Neuroregeneration in the nucleus ambiguus after recurrent laryngeal nerve avulsion in rats.

OBJECTIVES

The objective was to investigate neuroregeneration, the origins of newborn cells and the proliferation of neuronal and glial cells in the nucleus ambiguus (NA) after ipsilateral recurrent laryngeal nerve (RLN) avulsion.

METHODS

All of the animals received a CM-Dil injection in the left lateral ventricle. Forty-five adult rats were subjected to a left RLN avulsion injury, while 9 rats were used as controls. 5-Bromo-2-deoxyuridine (BrdU) was injected intraperitoneally. Neuron quantification and immunohistochemical analysis were performed in the brain stems at different time points after RLN injury.

RESULTS

After RLN avulsion, CM-Dil labeled neural progenitor cells (NPCs) migrated to the ipsilateral NA and differentiated into astrocytes but not into neurons. In the NA, the neuronal cells re-expressed nestin. Only a small number of neuronal and glial cells in the NA showed BrdU immunoreactivity.

CONCLUSIONS

After RLN avulsion, the NPCs in the ependymal layer of the fourth ventricle or central canal are activated, migrate to the lesion in the NA and differentiate exclusively into astrocytes. The newborn neural stem cells in the NA may arise from the mature region neurons. The presence of both cell types in the NA may play a role in repairing RLN injuries.