly reduced and does not extend into the lateral fibers of the muscle. It is concluded that the regeneration program of this neuron is not affected by the presence of other neurons growing at the same time into a denervated muscle. Since regeneration is seriously affected if growth occurs into a fully innervated target area, it is suggested that lack of growth stimuli from the target or competitive interactions between established and growing synaptic terminals could influence the regeneration program of this neuron.

ISSN:0022-3034    

DOI:10.1002/neu.480200805

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe constituent elements of the gills ofAplysia kurodaiandA. julianawere examined for the presence of biogenic amines using histochemical, immunocytochemical, and HPLC techniques. Aminergic elements were revealed by glyoxylic acid‐induced fluorescence in the branchial nerve, branchial ganglion, branchial vessels, and pinnules in both species. Three types of fluorescent cells were found in the neural plexus of the gill in each species. Two of them might be sensory neurons. Although HPLC analysis showed the presence of serotonin and dopamine in all gill structures including fluorescent neural elements, there were regional differences in concentrations of the monoamines. It was noted in the pinnules that there was a much higher concentration of dopamine than serotonin. Serotonin immunocytochemistry revealed neural processes which were immunoreactive to antiserotonin antibody, but serotonin immunoreactivity could not be found in a population of branchioganglionic neuron (BGN) somata. Serotonergic elements in the ganglion may be processes of the central ganglion, while dopaminergic elements may be processes of neurons in the neural plexus, located beyond the branchial ganglion. BGNs were activated by bath‐applied dopamine and serotonin. These results suggest that dopaminergic sensory inputs from the neural plexus and serotonergic descending inputs from the abdominal ganglion may be among the inputs received by BGNs.It was found that serotonin depressed excitatory junctional potentials in muscle cells of the efferent branchial vessel, which were induced by an identified neuron of the abdominal ganglion. The aminergic cellular organization of the gill may involve serotonergic presynaptic‐inhibitory fibers arising from the abdominal gan

ISSN:0022-3034    

DOI:10.1002/neu.480200806

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractWhile it is recognized that cAMP is able to regulate distinct cellular processes differentially, the molecular basis for the diversity of its effects remains unclear. Using photoaffinity labeling with32P‐8 azido‐cAMP and two‐dimensional gel analysis, we have identified 26 electrophoretic variants of cAMP‐binding proteins in the six different tissues of the marine molluscAplysia californicasampled. Some of these proteins are found in most tissues, others only in a few; still others appear to be restricted to a single tissue. All of these proteins bind cAMP specifically. The two‐dimensional polyacrylamide gel electrophoretic patterns of binding proteins seen in the different tissues fall into three classes. One pattern is shared by the nervous system and embryos. The second is found in muscular tissues (heart, buccal muscle, siphon, and gill). The third pattern is specific to sperm. The presence of distinct subsets of cAMP‐binding proteins in different tissues suggests that at least some of the diversity in cAMP's regulatory function may result from diversity in the proteins t

ISSN:0022-3034    

DOI:10.1002/neu.480200807

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe ventral giant interneurons (GIs) in the cockroach have two distinct dendritic fields: a small one ipsilateral to the soma, and a larger, contralateral field from which the axon arises. The major input to these GIs is from the cercus on the axon side; when this cercus is ablated in the last instar before the adult stage, input from the other cercus becomes more effective within 30 days (Vardi and Camhi, 1982b). I wished to determine if the input from the intact, soma‐ipsilateral cercus contacted the GIs purely ipsilaterally and if EPSPs at this site were larger in deafferented animals. Consistent with earlier anatomical findings, intracellular recordings from the GI somata showed that the majority of cercal inputs synapse on their own side of the ganglion in normal animals. This was evidenced by differences in the size and shape of the synaptic potentials evoked from the two cerci and by the presence of large EPSPs after a ganglion had been split along the midline. Unitary EPSPs produced by stimulation of single, identified cercal afferents, ipsilateral to the soma, were compared between normal and deafferented animals. Column “h” afferents were chosen because they make a large contribution to the receptive fields of GIs 1 and 2 after ablation of the contralateral cercus. In addition, the arbors of these afferents, when stained with cobalt, did not cross the ganglionic midline in normal animals. Unitary EPSPs recorded in GI 2 were significantly larger in the deafferented animals. There was, however, no significant change in the size of EPSPs in GI 1. Nevertheless, the results from GI 2 suggest that partial deafferentation in the central nervous system can increase the efficacy of synapses distant from the locus of denerv

ISSN:0022-3034    

DOI:10.1002/neu.480200808

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480200801

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY