title: Age-related changes in sensory and secretomotor nerve endings in the larynx of F344/N rat.
abstract: The aim of the present study was to define the age-related changes in sensory and secretomotor nerve endings in the larynx of F344/N rats. For this purpose, laryngeal tissue sections obtained from 12-, 24- and 35-month-old F344/N rats were compared with respect to the density, distribution and morphology of various types of sensory and secretomotor nerve endings immunoreactive for protein gene product 9.5 (PGP 9.5), calcitonin gene-related peptide (CGRP) and substance P (SP). Two distinct forms of PGP 9.5-immunoreactive motor end-plates were noted; the large sized motor end-plates localized in thyroarytenoid and cricoarytenoid muscles were degenerated in aged rats, while the small sized motor end-plates, localized predominantly in vocal muscles, did not show any age-related changes. CGRP- and SP-immunoreactive nerve fibres of the laryngeal glands did not show any age-related changes. Subepithelial laminar nerve endings immunoreactive to PGP 9.5 showed degeneration with ageing. Aggregates of terminal arborisations in the subepithelial region were smaller in aged animals. PGP 9.5-immunostained taste cells and well-developed subgemmal network were abundant in 12- and 24-month-old rats, but only a few were noted in aged rats. The total number of taste buds decreased significantly with ageing. CGRP- and SP-immunostained taste bud-nerve endings were noted in 12- and 24-month-old rats, but only rarely in 35-month-old rats. The laryngeal epithelium contained PGP 9.5-, CGRP- and SP-immunoreactive thin free nerve endings with many varicosities; their number and distribution were similar between 12- and 24-month-old rats, while only a few endings were observed in 35-month-old rats. Our results indicated that ageing is associated with the reduction of laryngeal sensory and secretomotor nerve endings.
authors.affiliation: Laboratory of Veterinary Anatomy, Faculty of Agriculture, Gifu University, Gifu 501-1193, Japan. yyoshio@iwate-u.ac.jp
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Shin
authors.initials: S
authors.lastname: Tanaka
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsubone
authors.forename: Yasuro
authors.initials: Y
authors.lastname: Atoji
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Suzuki
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D005260:Female; D007150:Immunohistochemistry; D007820:Laryngeal Mucosa / Q000473:pathology; D007830:Larynx / Q000473:pathology*; D008297:Male; D023421:Models, Animal; D009045:Motor Endplate / Q000473:pathology*; D009411:Nerve Endings / Q000473:pathology*; D051381:Rats; D011916:Rats, Inbred F344; D012680:Sensitivity and Specificity; D011984:Sensory Receptor Cells / Q000473:pathology*; D013650:Taste Buds