摘要:

AbstractDorsal unpaired median (DUM) cells in orthopteran insects are known to contain the neuromodulatory substance octopamine, and DUM cells with peripheral axons augment synaptic activity at neuromuscular junctions. One of the most studied systems in the cockroach is the giant interneuron (GI) system which controls the initial movements of a wind‐ mediated escape response. Our data demonstrate that DUM cells that are restricted to the central nervous system (DUM interneurons) receive inputs from ventral giant interneurons (vGIs) but not from dorsal giant interneurons (dGIs). In contrast, DUM cells that have peripheral axons consistently fail to be excited by any giant intereurons. The DUM interneurons are excited by vGIs on both sides of the CNS and, when the vGIs are excited in pairs, summation occurs. Wind fields that have been generated for two of the DUM interneurons are omnidirectional. These data, taken along with the known association of DUM cells with the neuromodulatory substance octopamine, suggest that the DUM interneurons may act to modulate central synapse

ISSN:0022-3034    

DOI:10.1002/neu.480190602

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of in vitro exposure of bullfrog spinal nerves to 0.2 mMchlorimipramine on the density of axonal microtubules was studied in an attempt to clarify the mechanism by which chlorimipramine inhibits fast axonal transport. A 17‐ h exposure to chlorimipramine reduced the density of microtubules in unmyelinated axons by only 18%; this microtubular loss does not reach the upper limit of the range of microtubule reduction associated with inhibition of fast axonal transport. A 23‐ h exposure to chlorimipramine, which had decreased microtubular density in unmyelinated axons by 40% in a previous study, did not decrease microtubular density in myelinated axons in the present study. These results rule out microtubular destruction as the mechanism responsible for inhibition of fast orthograde axonal transport by chorimipramine, and greatly reduce the likelihood that microtubular destruction plays a significant role in the inhibition of fast retrograde transport by chlorimipram

ISSN:0022-3034    

DOI:10.1002/neu.480190603

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe enteric nervous system is formed by cells that migrate to the bowel from the neural crest. Previous experiments have established that avian crest cells in vitro will colonize explants of murine bowel and there give rise to neurons. It has been proposed that phenotypic expression by the crest‐ derived precursors of enteric neurons and glia is critically influenced by the microenvironment these cells encounter within the gut. To test this hypothesis, quail crest cells were cocultured with explants of control or presumptive aganglionic bowel from thels/lsmutant mouse, and the effects of the enteric tissue on five phenotypic markers of crest cell development were followed. Aganglionosis develops in the terminal region of the colon of thels/lsmouse because viable crest‐ derived neural and glial precursors fail to colonize this tissue. Expression of the phenotypic markers in the cocultures was compared with that in cultures of crest alone, crest plus neural tube, and gut grown alone. The markers examined were melanogenesis and immunostaining with antisera to 5‐ hydroxytryptamine (5‐ HT) and tyrosine hydroxylase (TH) and the monoclonal antibodies, NC‐ 1 and GlN1. Explants of control, but not presumptive aganglionicls/lsgut were found to increase the incidence of the expression of 5‐ HT and NC‐ 1 immunoreactivities; moreover, especially near the gut, the assumption of a neuronal morphology by 5‐ HT‐, NC‐1‐, and GlN1‐ immunoreactive cells was also increased. Coincidence of expression of 5‐ HT with NC‐ 1 and GlN1 immunoreactivities was observed. The effect of the bowel was selective in that the expression of TH immunoreactivity, which is not a marker of mature enteric neurons, was reduced rather than enhanced. The effect of enteric explants on crest cell development was specific in that it was not mimicked by explants of metanephros, which inhibited expression of 5‐ HT immunoreactivity and the acquisition of a neuritic form by NC‐ 1‐ immunoreactive cells. It is concluded that theenteric microenvironment affects the phenotypic expression of subsets of crest cells and that this action of the bowel.Is manifested in vitro. The inability of presumptive aganglionic gut fromls/lsmice to influence neural phenotypic expression may be due to the failure of this tissue to produce putative factor(s) required for theeffector to the inability of the crest‐ derived precursor cells to migra

ISSN:0022-3034    

DOI:10.1002/neu.480190604

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe have performed surgical transections on nerves in the transforming claws of snapping shrimps. In normal transformation muscle restructuring occurs, involving degeneration of some fibers and biochemical changes in others. Surgical section of the entire second limb nerve root or of its distal, dorsal branch—both of which contain the motor axons to the closer muscle—prevents muscle restructuring, even though transformation of external claw morphology proceeds. Furthermore, nerve lesions must be performed within a specific time period after transformation has been triggered in order for the effects to be observed. We suggest that transformation involves an early sensitization of the targeted muscle and that this process depends upon an intact nervous pathway within the second nerve r

ISSN:0022-3034    

DOI:10.1002/neu.480190605

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn this study we report on morphological and physiological analysis of proprioceptive sensory input to thoracic interneurons. Sensory neurons from leg proprioceptors were filled using cobalt chloride. The morphological location of these sensory neurons was compared with that of the DPG interneurons. The interneurons investigated were found to have morphological overlap with the sensory neurons of the specific proprioceptors, suggesting that they have the potential to receive direct input from these proprioceptors. Individual interneurons were recorded intracellularly and identified by intracellular injection of Lucifer Yellow, and the responses of these cells to mechanical stimulation of specific proprioceptors were analyzed. All of the DPG interneurons tested as well as other interneurons receive input from one or more of these proprioceptors. In addition, DPG interneurons have ipsilateral/contralateral biases in their responses to proprioceptors. Paired stimulation of proprioceptors resulted in enhancement or decrement of the response in the interneurons, depending upon which sensory structures were stimulated together. The results of this study show that proprioceptive information is processed by DPG interneurons.

ISSN:0022-3034    

DOI:10.1002/neu.480190606

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

年代:1988

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480190601

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

年代:1988

数据来源: WILEY