Cholinergic Differentiation in Serum-Free Aggregating Fetal Brain Cells

Abstract

Several years ago we have reported the successful culture of fetal rat brain cells in a serum-free chemically defined medium using aggregating cell culture techniques (24). A comparison of serum-free cultures with their counterparts grown in the presence of fetal calf serum revealed certain morphological and biochemical differences, most notably a diminished developmental increase in choline acetyltransferase (CAT) activity, presumably due to a delayed maturation of cholinergic neurons (24). Therefore, we have examined different ways to optimize culture conditions in chemically defined media. A general improvement in longterm culture could be achieved by modifying the media composition according to the metabolic requirements of the cells (25,26). In addition, we have found factors which specifically stimulate the development of cholinergic neurons, particularly in cultures derived from fetal rat telencephalon: triiodothyronine (T3) greatly enhances the developmental increase in CAT activity (22); nerve growth factor (NGF) (23), and elevated potassium ion (K+) concentrations (21) further Stimulate CAT irreversibly. The present report shows that the stimulation of cholinergic differentiation by both NGF and K+ is controlled by T3, whereas the increase in CAT activity produced by a macromolecular fraction isolated from media conditioned by brain cells is independent of T3.KeywordsNerve Growth FactorConditioned MediumCholinergic NeuronCholine Acetyl TransferaseFetal Brain CellThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.