Effect of lingual paralysis on swallowing and breathing coordination in rats

Abstract

The tongue plays an important role in both swallowing and breathing. Lingual motor deficits with consequences for swallowing are often observed in many neurological disorders. However, the impact of such deficits on swallowing and breathing coordination is unknown. Our objective was to study the swallowing and ventilatory patterns in rats with unilateral lingual paralysis. Our study was carried out on 10 Wistar rats. Respiratory variables in unrestrained and healthy animals were measured at rest and during water swallowing using whole-body plethysmography and a video camera. The procedure was repeated after unilateral sectioning of the hypoglossal nerve (XII). Swallowing frequency and occurrence during inspiration and expiration, tidal volume, total time of the ventilatory cycle and respiratory drive were assessed. Unilateral sectioning of the hypoglossal nerve led to a swallowing deficit and drooling. Respiratory rhythm and ventilatory drive (16.39±2.13 ml/s vs. 13.67±1.28 ml/s) during swallowing decreased after hypoglossal nerve sectioning but were unaffected during rest without swallowing, while swallowing rate (17±5/15s) and occurrence during respiratory cycle phases did not change. A swallowing deficit induced by lingual paralysis decreased the ventilatory drive during swallowing. This may be a mechanism to reduce or prevent pulmonary aspiration.