Expression of insulin-like growth factor-I and related peptides during motoneuron regeneration.
The regulation of insulin-like growth factor-I (IGF-I) and related peptides during motoneuron regeneration was examined in the facial nerve following facial nerve transection. One to 39 days after axotomy, the mRNAs and peptides of IGF-I, type-I insulin-like growth factor receptor (IGFR), insulin-like growth factor binding proteins 1-5 (IGFBP-1-5), and glial fibrillary acidic protein (GFAP) were assayed in brain stem sections by in situ hybridization and immunohistochemistry. Relative mRNA levels of IGF-I, IGFR, IGFBP-2, and GFAP in the ipsilateral facial nucleus were highest 4-7 days after transection and declined thereafter. Double immunostaining experiments showed that both IGF-I and IGFBP-2 were localized in GFAP-positive astrocytic processes, many of which were perineuronal. Peak staining intensity was found 4-7 days after transection and immunoreactivity still was present after 21-35 days. IGFR mRNA was found in some regenerating neurons; however, IGFR peptide was not detected in these neurons or in any other cells in the facial nucleus. Our findings suggest that astrocytic production of IGF-I and IGFBP-2 may accompany regeneration of neurons undergoing retrograde changes induced by axotomy.
Gehrmann
J
J
Department of Neuromorphology, Max Planck Institute of Psychiatry, Martinsried near Munich, Germany.
Yao
D L
DL
Bonetti
B
B
Bondy
C A
CA
Brenner
M
M
Zhou
J
J
Kreutzberg
G W
GW
Webster
H D
HD
D000818:Animals; D001933:Brain Stem / Q000378:metabolism*; D003714:Denervation; D005154:Facial Nerve / Q000473:pathology / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009416:Nerve Regeneration; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D009479:Neuropeptides; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I