Functions and applications of neurotrophic molecules in the adult central nervous system

Although neurotrophic factors, such as nerve growth factor, are expressed in the adult central nervous system, the functions of their expression are largely unknown. The cholinergic basal forebrain provides a model system with which to test the functions of neurotrophins in the adult brain. Neurotrophic factors are present in the adult hippocampus, the target of the cholinergic septohippocampal projection, and nerve growth factor rescues cholinergic neurons following transection of the fimbria-fornix or in aging. By manipulating levels of exogenous neurotrophic factors in the adult brain, we may not understand the endogenous physiological role of NGF, but we gain insight into the effects of endogenous growth factors in vivo and the roles they might play in degeneration and regeneration.