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
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...
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Published in | Experimental brain research Vol. 238; no. 5; pp. 1293 - 1303 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Berlin/Heidelberg
Springer Berlin Heidelberg
01.05.2020
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | 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 α
1
-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 α
2
-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 α
1
-adrenoceptors and inhibits interneuronal pathways mediating PAD through the activation of α
1
- and α
2
-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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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 All authors contributed to the conception and design of the study. Material preparation, data collection and analysis were performed by Elvia Mena-Avila and Jonathan J. Milla-Cruz. The first draft of the manuscript was written by Elvia Mena-Avila and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. |
ISSN: | 0014-4819 1432-1106 |
DOI: | 10.1007/s00221-020-05805-y |