Distribution and possible functional roles of some neuroactive peptides in the mammalian superior olivary complex

Immunocytochemical distribution of Met-enkephalin-Arg6-Gly7-Leu8 (Met-8) in the auditory system of the rat

“…The same authors demonstrated that the mentioned e¡ect is blocked by naloxone, an opiate antagonist. These neuropharmacological experiments support the notion that the LOC ¢bers release enkephalins on their terminals upon di¡erent dendrites beneath the inner hair cells and have an overall inhibitory e¡ect upon the cochlear output (for review see Robertson and Mulders, 2000). We do not have a direct demonstration that the CNIC neurons labelled in our study project to the VNTB, but we strongly suggest so because the main target of the IC is to the MGV and in our material, no terminal ¢elds were observed in this subdivision of the MGB.…”

“…Thus, for example, some authors described neurons in the CNC (Ho¡man et al, 1993;Murakami et al, 1987), SOC (Abou-Madi et al, 1987;Murakami et al, 1987;Reuss et al, 1999;Robertson and Mulders, 2000) and IC (Tanaka et al, 1993;Murakami et al, 1987) but to the best of our knowledge, there are no studies that show labelled cells in the auditory cortex. Similarly, terminal ¢bers have been described in several studies (Fallon and Leslie, 1986;Merchenthaler et al, 1986;Palkovits, 1988;Abou-Madi et al, 1987;Murakami et al, 1987;Ho¡man et al, 1993;Tanaka et al, 1993; Reuss et al, 1999;Robertson and Mulders, 2000). However, terminal ¢elds in the MGB and in the ZI are ¢rst described in the present study.…”

“…These authors already suggested that enkephalin could be involved in both the LOC and the medial olivocochlear system (MOC). Since then some other studies have implicated Met 8 in the olivocochlear system, as a modulator of the cochlear activity (for review see Robertson and Mulders, 2000). This is because both the neurons from the VNTB (related to the MOC) and LSO (related to the LOC) are labelled.…”

“…The distribution of Met 8 has been studied using immunocytochemical, radioim-0378-5955 / 03 / $^see front matter ß 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0378-5955(03)00333-2 munoassay or in situ hybridization techniques in the rat (Pittius et al, 1984;Zamir et al, 1985;Fallon and Leslie, 1986;Merchenthaler et al, 1986;Murakami et al, 1987Murakami et al, , 1989Ho¡man et al, 1993;Tanaka et al, 1993;Wynne et al, 1995;Robertson and Mulders, 2000), cat (Belda et al, 2003), monkey (Ibuki et al, 1986) and human (Pittius et al, 1984;Iadarola et al, 1991) central nervous system.…”

“…The functional role of Met 8 in the auditory system is currently unknown and except for a few studies (e.g., Merchenthaler et al, 1986;Murakami et al, 1989;Ho¡man et al, 1993;Tanaka et al, 1993;Robertson and Mulders, 2000) describing the general distribution of Met 8 in the rat brain there are no detailed accounts of Met 8 in the auditory system of this animal model. The auditory system is made up of a series of relay nuclei from the cochlear nuclei to the cortex, each one having a distinct set of neuronal types.…”