Distinct influences of nerve growth factor and a central cholinergic trophic factor on medial septal explants.

A central cholinergic trophic factor (C-CTF), previously reported in hippocampal extracts, enhances acetylcholine synthesis (ACh) and to a lesser extent choline acetyltransferase (ChAT) activity in cultured explants of the rat medial septal nucleus. Nerve growth factor (NGF) has been reported to enhance ChAT in several systems in vitro and in vivo, and clearly stimulates septal explants. At optimal concentrations of NGF and C-CTF, there is an additive effect on ChAT activity. The effects of NGF on ACh synthesis are minimal. Antibodies to NGF block effects of added NGF but have no effects on C-CTF activity. The ability of C-CTF to enhance ACh synthesis appears related to its ability to enhance the acetylation of the choline that has been taken up by a sodium dependent, high affinity transport system. Thus, actions of NGF and C-CTF appear qualitatively and quantitatively distinct, yet both can influence the cholinergic activity of the developing medial septal nucleus.