摘要:

AbstractWe recently presented evidence that distinct morphine and enkephalin receptors coexist in an opioid receptor complex. These studies used membranes prepared from whole rat brain. In this paper the receptor complex is demonstrated to occur in membranes prepared from rat striatum, cortex, and pooled nonstriatal‐noncortical regions of the brain. The observation that morphine masks enkephalin receptors is confirmed using3H‐methionine enkephalin to label the enkephalin receptor. These data further support the hypothesis that populations of morphine and enkephalin receptors coexist in an opioid receptor comp

ISSN:0022-3034    

DOI:10.1002/neu.480140502

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

年代:1983

数据来源: WILEY

摘要:

AbstractExistence of the theoretically predicted spiral waves of excitation in intact two‐dimensional networks of excitable elements has been experimentally confirmed in the isolated chicken retina. The preparation supports the waves of Leão's spreading depression (SD) the concentric propagation of which from the point of origin can be directly observed as a change of the optical properties of the retinal tissue. The propagation rate of 3.7 mm/min (35°C) decreased to 1.5 mm/min for SD waves elicited during relative refractory period. When a several‐mm long segment of the SD wave had been blocked by anodal polarization, the laterally opened ends of the wavefront started to spread after termination of polarization into the previously blocked tissue, gradually turning around and penetrating into the region recovering from the original SD. One or two simultaneously generated spiral waves of SD continued to rotate for several cycles. Spiral SD could also be elicited by punctiform cathodal polarization (1 mA) applied to the SD wave‐rear. Since the new SD wave could only spread into the recovering tissue it formed a laterally open wavefront, the free ends of which eventually turned around and started spiral SD. With continued reverberation the nucleus of the spiral SD wave gradually migrated across the retina until it approached an obstacle (e.g., pecten) which stopped further spiral propagation. Spiral SD waves were elicited in 31 retinal preparations and lasted for 4.5 cycles on the average. Average cycle duration was 4.7 min. Spontaneous spiral SD waves were observed in preparations incubated in Mg2+‐free media. The spiral SD waves in retina are compared with mathematical models of analogous phenomena. It is argued that spiral SD waves probably exist in the cerebral cortex of rats and account for generation of repetitive SD waves sometimes elicited by overlapping stimulation of two cortica

ISSN:0022-3034    

DOI:10.1002/neu.480140503

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

年代:1983

数据来源: WILEY

摘要:

AbstractRepeated tactile stimulation of the skin evoked sensitization and subsequent habituation of a behavioral avoidance reaction of pneumstome closure in the land snail,Helix lucorumL. Spike responses in putative command neurons for avoidance behavior increased and subsequently decreased parallel to behavioral events. Decrease of spike responses in command neurons was due to decreased synaptic input evoked by repeated tactile stimulation. Intracellular investigation of the increase in the spike response in command neurons for pneumostome closure, which underlies behavioral sensitization, revealed a synpatically‐evoked, long‐lasting depolarization. No conductance changes during this depolarization were found, but neuronal excitability was alte

ISSN:0022-3034    

DOI:10.1002/neu.480140504

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

年代:1983

数据来源: WILEY

摘要:

AbstractBecause accurate neuronal dimensions are essential for mathematical modeling of neuronal properties, the effects of a number of salines and fixative procedures on neuronal size were compared, including the non‐chemical, freeze substitution method. Using an identified neuron we compared diameters and found some of the fixative‐saline combinations caused shrinkage by as much as a factor of four from our best estimates of thein vivosize from the quick frozen preparations. A glutaraldehyde based fixation procedure was found which gives results in good agreement with the frozen tis

ISSN:0022-3034    

DOI:10.1002/neu.480140505

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

年代:1983

数据来源: WILEY

摘要:

AbstractPresynaptic and postsynaptic potentials were examined by intracellular recording at a crayfish neuromuscular junction. During normal synaptic transmission, the action potentials were recorded in the terminal region of the excitatory axon and postsynaptic responses were obtained in the muscle fibers. We found that it was possible to modify the synaptic transmission by applying depolarizing or hyperpolarizing currents through the presynaptic intracellular electrode. Typically, a 7 15 mV depolarization lasting longer than 50 msec leads to a large (500%) enhancement of transmitter release, even though the preterminal action potential is reduced in amplitude. Hyperpolarization increases the amplitude of the action potential, but slightly reduces the transmitter release. These results are different from those reported for other neuromuscular synapses and the squid giant synapse, but are similar in many respects to the results reported for several invertebrate central synapses. We conclude, first, that different synapses may have markedly different responses to conditioning by membrane polarization and, secondly, that maintained low‐level depolarization may induce a potentiated state in the nerve terminal, perhaps brought about by slow entry of calciu

ISSN:0022-3034    

DOI:10.1002/neu.480140506

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe effects of c‐AMP, phosphodiesterase inhibitors (caffeine and theophylline) and vinblastine on spontaneous transmitter release was investigated at locust neuromuscular junctions. c‐AMP, theophylline, caffeine, and vinblastine caused facilitation of transmitter release. None of these drugs had any effect on the amplitude of miniature excitatory postsynaptic potentials (min. E.P.S.P.'s), or on the resting membrane potential, but vinblastine increased the proportion of [large] min. E.P.S.P.'s The effect of theophylline (but not c‐AMP and caffeine) on min. E.P.S.P. frequency was found to be calcium dependent. The effects of these drugs on the locust glutamatergic synapse are compared with their actions at other syn

ISSN:0022-3034    

DOI:10.1002/neu.480140507

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe pattern of innervation and motor program of the abdominal superficial flexor muscle was investigated electrophysiologically in larval lobsters (Homarus americanus). The muscle receives both excitatory and inhibitory innervation in the larval as well as in the embryonic stages. Individual muscle fibers receive a single inhibitory neuron (f5) and a maximum of three excitors. Based on spike heights these axons belong to either the small (f1 or f2) or large (f3, f4) motoneurons. While the small axons preferentially innervate the medial muscle fibers the large axons innervate medial as well as lateral fibers. This larval pattern of innervation resembles the pattern in the adult lobster. The resemblance extends to the firing patterns as well with both large and small excitors firing spontaneously. Furthermore, evoked activity in the larvae produces reciprocal (and occasionally cyclical) bursts of excitor and inhibitor neurons denoting abdominal extension and flexion and resembling the firing patterns in adults. Consequently motor programs employed in steering the pelagic larvae are reminiscent of the programs for maintaining posture in the benthic adult lobsters.

ISSN:0022-3034    

DOI:10.1002/neu.480140508

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.480140509

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.480140510

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.480140501

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

年代:1983

数据来源: WILEY