We compared age-related changes in the intrinsic laryngeal muscles of aged and young adult rats by determining the number and diameter of muscle fibers, contractile muscle protein (myosin heavy chain isoforms, MHC) composition, and the morphology of the subneural apparatuses. In aged rats, both the numbers and the diameters of muscle fibers decreased in the cricothyroid (CT) muscle. The number of fibers, but not diameter, decreased in the thyroarytenoid (TA) muscle. In the posterior cricoarytenoid (PCA) muscle, neither the number nor the diameter of fibers changed significantly. Aging was associated with a decrease in type IIB and an increase in type IIA MHC isoform levels in CT muscle, but no such changes were observed in the TA or PCA muscles. Morphological examination of primary synaptic clefts of the subneural apparatus revealed that aging resulted in decreased labyrinthine and increased depression types in only the CT muscle. In the aged group, morphologically immature subneural apparatuses were found infrequently in the CT muscle, indicating continued tissue remodeling. We suggest, therefore, that age-related changes in the intrinsic laryngeal muscles primarily involve the CT muscle, whereas the structures of the TA and PCA muscles may better resist aging processes and therefore are less vulnerable to functional impairment. This may reflect differences in their roles; the CT muscle controls the tone of the vocal folds, while the TA and PCA muscles play an essential role in vital activities such as respiration and swallowing.

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We examined changes in the expressions of three atrophy-related transcription factors (FOXO3a, P-FOXO3a, and PGC-1α) in the process of intrinsic laryngeal muscle atrophy after denervation. In total, 51 Wistar rats were used. After transection of the unilateral recurrent laryngeal nerve, the thyroarytenoid (TA) muscle and the posterior cricoarytenoid (PCA) muscle were excised and subjected to histological and Western blot studies. Relationships between the expressions of transcription factors during atrophy of the intrinsic laryngeal muscles were investigated by comparing the results of the treated side (T) with those of the untreated side (U), and sequential changes in the T/U ratio after denervation were assessed. Loss of wet muscle weight, together with a decrease in muscle fiber cross-sectional area and increase in the number of muscle fibers/mm(2), occurred more quickly in TA muscle than in PCA muscle. Muscle atrophy progressed rapidly between 7 and 28 days after denervation, while expression of FOXO3a was maximal on day 7, in both TA and PCA muscles. By contrast, P-FOXO3a expression decreased gradually after denervation. Expression of PGC-1α increased slowly until day 7, and then it declined. Denervation-induced atrophy of the intrinsic laryngeal muscles was closely linked with the expression of FOXO3a and PGC-1α, suggesting that atrophy of these muscles may involve the actions of these transcription factors. In addition, muscle atrophy progressed faster in TA muscle than in PCA muscle, due mainly to differences in muscle fiber composition.

Objective. To know the characteristics of endoscopic laryngeal and pharyngeal abnormalities in Japanese patients with laryngopharyngeal reflux symptoms (LPRS). Methods. A total of 146 endoscopic images of the larynx and pharynx (60 pairs for the rabeprazole group and 13 pairs for the control group) were presented to 15 otolaryngologists blinded to patient information and were scored according to several variables potentially associated with laryngopharyngeal reflux. The median value of the 15 scores for each item from each image was obtained. The mean pretreatment scores of each item and total score were assessed in both rabeprazole and control groups. In the rabeprazole group, the endoscopic findings before and after the 4-week treatment with rabeprazole were compared. Changes between corresponding duration in the control group were also evaluated. Results. The median and mean pretreatment total score was 3 and 3.02, respectively, from the 73 patients with LPRS. No significant differences were observed before and after treatment in either the rabeprazole or control groups for any item or total score. In 24 patients with a high pretreatment score (total score ≥ 4) from the rabeprazole group, significant decreases in scores for “thick endolaryngeal mucous” (0.54 to 0.17, P = 0.017) and total (4.77 to 3.58, P = 0.0003) were observed after the 4-week treatment.

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