Somatostatin (Somatostatinlike) Immunoreactive Cells in the Human Inner Ear

Abstract

\s=b\Certain epithelia of the human inner ear and human endolymphatic sac display somatostatin and/or somatostatinlike immunoreactivity. Histologic sections from 13 human temporal bones and from 15 endolymphatic sacs were studied using the unlabeled antibody peroxidaseantiperoxidase technique. The somatostatin and/or somatostatinlike immunoreactive cells were located exclusively in the covering epithelium of the spiral prominence and in the epithelium of the intermediate and rugosal part of the endolymphatic sac. In the epithelium of the spiral prominence and endolymphatic sac, secretory granules of the same size and appearance as those of intestinal or pancreatic somatostatin-producing cells were demonstrated ultrastructurally. The findings are consistent with a local exocrine, paracrine, and/or endocrine system of the inner ear. (Arch Otolaryngol Head Neck Surg 1986;112:934-937) The function of the spiral promi¬ nence is unknown. Its epithelium might exert a secretory1"4 and/or resorptive activity.511 In animals, the endolymphatic sac resorbs tracer substances, dyes, or cell debris from the cochlear endolymph1013 and actively transports potassium across the epi¬ thelium.1415 By immunohistochemical methods, the presence of IgA and the secretory component was demon¬ strated in distinct areas of the human endolymphatic sac epithelium.1617 Re¬ cent ultrastructural studies of the human endolymphatic sac in Me¬ niere's disease18 and of the normal human spiral prominence19 revealed secretory granules within epithelial cells that strongly resemble gastroin¬ testinal tract cells producing endo¬ crine, neurocrine, or paracrine sub¬ stances.20 The aim of this investiga¬ tion was to identify the character of these cells. MATERIALS AND METHODSThirteen human temporal bones and 15 human endolymphatic sacs from children and adults (age range, four months to 81 years) without known disease of the mid¬ dle or inner ear were removed at autopsy; fixed for three hours in a solution contain¬ ing 40% formaldehyde (10 mL), mercuric-(Il)-chloride (6 g), glacial acetic acid (5 mL), and distilled water to a total volume of 100 mL; and then rinsed for 21 hours in ethyl alcohol (70%). The temporal bones were decalcified in edetic acid and pro¬ cessed for conventional histology. Deparaffinized sections were stained for somato¬ statin, employing Sternberger's21 unla¬ beled antibody peroxidase-antiperoxidase technique. The somatostatin antiserum (antihuman somatostatin from goat, Dakopatts, Copenhagen) was used in a dilution of 1:3000.22 Tissue samples of human pancreas, small intestine, and colon were used as controls. The unlabeled anti¬ body peroxidase-antiperoxidase method was carried out with and without specific antisera; a positive somatostatin and/or somatostatinlike immunoreactive (SSLI) reaction was exclusively seen when using specific antisera. Sections were stained according to Grimelius to identify argyrophilic cells containing neurosecretory granules. Inner ear tissue from seven other healthy human temporal bones was pre¬ pa...

The Epithelium of the Human Endolymphatic Sac: Immunohistochemical Characterization (With 1 color plate)

“…le, inset). These findings are in accordance with previously published observations on cells in the human ES containing neurosecretory granules and somatostatin [8],…”

Human Endolymphatic Sac: Evidence for a Role in Inner Ear Immune Defence (With 1 color plate)

“…In a previous study, we have reported the presence of secretory immunoglobulin A (IgA) in the human ES [4,5]. Immunohisto chemical findings support the assumption that the human ES, like the gut, appears to have not only resorptive and secretory, but also immunologic and paracrine functions [2,[4][5][6], The present immunohistochemical study was designed to identify cells with immuno logical functions in the extraosseous part of the human ES.…”

Somatostatin and gentamicin‐induced auditory hair cell loss

“…It has been demonstrated that somatostatin immunoreactive cells can be found in the human inner ear, implicating a role of the somatostatinergic system in the inner ear. 20 Based on the analogy between the retina and the inner ear and the fact that somatostatin can be detected in the inner ear, we tested in this study whether somatostatin receptors are present within the cochlea and whether somatostatin is able to protect auditory hair cells from gentamicin-induced apoptotic cell death in vitro.…”