Research article summary (published 29 Jun 2009):

Locomotor-activated neurons of the cat. I. Serotonergic innervation and co-localization of 5-HT7, 5-HT2A, and 5-HT1A receptors in the thoraco-lumbar spinal cord.

Full Abstract

Monoamines are strong modulators and/or activators of spinal locomotor networks. Thus monoaminergic fibers likely contact neurons involved in generating locomotion. The aim of the present study was to investigate the serotonergic innervation of locomotor-activated neurons within the thoraco-lumbar spinal cord following induction of hindlimb locomotion. This was determined by immunohistochemical co-localization of serotonin (5-HT) fibers or 5-HT(7)/5-HT2A/5-HT1A receptors with cells expressing the activity-dependent marker c-fos. Experiments were performed on paralyzed, decerebrate cats in which locomotion was induced by electrical stimulation of the mesencephalic locomotor region. Abundant c-fos immunoreactive cells were observed in laminae VII and VIII throughout the thoraco-lumbar segments of locomotor animals. Control sections from the same segments showed significantly fewer labeled neurons, mostly within the dorsal horn. Multiple serotonergic boutons were found in close apposition to the majority (80-100%) of locomotor cells, which were most abundant in lumbar segments L3-7. 5-HT7 receptor immunoreactivity was observed on cells across the thoraco-lumbar segments (T7-L7), in a dorsoventral gradient. Most locomotor-activated cells co-localized with 5-HT7, 5-HT2A, and 5-HT1A receptors, with largest numbers in laminae VII and VIII. Co-localization of c-fos and 5-HT7 receptor was highest in the L5-L7 segments (>90%) and decreased rostrally (to approximately 50%) due to the absence of receptors on cells within the intermediolateral nucleus. In contrast, 60-80 and 35-80% of c-fos immunoreactive cells stained positive for 5-HT2A and 5-HT1A receptors, respectively, with no rostrocaudal gradient. These results indicate that serotonergic modulation of locomotion likely involves 5-HT(7)/5-HT2A/5-HT1A receptors located on the soma and proximal dendrites of serotonergic-innervated locomotor-activated neurons within laminae VII and VIII of thoraco-lumbar segments.

Author information

Author/s: Noga, Brian R (BR); Johnson, Dawn M G (DM); Riesgo, Mirta I (MI); Pinzon, Alberto (A);

Affiliation: The Miami Project to Cure Paralysis, University of Miami School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA. bnoga(-atsign-)miami.edu

Grants: R01 NS-46404 (Agency:NINDS NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Journal of neurophysiology (J Neurophysiol), published in United States. (Language: eng)

Reference: 2009-Sep; vol 102 (issue 3) : pp 1560-76

Dates: Created 2009/09/03; Completed 2009/10/23;

PMID: 19571190, status: MEDLINE (last retrieval date: 10/23/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals Cats Decerebrate State Electric Stimulation - methods Locomotion - physiology Lumbosacral Region Neural Pathways - physiology Neurons - physiology

Neurons - physiology Proto-Oncogene Proteins c-fos - metabolism Receptor, Serotonin, 5-HT1A - metabolism Receptor, Serotonin, 5-HT2A - metabolism Receptors, Serotonin - classification; metabolism Serotonin - metabolism Spinal Cord - cytology; metabolism Time Factors

Associated Chemicals: Proto-Oncogene Proteins c-fos (0) ; Receptor, Serotonin, 5-HT2A (0) ; Receptors, Serotonin (0) ; serotonin 7 receptor (0) ; Receptor, Serotonin, 5-HT1A (112692-38-3) ; Serotonin (50-67-9)

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