Age-related changes in Schwann cells of the internal branch of the rat superior laryngeal nerve

Quantitative, structural and molecular changes in neuroglia of aging mammals: A review

The neuroglia of the central and peripheral nervous systems undergo numerous changes during normal aging. Astrocytes become hypertrophic and accumulate intermediate filaments. Oligodendrocytes and Schwann cells undergo alterations that are often accompanied by degenerative changes to the myelin sheath. In microglia, proliferation in response to injury, motility of cell processes, ability to migrate to sites of neural injury, and phagocytic and autophagic capabilities are reduced. In sensory ganglia, the number and extent of gaps between perineuronal satellite cells – that leave the surfaces of sensory ganglion neurons directly exposed to basal lamina – increase significantly. The molecular profiles of neuroglia also change in old age, which, in view of the interactions between neurons and neuroglia, have negative consequences for important physiological processes in the nervous system. Since neuroglia actively participate in numerous nervous system processes, it is likely that not only neurons but also neuroglia will prove to be useful targets for interventions to prevent, reverse or slow the behavioral changes and cognitive decline that often accompany senescence.

Discoordination of laryngeal and respiratory movements in aged rats

Voice and swallowing actions require the coordination of multiple motor systems, and this coordination may be impaired with aging. Although recent work has reported impairments in age-related laryngeal kinematics in rats, the temporal relationship of laryngeal excursions to the respiratory cycle is unknown. The goal of this study was to assess laryngeal-respiratory coordination by examining temporal interrelationships between change in laryngeal aperture and chest wall movement during quiet breathing in a rat model. Glottal images were recorded, digitized, and synchronized with respiratory signals, and temporal features were measured. In the young animals, glottal opening began before the onset of inspiration, and glottal and respiratory cycles were phasic and stereotypic. In old animals, however, inspiration often began during the glottal closing phase, and both respiratory signals were asymmetric. Discoordination of laryngeal and respiratory motor actions associated with aging may be caused by a generalized decline in sensorimotor cranial functions and may contribute to age-related swallowing and communication impairment.