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001-es BibID:	BIBFORM029078
Első szerző:	Antal Miklós (orvos, anatómus)
Cím:	The termination pattern and postsynaptic targets of rubrospinal fibers in the rat spinal cord : a light and electron microscopic study / M. Antal, G. N. Sholomenko, A. K. Moschovakis, J. Storm-Mathisen, C. W. Heizmann, W. Hunziker
Dátum:	1992
ISSN:	0021-9967
Megjegyzések:	The spinal course, termination pattern, and postsynaptic targets of the rubrospinal tract, which is known to contribute to the initiation and execution of movements, were studied in the rat at the light and electron microscopic levels by using the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) in combination with calbindin-D28k (CaBP), gamma-aminobutyric acid (GABA), and glycine immunocytochemistry. After injections of PHA-L unilaterally into the red nucleus, labelled fibers and terminals were detected at cervical, thoracic, and lumbar segments of the spinal cord. Most of the descending fibers were located in the dorsolateral funiculus contralateral to the injection site, but axons descending ipsilaterally were also revealed. Rubrospinal axon terminals were predominantly found in laminae V-VI and in the dorsal part of lamina VII at all levels and on both sides of the spinal cord, but stained collaterals were also seen in the ventrolateral aspect of Clark's column and in the ventral regions of lamina VII on both sides. The proportion of axonal varicosities revealed on the ipsilateral side varied at different segments and represented 10-28% of the total number of labelled boutons. Most of the labelled boutons were engaged in synaptic contacts with dendrites. Of the 137 rubrospinal boutons investigated, only 2 were found to establish axosomatic synaptic junctions in the lumbar spinal cord contralateral to the PHA-L injection. With the postembedding immunogold method, 80.8% of dendrites establishing synaptic contacts with rubrospinal terminals did not show immunoreactivity for either GABA or glycine, whereas 19.2% of them were immunoreactive for both amino acids. Rubrospinal axons made multiple contacts with CaBP-immunoreactive neurons in laminae V-VI. Synaptic contacts between rubrospinal terminals and CaBP-immunoreactive dendrites were identified at the electron microscopic level, and all CaBP-containing postsynaptic dendrites investigated were negative for both GABA and glycine. The results suggest that rubrospinal terminals establish synaptic contacts with both excitatory and inhibitory interneurons in the rat spinal cord, and a population of excitatory interneurons receiving monosynaptic rubrospinal input is located in laminae V-VI.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban külföldön készült közlemény
Megjelenés:	Journal of Comparative Neurology. - 325 : 1 (1992), p. 22-37. -
További szerzők:	Sholomenko, Gerald N. Moschovakis, A. K. Storm-Mathisen, John Heizmann, C. W. Hunziker, W
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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001-es BibID:	BIBFORM029077
Első szerző:	O'Donovan, Michael
Cím:	Development of spinal motor networks in the chick embryo / Michael O'Donovan, Evelyne Sernagor, Gerald Sholomenko, Stephen Ho, Miklos Antal, Wayne Yee
Dátum:	1992
Megjegyzések:	We have examined the cellular and synaptic mechanisms underlying the genesis of alternating motor activity in the developing spinal cord of the chick embryo. Experiments were performed on the isolated lumbosacral cord maintained in vitro. Intracellular and whole cell patch clamp recordings obtained from sartorius (primarily a hip flexor) and femorotibialis (a knee extensor) motoneurons showed that both classes of cell are depolarized simultaneously during each cycle of motor activity. Sartorius motoneurons generally fire two bursts/cycle, whereas femorotibialis motoneurons discharge throughout their depolarization, with peak activity between the sartorius bursts. Voltage clamp recordings revealed that inhibitory and excitatory synaptic currents are responsible for the depolarization of sartorius motoneurons, whereas femorotibialis motoneurons are activated principally by excitatory currents. Early in development, the dominant synaptic currents in rhythmically active sartorius motoneurons appear to be inhibitory so that firing is restricted to a single, brief burst at the beginning of each cycle. In E7-E13 embryos, lumbosacral motor activity could be evoked following stimulation in the brainstem, even when the brachial and cervical cord was bathed in a reduced calcium solution to block chemical synaptic transmission. These findings suggest that functional descending connections from the brainstem to the lumbar cord are present by E7, although activation of ascending axons or electrical synapses cannot be eliminated. Ablation, optical, and immunocytochemical experiments were performed to characterize the interneuronal network responsible for the synaptic activation of motoneurons. Ablation experiments were used to show that the essential interneuronal elements required for the rhythmic alternation are in the ventral part of the cord. This observation was supported by real-time Fura-2 imaging of the neuronal calcium transients accompanying motor activity, which revealed that a high proportion of rhythmically active cells are located in the ventrolateral part of the cord and that activity could begin in this region. The fluorescence transients in the majority of neurons, including motoneurons, occurred in phase with ventral root or muscle nerve activity, implying synchronized neuronal action in the rhythm generating network. Immunocytochemical experiments were performed in E14-E16 embryos to localize putative inhibitory interneurons that might be involved in the genesis or patterning of motor activity. The results revealed a pattern similar to that seen in other vertebrates with the dorsal horn containing neurons with γ-aminobutyric acid (GABA)-like immunoreactivity and the ventral and intermediate regions containing neurons with glycine-like immunoreactivity.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban külföldön készült közlemény
Megjelenés:	Journal of Experimental Zoology. - 261 : 3 (1992), p. 261-273. -
További szerzők:	Sernagor, Evelyne Sholomenko, Gerald N. Ho, Stephen Yee, Wayne Antal Miklós (1951-) (orvos, anatómus)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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