Gerwin, L. ; Haupt, C.* ; Wilkinson, K.A.* ; Kröger, S.*
Acetylcholine receptors in the equatorial region of intrafusal muscle fibres modulate mouse muscle spindle sensitivity.
J. Physiol. 597, 1993-2006 (2019)
Key pointsAcetylcholine receptors are aggregated in the central regions of intrafusal muscle fibres. Single unit muscle spindle afferent responses from isolated mouse extensor digitorum longus muscle were recorded in the absence of fusimotor input to ramp and hold stretches as well as to sinusoidal vibrations in the presence and absence of the acetylcholine receptor blockers d-tubocurarine and alpha-bungarotoxin. Proprioceptive afferent responses to both types of stretch were enhanced in the presence of either blocker. Blocking acetylcholine uptake and vesicular acetylcholine release by hemicholinium-3 also enhanced stretch-evoked responses. These results represent the first evidence that acetylcholine receptors negatively modulate muscle spindle responses to stretch. The data support the hypothesis that the sensory nerve terminal is able to release vesicles to fine-tune proprioceptive afferent sensitivity. Muscle spindles are complex stretch-sensitive mechanoreceptors. They consist of specialized skeletal muscle fibres, called intrafusal fibres, which are innervated in the central (equatorial) region by afferent sensory axons and in both polar regions by efferent gamma-motoneurons. Previously it was shown that acetylcholine receptors (AChR) are concentrated in the equatorial region at the contact site between the sensory neuron and the intrafusal muscle fibre. To address the function of these AChRs, single unit sensory afferents were recorded from an isolated mouse extensor digitorum longus muscle in the absence of gamma-motoneuron activity. Specifically, we investigated the responses of individual sensory neurons to ramp-and-hold stretches and sinusoidal vibrations before and after the addition of the competitive and non-competitive AChR blockers d-tubocurarine and alpha-bungarotoxin, respectively. The presence of either drug did not affect the resting action potential discharge frequency. However, the action potential frequencies in response to stretch were increased. In particular, frequencies of the dynamic peak and dynamic index to ramp-and-hold stretches were significantly higher in the presence of either drug. Treatment of muscle spindle afferents with the high-affinity choline transporter antagonist hemicholinium-3 similarly increased muscle spindle afferent firing frequencies during stretch. Moreover, the firing rate during sinusoidal vibration stimuli at low amplitudes was higher in the presence of alpha-bungarotoxin compared to control spindles also indicating an increased sensitivity to stretch. Collectively these data suggest a modulation of the muscle spindle afferent response to stretch by AChRs in the central region of intrafusal fibres possibly fine-tuning muscle spindle sensitivity.
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Publikationstyp
Artikel: Journalartikel
Dokumenttyp
Wissenschaftlicher Artikel
Typ der Hochschulschrift
Herausgeber
Schlagwörter
Acetylcholine Receptor ; Intrafusal Fiber ; Proprioception ; Hemicholinium-3 ; D-tubocurarine ; Alpha-bungarotoxin; Synaptic-like Vesicles; Choline Transporter; Neuromuscular-junction; Contractile Properties; Glutamate Release; Skeletal-muscles; Fine-structure; Mechanotransduction; Excitability; Endings
Keywords plus
Sprache
englisch
Veröffentlichungsjahr
2019
Prepublished im Jahr
HGF-Berichtsjahr
2019
ISSN (print) / ISBN
0928-4257
e-ISSN
1769-7115
ISBN
Bandtitel
Konferenztitel
Konferzenzdatum
Konferenzort
Konferenzband
Quellenangaben
Band: 597,
Heft: 7,
Seiten: 1993-2006
Artikelnummer: ,
Supplement: ,
Reihe
Verlag
Elsevier
Verlagsort
111 River St, Hoboken 07030-5774, Nj Usa
Tag d. mündl. Prüfung
0000-00-00
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Gutachter
Prüfer
Topic
Hochschule
Hochschulort
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Veröffentlichungsdatum
0000-00-00
Anmeldedatum
0000-00-00
Anmelder/Inhaber
weitere Inhaber
Anmeldeland
Priorität
Begutachtungsstatus
Peer reviewed
POF Topic(s)
30204 - Cell Programming and Repair
Forschungsfeld(er)
Stem Cell and Neuroscience
PSP-Element(e)
G-500800-001
Förderungen
Copyright
Erfassungsdatum
2019-03-14