Immunoreactivity to calcitonin gene-related peptide in the superior olivary complex and cochlea of cat and rat

Lu, Shao‐Ming; Schweitzer, Laura; Cant, Nell B.; Dawbarn, David

doi:10.1016/0378-5955(87)90119-5

Cited by 44 publications

(29 citation statements)

References 35 publications

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“…Little is known about the developmental mechanisms of either synaptogenesis or synaptic modification in efferent olivocochlear (OC) neurons as they project to hair cells in the mammalian cochlea. In adult animals, the brainstem OC system is composed of three populations of neurons that reside mostly within medial and lateral divisions of the superior olivary complex (Rasmussen, 1960;White and Warr, 1983;Lu et al, 1987;Moore and Moore, 1987;Vetter et al, 1991). These OC populations differ in their neurotransmitters and their synaptic targets within the cochlea.…”

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confidence: 98%

“…Medial OC neurons contain acetylcholine, project mostly to the contralateral inner ear via the crossed OC bundles, and terminate on the cell bodies of outer hair cells (OHCs), whereas lateral OC neurons contain either acetylcholine or y-aminobutyric acid (GABA), project mostly to the ipsilatera1 inner ear, and terminate on afferent fibers below the inner hair cells (IHCs; Takeda et al, 1986;Aschoff and Ostwald, 1987;Vetter et al, 1991). In all studies to date, cholinergic lateral OC neurons co-contain calcitonin generelated peptide (CGRP) which further differentiates them from the medial OC population (Kawai et al, 1985;Lu et al, 1987;Kruger et al, 1988;Vetter et al, 1991).…”

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confidence: 99%

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Olivocochlear innervation of inner and outer hair cells during postnatal maturation: Evidence for a waiting period

1996

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Reconstructions of the efferent innervation of the hamster (Mesocricetus auratus) cochlea were done during postnatal development. Efferent neurons were labeled via injections of biocytin and horseradish peroxidase into the crossed olivocochlear (OC) bundles using an in vitro brainstem technique. Such injections retrogradely labeled cell bodies in ventral periolivary regions of the superior olive consistent with their being medial OC neurons. Anterogradely labeled axons were traced to the cochlea, where they terminated on or below inner hair cells (IHCs) prior to postnatal day 5 (P5). After P5, labeled axons terminated on IHCs and outer hair cells (OHCs) and after P10, the majority of labeled axons terminated on the OHCs. In the electron microscope, small labeled terminals containing densely packed synaptic vesicles were found both adjacent to IHCs (axosomatic) as well as apposed to afferent and efferent fibers below IHCs prior to P5. By P10, large labeled terminals were axosomatic to OHCs and no longer found on IHCs. Consistent with previous reports, these data suggest that medial OC axons form part of an early primary innervation on and below IHCs before terminating on OHCs. This raises the possibility that OC neurons demonstrate a period of waiting below an intermediate target similar to that described in the development of thalamocortical projections.

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confidence: 98%

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Olivocochlear innervation of inner and outer hair cells during postnatal maturation: Evidence for a waiting period

1996

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“…Two pieces of evidence suggest such a projection may indeed exist. First, in the brainstem, only LOC cell bodies are immunopositive for CGRP and/or enkephalin (Altschuler et al, 1984a;Abou-Madi et al, 1987;Lu et al, 1987;Vetter et al, 1991;Saffeidine and Eybalin, 1992), yet fibers immunopositive for CGRP and/or enkephalins have been reported in the OHC area, especially in apical cochlear regions (Altschuler et al, 1984b(Altschuler et al, , 1985Fex and Altschuler, 1984;Eybalin et al, 1988). Second, a population of thin beaded fibers, similar morphologically to spiraling ISB fibers, crosses the tunnel to OHC areas in the apical half of the cochlea (Liberman et al, 1990).…”

Section: Discussion Central Origin(s) Of the Isb Swellings Analyzedmentioning

confidence: 96%

Morphological subclasses of lateral olivocochlear terminals? Ultrastructural analysis of inner spiral bundle in cat and guinea pig

Satake

Liberman

1996

J. Comp. Neurol.

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The lateral olivocochlear efferent pathway terminates in vesicle-filled swellings in the inner spiral bundles under inner hair cells (IHCs) and has been suggested to include at least two chemically distinct subclasses (see, e.g., Vetter et al. [1991] Synapse 7:21-43). In the present study, the ultrastructure and peripheral targets of vesicle-filled swellings in the IHC area of the cat and guinea pig cochleas were quantitatively analyzed to determine 1) whether morphological subclasses could be defined based on swelling size or on the density, size or shape of clear and dense-cored vesicles and 2) whether swellings with different postsynaptic targets differed morphologically. In both cat and guinea pig, all swellings contained large, round, clear vesicles and a variable number of dense-core vesicles. Although evidence of clear-cut subclasses was not compelling, the smallest swellings tended to be rich in dense-core and poor in clear vesicles and rarely formed synaptic contacts. Most of the larger swellings, which tended to contain few dense-core vesicles and a rich complement of clear round vesicles, formed synapses with radial afferent fibers. However, there were no morphological differences between swellings contacting afferents originating on the modiolar vs. pillar sides of the IHC (the source of afferents with low and high spontaneous discharge rates, respectively). We conclude that 1) if distinct gamma-amino butyric acid (GABA)ergic and cholinergic subclasses of lateral olivocochlear (LOC) fibers exist, then the vesicle morphology of their terminals does not differ as it does in the central nervous system and that 2) if peptide neurotransmitters, such as calcitonin gene-related peptide and enkephalins, are packaged in dense-core vesicles, then the LOC terminals synapsing with IHC afferent fibers are not particularly rich in these peptides.

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“…In contrast, lateral efferent cells are clustered at the periphery of the LSO in the cat, gerbil and some bat species [3,[9][10][11]70]. Several studies have determined that peptides, including CGRP, are restricted to lateral efferent neurons [27,60] and are colocalized with ChAT in these cells [47,48,63,65].…”

Section: Human Homologue Of the Lateral Olivocochlear Systemmentioning

confidence: 99%

“…Calcitonin gene-related peptide (CGRP) is a widely distributed peptide that is colocalized with acetylcholine in most brainstem motor neurons [35,59] and has been suggested to regulate acetylcholine receptor synthesis [37]. CGRP is present in olivocochlear neurons in several mammalian species [27,47,48,60,65], and it has also been shown to be present in a cell group in the human superior olivary complex [4]. In the present study, we carried out ChAT and CGRP immunostaining in postmortem brainstems from human fetuses, infants, children and adolescents to identify olivocochlear neurons.…”

Section: Introductionmentioning

confidence: 99%

The Human Olivocochlear System: Organization and Development

1999

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The goals of the present study were to identify olivocochlear neurons in the human brainstem, to establish the time course of their early development and to compare the organization of the human olivocochlear system to that of other mammals. To accomplish these goals, we used immunohistochemistry for choline acetyltransferase (ChAT) and calcitonin gene-related peptide (CGRP) in postmortem brainstems of human subjects ranging in age from 16 fetal weeks to 17 years. By immunostaining, we identified two classes of cells in the superior olivary complex: both classes were seen to be present from the twenty-first fetal week to the seventeenth year. Neurons which are immunostained only for ChAT are located primarily in the dorsomedial, ventral and ventrolateral sectors of the periolivary region. These neurons are predominantly bipolar or multipolar cells, and are probably homologous to medial olivocochlear neurons in other species. A second population of cells is immunoreactive for both ChAT and CGRP. This population includes a cluster of mostly small oval neurons, located on the dorsal edge of the olivary complex, and a variable number of cells found along the margin of the lateral olivary nucleus. These ChAT- and CGRP-immunoreactive cells are likely to be homologous to the lateral olivocochlear system in other mammals. With increasing age, the dorsal cluster of small cells shifts from its original cap-like position over the lateral olivary nucleus to become an extended column of cells lying among the fibers of the olivocochlear bundle.

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Immunoreactivity to calcitonin gene-related peptide in the superior olivary complex and cochlea of cat and rat

Cited by 44 publications

References 35 publications

Olivocochlear innervation of inner and outer hair cells during postnatal maturation: Evidence for a waiting period

Olivocochlear innervation of inner and outer hair cells during postnatal maturation: Evidence for a waiting period

Morphological subclasses of lateral olivocochlear terminals? Ultrastructural analysis of inner spiral bundle in cat and guinea pig

The Human Olivocochlear System: Organization and Development

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