Hyperventilation and inhibitory synapses

Summary Injection of a subconvulsive dose of strychnine (which blocked the inhibitory synapses) increases respiratory muscle activity evoked by stimulation of the sciatic nerve as well as by inhalation of hypercapnic gas mixture. Thus the inhibitory synapses prevent an excessive hyperventilation.     

Hyperventilation and inhibitory synapses.

Injection of a subconvulsive dose of strychnine (which blocked the inhibitory synapses) increases respiratory muscle activity evoked by stimulation of a sciatic nerve as well as by inhalation of hypercapnic gas mixture. Thus the inhibitory synapses prevent an excessive hyperventilation.     

The presynaptic cytomatrix of brain synapses

Synapses are principal sites for communication between neurons via chemical messengers called neurotransmitters. Neurotransmitters are released from presynaptic nerve terminals at the active zone, a restricted area of the cell membrane situated exactly opposite to the postsynaptic neurotransmitter reception apparatus. At the active zone neurotransmitter-containing synaptic vesicles (SVs) dock, fuse, release their content and are recycled in a strictly regulated manner. The cytoskeletal matrix at the active zone (CAZ) is thought to play an essential role in the organization of this SV cycle. Several multi-domain cytoskeleton-associated proteins, including RIM, Bassoon, Piccolo/Aczonin and Munc-13, have been identified, which are specifically localized at the active zone and thus are putative molecular components of the CAZ. This review will summarize our present knowledge about the structure and function of these CAZ-specific proteins. Moreover, we will review our present view of how the exocytotic and endocytic machineries at the site of neurotransmitter release are linked to and organized by the presynaptic cytoskeleton. Finally, we will summarize recent progress that has been made in understanding how active zones are assembled during nervous system development.     

Axo-somatic synapses in procerebrum of Gastropoda

Zusammenfassung Es wurde gezeigt, dass im Procerebrum der Gastropoden axosomatische Synapsen von 2 Typen vorkommen. Diese Befunde sind ungewöhnlich, da axosomatische Synapsen in anderen Teilen des Zentralnervensystems nicht existieren.     

Dense-cored vesicles at neuromuscular synapses of arthropods and vertebrates

Résumé Les vésicules synaptiques granulées se trouvent dans les jonctions neuromusculaires de mammifères, des crustacés, et des araignées. On ne connait pas leur fonction.

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Supported by grants from the National Research Council of Canada and the Muscular Dystrophy Association of Canada.     

Localization and stabilization of ionotropic glutamate receptors at synapses

Appropriate targeting and clustering of ionotropic glutamate receptors (iGluRs) is critical for the formation and maintenance of excitatory synapses. Recent studies have demonstrated that the synaptic localization of iGluR subtypes is remarkably heterogeneous and subject to regulation over time scales ranging from minutes to months. These findings, together with the identification of key protein binding partners of iGluRs, have opened a window onto the complex cell biology of iGluR membrane trafficking. In this article, we review recent findings on the cellular and molecular mechanisms involved in localizing iGluRs at synapses and discuss their implications for synaptogenesis and synaptic plasticity.     

Occurrence of synapses in olfactory epithelium of fish

Zusammenfassung Nachweis von Synapsen in der Riechschleimhaut des FischesChanna punctatus, die als Verbindung zwischen primärer und sekundärer Riechzelle aufgefasst werden.

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We wish to thank Dr.Rameshwar Singh, our colleague in this department, for his helpful suggestions.     

Ultrastructure of synapses of the metacestode ofHymenolepis microstoma

Summary The ultrastructure of the synapses of the metacestode ofHymenolepsis microstoma is described. Many features observed are similar to those of many invertebrate and vertebrate synapses where mechanical strength is of importance. These observations indicate an early phylogenetic origin for this type of synapse.This work was supported by a grant from the University of New Brunswick Research Fund.     

Electrotonic synapses in the visceral ganglion of Planorbis

Summary In the visceral ganglion of Planorbis the postsynaptic neurones of the characterized dopamine neurone are connected by non-rectifying electrotonic junctions. The coupling, which is reduced by stimulation of the dopamine neurone and by applied dopamine, may be important in the generation of burst activity. Specialized areas of close apposition of membranes in the neuropile are considered to be the morphological correlate of electrotonic coupling.This work was supported by grants from the S. R. C. and M. R. C. to Dr G. A. Cottrell, whose help is gratefully acknowledged.     

Ultrastructure of spinal cord synapses during strychnine intoxication

Riassunto Gli autori studiando la ultrastruttura delle sinapsi del midollo spinale durante intossicazione stricnina non trovano nessuna differenza nei componenti sinaptici attribuibile al trattamento stricnico. Rilevano invece variazioni nella morfologia delle vescicole presinaptiche in relazione a differenti fissativi utilizzati.     

Neurexins and neuroligins: synapses look out of the nervous system

The scientific interest in the family of the so-called nervous vascular parallels has been growing steadily for the past 15 years, either by addition of new members to the group or, lately, by deepening the analysis of established concepts and mediators. Proteins governing both neurons and vascular cells are known to be involved in events such as cell fate determination and migration/guidance but not in the last and apparently most complex step of nervous system development, the formation and maturation of synapses. Hence, the recent addition to this family of the specific synaptic proteins, Neurexin and Neuroligin, is a double innovation. The two proteins, which were thought to be “simple” adhesive links between the pre- and post-synaptic sides of chemical synapses, are in fact extremely complex and modulate the most subtle synaptic activities. We will discuss the relevant data and the intriguing challenge of transferring synaptic activities to vascular functions.