Bovine pituitary Fibroblast Growth Factor has neurotrophic activity on newt limb regenerates and skeletal muscles in vitro

Bovine pituitary Fibroblast Growth Factor (FGF) stimulated increases in both the mitotic index (MI) and the rate of protein synthesis in cultured cone stage blastemata of the newt forelimb. These effects of FGF in vitro were dose-dependent with maximal stimulation occurring at a concentration of 10 ng/ml. In addition, after one week in organ culture, FGF-treated adult newt triceps muscles had significantly higher acetylcholinesterase (AChE) activity than had untreated, contralateral controls. This other neurotrophic effect of FGF was also dose-dependent and again maximally effective at 10 ng/ml. Whereas nerves or brain extracts normally maintain only those heavier forms of AChE with sedimentation coefficients of 12S and 16S respectively, FGF non-specifically maintained all five AChE species in newt triceps muscles in organ culture. Thus, the physiological significance of FGF in these neurotrophic processes is unclear and must be viewed against the possible contribution, by the nerve, of other as yet undefined trophic chemicals.