Masticatory effort is a complex process which relies on a mix of precisely coordinated neuromuscular activity and neural feedback from sensory afferents. Parkinson's disease is widely known to impair orofacial function, however there is minimal data regarding food texture in confluence with Parkinsonism on masticatory efficiency. In this study we tested how variations in food textures can affect masticatory kinematics in an animal model of Parkinson’s disease. We hypothesized that there would be differences in chewing kinematics between a hard and a soft food, and that hard food kinematics would be more impacted by Parkinsonism than soft food. We utilized daily intraperitoneal injections of 2.75 mg/kg of rotenone to induce a progressive parkinsonian model in a cohort of rats. Prior to injections, we implanted radio opaque tantalum beads in the upper jaw, lower jaw, and tongue. Rats were recorded with high speed (200 fps) videofluoroscopy while feeding at baseline, (day 0, pre-rotenone treatment) and at day 16 of treatment to analyze masticatory kinematics. Rats consumed both a barium coated fruit loop and a gel cube during recordings. Markers were tracked digitally to provide quantitative kinematics. We calculated chewing cycle duration, maximum gape size, and jaw range of motion. These kinematic variables were analyzed using linear mixed models with day, food type, and day - food interaction as fixed factors. At all timepoints, fruit loops had a greater gape size and cycle length compared to gel (p < 0.001) however over 16 days of treatment range of motion for gel decreased (p < 0.001), whereas range of motion for loop did not change, contrary to our hypothesis. The differences between soft and hard food masticatory patterns show that masticatory feedback plays an important role in the strength and frequency of masticatory efforts. Variability in the changes in chewing kinematics between gel and loops at 16 days show that masticatory kinematics may degenerate in a food specific manner in Parkinson’s disease. Together these findings show distinct, food dependent, degenerative patterns, which may help uncover mechanisms regarding dysphagia and masticatory dysfunction in neurodegenerative diseases. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Coren et al. (Fri,) studied this question.