Table_1_Altered tongue muscle contractile properties coincide with altered swallow function in the adult Ts65Dn mouse model of down syndrome.DOCX

PurposeDown syndrome (DS) is a developmental disability associated with difficulties in deglutition. The adult Ts65Dn mouse model of DS has been previously shown to have differences in measures of swallowing compared with euploid controls. However, the putative mechanisms of these differences in swallowing function are unclear. This study tested the hypothesis that the Ts65Dn genotype is associated with atypical measures of tongue muscle contractile properties, coinciding with atypical swallow function.
MethodsAdult (5-month-old) Ts65Dn (n = 15 female, 14 male) and euploid sibling controls (n = 16 female, 14 male) were evaluated through videofluoroscopy swallow studies (VFSS) to quantify measures of swallowing performance including swallow rate and inter-swallow interval (ISI). After VFSS, retrusive tongue muscle contractile properties, including measures of muscle fatigue, were determined using bilateral hypoglossal nerve stimulation.
ResultsThe Ts65Dn group had significantly slower swallow rates, significantly greater ISI times, significantly slower rates of tongue force development, and significantly greater levels of tongue muscle fatigue, with lower retrusive tongue forces than controls in fatigue conditions.
ConclusionTongue muscle contractile properties are altered in adult Ts65Dn and coincide with altered swallow function.

研究背景与目的：唐氏综合征（Down syndrome, DS）是一类常见的发育性残疾，常伴随吞咽功能障碍。既往研究表明，唐氏综合征Ts65Dn小鼠模型的吞咽相关指标与整倍体（euploid）对照小鼠存在显著差异，但此类吞咽功能差异的潜在机制仍不明确。本研究验证了如下假说：Ts65Dn基因型会导致舌肌收缩特性异常，同时伴随吞咽功能异常。

方法：本研究纳入5月龄成年Ts65Dn小鼠（雌性15只、雄性14只）及其同窝整倍体对照小鼠（雌性16只、雄性14只），通过透视吞咽检查（videofluoroscopy swallow studies, VFSS）量化吞咽速率、吞咽间期（inter-swallow interval, ISI）等吞咽表现指标。完成VFSS检测后，采用双侧舌下神经刺激法，测定舌后缩肌（retrusive tongue muscle）的收缩特性，包括肌肉疲劳相关指标。

结果：与对照组相比，Ts65Dn小鼠组的吞咽速率显著减慢，吞咽间期显著延长，舌肌力生成速率显著降低，舌肌疲劳程度显著升高；且在疲劳状态下，其舌后缩肌力低于对照组。

结论：成年Ts65Dn小鼠的舌肌收缩特性发生改变，且该改变与吞咽功能异常高度吻合。