Fibroblast growth factor and insulin-like growth factor rescue growth cones of sensory neurites from collapse after tetracaine-induced injury.
BACKGROUND
Basic fibroblast growth factor (bFGF) and insulin-like growth factor (IGF)-1 have multiple effects on cells, including proliferation, differentiation, and survival. In this study, we investigated the effects of different concentrations of IGF and bFGF on the morphology of growth cones of the developing sensory neurons after tetracaine-induced injury in vitro.


METHODS
Dorsal root ganglia were isolated from chick embryos on embryonic day 7 or 8 and cultured for 24 hours. Tissues were then exposed to 100 mumol/L tetracaine for 60 minutes. The media were replaced by tetracaine-free media containing different concentrations of IGF, bFGF, or combination of IGF 50 ng/mL and bFGF 5 ng/mL and incubated for a further 24 hours. Growth cone collapse assays were then performed to assess regeneration of neurons.


RESULTS
Exposure of dorsal root ganglia explants to tetracaine 100 mumol/L for 1 hour caused significant growth cone collapse 24 hours after washing out tetracaine (P < 0.01). It was found that adding bFGF (5, 10, 20, and 50 ng/mL) or IGF (50 and 100 ng/mL) to the replacement media significantly decreased growth cone collapse percentage at 24 hours after washout (P < 0.01); however, the low concentrations of bFGF (2 ng/mL) or IGF (25 ng/mL) did not cause significant change. Growth cone collapse after simultaneous addition of 5 ng/mL bFGF and 50 ng/mL IGF was statistically lower than the values after adding 5 ng/mL bFGF (P < 0.01), and it was marginally lower than 50 ng/mL IGF.


CONCLUSIONS
bFGF and bIGF decreased growth cone collapse after tetracaine-induced injury in vitro.
Seki
Tomoko
T
Department of Anesthesiology, Gunma University, Graduate School of Medicine, Maebashi, Japan. shigerus@showa.gunma-u.ac.jp
Abdel Nazeer
Ashraf
A
Sekimoto
Ken-ichi
K
Guao
Yao
Y
Al-jahdari
Wael
W
Saito
Shigeru
S
D000779:Anesthetics, Local / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D000818:Animals; D001369:Axons / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects; D020439:Growth Cones / Q000187:drug effects*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009416:Nerve Regeneration / Q000187:drug effects; D016501:Neurites / Q000187:drug effects*; D011984:Sensory Receptor Cells / Q000187:drug effects*; D013748:Tetracaine / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D046509:Tissue Culture Techniques
D000779:Anesthetics, Local; D013748:Tetracaine; D016222:Fibroblast Growth Factor 2; D007334:Insulin-Like Growth Factor I