Effects of monoamines on interneurons in four spinal reflex pathways from group I and/or group II muscle afferents

@article{Jankowska2000EffectsOM,
  title={Effects of monoamines on interneurons in four spinal reflex pathways from group I and/or group II muscle afferents},
  author={Elzbieta Jankowska and Ingela Hammar and B. Chojnicka and Carina Hed{\'e}n},
  journal={European Journal of Neuroscience},
  year={2000},
  volume={12}
}
Effects of locally applied serotonin (5‐HT) and noradrenaline (NA) were tested on extracellularly recorded responses of single spinal interneurons in deeply anaesthetized cats. These effects were tested on: (i) interneurons mediating reciprocal inhibition from group Ia afferents; (ii) interneurons mediating non‐reciprocal inhibition from group Ia and Ib afferents; (iii) intermediate zone interneurons co‐excited by group I and II afferents; and (iv) dorsal horn interneurons excited by group II… 
Differential presynaptic inhibition of actions of group II afferents in di‐ and polysynaptic pathways to feline motoneurones
TLDR
The results of this study lead to the conclusion that strong presynaptic inhibition of transmission to intermediate zone interneurones allows a selective depression of disynaptic actions of group II muscle afferents on α‐ and γ‐motoneurones, mediated by these interneURones, and favours polysynapticactions of these afferentS.
On organization of a neuronal network in pathways from group II muscle afferents in feline lumbar spinal segments
TLDR
The study indicates that intermediate zone interneurones may be activated by group II afferents both directly and via dorsal horn interneuranones and that synaptic actions of group II Afferents upon these interneuronones, and their subsequent actions upon motoneurones, may be modulated in parallel at the level of intermediate zone and dorsal horn.
Functional subdivision of feline spinal interneurons in reflex pathways from group Ib and II muscle afferents; an update
TLDR
The aim here is to reassess the basis for subdivision of adult mammalian spinal interneurons that mediate reflex actions from tendon organs and muscle spindle secondary endings into separate populations, and proposes renaming these neurons ‘group I/II interneeurons’.
Excitatory and inhibitory intermediate zone interneurons in pathways from feline group I and II afferents: differences in axonal projections and input
TLDR
The morphological and electrophysiological data show that individual excitatory and inhibitory intermediate zone interneurons may operate in a highly differentiated way and thereby contribute to a variety of motor synergies.
Serotonin, Dopamine and Noradrenaline Adjust Actions of Myelinated Afferents via Modulation of Presynaptic Inhibition in the Mouse Spinal Cord
TLDR
Both myelinated afferent-evoked DRPs and monosynaptic transmission in the dorsal horn are broadly reduced by descending monoamine transmitters, suggesting these actions likely integrate with modulatory actions elsewhere to reconfigure spinal circuits during motor behaviors.
Modulatory Effects of α1-, α2-, and β-Receptor Agonists on Feline Spinal Interneurons with Monosynaptic Input from Group I Muscle Afferents
TLDR
The findings lead to the conclusion that beneficial antispastic effects of clonidine and tizanidine in humans are unlikely to be associated with an enhancement of the actions of Ia- and Ia/Ib-inhibitory interneurons, and the findings support previous proposals that these compounds exert their antispastics actions via effects on other neuronal populations.
The actions of monoamines and distribution of noradrenergic and serotoninergic contacts on different subpopulations of commissural interneurons in the cat spinal cord
TLDR
Differences in modulatory actions of monoamines, and subsequent changes in the recruitment of subpopulations of commissural interneurons in various behavioural situations, depend on intrinsic interneuron properties rather than on the patterns of innervation by monoaminergic fibres.
Serotoninergic and noradrenergic axonal contacts associated with premotor interneurons in spinal pathways from group II muscle afferents
TLDR
Findings provide a morphological basis for the modulatory actions of monoamines on premotor spinal interneurons in pathways from group II muscle afferents.
Both dorsal horn and lamina VIII interneurones contribute to crossed reflexes from feline group II muscle afferents
TLDR
It is concluded that dorsal horn interneurones contribute to the late actions of group II muscle afferents on contralateral motoneurones through their disynaptic actions on commissural interneURones.
Spinal interneurons that receive input from muscle afferents are differentially modulated by dorsolateral descending systems.
TLDR
Results suggest that a disruption of the descending system, such as occurs in spinal cord injury, will lead to a suppression of the interneuronal pathways with group Ia input while enhancing excitability within interneURonal pathways transmitting actions from higher threshold afferents.
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 55 REFERENCES
Comparison of Effects of Various Types of NA and 5‐HT Agonists on Transmission from Group II Muscle Afferents in the Cat
TLDR
The results suggest that this depression may involve different membrane receptors at different locations, primarily α2 adrenoceptors in the intermediate zone/ventral horn and 5‐HT‐1A serotonin receptors in the dorsal horn.
New observations on coupling between group II muscle afferents and feline γ‐motoneurones
TLDR
Evidence is provided that some synaptic actions of group II Afferents, including afferents from the same muscle, are evoked monosynaptically, and may assist in sustaining the activation of γ‐motoneurones by positive feedback.
Characterization of a descending system that enables crossed group II inhibitory reflex pathways in the cat spinal cord
TLDR
A serotonergic pathway, descending via the dorsolateral funiculi and acting via 5-HT1A receptors, is involved: with the spinal cord intact, the pathway would be tonically active and thus enable the crossed inhibition.
Interneurones mediating presynaptic inhibition of group II muscle afferents in the cat spinal cord.
TLDR
The location of the first‐ and last‐order interneurones in pathways of primary afferent depolarization (PAD) could not be differentiated by this approach because the same stimuli induced positive potentials, which masked the onset of DRPs and precluded localization of the sites from which DRPs might be evoked monosynaptically.
Organization of neuronal systems mediating presynaptic inhibition of group II muscle afferents in the cat.
TLDR
The results suggest that the interneuronal systems responsible for the presynaptic control of transmission from group II muscle afferents have topographically restricted actions and an organization appropriate to a system of negative feedback control.
An interneuronal relay for group I and II muscle afferents in the midlumbar segments of the cat spinal cord.
TLDR
The study focused on interneurones projecting to hind‐limb motor nuclei and/or interposed in pathways from group II muscle afferents, which may reflect inhibitory interactions between subpopulations of L4 interneURones.
Noradrenergic synapses and effects of noradrenaline on interneurons in the ventral horn of the cat spinal cord.
TLDR
Fluorescence histochemical studies revealed that noradrenaline-containing fibers rarely form intimate contacts with alpha mot oneurons, whereas many small interneurons which are closely invested with fluorescent fibers can be found near the motoneurons.
Gating of transmission to motoneurones by stimuli applied in the locus coeruleus and raphe nuclei of the cat.
TLDR
It is concluded that neuronal systems activated by stimuli applied in the LC/SC and raphe nuclei are capable of gating transmission in all those interneuronal pathways which mediate the reflex actions of group II afferents on motoneurones in anaesthetized animals.
Modulation of Responses of Four Types of Feline Ascending Tract Neurons by Serotonin and Noradrenaline
TLDR
The results indicate that transfer of information from skin and group II muscle afferents to supraspinal centres may be gated by descending monoaminergic pathways in a highly differentiated manner, and is adjusted to the requirements of various behavioural situations.
...
1
2
3
4
5
...