摘要:

AbstractThe players all played at once, without waiting for turns, quarreling all the while and fighting for the hedgehogs; and in a very short time the queen was in a furious passion and went stamping about, and shouting “off with his head” or “off with her head,” about once a minute.Alice began to feel very uneasy: to be sure she had not as yet had any dispute with the queen, but she knew that it might happen any minute, “and then” thought she, “what would become of me? They're dreadfully fond of beheading people here: the great wonder is, that there's any on

ISSN:0022-3034    

DOI:10.1002/neu.480140202

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe possible role of cyclic AMP in mediating opposite modulatory effects of serotonin (5‐HT) onAplysiabuccal mass muscles E1 and E2 was examined. Serotonin enhances E1 contractions and inhibits E2 contractions. Adenylate cyclase in membranes of both E1 and E2 is stimulated approximately 180% by 10−6M5‐HT and 300% by 10−3M5‐HT. Dibutyryl cyclic AMP and 8‐benzylthio cyclic AMP mimicked the effect of 5‐HT on E1 but had no effect on E2. Theophylline (Th) and isobutylmethylxanthine (IBMX) mimicked the effect of 5‐HT on E1 at high concentrations. Concentrations of Th and IBMX low enough not to have any direct effect on contraction increased both the magnitude and duration of the effect of 5‐HT on E1 contraction. Neither Th nor IBMX had a direct effect on E2 contraction, although Th produced a small increase in the effect of 5‐HT on E2. These data are consistent with the hypothesis that cyclic AMP mediates the enhancement effect of 5‐HT on E1 contraction. Other mechanisms probably mediate the effect of 5

ISSN:0022-3034    

DOI:10.1002/neu.480140203

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

年代:1983

数据来源: WILEY

摘要:

AbstractExperiments were done on the inhibitory synapse of crayfish tonic muscle receptor organs (MROs) to determine whether gamma‐aminobutyric acid (GABA) receptors would be affected by denervation or axotomy. It was found that severing the dorsal nerve containing the MRO sensory and inhibitory neurons usually induced, in 30 days or less, a dramatic transformation in the responses of MROs to ionophoretically applied GABA. In contrast to normal MROs which show only inhibitory responses to GABA, transformed MROs were substantially depolarized and excited by GABA application to numerous points found on the axon, soma, and dendrites. Interspersed among the points of excitation, normal inhibitory points could still be found on the transformed cells. The results suggested that chronic lesions can induce structural changes in GABA receptors, whereby the Cl−ionophore is replaced by a cationic channel. It was possible to compare the effects of postsynaptic axotomy alone with those of postsynaptic plus presynaptic axotomy by testing MROs from animals whose ventral nerve cord was sectioned. These experiments suggested that interruption of the presynaptic neuron is an important factor in the transformation. It was not determined whether complete degeneration of the inhibitory synapse is necessary for the transformation, but the rapidity of the effect, coupled with the probability of long‐term survival of synaptic contacts, suggested that complete degeneration was not necessary. Similarities were found in the GABA responses of transformed MROs and those MROs which normally receive no innervation, which are located in the sixth abdominal segment. These results support the idea that trophic regulation from inhibitory neurons is a factor in stabilizing the association of the Cl−ionophore with GABA re

ISSN:0022-3034    

DOI:10.1002/neu.480140204

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

年代:1983

数据来源: WILEY

摘要:

AbstractAxoplasmic transport of free3H‐leucine has been studiedin vivoin the pike olfactory nerve following application of labeled leucine to the olfactory mucosa. A considerable amount of free3H‐leucine is transported at constant velocity along the axon in the form of a distinct peak. The maximum transport velocity for free3H‐leucine is the same as for rapidly transported3H‐protein (130 and 135 mm/day, respectively, at 19°C). Microtubule inhibitors block or significantly reduce the amount of free3H‐leucine transported, but do not influence the transport velocity. Disruption of the oxygen supply abolishes free3H‐leucine transport, so that this phenomenon cannot be explained by diffusion. The amount of free leucine in the rapidly moving peak decreases with time and distance along the axon and is not detectable after 5 h or more. The transported3H‐leucine is not derived from the circulation or from proteolysis of rapidly transported proteins. This study may help to resolve the controversy over the axoplasmic transport of free amino acids since it shows that free3H‐leucine is transported rapidly but does not travel by rapid axoplasmic transport to the end of axons longer

ISSN:0022-3034    

DOI:10.1002/neu.480140205

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

年代:1983

数据来源: WILEY

摘要:

AbstractAttempts were made to identify extraocular photosensitive cells in the subtentacular region (the area between the ocelli and the nerve ring) and around the inner‐nerve ring of the anthomedusanSpirocodon saltatrix. Irradiation with ultraviolet light (UV) led to inhibition of spontaneous impulses and after UV‐off, an afterinhibition which lasted for a few minutes. This afterinhibition was rapidly overcome by exposure to visible light (VIS). UV–VIS antagonism of this type was identified in six different impulse systems monitored in extracellular recordings. Intracellular recordings from two of the six cell types showed that UV irradiation causes hyperpolarization which inhibits spontaneous activity. The other cell types showed no membrane potential changes during UV irradiation even though the cells' spontaneous outputs were inhibited. It was concluded that the photosensitivity lies in three kinds of nerves which are distributed widely through the subtentacular region and the nerve

ISSN:0022-3034    

DOI:10.1002/neu.480140206

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

年代:1983

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480140207

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

年代:1983

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480140208

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

年代:1983

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480140201

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

年代:1983

数据来源: WILEY