1991 Fiscal Year Final Research Report Summary
A morphological study on the innervation of the larynx and on the degeneration and regeneration of the neuromuscular junction in the denervated laryngeal muscle
| Project/Area Number |
02670776
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Tokyo Women's Medical College, Faculty of Medicine |
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Principal Investigator |
YOSHIHARA Toshio Tokyo Women's Medical College, Faculty of Medicine, Associate Professor, 医学部, 助教授 (90220714)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Nobukazu Tokyo Momen's Medical College, Faculty of Medicine, Research Associate, 医学部, 助手 (90191428)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Intrinsic laryngeal muscle / Neuromuscular junction / electronmicroscopy / Histochemistry / Recurrent nerve palsy |
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| Research Abstract |
The purpose of this study is to demonstrate the morphological and histochemical characteristics of the neuromuscular junctions (NMJ) in the denervated and reinnervated laryngeal muscles. The posteriorcricoarytenoid muscles of the adult cats were used. The specimens were examined by electromicroscopy and various histochemical procedures such as acetylcholinesterase (AchE) reaction, . 5-hydroxydopamine (5-OHDA) injection and calcitonin-gene related peptide (CGRP) antibody.
Twenty-four hours after the transection of the left recurrent laryngeal nerve (RLN), no morphological changes were observed at the NMJ. Two days after denervation nerve terminals disappeared at the NMJ, and Scwann's cells covered the former junctional site (FJS). Six weeks after denervation the primary synaptic clefts were narrowed and flattened. The secondary synaptic clefts were still preserved. Nine weeks after denervation nerve terminals resembling autonomic nerves were observed at the FJS. Some of these terminals w
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ere labeled by 5-OHDA. Furthermre, the autonomic nerves around the vessels and the Schwann's tunnels increased. These findings indicate the newly denervated nerve fibers are adrenergic, and the autonomic nerves extend to the FJS and formate the synaptic contacts.
Although ultrastructural changes were remarkable after denervation, AchE activity was relatively stable at the FJS for a long period. To examine the NMJ in the reinnervated laryngeal muscles, 'end to end' sutures of the nerves were done just after the transection of the left RLN. Two weeks after sutures the nerve terminals were not observed at the FJS yet. After three weeks, the newly formated nerve terminals were found in one-thirds of the FJS.
It is well established that the neurotransmitter of the motor nerve fiber is Ach. The present study showed that CGRP immunoreactivity was demonstrated in the nerve terminals electronmicroscopically. These results suggest that CGRP is involved in the regulation of the complex contractile functions of the intrinsic laryngeal muscles. Less
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Research Products
(27 results)
