Focal delivery of fibroblast growth factor-1 by transfected cells induces spiral ganglion neurite targeting in vitro.
Sensory cells in the cochlea of the rat transiently express acidic fibroblast growth factor (FGF-1) during the developmental period of terminal innervation in the sensory epithelium. To explore the potential role of FGF-1 in terminal innervation events, the response of cochlear ganglion neurons to FGF-1 was evaluated in culture. Explants from the spiral ganglion of postnatal day 5 rats were cultured in the presence of exogenous FGF-1, with or without heparin. FGF-1 in the culture medium produced a dose-dependent increase in the number and length of neurites produced by spiral ganglion neurons, a response that was enhanced by heparin. To assess the effects of FGF-1 produced by a focal, cellular source, additional explants were cocultured with 3T3 cell transfectants that secrete FGF-1. Neurites that came into contact with FGF-1 secreting cells branched, formed bouton-like terminal swellings on the surface of the transfectants, and stopped extending. The results suggest that FGF-1 may stimulate neurite extension into the sensory epithelium of the cochlea and that focal production of FGF-1 may contribute to the formation of contacts on sensory cells by developing neurites.
Dazert
S
S
Department of Surgery/Otolaryngology, UCSD School of Medicine and VA Medical Center, La Jolla, California 92093, USA.
Kim
D
D
Luo
L
L
Aletsee
C
C
Garfunkel
S
S
Maciag
T
T
Baird
A
A
Ryan
A F
AF
D016475:3T3 Cells; D000818:Animals; D003470:Culture Media / Q000494:pharmacology; D016220:Fibroblast Growth Factor 1 / Q000235:genetics* / Q000493:pharmacokinetics*; D015870:Gene Expression / Q000502:physiology; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006497:Heparan Sulfate / Q000494:pharmacology; D051379:Mice; D016501:Neurites / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D013136:Spiral Ganglion / Q000166:cytology*; D014162:Transfection / Q000379:methods
D003470:Culture Media; D016220:Fibroblast Growth Factor 1; D006497:Heparan Sulfate; D011994:Recombinant Proteins