Neurite regeneration in the cat recurrent laryngeal nerve: an immunohistochemical study.
The recurrent laryngeal nerve (RLN) consists of various motor, sensory and autonomic nerve fibers, although it has not been established whether different neuronal types exhibit a similar ability to regenerate. To address this question, freezing was used to injure the cat RLN fibers and the presence or absence of immunoreactivity for neuropeptides or transmitter-synthesizing enzymes was then examined as a marker to classify the fibers. In the control RLN, calcitonin gene-related peptide-immunoreactive (CGRP-IR) fibers were the highest in number and were distributed throughout the nerve fascicles. The number of substance P-immunoreactive (SP-IR) fibers was about 40% that of CGRP-IR fibers, while a portion of CGRP-IR fibers was found to contain SP immunoreactivity. Relatively low numbers of tyrosine hydroxylase-immunoreactive (TH-IR) and neuropeptide Y (NPY-IR) nerve fibers were seen which tended to form clusters. The distribution pattern of NPY-IR fibers was very similar to that of TH-IR fibers. In the regenerating RLN 1 week after the freezing injury, the fastest growing axons were CGRP-IR, while the regenerating rates of SP-IR, TH-IR and NPY-IR fibers were slower than that of CGRP-IR fibers. These results suggest that the ability for neurite regeneration varies among neuron types and that CGRP-IR fibers possess the most rapid ability to regenerate.
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis; D002415:Cats; D005260:Female; D005615:Freezing; D007124:Immunoenzyme Techniques; D008297:Male; D009046:Motor Neurons / Q000502:physiology / Q000648:ultrastructure; D009412:Nerve Fibers / Q000502:physiology* / Q000648:ultrastructure; D009416:Nerve Regeneration / Q000502:physiology*; D016501:Neurites / Q000502:physiology* / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000502:physiology / Q000648:ultrastructure; D009478:Neuropeptide Y / Q000032:analysis; D012009:Recurrent Laryngeal Nerve / Q000503:physiopathology / Q000648:ultrastructure; D061226:Recurrent Laryngeal Nerve Injuries; D013373:Substance P / Q000032:analysis; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis
D015415:Biomarkers; D009478:Neuropeptide Y; D013373:Substance P; D014446:Tyrosine 3-Monooxygenase; D015740:Calcitonin Gene-Related Peptide