TY - JOUR
T1 - Olfactory Stimulation Successfully Improves Swallowing Function of Aged Rats Through Activating Central Neuronal Networks and Downstream DHPR-RyR-mediated Neuromuscular Activities
AU - Chen, Yea Tzy
AU - Chen, Li You
AU - Renn, Ting Yi
AU - Cheng, Meng Shan
AU - Wang, Chi Te
AU - Klimenkov, Igor V.
AU - Sudakov, Nikolay P.
AU - Liao, Wen Chieh
AU - Chen, Yea Jyh
AU - Chang, Hung Ming
N1 - Publisher Copyright:
© 2021 The Author(s). Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved.
PY - 2022/2/1
Y1 - 2022/2/1
N2 - Presbyphagia is age-related changes in swallowing function, which imposes a high risk of aspiration in older adults. Considering olfactory stimulation (OS) can influence behavioral activities by modulating neuronal excitability, the present study aims to determine whether OS could improve the swallowing function of aged rats through activating the central neuronal networks and downstream muscular activities participated in the control of swallowing. Aged male Wistar rats received OS by inhaling a mixture of plant-based volatile molecules twice a day for 12 days were subjected to functional magnetic resonance imaging (fMRI) and c-fos, choline acetyltransferase (ChAT) immunostaining to detect the neuronal activities of the orbitofrontal cortex (OFC) and medullary nuclei engaged in swallowing control, respectively. The functional effects of OS on downstream pharyngeal muscle activity were examined by evaluating the dihydropyridine receptor-ryanodine receptor (DHPR-RyR)-mediated intramuscular Ca2+ expression, and analyzing the amplitude/frequency of muscle contraction, respectively. In untreated rats, only moderate signal of fMRI and mild c-fos/ChAT expression was detected in the OFC and medullary nuclei, respectively. However, following OS, intense signals of fMRI and immunostaining were clearly expressed in the orbitofronto-medullary networks. Functional data corresponded well with above findings in which OS significantly enhanced DHPR-RyR-mediated intramuscular Ca2+ expression, effectively facilitated a larger amplitude of pharyngeal muscle contraction, and exhibited better performance in consuming larger amounts of daily dietary. As OS successfully activates the neuromuscular activities participated in the control of swallowing, applying OS may serve as an effective, easy, and safe strategy to greatly improve the swallow function of aging populations.
AB - Presbyphagia is age-related changes in swallowing function, which imposes a high risk of aspiration in older adults. Considering olfactory stimulation (OS) can influence behavioral activities by modulating neuronal excitability, the present study aims to determine whether OS could improve the swallowing function of aged rats through activating the central neuronal networks and downstream muscular activities participated in the control of swallowing. Aged male Wistar rats received OS by inhaling a mixture of plant-based volatile molecules twice a day for 12 days were subjected to functional magnetic resonance imaging (fMRI) and c-fos, choline acetyltransferase (ChAT) immunostaining to detect the neuronal activities of the orbitofrontal cortex (OFC) and medullary nuclei engaged in swallowing control, respectively. The functional effects of OS on downstream pharyngeal muscle activity were examined by evaluating the dihydropyridine receptor-ryanodine receptor (DHPR-RyR)-mediated intramuscular Ca2+ expression, and analyzing the amplitude/frequency of muscle contraction, respectively. In untreated rats, only moderate signal of fMRI and mild c-fos/ChAT expression was detected in the OFC and medullary nuclei, respectively. However, following OS, intense signals of fMRI and immunostaining were clearly expressed in the orbitofronto-medullary networks. Functional data corresponded well with above findings in which OS significantly enhanced DHPR-RyR-mediated intramuscular Ca2+ expression, effectively facilitated a larger amplitude of pharyngeal muscle contraction, and exhibited better performance in consuming larger amounts of daily dietary. As OS successfully activates the neuromuscular activities participated in the control of swallowing, applying OS may serve as an effective, easy, and safe strategy to greatly improve the swallow function of aging populations.
KW - DHPR
KW - Olfactory stimulation
KW - Orbitofronto-medullary networks
KW - Pharyngeal muscle
KW - Presbyphagia
KW - RyR-mediated activity
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U2 - 10.1093/gerona/glab229
DO - 10.1093/gerona/glab229
M3 - Article
C2 - 34378774
AN - SCOPUS:85124435635
SN - 1079-5006
VL - 77
SP - 235
EP - 242
JO - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
JF - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
IS - 2
ER -