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Majczyński H, Cabaj AM, Jordan LM, Sławińska U. Contribution of 5-HT 2 Receptors to the Control of the Spinal Locomotor System in Intact Rats. Front Neural Circuits 2020; 14:14. [PMID: 32425760 PMCID: PMC7212388 DOI: 10.3389/fncir.2020.00014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/24/2020] [Indexed: 11/13/2022] Open
Abstract
Applying serotonergic (5-HT) agonists or grafting of fetal serotonergic cells into the spinal cord improves locomotion after spinal cord injury. Little is known about the role of 5-HT receptors in the control of voluntary locomotion, so we administered inverse agonists of 5-HT2 (Cyproheptadine; Cypr), 5-HT2A neutral antagonist (Volinanserin; Volin), 5-HT2C neutral antagonist (SB 242084), and 5-HT2B/2C inverse agonist (SB 206553) receptors intrathecally in intact rats and monitored their effects on unrestrained locomotion. An intrathecal cannula was introduced at the low thoracic level and pushed caudally until the tip reached the L2/L3 or L5/L6 spinal segments. Locomotor performance was evaluated using EMG activity of hindlimb muscles during locomotion on a 2 m long runway. Motoneuron excitability was estimated using EMG recordings during dorsi- and plantar flexion at the ankle. Locomotion was dramatically impaired after the blockage of 5-HT2A receptors. The effect of Cypr was more pronounced than that of Volin since in the L5/L6 rats Cypr (but not Volin) induced significant alteration of the strength of interlimb coordination followed by total paralysis. These agents significantly decreased locomotor EMG amplitude and abolished or substantially decreased stretch reflexes. Blocking 5-HT2B/2C receptors had no effect either on locomotion or reflexes. We suggest that in intact rats serotonin controls timing and amplitude of muscle activity by acting on 5-HT2A receptors on both CPG interneurons and motoneurons, while 5-HT2B/2C receptors are not involved in control of the locomotor pattern in lumbar spinal cord.
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Affiliation(s)
- Henryk Majczyński
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Anna M Cabaj
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Larry M Jordan
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, MB, Canada
| | - Urszula Sławińska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
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Noga BR, Sanchez FJ, Villamil LM, O'Toole C, Kasicki S, Olszewski M, Cabaj AM, Majczyński H, Sławińska U, Jordan LM. LFP Oscillations in the Mesencephalic Locomotor Region during Voluntary Locomotion. Front Neural Circuits 2017; 11:34. [PMID: 28579945 PMCID: PMC5437718 DOI: 10.3389/fncir.2017.00034] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 04/28/2017] [Indexed: 11/28/2022] Open
Abstract
Oscillatory rhythms in local field potentials (LFPs) are thought to coherently bind cooperating neuronal ensembles to produce behaviors, including locomotion. LFPs recorded from sites that trigger locomotion have been used as a basis for identification of appropriate targets for deep brain stimulation (DBS) to enhance locomotor recovery in patients with gait disorders. Theta band activity (6–12 Hz) is associated with locomotor activity in locomotion-inducing sites in the hypothalamus and in the hippocampus, but the LFPs that occur in the functionally defined mesencephalic locomotor region (MLR) during locomotion have not been determined. Here we record the oscillatory activity during treadmill locomotion in MLR sites effective for inducing locomotion with electrical stimulation in rats. The results show the presence of oscillatory theta rhythms in the LFPs recorded from the most effective MLR stimulus sites (at threshold ≤60 μA). Theta activity increased at the onset of locomotion, and its power was correlated with the speed of locomotion. In animals with higher thresholds (>60 μA), the correlation between locomotor speed and theta LFP oscillations was less robust. Changes in the gamma band (previously recorded in vitro in the pedunculopontine nucleus (PPN), thought to be a part of the MLR) were relatively small. Controlled locomotion was best achieved at 10–20 Hz frequencies of MLR stimulation. Our results indicate that theta and not delta or gamma band oscillation is a suitable biomarker for identifying the functional MLR sites.
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Affiliation(s)
- Brian R Noga
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of MedicineMiami, FL, United States
| | - Francisco J Sanchez
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of MedicineMiami, FL, United States
| | - Luz M Villamil
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of MedicineMiami, FL, United States
| | - Christopher O'Toole
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of MedicineMiami, FL, United States
| | - Stefan Kasicki
- Department of Neurophysiology, Nencki Institute of Experimental BiologyWarsaw, Poland
| | - Maciej Olszewski
- Department of Neurophysiology, Nencki Institute of Experimental BiologyWarsaw, Poland
| | - Anna M Cabaj
- Department of Neurophysiology, Nencki Institute of Experimental BiologyWarsaw, Poland
| | - Henryk Majczyński
- Department of Neurophysiology, Nencki Institute of Experimental BiologyWarsaw, Poland
| | - Urszula Sławińska
- Department of Neurophysiology, Nencki Institute of Experimental BiologyWarsaw, Poland
| | - Larry M Jordan
- Department of Physiology, Spinal Cord Research Centre, University of ManitobaWinnipeg, MB, Canada
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Zmysłowski W, Cabaj AM, Sławińska U. Correction: Treatment with Riluzole Restores Normal Control of Soleus and Extensor Digitorum Longus Muscles during Locomotion in Adult Rats after Sciatic Nerve Crush at Birth. PLoS One 2017; 12:e0176490. [PMID: 28426787 PMCID: PMC5398670 DOI: 10.1371/journal.pone.0176490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Zmysłowski W, Cabaj AM, Sławińska U. Treatment with Riluzole Restores Normal Control of Soleus and Extensor Digitorum Longus Muscles during Locomotion in Adult Rats after Sciatic Nerve Crush at Birth. PLoS One 2017; 12:e0170235. [PMID: 28095499 PMCID: PMC5240973 DOI: 10.1371/journal.pone.0170235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 01/02/2017] [Indexed: 11/18/2022] Open
Abstract
The effects of sciatic nerve crush (SNC) and treatment with Riluzole on muscle activity during unrestrained locomotion were identified in an animal model by analysis of the EMG activity recorded from soleus (Sol) and extensor digitorum longus (EDL) muscles of both hindlimbs; in intact rats (IN) and in groups of rats treated for 14 days with saline (S) or Riluzole (R) after right limb nerve crush at the 1st (1S and 1R) or 2nd (2S and 2R) day after birth. Changes in the locomotor pattern of EMG activity were correlated with the numbers of survived motor units (MUs) identified in investigated muscles. S rats with 2-8 and 10-28 MUs that survived in Sol and EDL muscles respectively showed increases in the duration and duty factor of muscle EMG activity and a loss of correlation between the duty factors of muscle activity, and abnormal flexor-extensor co-activation 3 months after SNC. R rats with 5, 6 (Sol) and 15-29 MUs (EDL) developed almost normal EMG activity of both Sol and control EDL muscles, whereas EDL muscles with SNC showed a lack of recovery. R rats with 8 (Sol) and 23-33 (EDL) MUs developed almost normal EMG activities of all four muscles. A subgroup of S rats with a lack of recovery and R rats with almost complete recovery that had similar number of MUs (8 and 24-28 vs 8 and 23-26), showed that the number of MUs was not the only determinant of treatment effectiveness. The results demonstrated that rats with SNC failed to develop normal muscle activity due to malfunction of neuronal circuits attenuating EDL muscle activity during the stance phase, whereas treatment with Riluzole enabled almost normal EMG activity of Sol and EDL muscles during locomotor movement.
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Affiliation(s)
- Wojciech Zmysłowski
- Department of Engineering of Nervous and Muscular System, Nałęcz Institute of Biocybernetics and Biomedical Engineering, PAS, Warsaw, Poland
- * E-mail:
| | - Anna M. Cabaj
- Department of Engineering of Nervous and Muscular System, Nałęcz Institute of Biocybernetics and Biomedical Engineering, PAS, Warsaw, Poland
- Department of Neurophysiology, Nencki Institute of Experimental Biology, PAS, Warsaw, Poland
| | - Urszula Sławińska
- Department of Neurophysiology, Nencki Institute of Experimental Biology, PAS, Warsaw, Poland
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Cabaj AM, Majczyński H, Couto E, Gardiner PF, Stecina K, Sławińska U, Jordan LM. Serotonin controls initiation of locomotion and afferent modulation of coordination via 5-HT 7 receptors in adult rats. J Physiol 2016; 595:301-320. [PMID: 27393215 DOI: 10.1113/jp272271] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 06/30/2016] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Experiments on neonatal rodent spinal cord showed that serotonin (5-HT), acting via 5-HT7 receptors, is required for initiation of locomotion and for controlling the action of interneurons responsible for inter- and intralimb coordination, but the importance of the 5-HT system in adult locomotion is not clear. Blockade of spinal 5-HT7 receptors interfered with voluntary locomotion in adult rats and fictive locomotion in paralysed decerebrate rats with no afferent feedback, consistent with a requirement for activation of descending 5-HT neurons for production of locomotion. The direct control of coordinating interneurons by 5-HT7 receptors observed in neonatal animals was not found during fictive locomotion, revealing a developmental shift from direct control of locomotor interneurons in neonates to control of afferent input from the moving limb in adults. An understanding of the afferents controlled by 5-HT during locomotion is required for optimal use of rehabilitation therapies involving the use of serotonergic drugs. ABSTRACT Serotonergic pathways to the spinal cord are implicated in the control of locomotion based on studies using serotonin type 7 (5-HT7 ) receptor agonists and antagonists and 5-HT7 receptor knockout mice. Blockade of these receptors is thought to interfere with the activity of coordinating interneurons, a conclusion derived primarily from in vitro studies on isolated spinal cord of neonatal rats and mice. Developmental changes in the effects of serotonin (5-HT) on spinal neurons have recently been described, and there is increasing data on control of sensory input by 5-HT7 receptors on dorsal root ganglion cells and/or dorsal horn neurons, leading us to determine the effects of 5-HT7 receptor blockade on voluntary overground locomotion and on locomotion without afferent input from the moving limb (fictive locomotion) in adult animals. Intrathecal injections of the selective 5-HT7 antagonist SB269970 in adult intact rats suppressed locomotion by partial paralysis of hindlimbs. This occurred without a direct effect on motoneurons as revealed by an investigation of reflex activity. The antagonist disrupted intra- and interlimb coordination during locomotion in all intact animals but not during fictive locomotion induced by stimulation of the mesencephalic locomotor region (MLR). MLR-evoked fictive locomotion was transiently blocked, then the amplitude and frequency of rhythmic activity were reduced by SB269970, consistent with the notion that the MLR activates 5-HT neurons, leading to excitation of central pattern generator neurons with 5-HT7 receptors. Effects on coordination in adults required the presence of afferent input, suggesting a switch to 5-HT7 receptor-mediated control of sensory pathways during development.
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Affiliation(s)
- Anna M Cabaj
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, 02-093, Warsaw, Poland.,Department of Nerve-Muscle Engineering, Institute of Biocybernetics and Biomedical Engineering PAS, 02-109, Warsaw, Poland
| | - Henryk Majczyński
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, 02-093, Warsaw, Poland
| | - Erika Couto
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Phillip F Gardiner
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Katinka Stecina
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
| | - Urszula Sławińska
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, 02-093, Warsaw, Poland
| | - Larry M Jordan
- Department of Physiology & Pathophysiology, Spinal Cord Research Centre, University of Manitoba, Winnipeg, MB, R3E 0J9, Canada
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Leszczyńska AN, Majczyński H, Wilczyński GM, Sławińska U, Cabaj AM. Thoracic Hemisection in Rats Results in Initial Recovery Followed by a Late Decrement in Locomotor Movements, with Changes in Coordination Correlated with Serotonergic Innervation of the Ventral Horn. PLoS One 2015; 10:e0143602. [PMID: 26606275 PMCID: PMC4659566 DOI: 10.1371/journal.pone.0143602] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 11/06/2015] [Indexed: 11/18/2022] Open
Abstract
Lateral thoracic hemisection of the rodent spinal cord is a popular model of spinal cord injury, in which the effects of various treatments, designed to encourage locomotor recovery, are tested. Nevertheless, there are still inconsistencies in the literature concerning the details of spontaneous locomotor recovery after such lesions, and there is a lack of data concerning the quality of locomotion over a long time span after the lesion. In this study, we aimed to address some of these issues. In our experiments, locomotor recovery was assessed using EMG and CatWalk recordings and analysis. Our results showed that after hemisection there was paralysis in both hindlimbs, followed by a substantial recovery of locomotor movements, but even at the peak of recovery, which occurred about 4 weeks after the lesion, some deficits of locomotion remained present. The parameters that were abnormal included abduction, interlimb coordination and speed of locomotion. Locomotor performance was stable for several weeks, but about 3-4 months after hemisection secondary locomotor impairment was observed with changes in parameters, such as speed of locomotion, interlimb coordination, base of hindlimb support, hindlimb abduction and relative foot print distance. Histological analysis of serotonergic innervation at the lumbar ventral horn below hemisection revealed a limited restoration of serotonergic fibers on the ipsilateral side of the spinal cord, while on the contralateral side of the spinal cord it returned to normal. In addition, the length of these fibers on both sides of the spinal cord correlated with inter- and intralimb coordination. In contrast to data reported in the literature, our results show there is not full locomotor recovery after spinal cord hemisection. Secondary deterioration of certain locomotor functions occurs with time in hemisected rats, and locomotor recovery appears partly associated with reinnervation of spinal circuitry by serotonergic fibers.
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Affiliation(s)
| | | | | | | | - Anna M Cabaj
- Nencki Insitute of Experimental Biology, PAS, Warsaw, Poland.,Nałęcz Institute of Biocybernetics and Biomedical Engineering, PAS, Warsaw, Poland
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Jordan LM, McVagh JR, Noga BR, Cabaj AM, Majczyński H, Sławińska U, Provencher J, Leblond H, Rossignol S. Cholinergic mechanisms in spinal locomotion-potential target for rehabilitation approaches. Front Neural Circuits 2014; 8:132. [PMID: 25414645 PMCID: PMC4222238 DOI: 10.3389/fncir.2014.00132] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/13/2014] [Indexed: 01/08/2023] Open
Abstract
Previous experiments implicate cholinergic brainstem and spinal systems in the control of locomotion. Our results demonstrate that the endogenous cholinergic propriospinal system, acting via M2 and M3 muscarinic receptors, is capable of consistently producing well-coordinated locomotor activity in the in vitro neonatal preparation, placing it in a position to contribute to normal locomotion and to provide a basis for recovery of locomotor capability in the absence of descending pathways. Tests of these suggestions, however, reveal that the spinal cholinergic system plays little if any role in the induction of locomotion, because MLR-evoked locomotion in decerebrate cats is not prevented by cholinergic antagonists. Furthermore, it is not required for the development of stepping movements after spinal cord injury, because cholinergic agonists do not facilitate the appearance of locomotion after spinal cord injury, unlike the dramatic locomotion-promoting effects of clonidine, a noradrenergic α-2 agonist. Furthermore, cholinergic antagonists actually improve locomotor activity after spinal cord injury, suggesting that plastic changes in the spinal cholinergic system interfere with locomotion rather than facilitating it. Changes that have been observed in the cholinergic innervation of motoneurons after spinal cord injury do not decrease motoneuron excitability, as expected. Instead, the development of a “hyper-cholinergic” state after spinal cord injury appears to enhance motoneuron output and suppress locomotion. A cholinergic suppression of afferent input from the limb after spinal cord injury is also evident from our data, and this may contribute to the ability of cholinergic antagonists to improve locomotion. Not only is a role for the spinal cholinergic system in suppressing locomotion after SCI suggested by our results, but an obligatory contribution of a brainstem cholinergic relay to reticulospinal locomotor command systems is not confirmed by our experiments.
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Affiliation(s)
- Larry M Jordan
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, University of Manitoba Winnipeg, MB, Canada
| | - J R McVagh
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, University of Manitoba Winnipeg, MB, Canada
| | - B R Noga
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami Miami, FL, USA
| | - A M Cabaj
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS Warsaw, Poland ; Department of Nerve-Muscle Engineering, Institute of Biocybernetics and Biomedical Engineering PAS Warsaw, Poland
| | - H Majczyński
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS Warsaw, Poland
| | - Urszula Sławińska
- Department of Neurophysiology, Nencki Institute of Experimental Biology PAS Warsaw, Poland
| | - J Provencher
- Groupe de Recherche sur le Système Nerveux Central and Department of Neuroscience, Faculty of Medicine, Université de Montréal Montreal, QC, Canada
| | - H Leblond
- Groupe de Recherche sur le Système Nerveux Central and Department of Neuroscience, Faculty of Medicine, Université de Montréal Montreal, QC, Canada
| | - Serge Rossignol
- Groupe de Recherche sur le Système Nerveux Central and Department of Neuroscience, Faculty of Medicine, Université de Montréal Montreal, QC, Canada
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Affiliation(s)
- Anna M. Cabaj
- Institute of Biocybernetics and Biomedical Engineering PAS, Warsaw, Poland
- Nencki Institute of Experimental Biology PAS, Warsaw, Poland
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