1
|
Goodlich BI, Pearcey GEP, Del Vecchio A, Horan SA, Kavanagh JJ. Antagonism of 5-HT 2 receptors attenuates self-sustained firing of human motor units. J Physiol 2024; 602:1759-1774. [PMID: 38502567 DOI: 10.1113/jp285867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/29/2024] [Indexed: 03/21/2024] Open
Abstract
5-HT2 receptors on motoneurones play a critical role in facilitating persistent inward currents (PICs). Although facilitation of PICs can enhance self-sustained firing after periods of excitation, the relationship between 5-HT2 receptor activity and self-sustained firing in human motor units (MUs) has not been resolved. MU activity was assessed from the tibialis anterior of 10 healthy adults (24.9 ± 2.8 years) during two contraction protocols. Both protocols featured steady-state isometric contractions with constant descending drive to the motoneurone pool. However, one protocol also included an additional phase of superimposed descending drive. Adding and then removing descending drive in the middle of steady-state contractions altered MU firing behaviour across the motor pool, where newly recruited units in the superimposed phase were unable to switch off (P = 0.0002), and units recruited prior to additional descending drive reduced their discharge rates (P < 0.0001, difference in estimated marginal means (∆) = 2.24 pulses/s). The 5-HT2 receptor antagonist, cyproheptadine, was then administered to determine whether changes in MU firing were mediated by serotonergic mechanisms. 5-HT2 receptor antagonism caused reductions in MU discharge rate (P < 0.001, ∆ = 1.65 pulses/s), recruitment threshold (P = 0.00112, ∆ = 1.09% maximal voluntary contraction) and self-sustained firing duration (P < 0.0001, ∆ = 1.77s) after the additional descending drive was removed in the middle of the steady-state contraction. These findings indicate that serotonergic neuromodulation plays a key role in facilitating discharge and self-sustained firing of human motoneurones, where adaptive changes in MU recruitment must occur to meet the demands of the contraction. KEY POINTS: Animal and cellular preparations indicate that somato-dendritic 5-HT2 receptors regulate the intrinsic excitability of motoneurones. 5-HT2 receptor antagonism reduces estimates of persistent inward currents in motoneurones, which contribute to self-sustained firing when synaptic inputs are reduced or removed. This human study employed a contraction task that slowly increased (and then removed) the additional descending drive in the middle of a steady-state contraction where marked self-sustained firing occurred when the descending drive was removed. 5-HT2 receptor antagonism caused widespread reductions in motor unit (MU) discharge rates during contractions, which was accompanied by reduced recruitment threshold and attenuation of self-sustained firing duration after the removal of the additional descending drive to motoneurones. These findings support the role that serotonergic neuromodulation is a key facilitator of MU discharge and self-sustained firing of human motoneurones, where adaptative changes in MU recruitment must occur to meet the demands of the contraction.
Collapse
Affiliation(s)
- Benjamin I Goodlich
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Gregory E P Pearcey
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Canada
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, USA
| | - Alessandro Del Vecchio
- Department Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University (FAU), Erlangen-Nuremberg, Erlangen, Germany
| | - Sean A Horan
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| |
Collapse
|
2
|
Koning HK, Ahemaiti A, Boije H. A deep-dive into fictive locomotion - a strategy to probe cellular activity during speed transitions in fictively swimming zebrafish larvae. Biol Open 2022; 11:274799. [PMID: 35188534 PMCID: PMC8966775 DOI: 10.1242/bio.059167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/14/2022] [Indexed: 11/20/2022] Open
Abstract
Fictive locomotion is frequently used to study locomotor output in paralyzed animals. We have evaluated the character of swim episodes elicited by different strategies in zebrafish. Motor output was measured on both sides of a body segment using electrodes and a pipeline for synchronizing stimulation and recording, denoising data and peak-finding was developed. The optomotor response generated swims most equivalent to spontaneous activity, while electrical stimulation and NMDA application caused various artefacts. Our optimal settings, optomotor stimulation using 5-day-old larvae, were combined with calcium imaging and optogenetics to validate the setup's utility. Expression of GCaMP5G by the mnx1 promoter allowed correlation of calcium traces of dozens of motor neurons to the fictive locomotor output. Activation of motor neurons through channelrhodopsin produced aberrant locomotor episodes. This strategy can be used to investigate novel neuronal populations in a high-throughput manner to reveal their role in shaping motor output. This article has an associated First Person interview with the first author of the paper. Summary: This approach combines fictive locomotion, elicited through the optomotor response, and calcium imaging or optogenetics, to investigate the role of neuronal populations in shaping motor output.
Collapse
Affiliation(s)
- Harmen Kornelis Koning
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
| | - Aikeremu Ahemaiti
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
| | - Henrik Boije
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
| |
Collapse
|
3
|
Schmidt E, Raposo P, Vavrek R, Fouad K. Inducing inflammation following subacute spinal cord injury in female rats: A double-edged sword to promote motor recovery. Brain Behav Immun 2021; 93:55-65. [PMID: 33358981 DOI: 10.1016/j.bbi.2020.12.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 11/20/2020] [Accepted: 12/16/2020] [Indexed: 12/20/2022] Open
Abstract
The inflammatory response following spinal cord injury is associated with increased tissue damage and impaired functional recovery. However, inflammation can also promote plasticity and the secretion of growth-promoting substances. Previously we have shown that inducing inflammation with a systemic injection of lipopolysaccharide in the chronic (8 weeks) stage of spinal cord injury enhances neuronal sprouting and the efficacy of rehabilitative training in rats. Here, we tested whether administration of lipopolysaccharide in female rats in the subacute (10 days) stage of spinal cord injury would have a similar effect. Since the lesioned environment is already in a pro-inflammatory state at this earlier time after injury, we hypothesized that triggering a second immune response may not be beneficial for recovery. Contrary to our hypothesis, we found that eliciting an inflammatory response 10 days after spinal cord injury enhanced the recovery of the ipsilesional forelimb in rehabilitative training. Compared to rats that received rehabilitative training without treatment, rats that received systemic lipopolysaccharide showed restored motor function without the use of compensatory strategies that translated beyond the trained task. Furthermore, lipopolysaccharide treatment paradoxically promoted the resolution of chronic neuroinflammation around the lesion site. Unfortunately, re-triggering a systemic immune response after spinal cord injury also resulted in a long-term increase in anxiety-like behaviour.
Collapse
Affiliation(s)
- Emma Schmidt
- Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Pamela Raposo
- Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada
| | - Romana Vavrek
- Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada
| | - Karim Fouad
- Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada; Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada.
| |
Collapse
|
4
|
Porta LC, Campeiro JD, Papa GB, Oliveira EB, Godinho RO, Rodrigues T, Hayashi MAF. In vivo effects of the association of the psychoactive phenotiazine thioridazine on antitumor activity and hind limb paralysis induced by the native polypeptide crotamine. Toxicon 2020; 185:64-71. [PMID: 32621838 DOI: 10.1016/j.toxicon.2020.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/28/2020] [Accepted: 06/21/2020] [Indexed: 11/18/2022]
Abstract
Crotamine is a cationic polypeptide composed by 42 amino acid residues with several pharmacological and biological properties, including the selective ability to enter and kill actively proliferating tumour cells, which led us to propose its use as a theranostic agent for cancer therapy. At the moment, the improvement of crotamine antitumoral efficacy by association with chemotherapeutic adjuvants is envisioned. In the present work, we evaluated the association of crotamine with the antitumoral adjuvant phenotiazine thioridazine (THD). In spite of the clear efficacy of these both compounds as anticancer agents in long-term in vivo treatment of animal model bearing implanted xenograph melanoma tumor, the expected mutual potentiation of the antitumor effects was not observed here. Moreover, this association revealed for the first time the influence of THD on crotamine ability to trigger the hind limb paralysis in mice, and this discovery may represent the first report suggesting the potential involvement of the CNS in the action of this snake polypeptide on the skeletal muscle paralysis, which was classically believed to be essentially limited to a direct action in peripheral tissues as the skeletal muscle. This is also supported by the observed ability of crotamine to potentiate the sedative effects of THD which action was consistently demonstrated to be based on its central action. The better characterization of crotamine properties in CNS may certainly bring important insights for the knowledge needed to pave the way toward the use of this molecule as a theranostic compound in human diseases as cancer.
Collapse
Affiliation(s)
- Lucas C Porta
- Departamento de Farmacologia, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), SP, Brazil
| | - Joana D Campeiro
- Departamento de Farmacologia, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), SP, Brazil
| | - Giovanna B Papa
- Departamento de Farmacologia, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), SP, Brazil
| | - Eduardo B Oliveira
- Departamento de Bioquímica e Imunologia, Universidade de São Paulo (USP-RP), Ribeirão Preto, Brazil
| | - Rosely O Godinho
- Departamento de Farmacologia, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), SP, Brazil
| | | | - Mirian A F Hayashi
- Departamento de Farmacologia, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), SP, Brazil.
| |
Collapse
|
5
|
Coslovich T, Della Mora A, D'Angelo G, Ortolani F, Taccola G. Histamine H 3 Receptors Expressed in Ventral Horns Modulate Spinal Motor Output. Cell Mol Neurobiol 2020; 41:185-190. [PMID: 32211996 DOI: 10.1007/s10571-020-00831-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/16/2020] [Indexed: 11/29/2022]
Abstract
Motoneuron activity is modulated by histamine receptors. While H1 and H2 receptors have been widely explored, H3 histamine receptors (H3Rs) have not been sufficiently characterized. This paper targets the effects of the selective activation of H3Rs and their expression on the membranes of large ventral horn cells. The application of selective pharmacological agents to spinal cords isolated from neonatal rats was used to identify the presence of functional H3Rs on the membrane of physiologically identified lumbar motoneurons. Intra and extracellular recordings revealed that H3R agonist, α-methylhistamine, depolarized both single motoneurons and ventral roots, even in the presence of tetrodotoxin, an effect prevented by H3R antagonist, thioperamide. Finally, immunohistochemistry located the expression of H3Rs on a subpopulation of large cells in lamina IX. This study identifies H3Rs as a new exploitable pharmacological target against motor disturbances.
Collapse
Affiliation(s)
- Tamara Coslovich
- Neuroscience Department, International School for Advanced Studies (SISSA), via Bonomea 265, 34136, Trieste, TS, Italy.,SPINAL (Spinal Person Injury Neurorehabilitation Applied Laboratory), Istituto di Medicina Fisica e Riabilitazione (IMFR), via Gervasutta 48, Udine, UD, Italy
| | - Alberto Della Mora
- Department of Experimental Clinical Medicine, University of Udine, Piazzale Kolbe 3, Udine, Italy
| | - Giuseppe D'Angelo
- Neuroscience Department, International School for Advanced Studies (SISSA), via Bonomea 265, 34136, Trieste, TS, Italy.,SPINAL (Spinal Person Injury Neurorehabilitation Applied Laboratory), Istituto di Medicina Fisica e Riabilitazione (IMFR), via Gervasutta 48, Udine, UD, Italy
| | - Fulvia Ortolani
- Department of Experimental Clinical Medicine, University of Udine, Piazzale Kolbe 3, Udine, Italy
| | - Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (SISSA), via Bonomea 265, 34136, Trieste, TS, Italy. .,SPINAL (Spinal Person Injury Neurorehabilitation Applied Laboratory), Istituto di Medicina Fisica e Riabilitazione (IMFR), via Gervasutta 48, Udine, UD, Italy.
| |
Collapse
|