Calbindin D28k-immunoreactive afferent nerve endings in the laryngeal mucosa

Abstract

The distribution of the calbindin D28k in the laryngeal sensory structures was studied by immunohistochemistry, immunoelectronmicroscopy, and double immunofluorescence with calretinin‐immunoreactivity. Moreover, origin of the nerve endings were observed using retrograde tracer, fast blue. Immunoreactivity for calbindin D28k was found in the various types of nerve endings in the larynx, namely, laminar nerve endings, nerve endings associated with the taste buds, intraepithelial nerve endings, and endocrine cells. The laminar endings with calbindin D28k‐immunoreactivity were observed in the subepithelial connective tissue. In some endings, terminals were expanded. The laminar endings were also observed in the perichondrium of the epiglottic cartilage. In the epiglottic and arytenoid epithelia, thick nerve fibers with calbindin D28k‐immunoreactivity ascending to taste buds and intragemmal nerve fibers were also observed. Within the epithelial layer, intraepithelial free nerve endings with calbindin D28k‐immunoreactivity were observed. Furthermore, diffuse endocrine cells were observed within the laryngeal epithelium. By immunoelectron microscopy, immunoreaction products in the endings mentioned above were localized in the cytoplasm of the axon terminals and nerve fibers which contained with numerous mitochondria. Out of the 100 laminar endings, 18 endings were immunopositive for both calbindin D28k and calretinin, 33 were positive for calbindin D28k but negative for calretinin, and 49 were positive for only calretinin in the double immunofluorescence microscopy. The nerve fibers associated with the taste buds and the free nerve endings, which immunostained for calbindin D28k, were not stained with antibody against calretinin. After injection of the fast blue in the laryngeal mucosa, fast blue‐labeled cells were mainly observed in the nodose ganglia. Of the total number of labeled cell in the nodose and dorsal root ganglia at the level C1 to Th2, 65.1% occurred in nodose ganglia (572/879, n = 6). In the nodose ganglia, 79.7% of labeled cells (456/572) were immunoreacted for calbindin D28k. The distribution of calbindin D28k‐immunoreactivity may be differnt from that of calretinin. It is suggested that calbindin D28k have regulatory role on intracellular calcium concentration in the laryngeal sensory corpuscles. Anat Rec 259:237–247, 2000. © 2000 Wiley‐Liss, Inc.

Morphology and chemical characteristics of subepithelial laminar nerve endings in the rat epiglottic mucosa

“…Taking these findings together, a 3 subunit may be expressed in thick myelinated afferents. In the present study, the laminar nerve endings in the epiglottic mucosa seem to be endings of A-fibers originating from large neurons in the sensory ganglion, possibly the nodose ganglion as previously suggested (Yamamoto et al 2000). Although direct evidences are not shown, it is possible that nodose ganglion cells with immunoreactivity for a 3 subunit may project to the laryngeal laminar endings.…”

“…However, in recent studies, it was discussed that the immunohistochemical markers used in our previous studies are not the best tools for visualization of mechanoreceptors in the airway muscles (Yu 2005). Indeed, we observed that calbindin D28k and calretinin were not equally expressed in terms of their patterns and not specific for the laminar endings (Yamamoto et al 2000). In the tracheobronchial smooth muscle, branching nerve endings that seem to be stretch receptors can be visualized by immunohistochemistry for Na ?…”

“…We re-examined these uncapsulated sensory nerve endings as laminar endings by immunohistochemistry in the dog and rat (Yamamoto et al 1997(Yamamoto et al , 1998(Yamamoto et al , 2000. Although the subepithelial laminar endings were not reported in the horse and humans, subepithelial glomerular nerve endings similar to the laminar endings were reported (Chiba et al 1985;Yamamoto et al 2001).…”

“…In our previous studies, we examined the laryngeal laminar endings by immunohistochemistry for neurofilament protein, protein gene-product 9.5 (PGP9.5) and calcium-binding proteins such as calretinin and calbindin 28k (Yamamoto et al 1997(Yamamoto et al , 1998(Yamamoto et al , 2000. However, in recent studies, it was discussed that the immunohistochemical markers used in our previous studies are not the best tools for visualization of mechanoreceptors in the airway muscles (Yu 2005).…”

Laryngeal endocrine cells: topographic distribution and adaptation to chronic hypercapnic hypoxia

“…In the respiratory tract, endocrine cells have been observed in the nasal cavity (Johnson et al 1997), larynx (Kirkby and Romert 1977;Luts et al 1991;McDowell et al 1994;Yamamoto et al 2000;Yu et al 1996), trachea (Shimosegawa and Said 1991;Terada et al 1992), and bronchi and alveoli (Adriaensen and Scheuermann 1993;Adriaensen et al 1998;Van Lommel et al 1999). According to these reports, respiratory endocrine cells showed immunoreactivities for general endocrine markers such as protein gene product 9.5 (PGP 9.5), chromogranin, calbindin D28k, and neuron-specific enolase (NSE).…”