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Domínguez-Rodríguez LE, Stecina K, García-Ramírez DL, Mena-Avila E, Milla-Cruz JJ, Martínez-Silva L, Zhang M, Hultborn H, Quevedo JN. Candidate Interneurons Mediating the Resetting of the Locomotor Rhythm by Extensor Group I Afferents in the Cat. Neuroscience 2020; 450:96-112. [PMID: 32946952 DOI: 10.1016/j.neuroscience.2020.09.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 05/18/2020] [Revised: 08/07/2020] [Accepted: 09/04/2020] [Indexed: 10/23/2022]
Abstract
Sensory information arising from limb movements controls the spinal locomotor circuitry to adapt the motor pattern to demands of the environment. Stimulation of extensor group (gr) I afferents during fictive locomotion in decerebrate cats prolongs the ongoing extension, and terminates ongoing flexion with an initiation of the subsequent extension, i. e. "resetting to extension". Moreover, instead of the classical Ib non-reciprocal inhibition, stimulation of extensor gr I afferents produces a polysynaptic excitation in extensor motoneurons with latencies (∼3.5-4.0 ms) compatible with 3 interposed interneurons. We assume that some interneurons in this pathway actually belong to the rhythm-generating layer of the locomotor Central Pattern Generator (CPG), since their activity was correlated to a resetting of the rhythm. In the present work fictive locomotion was (mostly) induced by i.v. injection of nialamide followed by l-DOPA in paralyzed cats following decerebration and spinalization at C1 level. In some experiments, we extended previous observations during fictive locomotion on the emergence and locomotor state-dependence of polysynaptic excitatory postsynaptic potentials from extensor gr I afferents to ankle extensor motoneurons. However, the main focus was to record location and properties of interneurons (n = 62) that (i) were active during the extensor phase of fictive locomotion and (ii) received short-latency excitation (mono-, di- or polysynaptic) from extensor gr I afferents. We conclude that the interneurons recorded fulfill the characteristics to belong to the neuronal pathway activated by extensor gr I afferents during locomotion, and may contribute to the 'resetting to extension' as part of the locomotor CPG.
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Affiliation(s)
| | - K Stecina
- Spinal Cord Research Centre, University of Manitoba, Winnipeg, Canada; Dept. of Neuroscience, University of Copenhagen, Denmark
| | - D L García-Ramírez
- Dept. of Physiology, Biophysics and Neuroscience, CINVESTAV del IPN, Mexico City, Mexico; Department of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - E Mena-Avila
- Dept. of Physiology, Biophysics and Neuroscience, CINVESTAV del IPN, Mexico City, Mexico
| | - J J Milla-Cruz
- Dept. of Physiology, Biophysics and Neuroscience, CINVESTAV del IPN, Mexico City, Mexico
| | - L Martínez-Silva
- Dept. of Physiology, Biophysics and Neuroscience, CINVESTAV del IPN, Mexico City, Mexico; Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - M Zhang
- Dept. of Neuroscience, University of Copenhagen, Denmark; Inst. of Molecular Medicine, Medical Faculty, University of Southern Denmark, Odense, Denmark
| | - H Hultborn
- Dept. of Neuroscience, University of Copenhagen, Denmark.
| | - J N Quevedo
- Dept. of Physiology, Biophysics and Neuroscience, CINVESTAV del IPN, Mexico City, Mexico.
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Milla-Cruz JJ, Mena-Avila E, Calvo JR, Hochman S, Villalón CM, Quevedo JN. The activation of D 2 and D 3 receptor subtypes inhibits pathways mediating primary afferent depolarization (PAD) in the mouse spinal cord. Neurosci Lett 2020; 736:135257. [PMID: 32682848 DOI: 10.1016/j.neulet.2020.135257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 03/31/2020] [Revised: 07/05/2020] [Accepted: 07/14/2020] [Indexed: 12/22/2022]
Abstract
Somatosensory information can be modulated at the spinal cord level by primary afferent depolarization (PAD), known to produce presynaptic inhibition (PSI) by decreasing neurotransmitter release through the activation of presynaptic ionotropic receptors. Descending monoaminergic systems also modulate somatosensory processing. We investigated the role of D1-like and D2-like receptors on pathways mediating PAD in the hemisected spinal cord of neonatal mice. We recorded low-threshold evoked dorsal root potentials (DRPs) and population monosynaptic responses as extracellular field potentials (EFPs). We used a paired-pulse conditioning-test protocol to assess homosynaptic and heterosynaptic depression of evoked EFPs to discriminate between dopaminergic effects on afferent synaptic efficacy and/or on pathways mediating PAD, respectively. DA (10 μM) depressed low-threshold evoked DRPs by 43 %, with no effect on EFPs. These depressant effects on DRPs were mimicked by the D2-like receptor agonist quinpirole (35 %). Moreover, by using selective antagonists at D2-like receptors (encompassing the D2, D3, and D4 subtypes), we found that the D2 and D3 receptor subtypes participate in the quinpirole depressant inhibitory effects of pathways mediating PAD.
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Affiliation(s)
- Jonathan J Milla-Cruz
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - Elvia Mena-Avila
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - Jorge R Calvo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - Shawn Hochman
- Physiology Department, Emory University, Atlanta, GA, United States
| | - Carlos M Villalón
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Sede-Sur, Ciudad de México, Mexico
| | - Jorge N Quevedo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, Mexico.
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Mena-Avila E, Milla-Cruz JJ, Calvo JR, Hochman S, Villalón CM, Arias-Montaño JA, Quevedo JN. Activation of α-adrenoceptors depresses synaptic transmission of myelinated afferents and inhibits pathways mediating primary afferent depolarization (PAD) in the in vitro mouse spinal cord. Exp Brain Res 2020; 238:1293-1303. [PMID: 32322928 PMCID: PMC10751985 DOI: 10.1007/s00221-020-05805-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 04/07/2020] [Indexed: 12/25/2022]
Abstract
Somatosensory afferent transmission strength is controlled by several presynaptic mechanisms that reduce transmitter release at the spinal cord level. We focused this investigation on the role of α-adrenoceptors in modulating sensory transmission in low-threshold myelinated afferents and in pathways mediating primary afferent depolarization (PAD) of neonatal mouse spinal cord. We hypothesized that the activation of α-adrenoceptors depresses low threshold-evoked synaptic transmission and inhibits pathways mediating PAD. Extracellular field potentials (EFPs) recorded in the deep dorsal horn assessed adrenergic modulation of population monosynaptic transmission, while dorsal root potentials (DRPs) recorded at root entry zone assessed adrenergic modulation of PAD. We found that noradrenaline (NA) and the α1-adrenoceptor agonists phenylephrine and cirazoline depressed synaptic transmission (by 15, 14 and 22%, respectively). DRPs were also depressed by NA, phenylephrine and cirazoline (by 62, 30, and 64%, respectively), and by the α2-adrenoceptor agonist clonidine, although to a lower extent (20%). We conclude that NA depresses monosynaptic transmission of myelinated afferents onto deep dorsal horn neurons via α1-adrenoceptors and inhibits interneuronal pathways mediating PAD through the activation of α1- and α2-adrenoceptors. The functional significance of these modulatory actions in shaping cutaneous and muscle sensory information during motor behaviors requires further study.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Animals
- Animals, Newborn
- Electrophysiological Phenomena/drug effects
- Electrophysiological Phenomena/physiology
- In Vitro Techniques
- Mice
- Mice, Inbred BALB C
- Nerve Fibers, Myelinated/physiology
- Neural Pathways/physiology
- Neurons, Afferent/physiology
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/physiology
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/physiology
- Spinal Cord Dorsal Horn/physiology
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- Elvia Mena-Avila
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Jonathan J Milla-Cruz
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Jorge R Calvo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Shawn Hochman
- Physiology Department, Emory University, Atlanta, GA, USA
| | - Carlos M Villalón
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Sede-Sur, Ciudad de México, Mexico
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico
| | - Jorge N Quevedo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Cinvestav del IPN, Av. IPN 2508, San Pedro Zacatenco, 07360, Ciudad de México, Mexico.
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Martínez-Silva L, Manjarrez E, Gutiérrez-Ospina G, Quevedo JN. Electrophysiological representation of scratching CpG activity in the cerebellum. PLoS One 2014; 9:e109936. [PMID: 25350378 PMCID: PMC4211676 DOI: 10.1371/journal.pone.0109936] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [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: 05/12/2014] [Accepted: 09/14/2014] [Indexed: 11/19/2022] Open
Abstract
We analyzed the electrical activity of neuronal populations in the cerebellum and the lumbar spinal cord during fictive scratching in adult decerebrate cats before and after selective sections of the Spino-Reticulo Cerebellar Pathway (SRCP) and the Ventral-Spino Cerebellar Tract (VSCT). During fictive scratching, we found a conspicuous sinusoidal electrical activity, called Sinusoidal Cerebellar Potentials (SCPs), in the cerebellar vermis, which exhibited smaller amplitude in the paravermal and hemisphere cortices. There was also a significant spino-cerebellar coherence between these SCPs and the lumbar sinusoidal cord dorsum potentials (SCDPs). However, during spontaneous activity such spino-cerebellar coherence between spontaneous potentials recorded in the same regions decreased. We found that the section of the SRCP and the VSCT did not abolish the amplitude of the SCPs, suggesting that there are additional pathways conveying information from the spinal CPG to the cerebellum. This is the first evidence that the sinusoidal activity associated to the spinal CPG circuitry for scratching has a broad representation in the cerebellum beyond the sensory representation from hindlimbs previously described. Furthermore, the SCPs represent the global electrical activity of the spinal CPG for scratching in the cerebellar cortex.
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Affiliation(s)
| | - Elias Manjarrez
- Instituto de Fisiología, BUAP, Puebla, México
- * E-mail: (JNQ); (EM)
| | | | - Jorge N. Quevedo
- Departamento de Fisiología, Biofísica y Neurociencias CINVESTAV, México City, México
- * E-mail: (JNQ); (EM)
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García-Ramírez DL, Calvo JR, Hochman S, Quevedo JN. Serotonin, dopamine and noradrenaline adjust actions of myelinated afferents via modulation of presynaptic inhibition in the mouse spinal cord. PLoS One 2014; 9:e89999. [PMID: 24587177 PMCID: PMC3938568 DOI: 10.1371/journal.pone.0089999] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [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: 06/12/2013] [Accepted: 01/29/2014] [Indexed: 01/20/2023] Open
Abstract
Gain control of primary afferent neurotransmission at their intraspinal terminals occurs by several mechanisms including primary afferent depolarization (PAD). PAD produces presynaptic inhibition via a reduction in transmitter release. While it is known that descending monoaminergic pathways complexly regulate sensory processing, the extent these actions include modulation of afferent-evoked PAD remains uncertain. We investigated the effects of serotonin (5HT), dopamine (DA) and noradrenaline (NA) on afferent transmission and PAD. Responses were evoked by stimulation of myelinated hindlimb cutaneous and muscle afferents in the isolated neonatal mouse spinal cord. Monosynaptic responses were examined in the deep dorsal horn either as population excitatory synaptic responses (recorded as extracellular field potentials; EFPs) or intracellular excitatory postsynaptic currents (EPSCs). The magnitude of PAD generated intraspinally was estimated from electrotonically back-propagating dorsal root potentials (DRPs) recorded on lumbar dorsal roots. 5HT depressed the DRP by 76%. Monosynaptic actions were similarly depressed by 5HT (EFPs 54%; EPSCs 75%) but with a slower time course. This suggests that depression of monosynaptic EFPs and DRPs occurs by independent mechanisms. DA and NA had similar depressant actions on DRPs but weaker effects on EFPs. IC50 values for DRP depression were 0.6, 0.8 and 1.0 µM for 5HT, DA and NA, respectively. Depression of DRPs by monoamines was nearly-identical in both muscle and cutaneous afferent-evoked responses, supporting a global modulation of the multimodal afferents stimulated. 5HT, DA and NA produced no change in the compound antidromic potentials evoked by intraspinal microstimulation indicating that depression of the DRP is unrelated to direct changes in the excitability of intraspinal afferent fibers, but due to metabotropic receptor activation. In summary, both myelinated afferent-evoked DRPs and monosynaptic transmission in the dorsal horn are broadly reduced by descending monoamine transmitters. These actions likely integrate with modulatory actions elsewhere to reconfigure spinal circuits during motor behaviors.
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Affiliation(s)
- David L García-Ramírez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, D.F., México
| | - Jorge R Calvo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, D.F., México
| | - Shawn Hochman
- Department of Physiology, Emory University, Atlanta, Georgia, United States of America
| | - Jorge N Quevedo
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, D.F., México
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