Expression of fibroblast growth factor-2 in the nucleus ambiguus following recurrent laryngeal nerve injury in the rat.
OBJECTIVE
To examine fibroblast growth factor-2 (FGF-2) immunoreactivity in the nucleus ambiguus (NA) after three different recurrent laryngeal nerve (RLN) injuries.


METHODS
Immunohistochemical analysis of FGF-2.


METHODS
Thirty adult rats underwent left-sided RLN crush (group A). The left RLN was transected in groups B (n = 30) and C (n = 30); in group C, both nerve stumps were covered with silicone caps. FGF-2 in the NA was assessed as the ratio of the positive areas on the left (operated [O]) and right (unoperated [U]) sides. The ratio (O/U) was measured 1, 3, 7, 14, and 28 days after the procedure. Three rats underwent left-sided RLN exposure and were killed 7 days later (control).


RESULTS
Left-sided RLN paralysis occurred until day 28 in group A. In the control group, O/U was approximately 1. In group A, O/U was significantly elevated on day 7; in group B, on days 3, 7, and 14; and in group C, on day 3. O/U in group B was significantly greater than that in group A on days 14 and 28. Maximal FGF-2 immunoreactivity was significantly lower in group C than in groups A and B.


CONCLUSIONS
We demonstrated elevated production of FGF-2 in the NA after RLN injury. This endogenous FGF-2 might contribute to preventing lesion-induced neuronal death. Blockage of axonal regeneration might suppress FGF-2 production in the NA. Further understanding of the roles of FGF-2 after RLN injury may contribute to the prevention of neuronal death and facilitation of axonal regeneration.
Sanuki
T
T
Department of Otolaryngology, Ehime University School of Medicine, Onsen-gun, Japan.
Yumoto
E
E
Komori
M
M
Hyodo
M
M
D000818:Animals; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D061226:Recurrent Laryngeal Nerve Injuries; D014826:Vocal Cord Paralysis / Q000378:metabolism*; D014827:Vocal Cords / Q000378:metabolism*
D016222:Fibroblast Growth Factor 2