[Expression of BDNF and FGF-2 following axotomy in rat facial motoneurons].
OBJECTIVE
To study the expression and distribution of brain derived neurotrophic factor (BDNF) and fibroblast growth factor-2 (FGF-2) in normal facial motoneurons (FMNs) and in FMNs following axotomy.


METHODS
The right facial nerves were transected 6 mm distal to the stylomastoid foraman in adult Wistar rats except the normal group. Serial 20 microns cryosections were cut through the whole brainstems. Expressions of BDNF and FGF-2 mRNA as well as BDNF and FGF-2 protein were studied by in situ hybridization, immunohistochemistry and image analysis.


RESULTS
BDNF mRNA and its protein were observed in widespread areas of normal rat facial nucleus, and those increased 1 day after axotomy. In addition to neurons, glial cells were also stained. FGF-2 mRNA and its protein were mainly localized in normal FMNs of ventral facial nucleus. After axotomy, expression of FGF-2 mRNA started to up-regulate in FMNs at 7 days, however FGF-2 protein drastically reduced at 3 and 7 days.


CONCLUSIONS
In addition to target-supporting, there may be BDNF autocrine and paracrine mechanisms as well as FGF-2 autocrine mechanisms in normal rat FMN. When target-derived BDNF is deprived, alternative sources of BDNF support may substitute immediately after axotomy. However, deprivating of target--derived FGF-2 may result in down-regulation of FGF-2 protein in adult rat FMNs at early stage after axotomy. These suggest that the exogenous FGF-2 might provide a supportive environment for the recovery of metabolism and function of FMNs at early stage following axotomy.
Qin
Z
Z
Department of Otorhinolaryngology, First Affiliated Hospital of Henan Medical University, Zhengzhou 450052, China. qinzhb@371.net
Dong
M
M
D000818:Animals; D019771:Axotomy; D019208:Brain-Derived Neurotrophic Factor / Q000096:biosynthesis* / Q000235:genetics; D005154:Facial Nerve / Q000502:physiology* / Q000648:ultrastructure; D016222:Fibroblast Growth Factor 2 / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D009046:Motor Neurons / Q000378:metabolism* / Q000648:ultrastructure; D009416:Nerve Regeneration; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar
D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger; D016222:Fibroblast Growth Factor 2