Marmoset (Callithrix jacchus) Swallowing Physiology: Novel Dysphagia Model Across Lifespan.

Dysphagia, a pervasive global health issue, is increasingly prevalent with age (presbyphagia), significantly impacting well-being. Studying its complex mechanisms in humans is challenging, often necessitating animal models. Ideally, such models should combine close anatomical and physiological similarity to humans with practical attributes that facilitate longitudinal research, including ease of handling and housing, manageable lifespan, compressed developmental timelines, and high fecundity. Marmosets (Callithrix jacchus), with their notable human-like similarities and practical advantages, represent an ideal biogerontology model, though their swallowing physiology remains largely underexplored. From a comparative biology perspective, this study aims to elucidate swallowing biomechanics and physiology across the lifespan of healthy captive common marmosets using cineradiographic imaging. We used cineradiography to examine swallowing function and spinal posture in 26 healthy marmosets, ranging from 0 to 19 years old. A high-resolution microfocal X-ray source and beryllium fast-response image intensifier, housed in a radiation-proof chamber, were employed. Animals consumed barium-mixed Castella cake while a dual video camera system captured synchronized visual and audio data. Researchers remotely manipulated the animal cage via an X-ray control desk. We measured bolus size, inter-swallow intervals, pharyngeal inlet angle (PIA), and spinal angles during swallowing. Analyzing 784 swallows from 56 recordings, we found significant age-related differences in bolus size, inter-swallow interval, and PIA (P < 0.001). Elderly marmosets displayed longer inter-swallow intervals, and had wider PIAs than younger animals; poorer dental health also correlated with these changes. Postural analysis revealed older marmosets exhibited more flexed cervicothoracic and thoracolumbar angles and increased spinal sinuosity. Importantly, narrower spinal angles correlated with larger boluses, wider PIAs, and longer inter-swallow intervals. This study provides a comprehensive lifespan investigation of marmoset swallowing, revealing distinct age-related changes in anatomy and swallowing physiology. Our findings significantly advance the understanding of aging in this species and underscore the marmoset's potential as a valuable model for future swallowing research, particularly for investigating disease conditions and testing interventions relevant to human dysphagia.