Serotonergic modulation of the mudpuppy (Necturus maculatus) locomotor pattern in vitro

Jovanovic, Ksenija; Petrov, Tatjana; Greer, John J.; Stein, Richard B.

doi:10.1007/bf00229556

Cited by 26 publications

(27 citation statements)

References 45 publications

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“…18C,D) suggests that it may be a site for additional synaptic input to MNs, and possibly some INs, either directly or via nonsynaptic release of neurotransmitters. Findings that serotonergic, GABA-ergic, and glycinergic neurons also terminate in this region (Jovanovic et al, 1996 may support this notion. On the other hand, the Necturus spinal cord also contains marginal neurons concentrated near the denticulate ligaments at the lower lateral corner of the cord (see Fig.…”

Section: Subpial Plexusmentioning

confidence: 80%

“…After immersion fixation in 4% paraformaldehyde (PFA) overnight, the spinal cords were cryoprotected in ascending concentrations of sucrose (5-20%) and sectioned horizontally on a freezing microtome. For visualization of biocytin, the tissue was treated with 0.05% diaminobenzidine tetrahydrochloride (DAB) as a chromagen (Jovanovic et al, 1996) Fluorescent markers: preparation for confocal microscopy…”

Section: In Vitro Preparation and Retrograde Labeling Of Spinal Neuronsmentioning

confidence: 99%

“…When pharmacologically activated, the brachial spinal cord, isolated in vitro along with attached limbs, can generate a coordinated rhythmic alternation between antagonistic muscles within each limb and between the opposite limbs, as in intact locomotion Jovanovic et al, 1996Jovanovic et al, , 1999Cheng et al, 1998). Two functional CPG networks, one generating flexion and the other extension of the elbow, can operate independently despite the fact that there are reciprocal inhibitory connections between them (Cheng et al, 1998).…”

mentioning

confidence: 99%

“…Although a considerable amount of data has accumulated during the last decade regarding the locomotor CPG in Necturus (Wheatley et al, , 1994Jovanovic et al, 1996Jovanovic et al, , 1999Cheng et al, 1998Cheng et al, , 2002Jovanovic, 1999;Fok and Stein, 2002), the anatomical organization of the spinal cord segments in which the CPG resides has not been adequately described. With the exception of work on axial motoneurons (Fetcho, 1986) and marginal neurons (Schroeder and Egar, 1990), the available information is scarce and pertains mostly to the early stages of development in related species, including Ambystoma (Coghill, 1913;Herrick, 1948), Salamandra (van Gehuchten, 1897; see also Cajal, 1995, for other references), and Triturus (Blight, 1978;Harper and Roberts, 1993).…”

mentioning

confidence: 99%

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Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Jovanovic

Burke

2004

J of Comparative Neurology

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The isolated brachial spinal cord of Necturus maculosus is useful for studies of neural networks underlying forelimb locomotion, but information about its cellular morphology is scarce. We addressed this issue by using confocal and electron microscopy. Remarkably, the central region of gray matter was aneural and consisted exclusively of a tenuous meshwork of glial fibers and large extracellular spaces. Somata of motoneurons (MNs) and interneurons (INs), labeled by retrograde transport of fluorescent tracers from ventral roots and axons in the ventrolateral funiculus, respectively, were confined within a gray neuropil layer abutting the white matter borders, whereas their dendrites projected widely throughout the white matter. About one-third of labeled INs were found contralaterally, with axons crossing ventral to a thick layer of ependyma surrounding the central canal. Lateral MN dendrites proliferated under the pial surface to form a dense, thin (1-2 m) plexus immediately beneath a thin layer of glial fibrillary acidic protein-positive glia limitans. The latter contained arrays of unusual tubular structures (diameter 200 -400 nm, length 3 m) that resembled mitochondria but lacked double membranes or cristae. Dorsal roots (DRs) produced dense presynaptic arbors within a wedge-shaped afferent termination zone medial to the dorsal root entry, within which dendrites of MNs and INs mingled with dense collections of synaptic boutons. Our data suggest that a major fraction of synaptic interactions takes place within the white matter. This study provides a detailed foundation for designing electrophysiological experiments to study the neural circuits involved in locomotor pattern generation.

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Section: Subpial Plexusmentioning

confidence: 80%

Section: In Vitro Preparation and Retrograde Labeling Of Spinal Neuronsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Jovanovic

Burke

2004

J of Comparative Neurology

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“…As we find in postmetamorphic Xenopus, NA modulates ongoing locomotor rhythmicity in the spinal cat (Rossignol et al, 1998) and the isolated neonatal rat spinal cord (Kiehn et al, 1999) by increasing both motor cycle periods and burst durations. However, it must be emphasized that our Xenopus experiments on spontaneously expressed patterns of fictive swimming differed fundamentally from most other vertebrate studies in which extant locomotor activity required sensory (e.g., via treadmill walking) or supraspinal stimulation in vivo (Steeves et al, 1980), or additional neurochemical stimulation in vitro (Grillner, 1986;Cazalets et al, 1992;Jovanovic et al, 1996;Delvolve et al, 1999;Jiang et al, 1999). Thus, distinguishing aminespecific actions from a combination of inductive/modulatory processes becomes problematic.…”

mentioning

confidence: 93%

Opposing Aminergic Modulation of Distinct Spinal Locomotor Circuits and Their Functional Coupling during Amphibian Metamorphosis

Rauscent¹,

Einum²,

Ray³

et al. 2009

J. Neurosci.

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The biogenic amines serotonin (5-HT) and noradrenaline (NA) are well known modulators of central pattern-generating networks responsible for vertebrate locomotion. Here we have explored monoaminergic modulation of the spinal circuits that generate two distinct modes of locomotion in the metamorphosing frog Xenopus laevis. At metamorphic climax when propulsion is achieved by undulatory larval tail movements and/or by kicking of the newly developed adult hindlimbs, the underlying motor networks remain spontaneously active in vitro, producing either separate fast axial and slow appendicular rhythms or a single combined rhythm that drives coordinated tail-based and limb-based swimming in vivo. In isolated spinal cords already expressing distinct axial and limb rhythms, bath-applied 5-HT induced coupled network activity through an opposite slowing of axial rhythmicity (by increasing motoneuron burst and cycle durations) and an acceleration of limb rhythmicity (by decreasing burst and cycle durations). In contrast, in preparations spontaneously expressing coordinated fictive locomotion, exogenous NA caused a dissociation of spinal activity into separate faster axial and slower appendicular rhythms by decreasing and increasing burst and cycle durations, respectively. Moreover, in preparations from premetamorphic and postmetamorphic animals that express exclusively axial-based or limb-based locomotion, 5-HT and NA modified the developmentally independent rhythms in a similar manner to the amines' opposing effects on the coexisting circuits at metamorphic climax. Thus, by exerting differential modulatory actions on one network that are opposite to their influences on a second adjacent circuit, these two amines are able to precisely regulate the functional relationship between different rhythmogenic networks in a developing vertebrate's spinal cord.

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Serotonergic systems in the spinal cord of the amphibian urodele Pleurodeles waltl

Branchereau

Delvolvé

et al. 2000

J. Comp. Neurol.

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Serotonergic modulation of the mudpuppy (Necturus maculatus) locomotor pattern in vitro

Cited by 26 publications

References 45 publications

Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Morphology of brachial segments in mudpuppy (Necturus maculosus) spinal cord studied with confocal and electron microscopy

Opposing Aminergic Modulation of Distinct Spinal Locomotor Circuits and Their Functional Coupling during Amphibian Metamorphosis

Serotonergic systems in the spinal cord of the amphibian urodele Pleurodeles waltl

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