Nerve growth factor induces a dose-dependent and long-lasting increase of choline acetyltransferase activity in the septal area and hippocampus of uninjured rats.

The effect of nerve growth factor (NGF) on the intact septohippocampal cholinergic system of adult rats was studied. Nerve growth factor was continuously infused at different doses (5-100 micrograms) for two weeks into the lateral ventricle of adult rats. Controls received intracerebroventricular infusion of equal amounts of cytochrome c. Nerve growth factor treatment was capable of inducing a dose-dependent increase of choline acetyltransferase activity (ChAT) in septal area and ventral hippocampus. In both areas, the NGF-induced rise of ChAT activity was sustained for at least one week after infusion, then it progressively declined towards control values. By three and five weeks, using NGF at 25 and 100 micrograms respectively, ChAT increase was still significant in both septum and ventral hippocampus. The present findings corroborate a role for NGF in adult septohippocampal cholinergic system and indicate that the "pharmacological" modulation of these neurons by NGF may last several weeks following withdrawal of this trophic factor.