Localization, origin and fine structure of calcitonin gene-related peptide-containing fibers in the vestibular end-organs of the rat.
The localization, origin and fine structure of nerve terminals immunoreactive for calcitonin gene-related peptide (CGRP) were examined in the vestibular end-organs of rats using immunocytochemistry. Many CGRP-like immunoreactive (CGRP-IR) fibers were observed in the vestibular sensory epithelial layer. By electronmicroscopy, CGRP-IR terminals were found to make synaptic contacts with the chalyces of the vestibular nerves terminating on type I cells. The origin of these vestibular CGRP-IR fibers was examined by a combination of a retrograde fiber tracing technique (using Fast blue) and immunocytochemistry. Injections of the tracer into the vestibular cistern, resulted in fast blue-labeled neurons bilaterally in the area dorsolateral to the genu of the facial nerve; these labeled neurons also contained CGRP. These findings indicate that CGRP-IR fibers originate bilaterally from the area dorsolateral to the genu of the facial nerve and that CGRP plays a modulatory role in the transmission of vestibular information from type I cells.
Tanaka
M
M
Department of Otolaryngology, Osaka University School of Medicine, Japan.
Takeda
N
N
Senba
E
E
Tohyama
M
M
Kubo
T
T
Matsunaga
T
T
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D005154:Facial Nerve / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D008297:Male; D009475:Neurons, Afferent / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D014722:Vestibule, Labyrinth / Q000294:innervation*
D015740:Calcitonin Gene-Related Peptide