Effects of oral deprivation and continuous gastrostomy feeding on masticatory function in rats

Abstract

Purpose: Tube feeding is frequently used in older adults and patients with dysphagia. However, when oral intake cannot be resumed, masticatory function may decline. Eating provides nutrition and helps maintain oral function, but the effects of different nutritional routes on masticatory muscles remain unclear. This study investigated the effects of a feeding model that combined differences in feeding route, diet form, and oral deprivation on masticatory-related muscles and masticatory function.Methods: Seven-week-old male Sprague–Dawley rats were assigned to receive a solid diet (solid group), a liquid diet (liquid group), or continuous gastric feeding via gastrostomy (gastrostomy group) for 3 weeks. The time required to complete feed intake, masseter electromyographic activity, and masticatory muscles weights were evaluated.Results: Energy intake and body weight changes did not differ significantly among the groups during the feeding period. Masseter muscle weight was significantly lower in the liquid group than in the other groups, whereas temporalis muscle weight tended to be higher in the solid group. The time required to complete feed intake was significantly longer in the gastrostomy group (389.7±210.4 sec/g) than in the solid and liquid groups (140.0±21.4 and 207.8±82.2 sec/g, respectively; P<0.01). When solid food was consumed after the 3-week feeding period, muscle activity during eating was higher in both the liquid and gastrostomy groups than in the solid group.Conclusion: Feeding models involving oral deprivation or gastrostomy feeding altered masticatory-related muscle characteristics and chewing performance in rats. Reduced feeding activity may contribute to impaired chewing and changes in tongue weight.