HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

Changes in the immunoreactivity of substance P and calcitonin gene-related peptide in the laryngeal taste buds of chronically hypoxic rats

T. Kusakabe1, T. Yoshida2, H. Matsuda2, Y. Yamamoto3, Y. Hayashida4, T. Kawakami5 and T. Takenaka1

1Laboratory for Anatomy and Physiology, Department of Sport and Medical Science, Kokushikan University, Tokyo, 2Department of Otorhinolaryngology, Yokohama City University School of Medicine, Kanazawa-ku, Yokohama, 3Laboratory of Veterinary Anatomy, Department of Veterinary Science, Faculty of Agriculture, Gifu University, Gifu, 4Department of Systems Physiology, University of Occupational and Environmental Health, Kitakyushu, 5Department of Physiology, Kitasato University School of Medicine, Sagamihara, Japan

Offprint requests to: Dr. Tatsumi Kusakabe, Laboratory for Anatomy and Physiology, Department of Sport and Medical Science, Kokushikan University, 7-3-1 Nagayama, Tama-shi, Tokyo 206-8515, Japan. Fax: 81-42-339-7238. e-mail: kusakabe@kokushikan.ac.jp

 

Summary. The distribution of substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers in the taste buds of the epiglottis and aryepiglottic folds was compared between normoxic control and chronically isocapnic hypoxic rats (10% O2 and 3-4% CO2 for 3 months). In the normoxic laryngeal taste buds, SP- and CGRP-immunoreactive fibers were detected within the taste buds, where they appeared as thin processes with many varicosities. Most CGRP fibers showed coexistence with SP, but a few fibers showed the immunoreactivity of CGRP only. The density of intra- and subgemmal SP and CGRP fibers penetrating into the laryngeal taste buds was significantly higher in chronically hypoxic rats than in normoxic control rats. Water intake in the hypoxic rats was significantly lower than in the normoxic rats. These results indicate that the increased density of SP- and CGRP-containing nerve fibers within the laryngeal taste buds is a predominant feature of hypoxic adaptation. The altered peptidergic innervation and reduced water intake support the hypothesis that the laryngeal taste buds are involved in water reception, and that the water reception may be under the control of peptidergic innervation. Histol. Histopathol. 15, 683-688 (2000)

Key words: Chronic hypoxia, Laryngeal taste bud, Substance P, Calcitonin gene-related peptide, Immunohistochemistry

DOI: 10.14670/HH-15.683