Quantitative inter-strain comparison of the distribution of choline acetyltransferase activity in the rat cochlear nucleus (original) (raw)
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Journal of Histochemistry & Cytochemistry, 1981
Within the cochlear nucleus of the rat, as well as some nearby regions, quantitative histochemical mapping procedures were used to construct maps of the distributions of choline acetyltransferase and acetylcholinesterase activities. The results were in some ways consistent with results previously reported for cat, e.g., very low activities of both enzymes were found in the auditory nerve root, and also in the vestibular nerve root, except where acetylcholinesterase-positive centrifugal fibers are located, very high activities were found in the facial nerve system. In many ways, however, the results for the rat cochlear nucleus contrasted with those for the cat. Notably, choline acetyltransferase activities in some regions of the rat coch-'Supported by the National Institutes of Health through Research Grant NS 08000 and a National Institutes of Health Postdoctoral Fellowship to D.A.G.
ACTA HISTOCHEMICA ET CYTOCHEMICA, 2013
We previously discovered a splice variant of choline acetyltransferase (ChAT) mRNA, and designated the variant protein pChAT because of its preferential expression in peripheral neuronal structures. In this study, we examined the immunohistochemical localization of pChAT in rat cochlea and compared the distribution pattern to those of common ChAT (cChAT) and acetylcholinesterase. Some neuronal cell bodies and fibers in the spiral ganglia showed immunoreactivity for pChAT, predominantly the small spiral ganglion cells, indicating outer hair cell type II neurons. In contrast, cChAT-and acetylcholinesterase-positive structures were localized to fibers and not apparent in ganglion cells. After ablation of the cochlear nuclei, many pChAT-positive cochlear nerve fibers became clearly visible, whereas fibers immunopositive for cChAT and acetylcholine esterase disappeared. These results suggested that pChAT and cChAT are localized in different systems of the rat cochlea; pChAT in the afferent and cChAT in the efferent structures.
Hearing Research, 2006
Choline acetyltransferase (ChAT) activity has been mapped in the cochlear nucleus (CN) of control hamsters and hamsters that had been exposed to an intense tone. ChAT activity in most CN regions of hamsters was only a third or less of the activity in rat CN, but in granular regions ChAT activity was similar in both species. Eight days after intense tone exposure, average ChAT activity increased on the tone-exposed side as compared to the opposite side, by 74% in the anteroventral CN (AVCN), by 55% in the granular region dorsolateral to it, and by 74% in the deep layer of the dorsal CN (DCN). In addition, average ChAT activity in the exposed-side AVCN and fusiform soma layer of DCN was higher than in controls, by 152% and 67%, respectively. Two months after exposure, average ChAT activity was still 53% higher in the exposed-side deep layer of DCN as compared to the opposite side. Increased ChAT activity after intense tone exposure may indicate that this exposure leads to plasticity of descending cholinergic innervation to the CN, which might affect spontaneous activity in the DCN that has been associated with tinnitus.
Effects of surgical lesions on choline acetyltransferase activity in the cat cochlea
Hearing research, 2017
Although it is well established that the choline acetyltransferase (ChAT, the enzyme for acetylcholine synthesis) in the mammalian cochlea is associated with its olivocochlear innervation, the distribution of this innervation in the cochlea varies somewhat among mammalian species. The quantitative distribution of ChAT activity in the cochlea has been reported for guinea pigs and rats. The present study reports the distribution of ChAT activity within the organ of Corti among the three turns of the cat cochlea and the effects of removing olivocochlear innervation either by a lateral cut aimed to totally transect the left olivocochlear bundle or a more medial cut additionally damaging the superior olivary complex on the same side. Similarly to results for guinea pig and rat, the distribution of ChAT activity in the cat outer hair cell region showed a decrease from base to apex, but, unlike in the guinea pig and rat, the cat inner hair cell region did not. As in the rat, little ChAT ac...
Hearing Research, 1987
Using a microdissection and quantitative microassay approach, choline acetyltransferase activities were mapped in the cochlear nuclei of rats having either transection of the trapezoid body or destruction of the superior olivary complex on one side in the brain stem. Lateral trapezoid body transection resulted in dramatic loss of choline acetyltransferase activity in all parts of the ipsilateral cochlear nucleus, while more medial transection had little effect. Destruction of the superior olivary complex resulted in dramatic loss of choline acetyltransferase activity in the ipsilateral co&ear nucleus, and detectable loss also contralaterally. The results suggest that most of the centrifugal chohnergic projections to the rat eochiear nucleus derive from or traverse the vicinity of the superior ohvary complex bilaterally and enter the cochlear nucleus ventrally from the region of the trapezoid body.
Quantitative distribution of choline acetyltransferase activity in rat trapezoid body
Hearing research, 2018
There is evidence for a function of acetylcholine in the cochlear nucleus, primarily in a feedback, modulatory effect on auditory processing. Using a microdissection and quantitative microassay approach, choline acetyltransferase activity was mapped in the trapezoid bodies of rats, in which the activity is relatively higher than in cats or hamsters. Maps of series of sections through the trapezoid body demonstrated generally higher choline acetyltransferase activity rostrally than caudally, particularly in its portion ventral to the medial part of the spinal trigeminal tract. In the lateral part of the trapezoid body, near the cochlear nucleus, activities tended to be higher in more superficial portions than in deeper portions. Calculation of choline acetyltransferase activity in the total trapezoid body cross-section of a rat with a comprehensive trapezoid body map gave a value 3-4 times that estimated for the centrifugal labyrinthine bundle, which is mostly composed of the olivoco...
Hearing Research, 1982
Picogram quantities of norcpinephrinc were found in coch'ear regions of pigmented and non-pigmented rats. These regions of the cochlea were the modiolus. organ of Corti-osseous spiral lamina and the lateral cochlear wall. The content of norepinephrinc in the modiolus and lateral cochlcar wall of the pigmcntcd rat was significantly greater than that in areas of the non-pigmented rat. In contrast, there was no statistical difference between the norcpincphrine content of the organ of Corti-osseous spiral lamina region of the pigmented rat and that of the albino rat. Since a major difference between the pigmcntcd and albino rats is the presence of melanin-containing melanocytes in the modiolus and lateral cochlcar wall region of the pigmented animals. it is possible that norcpincphrine is stored in cochlcar melanocytcs.