Study of brainstem motor networks involved in the rhythmic activity of upper airway muscles
Team “Perinatal Imprintings and Neurodevelopmental Disorders”
The oropharynx is a common passage for air and food and is mobilized by the muscles of the upper airways. Brainstem central pattern generators elaborate rhythmic command to the tongue and larynx during breathing, swallowing and sucking. What are the mechanisms modulating and controlling the activity of the same muscles during distinct motor tasks? What are the main structures involved in airway protection?
Here, we show that quipazine, a serotonergic agonist, can be administrated in the rat perfused preparation to increase swallowing. The caudal raphe nuclei are likely mediating this modulatory effect. Using this model, we examined whether ponto-bulbar nuclei participate in the motor control of the tongue and larynx during swallowing and contribute to reflex protection of the lungs. A ponto-bulbar transection disrupts the laryngeal respiratory drive but does not alter laryngeal control during swallowing. Also, the lesion decreases the swallowing hypoglossal activity and alters the swallow-breathing coordination. Thus, the pons plays a key role in protecting the lungs. We show that some motoneurons to tongue protrudors and many neurons of the ventral respiratory column discharge during breathing and swallowing. These results confirm the dynamic function of brainstem networks. Perfused preparations were also developed in 6-9 days old rat and sucking-like activity was observed. The oxytocinergic agonist TGOT increases sucking, this effect being abolished by prior administration of an oxytocin receptor antagonist.
This work provides new data on the neural mechanisms allowing rhythmic motor control of the upper airways and represents an important methodological advance.
Florence Cayetanot, Rapportrice – Neurophysiologie respiratoire expérimentale et clinique, UMR S1158, Paris
Jean-Paul Praud, Rapporteur – Département de pédiatrie, Université de Sherbrooke, Québec
Muriel Thoby-Brisson, Examinatrice – INCIA, Bordeaux
Alain Frugiere, Président – ENS, Paris
Christian Gestreau, Directeur de thèse – Inmed, Marseille
Friday, July 15th at 2pm – Inmed conference room