Immunohistochemical localization of nerve growth factor receptor in the cochlea and in the brainstem of the perinatal rat.

Nerve growth factor receptor (NGF-R) localization was studied immunohistochemically in the cochlea and in the brainstem of the perinatal rat, using a specific monoclonal antibody directed against the rat NGF-R. In the cochlea, NGF-R immunoreactivity is positive during the whole perinatal period studied, and is located at the hair cell level, in fibers that reach the organ of Corti, in the intraganglionic spiral bundle and in some small bundles of fibers in the auditory nerve. In the brainstem, NGF-R is detected in auditory structures such as the ventral cochlear nucleus, the superior olivary complex, the nuclei of the trapezoid body and the trapezoid body. Many auditory structures labelled by the NGF-R antibody are implicated in the efferent cochlear innervation. These results suggest that NGF could be implicated in interactions between auditory receptors and efferent innervation of the developing cochlea. This coincides with findings on the immunohistochemical localization of NGF-like protein in the organ of Corti of the developing rat. Moreover, these observations could be related to an early prenatal development of auditory efferent innervation.