Nerve trophic effects: an in vitro assay for factors involved in regulation of protein synthesis in regenerating amphibian limbs.

We have developed a rapid sensitive test for factors that mimic the trophic effects of nerves by maintaining normal rates of protein synthesis in denervated forelimb blastemata of adult newts (Notophthalmus viridescens). Rates of protein synthesis in secondary blastemata are similar. However, after they are denervated and explanted into organ culture the rates of protein synthesis first increase and later fall below control values. Similar changes occur after denervation in vivo. The alterations in the rates of protein synthesis are prevented by adding to the culture medium aqueous extracts from brains of adult newts or chicken embryos. The active material is either a peptide or a protein.