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Glucocorticoid receptors were detected in the human inner ear. The highest concentration of glucocorticoid receptor protein was measured by enzyme-linked immunosorbent assay in the spiral ligament tissues; the lowest concentration of glucocorticoid receptors was measured in the macula of the saccule. The demonstration of the presence of glucocorticoid receptors in human Inner ear tissues provides a basis to consider the direct effects of glucocorticoid action on select inner ear cells, rather than assuming a systemic antiinflammatory or immunosuppressive effect during the therapeutic treatment of patients with given inner ear disorders.

In this report we demonstrate the pattern of calcitonin gene-related peptide (CGRP) mRNA and immunoreactivity in the central and peripheral vestibular system of the rat, using a CGRP cRNA probe and a polyclonal CGRP antiserum. We present evidence that somata in all regions of efferent vestibular neurons contain CGRP based on the correspondence between in situ hybridization (mRNA) and immunohistochemistry (mRNA translation product). CGRP immunohistochemistry (CGRPi) and in situ hybridization confirm that CGRPi axons and terminals present in the vestibular neuroepithelium are efferent in origin. Immunoelectron microscopy revealed an extensive innervation of the afferent vestibular pathway by CGRPi terminals that was not limited to the primary afferent chalice, as previously reported by Tanaka et al. (Brain Res 1989;504:31-5). An efferent neuromodulatory role of CGRP can be inferred from the distribution of terminals found on the primary afferent fibers, and type I and type II hair cells. In addition, we present evidence that nicotinic acetylcholine receptor (nAChR) subunit mRNA is expressed by primary afferent cell bodies. On the basis of these data, a hypothetical molecular mechanism of vestibular efferent modulation of the primary afferent pathway is proposed.