Nerve growth factor increases the synthesis and release of acetylcholine and the expression of vesicular acetylcholine transporter in primary cultured rat embryonic septal cells

Acetylcholine (ACh) is synthesized by choline acetyltransferase (ChAT) in t he cytoplasm of cholinergic nerve terminals and transported into synaptic v esicles by vesicular ACh transporter (VAChT), The genes encoding ChAT and V AChT are colocalized within the genome, and their products are known to be coregulated by various neurotrophic factors, In the present study, nerve gr owth factor (NGF; 100 ng/ml) was shown to enhance expression of VAChT and C hAT mRNA in primary cultured rat embryonic septal cells. By using a radioim munoassay, we also found that NGF increased both neuronal content and spont aneous release of ACh, which were first detected on day 2 of culture and ti me-dependently increased up to day 10, Stimulated release of ACh elicited b y high K+ (50 mM KCI) was also significantly greater in NGF-treated cells t han in control cells. NGF enhanced immunoreactivity to antiserum against VA ChT, indicating that the augmented responses were due to, at least in part, increased expression of VAChT protein. In contrast, the numbers of immunoc ytochemically positive cells were unaffected. Thus, NGF appears to augment ACh synthesis, its transport into synaptic vesicles, and its subsequent rel ease. The data also suggest that NGF facilitates growth and development of cholinergic neurons, but not their survival. (C) 1999 Wiley-Liss, Inc.