Somatotopy of the Neurons Innervating the Cricothyroid, Posterior Cricoarytenoid, and Thyroarytenoid Muscles of the Rat's Larynx

Hernández-Morato, Ignacio; Pascual‐Font, Arán; Ramírez, Carlos; Matarranz-Echeverría, Jorge; McHanwell, Stephen; Vázquez, Teresa; Sañudo, José Ramón; Valderrama-Canales, Francisco J.

doi:10.1002/ar.22643

Cited by 23 publications

(38 citation statements)

References 45 publications

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“…; Portillo & Pásaro, ; Hernández‐Morato et al. ), while other authors suggest that there are two distinct columns (Gacek, ; Wetzel et al. ; Bieger & Hopkins, ; Patrickson et al.…”

Section: Introductionmentioning

confidence: 98%

Reorganization of laryngeal motoneurons after crush injury in the recurrent laryngeal nerve of the rat

et al. 2013

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Motoneurons innervating laryngeal muscles are located in the nucleus ambiguus (Amb), but there is no general agreement on the somatotopic representation and even less is known on how an injury in the recurrent laryngeal nerve (RLN) affects this pattern. This study analyzes the normal somatotopy of those motoneurons and describes its changes over time after a crush injury to the RLN. In the control group (control group 1, n = 9 rats), the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were injected with cholera toxin-B. In the experimental groups the left RLN of each animal was crushed with a fine tip forceps and, after several survival periods (1, 2, 4, 8, 12 weeks; minimum six rats per time), the PCA and TA muscles were injected as described above. After each surgery, the motility of the vocal folds was evaluated. Additional control experiments were performed; the second control experiment (control group 2, n = 6 rats) was performed labeling the TA and PCA immediately prior to the section of the superior laryngeal nerve (SLN), in order to eliminate the possibility of accidental labeling of the cricothyroid (CT) muscle by spread from the injection site. The third control group (control group 3, n = 5 rats) was included to determine if there is some sprouting from the SLN into the territories of the RLN after a crush of this last nerve. One week after the crush injury of the RLN, the PCA and TA muscles were injected immediately before the section of the SLN. The results show that a single population of neurons represents each muscle with the PCA in the most rostral position followed caudalwards by the TA. One week post-RLN injury, both the somatotopy and the number of labeled motoneurons changed, where the labeled neurons were distributed randomly; in addition, an area of topographical overlap of the two populations was observed and vocal fold mobility was lost. In the rest of the survival periods, the overlapping area is larger, but the movement of the vocal folds tends to recover. After 12 weeks of survival, the disorganization within the Amb is the largest, but the number of motoneurons is similar to control, and all animals recovered the movement of the left vocal fold. Our additional controls indicate that no tracer spread to the CT muscle occurred, and that many of the labeled motoneurons from the PCA after 1 week post-RLN injury correspond to motoneurons whose axons travel in the SLN. Therefore, it seems that after RLN injury there is a collateral sprouting and collateral innervation. Although the somatotopic organization of the Amb is lost after a crush injury of the RLN and does not recover in the times studied here, the movement of the vocal folds as well as the number of neurons that supply the TA and the PCA muscles recovered within 8 weeks, indicating that the central nervous system of the rat has a great capacity of plasticity.

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“…; Portillo & Pásaro, ; Hernández‐Morato et al. ), while other authors suggest that there are two distinct columns (Gacek, ; Wetzel et al. ; Bieger & Hopkins, ; Patrickson et al.…”

Section: Introductionmentioning

confidence: 98%

Reorganization of laryngeal motoneurons after crush injury in the recurrent laryngeal nerve of the rat

et al. 2013

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“…; Hernandez‐Morato et al . ) and several cellular properties and synaptic inputs that may play a role in shaping their firing pattern have been described (Richter et al . ; Dutschmann & Paton, ; Ono et al .…”

Section: Introductionmentioning

confidence: 99%

Electrophysiological properties of laryngeal motoneurones in rats submitted to chronic intermittent hypoxia

Moraes

Machado

2015

The Journal of Physiology

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Key pointsr The respiratory control of the glottis by laryngeal motoneurones is characterized by inspiratory abduction and post-inspiratory adduction causing decreases and increases in upper airway resistance, respectively.r Chronic intermittent hypoxia (CIH), an important component of obstructive sleep apnoea, exaggerated glottal abduction (before inspiration), associated with active expiration and decreased glottal adduction during post-inspiration.r CIH increased the inspiratory and decreased the post-inspiratory laryngeal motoneurone activities, which is not associated to changes in their intrinsic electrophysiological properties.r We conclude that the changes in the respiratory network after CIH seem to be an adaptive process required for an appropriated pulmonary ventilation and control of upper airway resistance under intermittent episodes of hypoxia.Abstract To keep an appropriate airflow to and from the lungs under physiological conditions a precise neural co-ordination of the upper airway resistance by laryngeal motoneurones in the nucleus ambiguus is essential. Chronic intermittent hypoxia (CIH), an important component of obstructive sleep apnoea, may alter these fine mechanisms. Here, using nerve and whole cell patch clamp recordings in in situ preparations of rats we investigated the effects of CIH on the respiratory control of the upper airway resistance, on the electrophysiological properties of laryngeal motoneurones in the nucleus ambiguus, and the role of carotid body (CB) afferents to the brainstem on the underlying mechanisms of these effects. CIH rats exhibited longer pre-inspiratory and lower post-inspiratory superior laryngeal nerve activities than control rats. These changes produced exaggerated glottal abduction (before inspiration) and decreased glottal adduction during post-inspiration, indicating a reduction of upper airway resistance during these respiratory phases after CIH. CB denervation abolished these changes produced by CIH. Regarding choline acetyltransferase positive-laryngeal motoneurones, CIH increased the firing frequency of inspiratory and decreased the firing frequency of post-inspiratory laryngeal motoneurones, without changes in their intrinsic electrophysiological properties. These data show that the effects of CIH on the upper airway resistance and laryngeal motoneurones activities are driven by the integrity of CB, which afferents induce changes in the central respiratory generators in the brainstem. These neural changes in the respiratory network seem to be an adaptive process required for an appropriated pulmonary ventilation and control of upper airway resistance under intermittent episodes of hypoxia.

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“…; Hernández‐Morato et al. ); for the neuronal somata contributing to the RLN: –900 to 1680 μm and for the SLN: 1440 to 2590 μm in relation to the obex.…”

Section: Resultsmentioning

confidence: 94%

“…These motor neuron somata are located rostrally in the ‘loose’ and the ‘semicompact’ formations of the Amb, respectively (Hernández‐Morato et al. ).…”

Section: Discussionmentioning

confidence: 99%

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GFAP immunoreactivity within the rat nucleus ambiguus after laryngeal nerve injury

et al. 2014

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Changes that occur in astroglial populations of the nucleus ambiguus after recurrent (RLN) or superior (SLN) laryngeal nerve injury have hitherto not been fully characterised. In the present study, rat RLN and SLN were lesioned. After 3, 7, 14, 28 or 56 days of survival, the nucleus ambiguus was investigated by means of glial fibrillary acidic protein (GFAP) immunofluorescence or a combination of GFAP immunofluorescence and the application of retrograde tracers. GFAP immunoreactivity was significantly increased 3 days after RLN resection and it remained significantly elevated until after 28 days post injury (dpi). By 56 dpi it had returned to basal levels. In contrast, following RLN transection with repair, GFAP immunoreactivity was significantly elevated at 7 dpi and remained significantly elevated until 14 dpi. It had returned to basal levels by 28 dpi. Topographical analysis of the distribution of GFAP immunoreactivity revealed that after RLN injury, GFAP immunoreactivity was increased beyond the area of the nucleus ambiguus within which RLN motor neuron somata were located. GFAP immunoreactivity was also observed in the vicinity of neuronal somata that project into the uninjured SLN. Similarly, lesion of the SLN resulted in increased GFAP immunoreactivity around the neuronal somata projecting into it and also in the vicinity of the motor neuron somata projecting into the RLN. The increase in GFAP immunoreactivity outside of the region containing the motor neurons projecting into the injured nerve, may reflect the onset of a regenerative process attempting to compensate for impairment of one of the laryngeal nerves and may occur because of the dual innervation of the posterior cricoarytenoid muscle. This dual innervation of a very specialised muscle could provide a useful model system for studying the molecular mechanisms underlying axonal regeneration process and the results of the current study could provide the basis for studies into functional regeneration following laryngeal nerve injury, with subsequent application to humans.

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Somatotopy of the Neurons Innervating the Cricothyroid, Posterior Cricoarytenoid, and Thyroarytenoid Muscles of the Rat's Larynx

Cited by 23 publications

References 45 publications

Reorganization of laryngeal motoneurons after crush injury in the recurrent laryngeal nerve of the rat

Reorganization of laryngeal motoneurons after crush injury in the recurrent laryngeal nerve of the rat

Electrophysiological properties of laryngeal motoneurones in rats submitted to chronic intermittent hypoxia

GFAP immunoreactivity within the rat nucleus ambiguus after laryngeal nerve injury

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